UNIVERSITY OF CALGARY
Using Stepping Stones and Translocations to Facilitate Dispersal for the Endangered
Ord's Kangaroo Rat, Dipodomys ordii.
by
Lia K. Brands
A THESIS
SUBMITTED TO THE FACULTY OF GRADUATE STUDIES
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE
DEGREE OF MASTER OF SCIENCE
GRADUATE PROGRAM IN GEOGRAPHY
CALGARY, ALBERTA
APRIL, 2016
© Lia K. Brands 2016
Abstract
Animals with restricted dispersal, like the Ord’s kangaroo rat (Dipodomys ordii),
are sensitive to habitat loss and fragmentation. I researched two conservation tools that
have the potential to help stabilize the Alberta kangaroo rat population: stepping stones
and translocations. Using survey data and habitat mapping, I determined that many interdune distances in Alberta exceed the estimated dispersal ability of most kangaroo rats. I
developed an algorithm to locate potential stepping stone locations to restore connectivity
and prioritized them based on their contribution to the network functional connectivity. I
then evaluated if translocations could be used in place of natural dispersal to increase
rescue and recolonization of isolated habitats. My findings indicate that (1) four
strategically placed stepping stones will positively impact the functional connectivity of
the dune network, and (2) translocations can lead to successful site establishment, with
evidence of occupancy observed in seven of the sixteen translocations.
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Acknowledgements
I would like to thank the University of Calgary, Wildlife Preservation Canada,
Cenovus, Alberta Conservation Association, Environment Canada, Royal Alberta
Museum, Canadian Forces Base Suffield, and Alberta Sustainable Resource
Development for providing resources, funding, and support that was essential to the
completion of this project.
I would also like to thank my committee members, Steven Vamosi, Chris
Hugenholtz, Shelley Alexander, and Joe Arvai for contributing valuable advice to help
improve my research and writing. I am grateful to my field assistants, Sultana Majid,
Kira Roberts, and Kirsten Pearson for spending long hours trudging through the prairies
with me through the best and worst conditions. I am especially appreciative of my
dependable field assistant, Greg Deibert, who worked for the project three summers in a
row. I could always rely on him to work hard and to provide fresh optimism in every
situation. I would like to thank Bart Hulshof for guiding me through the use of new GIS
tools that proved critical to my research analysis. Similarly, I would like to thank Shantel
Koenig for not only providing me with GIS data from her own research but also sharing
helpful tips for running difficult GIS programs. I thank Ben McWilliams as well for also
sharing GIS data with me. Many thanks also go to Sandi Robertson who joined me in the
field on occasion and provided helpful guidance. I am very thankful to my supervisor,
Darren Bender, for inspiring my love of kangaroo rats, teaching me the many valuable
uses of GIS, and encouraging me to take on this project. I am grateful for his guidance,
his time, and his willingness to both teach me and push me to my academic limits so that
I can reach my potential.
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Finally, I must thank my mom for her love, support, patience, advice, and time
spent editing my many pages of work. I couldn’t have achieved my goals without her and
I can’t possibly thank her enough.
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Dedication
I dedicate this thesis to my mom, Kendra Schreuder Brands. She has fully and
continuously supported me without reservation. She inspired my love of nature, science,
and learning from a young age, stimulating my curiosity by encouraging me to go
outside, explore the wild, and ask questions. She has spent long hours helping me study
for exams, editing my papers, listening to practice presentations, and even reminding me
to take breaks. It is because of her love, support, guidance, and hard work that I have
been able to follow my dreams.
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Table of Contents
Abstract ............................................................................................................................... ii
Acknowledgements ............................................................................................................ iii
Dedication ............................................................................................................................v
Table of Contents ............................................................................................................... vi
List of Tables ................................................................................................................... viii
List of Figures and Illustrations ......................................................................................... ix
CHAPTER ONE: INTRODUCTION ..................................................................................1
1.1 Introduction ................................................................................................................1
1.2 Species description ....................................................................................................3
1.3 Population decline in kangaroo rats ...........................................................................4
1.3.1 Habitat loss and fragmentation ..........................................................................5
1.3.2 Anthropogenic development .............................................................................7
1.3.3 Soil moisture ......................................................................................................8
1.3.4 Parasites .............................................................................................................9
1.3.5 General focus of research ................................................................................10
1.4 Conservation and population recovery ....................................................................11
1.5 Research objectives..................................................................................................13
1.6 Thesis outline ...........................................................................................................13
CHAPTER TWO: DISPERSAL AND THE USE OF STEPPING STONES ...................15
2.1 Introduction ..............................................................................................................15
2.1.1 Dispersal distance ............................................................................................16
2.1.2 Stepping stones ................................................................................................17
2.2 Methods ...................................................................................................................20
2.2.1 Study area ........................................................................................................20
2.2.2 Survey methods ...............................................................................................26
2.2.3 Estimating the dispersal distances of kangaroo rats ........................................27
2.2.4 Dispersal distance assumptions .......................................................................30
2.2.5 Assessing landscape resistance to dispersal ....................................................32
2.2.6 Identification of stepping stone locations ........................................................36
2.2.7 Algorithm to determine and prioritize stepping stone locations .....................40
2.3 Results ......................................................................................................................45
2.4 Discussion ................................................................................................................60
2.4.1 Dispersal distance ............................................................................................62
2.4.2 Stepping stones ................................................................................................65
2.4.3 Limitations of this study ..................................................................................68
2.5 Conclusion ...............................................................................................................71
CHAPTER THREE: TRANSLOCATIONS......................................................................73
3.1 Introduction ..............................................................................................................73
3.1.1 The benefits of using translocations in the Alberta kangaroo rat
metapopulation .................................................................................................74
3.1.2 Design considerations ......................................................................................76
3.1.3 Objectives ........................................................................................................79
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3.2 Translocation methods .............................................................................................79
3.2.1 Study area ........................................................................................................79
3.2.2 Performing translocations ................................................................................81
3.2.3 Radio collaring ................................................................................................84
3.2.4 Release of kangaroo rats ..................................................................................85
3.2.5 Evaluating the success of translocations .........................................................87
3.3 Results ......................................................................................................................91
3.3.1 Translocation to the Pipeline site, 2012 ..........................................................91
3.3.2 Translocation to Empress Huge Dune, 2013 ...................................................93
3.3.2 Translocation to Ypres West, 2013 .................................................................96
3.3.3 Translocation to Bagnold’s Dune, 2014 ..........................................................99
3.3.4 Translocation to Mounted Rifle Blowout, 2014 ............................................101
3.3.6 Summary of Results ......................................................................................104
3.4 Discussion ..............................................................................................................106
3.4.1 Reasons why kangaroo rats may not have remained at the release sites .......108
3.4.2 Evaluating quantitative and qualitative approaches to determining
translocation success ......................................................................................110
3.4.3 Increasing future reliability of translocation assessment ...............................111
3.4.4 Radio collaring kangaroo rats ........................................................................112
3.5 Conclusion .............................................................................................................114
CHAPTER FOUR: CONCLUSIONS AND RECOMMENDATIONS ..........................115
4.1 Synthesis of conclusions ........................................................................................115
4.1.1 Stepping stones ..............................................................................................115
4.1.2 Translocations................................................................................................116
4.2 Using stepping stones and translocations together ................................................117
4.3 Using stepping stones and translocations to mitigate human disturbance .............118
4.4 Opportunities for future research ...........................................................................120
4.4.1 The number and size of patches required to facilitate dispersal ....................120
4.4.2 Habitat restoration techniques .......................................................................121
4.4.3 Timing of translocations ................................................................................123
4.4.4 Which sex and age group should be targeted for translocations?..................124
4.4.5 Group translocations ......................................................................................124
4.5 Conclusion .............................................................................................................125
REFERENCES ................................................................................................................127
APPENDIX A ..................................................................................................................150
APPENDIX B ..................................................................................................................159
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List of Tables
Table 2.1 A list of slopes and their associated resistance values. These values were
used to create a slope friction layer. .......................................................................... 34
Table 2.2 A list of land cover types and their associated resistance values. These
values were used to create a land cover friction surface. .......................................... 35
Table 2.3 Distance (km) between each dune in the Amiens region of Suffield (B.O =
Blowout). .................................................................................................................. 39
Table 2.4 Table summarizing the number of primary connections formed after all four
stepping stones had been added to the dune network. .............................................. 56
Table 3.1 Translocations performed between 2012 and 2014 in the Middle Sand Hills
of southern Alberta (M= Male; F=Female). Empress Huge, Empress Big, Ypres
West, Bagnold’s, and Mounted Rifle are natural dune sites. Pipeline is a sandy
river valley site. ......................................................................................................... 82
Table 3.2 Criteria for kangaroo rat translocation success in the Middle Sand Hills of
Alberta....................................................................................................................... 90
Table 3.3 Translocation observations at the Pipeline site. ................................................ 92
Table 3.4 Translocation observations at Empress Huge Dune. ........................................ 95
Table 3.5 Translocation observations at Ypres West Dune. ............................................. 98
Table 3.6 Translocation observations at Bagnold’s Dune. ............................................. 100
Table 3.7 Translocation observations at Mounted Rifle Blowout. ................................. 103
Table 3.8 Kangaroo rat translocation success for individuals translocated between
2012 and 2014. Short-term success was indicated if the kangaroo rat was found
at the dune upon which they were released within two days after release.
Intermediate-term success was indicated if kangaroo rat was found at the dune
upon which they were released during the active period following release. Longterm success was reported if the translocated kangaroo rats or their offspring
were found at the dune upon which they were released the following year. .......... 105
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List of Figures and Illustrations
Figure 1.1‘A’ represents a landscape where the distance between habitat patches may
exceed the dispersal ability of kangaroo rats. Individuals dispersing in this
landscape have to disperse through less hospitable terrain (the matrix) in a
single, long movement between Habitat 1 and Habitat 2. ‘B’ represents a
landscape where a stepping stone is placed at a distance within the dispersal
ability of kangaroo rats, bridging the gap between two habitat patches
(accessible from either Habitat 1 or Habitat 2). Kangaroo rats can then survive
and reproduce on the stepping stone. Their offspring may then have the potential
to disperse to Habitat 2. ............................................................................................ 12
Figure 2.1 The Ord’s kangaroo rat (OKR) range in Alberta............................................ 22
Figure 2.2 Map of the Middle Sand Hills region, where the Ord’s kangaroo rat is
commonly found. ...................................................................................................... 23
Figure 2.3 The Amiens region of CFB Suffield was used in the stepping stone
analysis. This area has a relatively high density of natural sites with nine actively
eroding dunes and three southeast-facing, sandy river valley sites. Source: R.
Dzenkiw. ................................................................................................................... 25
Figure 2.4 Histogram of the maximum distances moved through natural grassland
habitat for each kangaroo rat that was recaptured over the last nineteen years.
The vertical axis has been log transformed. .............................................................. 29
Figure 2.5 This flow chart depicts the stepping stone algorithm. ..................................... 43
Figure 2.6 Diagram of functional connections. ‘Site A’ is functionally connected to
‘Site B’ through a primary functional connection. ‘Site B’ is also functionally
connected to ‘Site C’ by a primary functional connection. ‘Site A’ is functionally
connected to ‘Site C’ through a secondary functional connection............................ 44
Figure 2.7 Stepping Stone 1 with a 1.6 km buffer added to the dune network................. 47
Figure 2.8 Stepping Stone 2 with a 1.6 km buffer added to the dune network................. 49
Figure 2.9 Stepping Stone 3 with a 1.6 km buffer added to the dune network................. 51
Figure 2.10 Stepping Stone 4 with a 1.6 km buffer added to the dune network............... 53
Figure 2.11 Graph depicting the primary functional connections formed through the
addition of stepping stone habitat patches (SS = stepping stone). ............................ 55
Figure 2.12 Dunefields in the species range in Alberta. Source: R. Dzenkiw. ................. 57
Figure 3.1 Sites involved in the translocations performed between 2012 and 2014……..80
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Chapter One: Introduction
1.1 Introduction
The process of breeding dispersal is described as the movement of an organism
from its birth site to another area with the intention to reproduce (Johnson & Gaines,
1990). This kind of dispersal is important in maintaining the stability of metapopulations
(Roff, 1974), which are populations composed of multiple sub-populations (spatially
isolated subdivisions of the larger population) that are subject to inter-patch dispersal
(Hanski, 1998; Hanski & Gilpin, 1991; Levins, 1969). Breeding dispersal (henceforth
dispersal) increases outbreeding events, expands ranges, decreases intraspecific
competition thereby increasing resource availability (Howard, 1960; Matthysen, 2005),
and most importantly can contribute to metapopulation persistence by rescuing declining
populations and recolonizing extirpated patches (den Boer, 1981; Fahrig & Merriam,
1985). Population persistence is often dependant upon the relationship between the
structure of the landscape and the movement ability of organisms (With, Gardner, &
Turner, 1997) because dispersal is the means by which sub-populations are recolonized
and rescued (den Boer, 1981). Furthermore, having spatially isolated populations that can
interact through dispersal spreads the risk of extirpation over multiple sub-populations
(den Boer, 1981). I define extirpation as the loss of the species at a regional scale, which
in the case of this study is Alberta. In order for dispersal to occur, the landscape must
have sufficient connectivity. Landscape connectivity can be defined as the degree to
which organisms can move between habitat patches (Taylor, Fahrig, Henein, & Merriam,
1993). This connectivity can be quickly lost when a habitat becomes fragmented (Fahrig
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& Merriam, 1985; Taylor et al., 1993). Fahrig and Merriam (1994) describe habitat
patches as discrete areas where a species can breed and acquire resources. They are
therefore important to preserve. Habitat fragmentation divides the habitat into smaller,
more isolated fragments, which changes the structure and composition of the landscape,
often decreasing its continuity (Rolstad, 1991). This can have a significant effect on
sensitive species and those with limited dispersal capabilities.
A landscape that exhibits high connectivity would be one where organisms are able
to move with relative ease between habitat patches through some sort of corridor or by
means of close proximity (Bennett, 1990; Fahrig & Merriam, 1985). Such conduits allow
for the movement of individuals between sub-populations, and therefore affect population
dynamics (number of individuals, growth rate, ages, etc.). Thus, the stability of a
metapopulation is dependent upon this movement between patches (Levins, 1969; Roff,
1974). Isolated patches experience both re-colonization and local extirpation (the loss of
all the individuals in a sub-population) with sub-populations winking out and starting up
in a variety of locations (Hanski, 1998). Such sub-population dynamics can occur without
any negative impacts on the metapopulation as a whole, although if local extirpation
events occur more frequently than colonization events, metapopulation stability can
become compromised (Hanski, 1991). The loss of habitat patches, including those that
are currently unoccupied, can further reduce the likelihood that a metapopulation will
persist over the long-term (Bascompte & Sole, 1996; den Boer, 1981). The issue of
habitat loss and fragmentation is having a particularly negative effect on the endangered
Ord’s kangaroo rat, (Dipodomys ordii Woodhouse, 1853). It is the only species of
kangaroo rat to occur in Canada and can be found in and around the Middle Sand Hills of
2
southern Alberta and the Great Sand Hills of Saskatchewan (COSEWIC, 2006; Nero &
Fyfe, 1956). These sand hill ecosystems are some of the most biologically heterogeneous
landscapes on the prairies, with actively eroding sand dunes providing habitat to many
endangered species (Hugenholtz, Bender, & Wolfe, 2010). They are islands of
biodiversity that are rapidly decreasing in number and quality, in part due to climate
change (Hugenholtz & Wolfe, 2005). Dunes rely mainly on wind erosion to create loose,
sandy soil habitats that sustain highly specialized organisms such as the kangaroo rat
(Alberta Environmental Resource Development, 2013; Riksen, Spaan, & Stroosnijder,
2007). The loss of this specialized habitat is negatively affecting the Ord’s kangaroo rat
because they require actively eroding dune habitats to survive (Alberta Environmental
Resource Development, 2013).
1.2 Species description
The Ord’s kangaroo rat is a small to medium sized, nocturnal (Jorgenson &
Hayward, 1965), granivorous (seed-eating) (Morton, Hinds, & MacMillen, 1980) rodent
belonging to the family Heteromyidae (Allen & Chapman, 1893). This species can be
found in the arid grassland regions of western North America. It is estimated that the
Canadian metapopulation has been geographically isolated from their southern
counterparts in Midwestern United States and Central Mexico by approximately 6000
years (COSEWIC, 2006). Their characteristic enlarged hind limbs, reduced forelimbs,
and elongated tail allows them to hop bipedally, which is their primary method of
locomotion (Bartholomew & Caswell, 1951). Because they use a hopping style of
locomotion, they require specific land cover types that allow for such movement.
3
Vegetation can impede movement and burrowing, so partially vegetated, sandy soils are
preferred (Bartholomew & Caswell, 1951). The Canadian metapopulations are also
adapted to the cool, northern climate, displaying characteristics that differ from more
southerly regions, such as a larger body size to aid in thermoregulation, the facultative
use of daily torpor to decrease their metabolic requirements, and an increased rate of
reproduction to compensate for the high rate of over-winter mortality (Gummer, 1997a;
O’Farrell, 1974). Unfortunately, despite these adaptations to the harsh, northern climate,
kangaroo rat metapopulations in Canada continue to decline (Alberta Environment and
Sustainable Resource Development, 2013; COSEWIC, 2006; Gummer, 1997b).
1.3 Population decline in kangaroo rats
The Alberta kangaroo rat metapopulation has been the subject of research since
1995 (Bender et al., 2007) when it was first designated as a species of special concern
(COSEWIC, 2006) and a standardized population monitoring protocol was then
established in 2005 (see Bender, Gummer, & Dzenkiw, 2007). The population surveys
show a continuing decline in the kangaroo rat populations and by 2006 the Ord’s
kangaroo rat was uplisted to endangered in Canada (COSEWIC, 2006). The species
received this status as a result of its small population size (<1000 individuals some years)
in combination with a restricted distribution, extreme fluctuations in population size, and
because of declines in its natural habitat: actively-eroding sand dunes (Environment
Canada, 2012). The metapopulation has been documented to decline to as much as 90%
over a single winter, mainly because of starvation and hypothermia (Gummer, 1997a). A
variety of other factors can also influence their survival, as described below.
4
1.3.1 Habitat loss and fragmentation
The loss and fragmentation of kangaroo rat habitat has a number of causes, one of
which is climate change (COSEWIC, 2006). Climate change has caused decreased
aridity, and to a lesser extent, a decrease in wind erosion leading towards dune
stabilization by vegetation (Hugenholtz & Wolfe, 2005). In fact, the area of open sand
habitat has decreased by 94% between 1947 and 2005 (Hugenholtz et al., 2010). Through
accounts given by Palliser (1862) it appears as though the Middle Sand Hills used to be
reasonably active in the mid to late eighteen hundreds. However, there is a two hundred
year, long-term trend towards stabilization (Hugenholtz & Wolfe, 2005), with a warming
and increasingly wetter climate stimulating more vegetation growth (David, 1998).
Vegetation protects soils from erosion, trapping particles, and decreasing air momentum
near the soil surface (van de Ven, Fryrear, & Spaan, 1989; Wolfe & Nickling, 1993).
Furthermore, following the dustbowl period in the 1930s, government programs, such as
the Prairie Farm Rehabilitation Administration, were issued to decrease soil erosion.
Shelterbelts were constructed to decrease wind speeds and prevent sand drifting (FAO,
1985; Wang, 2001). Strips of vegetation were planted to decrease the speed of runoff so
that water could be absorbed into the ground and nutrient uptake could be enhanced
(Wang, 2001). Some farms in Alberta even adopted minimum tilling systems to decrease
soil erosion (Hao, Chang, Larney, Nitschelm, & Regitnig, 2000; Wang, 2001). In the
Great Plains of North America, erosion was decreased through irrigation, fire
suppression, and a reduction in grazing animals such as bison (Loop, 1986; Forman,
Oglesby, & Webb, 2001). Even now, on CFB Suffield, fires are extinguished shortly after
they begin. Soil disturbances are actually often beneficial for Ord’s kangaroo rats because
5
the species requires actively eroding sand dunes with sparse vegetation, and the
prevention of these practices only serves to increase the rate of stabilization.
Compounding this problem, anthropogenic features such as roads, agriculture, and a
dramatic increase in well sites have both fragmented the landscape and decreased
available natural habitat (COSEWIC, 2006; Hugenholtz et al., 2010; Hugenholtz &
Wolfe, 2005). Although road sites are still habitable, they represent sink habitats, which
can be detrimental to the metapopulation (Heinrichs, Bender, Gummer, & Shumaker,
2010). Habitat loss is continuing, with sand dunes becoming vegetated throughout the
Middle Sand Hills region. Natural sand dune habitats are integral to long-term population
persistence and with them becoming increasingly stabilized, the risk of extirpation grows
(Heinrichs et al., 2010).
The stabilization of dunes reduces patch connectivity by increasing the distances
required to disperse between suitable habitats, which may limit the number of individuals
who can successfully disperse. This increases the isolation of habitat patches, augmenting
the likelihood of local extirpation (den Boer, 1981; Fahrig & Merriam, 1985).
Furthermore, isolated patches take longer to recolonize after local extirpation than do
connected ones (Fahrig & Merriam, 1985). With the stability of the metapopulation
influenced by individuals moving between habitat patches (Roff, 1974; Fahrig &
Merriam, 1985), it is important that kangaroo rats have the ability to disperse, either
naturally from patch to patch, or artificially through translocations, which involve the
human-induced movement of individuals from source patches and placing them in new
habitats (Alberta Environment and Sustainable Resource Development, 2013; IUCN,
1987; IUCN/SSC, 2013). In fact, sub-populations that are declining and have an
6
increased probability of local extirpation may be the best candidates for measures such as
translocations (IUCN/SSC, 2013).
1.3.2 Anthropogenic development
Anthropogenic development also causes fragmentation and habitat loss. Some
land-use disturbances in the area include infrastructure associated with natural gas
extraction, such as gas wells, trails, and pipelines as well as agricultural development
(COSEWIC, 2006; Bender, Dzenkiw, & Gummer, 2010a; Hugenholtz et al., 2010), and
soil/vegetation compaction (Smith & McDermid, 2014). These disturbances fragment the
landscape and decrease high-quality habitat. Sandy roads, trails, and ploughed fireguards
are often habitable, as they provide flat, sandy, habitat with vegetation only at the edges;
but the habitat is lower in quality (Teucher, 2007). These sites are less habitable for a
variety of reasons. Road habitats have greater soil compaction, which increases the depth
to which cold temperatures can permeate (Teucher, 2007). This heightens the risk of
hypothermia and ultimately over-winter mortality (Teucher, 2007). Furthermore, soil
compaction has been linked to decreased burrow depth in other studies (Germano &
Rhodehamel, 1995). Roads are also corridors for many predators, which put kangaroo
rats at greater risk of mortality (Brock & Kelt, 2004; Reynolds, Barry, & Kiliaan, 1999;
Simberloff & Cox, 1987). Predators of kangaroo rats include the great horned owl (Bubo
virginiansis) (Gummer & Robertson, 2003; Schowalter, Engly, & Digby, 2002),
burrowing owl (Speotyto cuniculara) (Smith & Murphy, 1973), short-eared owl (Asio
flammeus), long-eared owl (Asio otus), snowy owl (Nyctea scandiaca) (Gummer, 1997b),
barn owl (Tyto alba) (Huebschman, Genoways, Freeman, & Gubanyi, 2000), coyote
(Canis latrans) (Bender et al., 2010; Gummer & Robertson, 2003; Johnson & Hansen,
7
1979; Teucher, 2007), American badger (Taxidea taxus) (Gummer, 1997b), striped skunk
(Mephitis memphitis), red fox (Vulpes vulpes), swift fox (Vulpes velox), long-tailed
weasel (Mustela frenata), least weasel (Mustela nivalis) (Gummer, 1997b), raccoon
(Procyon lotor) (COSEWIC, 2006), bobcat (Felis rufus) (Gummer, 1997b), prairie
rattlesnake (Crotalis viridis viridis) (Gummer & Robertson, 2003), and bullsnake
(Pituophis melanoleucus) (Gummer, 1997b). Moreover, vehicles carry invasive plant
species, which end up growing along the road edges (Gelbard & Belnap, 2003; Gummer,
Beaudoin, & Bender, 2005). Analyses of cheek pouch contents reveal that kangaroo rats
occupying road habitats collect a greater number of non-native seeds than on dune sites
(Gummer et al., 2005). These plants may yield seeds of lower nutritive quality, and may
be more difficult to harvest, further decreasing the quality of road habitats (Gummer et
al., 2005). All these factors make road habitats unfavourable and prone to kangaroo rat
mortality.
1.3.3 Soil moisture
Particularly wet winters and springs can increase the productivity of vegetation on
habitat patches and increase surface humidity and soil moisture (Single, Germano, &
Wolfe, 1996). The increased ground cover that comes with high precipitation can make it
difficult to effectively forage and escape predation, which further increases their risk of
mortality (Single et al., 1996). The increased soil moisture can cause fungal or microbial
infections in seeds, decreasing their caloric value and sometimes leaving residual
myotoxins that get passed along to the kangaroo rats (Valone, Brown, & Jacobi, 1995). A
rise in soil moisture also increases the thermal conductivity of burrows, creating
physiological stress in some situations (Single et al., 1996). This is not to say that
8
precipitation has an entirely negative effect, however. Precipitation is in fact quite
important, with reproduction relying on vegetation (Soholt, 1977). Females require the
moisture from green vegetation to lactate and subsequently rear offspring (Soholt, 1977)
and climate-induced growth in vegetation can also positively influence the competitive
structure of a community, especially in high-density populations (Lima, Ernst, Brown,
Belgrano, & Stenseth, 2008). Therefore, vegetation is required for survival, but in excess,
vegetation can reduce available habitat.
1.3.4 Parasites
Parasites can also have an effect on kangaroo rat survival. The bot fly, Cuterebra
polita, is a parasite that primarily infects pocket gophers, but can secondarily infect other
rodents (Capelle, 1970) such as kangaroo rats (Gummer, Forbes, Bender, & Barclay,
1997). The bot fly deposits its eggs on vegetation near the burrow entrance of its host
(Catts, 1982). The eggs are stimulated to hatch by the body heat of the host. They
subsequently enter the host’s body through moist openings such as the nose, ears, or
mouth (Catts, 1982). They remain beneath the skin of the host, growing up to 2.0 cm in
length (Capelle, 1970). Bot fly infection can decrease the overall fitness in some
individuals, particularly in juveniles and lactating females (Gummer, Forbes, Bender, &
Barclay, 1997; Robertson, 2007). It is possible that the bot flies impede movement,
decreasing predator avoidance (Dunway, Payne, Lewis, & Story, 1967; Smith, 1978).
Robertson (2007) and Gummer et al. (1997) suggest that bot fly parasitism could pose a
significant threat to kangaroo rat persistence. That being said, further studies are required.
9
1.3.5 General focus of research
All these factors contribute to the decline of the Ord’s kangaroo rat in Alberta.
However, some of them may be more feasible to mitigate than others. The focus of my
research will be to address the problems of habitat loss and fragmentation, which are
issues that have the potential to be resolved through research and implementation of
recommended mitigation methods. Metapopulation theory developed by Levins (1969)
and later expanded upon by researchers like Ilkka Hanski suggests that a metapopulation
requires the movement of individuals between sub-populations to persist (Hanski, 1991).
Dispersing individuals have the potential to rescue sub-populations that are in danger of
extirpation (Brown & Kodric-Brown, 1977; Eriksson, Elias-Wolff, Mehlig, & Manica,
2014; Hanski et al., 1995) by increasing the number of breeding individuals. Dispersers
can also recolonize sites that have been locally extirpated (Andrewartha & Birch, 1954;
Brown & Kodric-Brown, 1977; den Boer, 1981; Fahrig & Merriam, 1985). Such
movements can balance local extirpation and recolonization, stabilizing the
metapopulation (Hanski, 1991). This balance can be disrupted when patches become
isolated through habitat loss and fragmentation (Hanski & Gilpin, 1991). Isolation
increases the distance dispersers have to travel, making rescue and recolonization less
likely (Brown & Kodric-Brown, 1977; Fahrig & Paloheimo, 1988; Hanski & Gilpin,
1991). Metapopulation theory predicts that increasing dispersal in a highly fragmented
population, such as the Ord’s kangaroo rat metapopulation in Alberta, will increase its
future stability. A couple of methods have been proposed to help facilitate dispersal,
which may have significant conservation value.
10
1.4 Conservation and population recovery
The current recovery plan for kangaroo rats in Alberta highlights and
recommends a variety of population recovery activities, including habitat restoration and
the use of translocations, if they are shown to be successful (Alberta Environment and
Sustainable Resource Development, 2013). Because movement between habitat patches
is so important, an analysis of kangaroo rat dispersal distances in Alberta is also
recommended (Alberta Sustainable Resources and Development, 2013). Loew, Williams,
Ralls, Pilgrim, & Fleischer (2005) performed a study on the endangered giant kangaroo
rat (Dipodomys ingens) which, like the Ord’s kangaroo rat, is experiencing population
isolation and habitat fragmentation. They recommended that future management plans
should focus on protecting kangaroo rat habitat, as well as maintaining habitat
connectivity and augmenting effective dispersal through the use of dispersal corridors
(strips of favourable habitat that provide a link between habitat patches (Bennett, 1987;
Fried, Levy, & Hogsette, 2005)) and translocations. Heinrichs et al. (2010) suggest
selectively restoring semi-stabilized dunes, which are already important to population
persistence. These restored dunes may then have the potential to act as stepping stones
(Figure 1.1), which are habitat patches that facilitate movement between at least two
other habitat patches (Saura, Bodin, & Fortin, 2014). By decreasing the isolation of
habitat patches, stepping stone networks can be integral to species persistence, especially
in those with limited mobility (Saura et al., 2014).
11
Figure 1.1‘A’ represents a landscape where the distance between habitat patches may
exceed the dispersal ability of kangaroo rats. Individuals dispersing in this landscape
have to disperse through less hospitable terrain (the matrix) in a single, long movement
between Habitat 1 and Habitat 2. ‘B’ represents a landscape where a stepping stone is
placed at a distance within the dispersal ability of kangaroo rats, bridging the gap
between two habitat patches (accessible from either Habitat 1 or Habitat 2). Kangaroo
rats can then survive and reproduce on the stepping stone. Their offspring may then have
the potential to disperse to Habitat 2.
12
1.5 Research objectives
Previous studies indicate that there are sub-populations of kangaroo rats in
Alberta that are already in danger of extirpation (Heinrichs et al., 2010). In fact, the entire
metapopulation in Alberta is headed toward local extirpation, should habitat loss and
fragmentation continue (Heinrichs et al., 2010). Considering this, the objective of my
research is to estimate the dispersal capability of kangaroo rats in Alberta and to
determine the feasibility of facilitating inter-patch dispersal in kangaroo rats, which may
increase rescue and recolonization of isolated habitat patches, and ultimately increase
their likelihood of metapopulation persistence. Specifically, this study looks to determine
the necessity and viability of two potential mitigation techniques: (1) stepping stone
generation, and (2) kangaroo rat translocations. Managers may use the results of this
study to help guide future mitigation actions.
1.6 Thesis outline
Chapter 2 uses kangaroo rat recapture distances to estimate the dispersal ability of
kangaroo rats in Alberta, which is then used to guide the identification and prioritization
of potential future stepping stone habitat patch locations. In situations where stepping
stones are unlikely to facilitate dispersal, such as when patch isolation is far greater than
the estimated dispersal ability of kangaroo rats, I look at translocations as an alternative
means to facilitate the rescue of sub-populations that are in decline or recolonization of
suitable habitats that are no longer occupied by kangaroo rats. We have very little
information on the use of kangaroo rat translocations in Alberta, so investigating the
potential of using translocations as an effective tool to increase population viability is
13
highly valuable (Alberta Sustainable Resources and Development, 2013). In Chapter 3, I
conduct a study of experimental translocations of kangaroo rats and assess if translocated
individuals can successfully establish themselves at the release site, using the length of
occupancy as an indicator of efficacy. If so, translocations can then be considered as a
potential future mitigation method. Chapter 4 addresses the key conclusions from my
study as well as its limitations. I then make recommendations on how to improve the
study, when these methods should and should not be used, and what needs to be
researched further.
14
Chapter Two: Dispersal and the use of stepping stones
2.1 Introduction
A metapopulation is a set of sub-populations (localized subsets of the greater
population) within spatially isolated patches of habitat that are in a balance between local
extirpation and colonization (Hanski & Gilpin, 1991; Harrison, 1991). In a
metapopulation, the movement of individuals between habitat patches is important as this
facilitates gene flow (Nelson, 1993; Wright, 1942), colonization of unoccupied habitats
(Hanski, 1991), and affects the local dynamics of sub-populations (Kuussaarri, Saccheri,
Camera, & Hanski, 1998). The persistence of a metapopulation does not depend on all
habitat patches being occupied; it depends on the colonization rate being greater than the
extirpation rate of local sub-populations (den Boer, 1981; Hanski, 1991). Dispersing
individuals can help stabilize declining sub-populations through rescue (Brown &
Kodric-Brown, 1977) and recolonization of unoccupied habitats (Fahrig & Paloheimo,
1988; Roff, 1974), increasing the stability and persistence of the entire metapopulation.
Landscape functional connectivity has been described as the degree to which the
landscape allows for movement of organisms between resource patches (Taylor et al.,
1993), and it results from the ways the ecological characteristics of the organisms interact
with the structural characteristics of the landscape (Rudnick et al., 2012). Any adjacent
habitats that are unreachable through dispersal are not considered functionally connected,
as individuals are unable to move between sites. This has a negative impact on the
surrounding sub-populations because individuals cannot rescue or recolonize subpopulations that are declining or have become locally extirpated. As mentioned in
Chapter 1, the stability of a metapopulation relies on the movement of individuals
15
between sub-populations and without that they are subject to decline (Levins, 1969; Roff,
1974). To mitigate reduced functional connectivity, stepping stone habitat patches have
been suggested as a method to facilitate dispersal (Saura, Bodin, & Fortin, 2014). These
are patches that decrease habitat (e.g. dune) isolation by providing a link between two or
more habitat patches, decreasing the distance individuals have to disperse when locating
new territory (Saura et al., 2014). They are valuable to conservation, albeit more so in the
following generations, as these patches allow colonizers’ offspring to reach more isolated
patches (Saura et al., 2014).
2.1.1 Dispersal distance
Dispersal is a continuous process that can occur within or between generations
(Gaines & McClenaghan, 1980). It drives gene flow, the spatial spread of a population,
and recolonization, and it is essential for determining the effects of landscape change on
the persistence of metapopulations, as described in Chapter 1 (Beisinger & Westphal,
1998; Sutherland, Harestad, Price, & Lertzman, 2000). Net dispersal from source subpopulations (where the population growth rate exceeds the death rate) to sink habitats
(where the population mortality rate is greater than the growth rate) can decrease the risk
of local extirpation (Holt, 1985). For an organism to perceive the landscape as
functionally connected, it must be capable of dispersing the distance between habitat
patches (Keitt et al., 1997). For animals with limited dispersal ability, fragmentation may
limit successful dispersal, decreasing the probability of recolonization and increasing the
probability of local extirpation (Fahrig & Merriam, 1994; Keitt, et al., 1997). In
landscapes with a high degree of fragmentation, individuals have to move longer
distances, increasing the cost of dispersal (e.g. mortality risk, Johnson, Fryxell,
16
Thompson, & Baker, 2009) and decreasing the fitness of the organism (Schtickzelle &
Baguette, 2003; Stamps, Krishnan, & Reid, 2005).
Dispersal is particularly important in this study because it is currently unknown
whether or not kangaroo rats in Alberta have the ability to move between habitat patches.
Dispersal is quite difficult to record. It is likely that many juvenile kangaroo rats disperse
(Bender et al., 2010; Gummer, 1997a) without being captured before the dispersal event.
It is also possible that some kangaroo rats are never recaptured. Furthermore, if they are
not monitored frequently or continuously, dispersal movements may easily be missed.
With the Ord’s kangaroo rat population in decline, it is imperative that they have the
ability to rescue sub-populations and recolonize habitat patches through dispersal. To
increase the likelihood of successful dispersal, the gap between habitat patches must be
decreased. Mitigation techniques, such as using habitat restoration to create stepping
stone habitat patches, can increase the connectivity between occupied habitats and
subsequently facilitate dispersal (Alberta Sustainable Resources and Development, 2013;
Saura et al., 2014). This chapter will investigate kangaroo rat dispersal potential and the
use of stepping stones.
2.1.2 Stepping stones
For species with limited dispersal abilities, the mortality rate during dispersal is
expected to be positively associated with distance between habitat patches (Johnson et al.,
2009). Animals often have to move through a matrix of less suitable habitat when
dispersing among patches of adequate habitat (Kueffler, Hudgens, Haddad, Morris, &
Thurgate, 2010). Dispersers are more exposed and susceptible to predation (Johnson et
al., 2009), especially when individuals are unfamiliar with the habitat (Ambrose III,
17
1972; Metzgar, 1967). Additionally, the lack of parental resources, inherent physiological
costs of movement, and competition with unfamiliar individuals in alien territory, makes
dispersal hazardous (Plissner & Gowaty, 1996; Waser, Creel, & Lucas, 1994). The
individual success of dispersers is important to consider because rescue and
recolonization depend on the successful movement of individuals between habitat
patches.
The addition of small amounts of habitat to act as stepping stones can be
particularly beneficial in landscapes where fragmentation and habitat loss has increased
patch isolation (Saura et al., 2014). This is especially true for species with limited
dispersal abilities (Sondgerath & Schroder, 2002). According to Gummer (1997a), Ord’s
kangaroo rats typically do not move distances exceeding 500 m, which may not be
sufficient to reach adjacent dune habitats. With kangaroo rat habitat becoming
increasingly patchy and isolated in Alberta, increasing the functional connectivity of the
landscape through the use of stepping stones should be further investigated as a method
to enhance dispersal. Heinrichs et al. (2010) support this recommendation. In a study on
the contribution of habitats to kangaroo rat population persistence, Heinrichs et al. (2010)
determined that although actively eroding sand dunes are integral to population
persistence, the destabilization of vegetated sand dunes could also decrease the risk of
extirpation.
Restoring semi-stabilized dunes can create stepping stone habitats. There are a
few different methods that can be used to restore dunes, although further investigation is
required. One method that has already been used is controlled burns. These temporarily
remove surface vegetation, which increases erosion and provides ground upon which
18
kangaroo rats can easily move and dig their burrows (Price, Waser, Taylor, & Pluff,
1995). The fires have to be repeated every few years to remove new vegetation (Bender,
2009). Other restoration methods such as grazing, herbicide, and mechanical restoration
have yet to be investigated in Alberta, but could be useful in the future (Alberta
Environment and Sustainable Resource Development, 2013), although these methods are
more invasive and may have greater potential for harm. Such methods should be
approached with caution.
All restored habitats will function as stepping stones. To serve as viable stepping
stones, the habitat patches need to be of sufficient size to be beneficial (Kramer-Schadt,
Kaiser, & Frank, 2011; Saura et al., 2014). They must be large enough that those who
disperse there may reproduce, yielding more dispersers who can continue on to other
patches. The creation of stepping stones should increase the landscape-level functional
connectivity between habitat patches that were previously isolated from one another,
making dispersal more likely (Saura et al., 2014). The inter-patch movement facilitated
by stepping stone habitat patches can then help to stabilize metapopulations through both
rescue and recolonization. Knowing this, the next step would be to consider potential
locations for implementation. One of my research objectives is to determine possible
stepping stone locations.
The purpose of this chapter is to estimate the dispersal ability of Ord’s kangaroo
rats in Alberta and to use the estimated distance to assess the functional connectivity
between habitat patches. Where functional connectivity is lacking, I locate neighbouring
habitat patches that are just beyond the range of natural dispersal and determine if the
addition of stepping stones between those patches could be used to facilitate dispersal. I
19
then prioritize these potential stepping stone locations based on how many habitat patches
they have the potential to functionally connect. The results of this study can be used to
guide managers on where to restore habitat to best facilitate dispersal. I expect that,
because dune habitats are becoming more isolated with habitat loss and fragmentation,
the dispersal ability of kangaroo rats will not be sufficient to reach adjacent dune habitats,
making the addition of strategically placed stepping stones necessary.
2.2 Methods
2.2.1 Study area
My study takes place within the Ord’s kangaroo rat species range in Alberta
(Figure 2.1), which is centered on the Middle Sand Hills region (Figure 2.2) (Bender,
Gummer, Dzenkiw, & Heinrichs, 2010). The Middle Sand Hills region is within the arid,
dry, mixed grass, prairie ecoregion and contains actively eroding, partially vegetated sand
dunes, blowouts, and sandy river valley slopes (Natural Regions Committee, 2006;
Bender, 2010b; Gummer, 1997a). A major portion of the Middle Sand Hills and the
species range in Alberta falls within the National Wildlife Area of the CFB Suffield
(76%) (Heinrichs et al., 2010), a military base that covers 2690 km2 (Smith & McDermid,
2014) (Figure 2.1; Figure 2.2).
Wind erosion is important in arid and semi-arid regions, maintaining sand dune
activity (Hugenholtz & Wolfe, 2005). It removes the nutrient-rich layer of soil near the
surface and subsequently decreases vegetation growth (Pimental et al., 1995). The soil
comprising the dunes is primarily aeolian sand deposits and xeric soil, with wind being
the most important factor influencing dune stability (Hulett, Coupland & Dix, 1966;
20
Tsoar, 2005). Because kangaroo rats depend on these unique habitats, they are important
to preserve.
21
Figure 2.1 The Ord’s kangaroo rat (OKR) range in Alberta.
22
Figure 2.2 Map of the Middle Sand Hills region, where the Ord’s kangaroo rat is
commonly found.
23
I used population data collected from the entire kangaroo rat range in Alberta to
estimate the dispersal ability of the Ord’s kangaroo rat (Figure 2.2). A smaller subsection
of the species’ range was used to investigate potential stepping stone locations. I only
considered the habitat within the northern part of CFB Suffield because other locations
are isolated by many kilometers and are sure to greatly exceed the dispersal ability of
kangaroo rats (Heinrichs et al., 2010). This sub-section is known as the Amiens region of
Suffield. It has a cluster of natural sites, both dune and river valley, that are all within a
few kilometers of one another (Figure 2.3). From preliminary assessments of the distance
between dunes and known kangaroo rat movement distances (observed in the recapture
data), the dunes in this region appear to be located such that the addition of a few
strategically-placed stepping stones should functionally connect the majority of the
habitat patches in the area.
24
Figure 2.3 The Amiens region of CFB Suffield was used in the stepping stone analysis.
This area has a relatively high density of natural sites with nine actively eroding dunes
and three southeast-facing, sandy river valley sites. Source: R. Dzenkiw.
25
2.2.2 Survey methods
To conduct this study, I used long-term population monitoring data (1995-2015),
the latter four years of which I helped collect. This database was originally created to
allow for comparison of population distribution, persistence, trends in abundance and
survival over the years, and to later guide population management. Extensive details can
be found in Bender et al. (2007).
I began my study by conducting mark-recapture population surveys, as outlined in
the Ord’s kangaroo rat monitoring protocol (Bender et al., 2007). I surveyed natural sites
(dunes and river valleys) on foot and anthropogenic sites (sandy roads, trails, fireguards)
by vehicle. In total, there were 20 natural sites and 17 anthropogenic sites. The field
seasons were divided into two main survey periods that captured both the minimum and
peak population sizes of each year. Mid April to early June comprised the spring surveys
while late July to early September comprised the summer surveys. The surveys were
conducted during the nights when kangaroo rats are most active. Their activity cycle is
based around the lunar cycle (O’Farrell, 1974). They limit their above ground activity
during periods of moderate ambient light, becoming most active during the darker nights
surrounding the new moon (Bender et al., 2007; O’Farrell, 1974). Increased light levels
make kangaroo rats easier targets for visually orienting predators such as foxes, coyotes,
and owls (Bender et al., 2010). Therefore, to increase the likelihood of capturing
kangaroo rats, I conducted surveys during the 17-day period surrounding the new moon
where ambient light levels were minimized.
Natural sites were surveyed on foot while roads were surveyed by vehicle.
Kangaroo rats were located, captured, and processed at each survey site. I used the same
26
techniques that have been performed over the last nineteen years, so the database had
consistent information upon which I could base my analysis. Each kangaroo rat was
placed into a catch bag immediately following its capture. I recorded the date and time of
capture as well as the name of the site. Using a handheld Global Positioning System
(GPS) unit I recorded the location of capture for each individual. These locations, as well
as the locations recorded over the last nineteen years, would later be used in estimating
dispersal distances. While the animal was still within the bag, I scanned it for an
identification number. If it did not yet have one, it was removed from the bag and a
passive integrated transponder (PIT) tag was inserted. This way, each individual could be
uniquely identified. The unique identification number was key, as I used the locations of
capture for each individual to estimate the maximum distances travelled. After
processing, the kangaroo rats were released back to the point of capture. Surveys were
conducted in accordance with the relevant permits and animal care protocols. Provincial
research permits were obtained from Alberta Fish and Wildlife Division while the
Federal Species at Risk Permit was obtained from Environment Canada. The research
performed in this thesis followed methods approved in Protocol BI11R-23 by the
University of Calgary Life and Environmental Sciences Animal Care Committee and was
in compliance with the Canada Council for Animal Care guidelines.
2.2.3 Estimating the dispersal distances of kangaroo rats
The maximum dispersal distance of kangaroo rats is important to consider, as they
need to be able to reach adjacent dune habitats through dispersal. However, dispersal is
difficult to measure and there is very little known about the dispersal distances of
kangaroo rats in Alberta. Because of this lack of data, I had to find a proxy measurement
27
of dispersal. Dispersal in small mammals is often measured through mark-recapture
surveys (Hanski, Alho, & Moilanen, 2000; Schtickzelle, Mennechez, & Baguette, 2006).
I decided to use the maximum distance travelled between captures for each individual to
represent the maximum dispersal distance. The movement distances of kangaroo rats in
Alberta were calculated using the recapture data from the population surveys conducted
over the last nineteen years throughout the entire species range in Alberta (Figure 2.1).
Because I only had recapture data, this provided the best available information upon
which to estimate their dispersal ability.
I determined the Euclidean (shortest straight-line) distance between the two
farthest capture locations for each kangaroo rat by calculating the distance between every
pairwise combination of capture locations for each recaptured individual in the database
(Figure 2.4). This distance represented the maximum observed distance travelled for each
kangaroo rat. I did not study the motives for each individual movement, only the
distances moved. In a study by Jones (1989), dispersal in the Merriam’s kangaroo rat was
determined by measuring the distance between the locations of the first and last capture.
My study followed a similar method of analysis, although rather than measuring between
the first and last capture, I measured between the two farthest captures as this indicates
their potential for movement, not just where they decided to settle. I determined the
maximum observed distance moved through both grassland habitat and along roads.
28
Number of Kangaroo Rats
10000
1759
1000
100
14
10
2
1
3
1
1
1
1
1
2
Distance Moved (m)
Figure 2.4 Histogram of the maximum distances moved through natural grassland habitat
for each kangaroo rat that was recaptured over the last nineteen years. The vertical axis
has been log transformed.
29
It is likely that many of the movements observed in the database were that of
daily movements such as foraging, with some movements including mate searching.
According to Behrends, Daly, and Wilson, (1986) the majority of kangaroo rat
movements in D. Merriami were centered on their burrows. This was also seen in
Schroder (1979) with D. spectabillis remaining within 6 m of their home burrows. Most
of the observed movements involved foraging. Daily movements of the Ord’s kangaroo
rat are likely similar, with most of their activity occurring on the dune searching for food
around the burrows. Mate searching occurs during breeding season with males moving
slightly longer distances in search of females (Jones, 1989). These distances are likely to
be shorter and more frequent than dispersal events, which are longer, less frequent, and
generally permanent. This is why I did not use an average of all the distances observed in
the database. It is far more likely that the long, infrequent distances observed were
dispersal events.
2.2.4 Dispersal distance assumptions
I have made the following assumptions to estimate dispersal distance: (1) at least
some of the movements observed through recapture were dispersal movements;
especially where the distances moved were particularly long. Many kangaroo rats do not
typically venture far from their burrows, with foraging generally occurring in the vicinity
of the burrow (Behrends et al., 1986; Schroder, 1979). Therefore, any movements that
involved the relocation from one dune to another were considered dispersal movements,
(2) there were likely many individuals that were not captured before the dispersal event
or not recaptured after, so it was only those that were captured and recaptured that were
used to represent the metapopulation as a whole. It is difficult to capture a kangaroo rat
30
both before and after a dispersal event. It is also easy to miss observing a kangaroo rat
during a survey, because each survey site was only visited 1 – 2 times each month and
kangaroo rats do not spend extended periods of time outside their burrows (Braun, 1985;
O’Farrell, 1974; Schroder, 1979). If I did not capture an individual before it dispersed,
then I was not able to determine its dispersal distance. Therefore, dispersal ability may be
underrepresented, (3) the maximum distance observed was the maximum possible
distance kangaroo rats could move, and to an extent, was representative of the
metapopulation as a whole. Moreover, this algorithm did not take into consideration the
fact that kangaroo rats continue moving again after each capture and release. Therefore,
it is possible that they moved farther than the data suggest.
Because movement among dunes in the Amiens region almost entirely involves
travel through natural habitat and not along roads, I used the maximum recapture distance
for grassland travel to create dispersal buffers in the following section. This distance was
3.2 km and was observed in two individuals. As shown in Figure 2.4, most recapture
distances through natural habitat do not exceed 400 m. These shorter distances likely
represent daily movements on and around the dunes. However, I was not interested in
daily movements; I was interested in maximum movement distances as these are more
likely to represent dispersal events and indicate maximum movement potential in the
Alberta metapopulation. It is because I was unable to directly measure dispersal that I
used the maximum recapture distance through grassland habitat to estimate the dispersal
potential of kangaroo rats. I calculated the maximum observed distance moved along
roads, but I did not use it for the creation of dispersal buffers around sand dune habitats,
which are generally not connected by roads. I will henceforth use the term ‘dune’ to
31
represent all natural habitat patches including the river valley sites, as they do not differ
from dunes in their function.
2.2.5 Assessing landscape resistance to dispersal
I intended to use the maximum recapture distance to estimate the distance around
each habitat type that could be reached by a dispersing individual. However, the
calculated maximum recapture distance may not accurately represent how far kangaroo
rats could disperse in all locations because different land cover types may affect how
easily kangaroo rats can move. Animals tend to select travel routes based on the same
factors they use to choose suitable habitat (Chetkiewicz et al., 2006). A species’ food
requirements, shelter, nesting sites, and areas of escape are factors that often define their
habitat (Beier, Majka, & Spencer, 2008). These facts are not easily mapped so geographic
information system (GIS) layers are generally used as proxies. I used layers that included
different types of vegetation, water bodies, and slope to determine if the landscape had an
effect on kangaroo rat movement in Alberta.
If the landscape were homogeneous from the perspective of a dispersing kangaroo
rat, circular dispersal buffers would be sufficient to represent dispersal in all directions
from a dune location. However, if different land cover types significantly impede
movement, then I would have to create dispersal polygons (buffers that vary in shape
based on resistance of the landscape to movement). This would allow for more accurate
dispersal distances because they would change depending on the land cover type. For
example, grass height can change movement probabilities in banner-tailed kangaroo rats
(Skvarla, Nichols, Hines, & Waser, 2004) while bare, sandy soils facilitate their hopping
style of locomotion (COSEWIC, 2006).
32
To assess landscape heterogeneity, and therefore any effect on dispersal, the
relative resistance to movement for each land cover type was estimated and a friction
surface was created (Wikramanayake. et al., 2004). Friction surfaces represent the
hypothesized relationship between landscape features and movement probabilities
through different land cover types (Spear, Balkenhol, Fortin, McRae, & Scribner, 2010).
In this case, the friction surface was a GIS layer that included multiple land cover types
and features (vegetation, slope, water bodies, etc.) that were reclassified with their
associated resistance percentages, yielding maps that displayed different colours for
different resistances to movement (Table 2.1; Table 2.2; Appendix A, Figures A1-A7).
Resistance percentages represent the percentage resistance to movement, so each land
cover type had a different percentage based on how impermeable it was to kangaroo rat
movement. The percentages reflect a judgement of the biological cost associated with
dispersal, where I arbitrarily chose resistance percentages that seemed reasonable to me
given my knowledge of the species (Table 2.1; Table 2.2). I created a friction surface for
slope and for land cover.
33
Table 2.1 A list of slopes and their associated resistance values. These values were used
to create a slope friction layer.
Slope (degrees)
Resistance (%)
0 – 5 (low)
1
5 – 20 (moderate)
50
20 – 35 (high)
75
35 – 61 (extreme)
100
34
Table 2.2 A list of land cover types and their associated resistance values. These values
were used to create a land cover friction surface.
Land Cover Type
Resistance (%)
Exposed Soil
1
Sparsely Vegetated Soil
5
Partially Vegetated Soil near Exposed Soil
10
Partially Vegetated Soil farther from Exposed Soil
20
Medium Vegetation
30
Grassland
60
Shrublands
75
Water
100
35
A cumulative friction surface was created by adding together the reclassified
slope and land cover layers (using a raster calculator), and was used to create multiple
cost distance surfaces for each dune location (Wikramanayake et al., 2004). The cost
distance surfaces represent not the actual distance from one point to another, but the
weighted Euclidean distance from one point to another taking into account any resistance
to movement created by the landscape (ESRI, 2011; Graves, Chandler, Royle, Beier, &
Kendal, 2014). The cost distance surface showed that, with the exception of the river
valley sites, the landscape resistance around each dune was relatively uniform (see
Appendix A, Figures A1-A7). According to the cost distance surfaces, the landscape
remained homogeneous for a minimum of roughly 3 km in all directions from each dune.
Therefore, given the maximum recapture distance of 3.2 km and the fact that I used half
of that distance to create buffers representing dispersal (see explanation below), I
determined that it was unnecessary to employ cost distance surfaces to generate dispersal
polygons that varied with underlying resistance values. With the resistance to kangaroo
rat movement being the same in all directions around each dune, circular buffers could be
used instead of non-uniform dispersal polygons to represent the potential for dispersal
away from the dune. Although the resistance around the river valley sites was not
uniform due to the close proximity of the river, this did not affect the analysis because it
was evident that I would not be placing stepping stones in or across the river valley itself.
2.2.6 Identification of stepping stone locations
My goal was to look for areas that only required the addition of one stepping
stone to link existing habitats. This is because the use of two or more stepping stones to
connect two habitats would likely be less effective as it may require multiple generations
to facilitate dispersal between the habitats (Saura et al., 2014) and would promote the
36
occupancy of lower quality habitats. Therefore, if habitats required more than one
stepping stone to create a functional connection, those stepping stones were not included.
I compared the maximum recapture distance to the distance between dunes to determine
if stepping stones would be necessary (Table 2.3). To do this, I used a geographic
information system (ArcGIS 10, ESRI Inc., Redlands, CA) to measure the distances
between neighbouring dunes (Table 2.3) and I visualized the dune locations by mapping
them. If the distance between dunes exceeded the maximum recapture distance of
kangaroo rats, stepping stones would need to be considered in those areas.
The landscape was shown to be relatively homogeneous from the perspective of a
kangaroo rat, with the cost of movement being the same in each direction from the dune
(see Appendix A, Figures A1-A7). So, instead of using the dispersal polygons considered
above, I used the maximum recapture distance through grassland habitat to create circular
dispersal buffers around each dune. I call these ‘dispersal buffers’ because they represent
the zone over which dispersal is expected to be possible around the dune for which the
buffer was created. I began by creating three sets of buffers for each dune using 100%,
75%, and 50% of the maximum recapture distance. The first set of buffers used the
maximum dispersal distance (3.2 km) as the radius (Figure A8). Using this distance
would yield a map where nearly all the dunes in the study area were already connected by
the addition of a single stepping stone between dunes. Only the Carbine dunes would
remain isolated with such a large buffer and therefore only one stepping stone would be
required. Considering that dispersal between these dunes is not frequently observed, it is
likely that although some individuals could span a gap of 3.2 km, many would still
require stepping stones to survive such a journey. Therefore, I tried a smaller dispersal
37
buffer radius. The second set of dispersal buffers used 75% of the maximum distance
(2.4 km) as the radius and although more stepping stones would be required (two
stepping stones in total), most dunes were still functionally connected (Figure A9). The
last set of buffers used 50% of the maximum distance (1.6 km) as the radius. This yielded
a map where the dunes were not very well connected. Four stepping stones would be
necessary in this situation. Using a more conservative estimate of dispersal ability could
be more beneficial to dispersing kangaroo rats. This is because the maximum recapture
distance of 3.2 km is a particularly long distance for most kangaroo rats to travel, given
what I have observed in the recapture data (on average they only move a maximum of
40.1 m). Realistically it is unlikely that most kangaroo rats could meet or exceed this
distance so I arbitrarily decided that a smaller distance for stepping stone modelling
would likely be more representative of the population as a whole and may have a greater
conservation value. After viewing the use of various dispersal buffers, I decided that 50%
of the maximum recapture distance would be used perform my analysis. I created circular
buffers around each dune using the 1.6 km as the radius.
38
39
2.61
3.52
4.31
4.86
4.89
5.37
5.96
7.17
6.84
4.89
Aurora
Woodhouse
Bagnold's
Dejean's
Butler's
Carbine
Dune
Carbine
South B.O
SNWA1
SNWA2
SNWA3
Mounted
Rifle B.O
Mounted
Rifle B.O
2.3
4.83
4.71
4.7
4.22
2.3
2.33
2.34
0.92
Aurora
3.51
4.25
3.88
4.57
4.17
1.42
1.48
1.99
Woodhouse
3.7
2.56
3.09
6.52
6.15
2.61
1.6
Bagnold's
2.29
3.04
2.4
5.34
5.07
1.13
Dejean's
2.22
4.11
3.07
4.25
4.02
Butler's
5.61
8.11
6.98
0.6
Carbine
Dune
5.64
8.36
7.11
Carbine
South B.O
Table 2.3 Distance (km) between each dune in the Amiens region of Suffield (B.O = Blowout).
1.76
2.04
SNWA1
3.76
SNWA2
SNWA3
2.2.7 Algorithm to determine and prioritize stepping stone locations
I developed an algorithm to evaluate potential stepping stone locations and
prioritize them based on their contribution to the functional connectivity of the dune
network (Figure 2.5). This algorithm used the 1.6 km dispersal buffers to determine how
many functional connections could be formed through the addition of each potential
stepping stone. If stepping stones are added to areas where buffers overlap, new viable
functional connections can be formed. To make the algorithm easier to understand, I will
first define primary and secondary functional connections (Figure 2.6). A primary
functional connection means that one site (‘Site A’) falls within the maximum dispersal
distance from another site (‘Site B’), and individuals can move directly between those
two sites. A secondary functional connection refers to a site (‘Site A’) that does not fall
within the maximum dispersal distance from ‘Site C’, but does fall within the dispersal
buffer of another site (‘Site B’) that is directly functionally connected to ‘Site C’. Thus
‘Site A’ would be indirectly connected to ‘Site C’ through ‘Site B’.
The algorithm is as follows: (1) add the dunes and their dispersal buffers to the
map (in this case the buffers each had a 1.6 km radius), (2) logically group (merge)
buffers that overlap with neighbouring dunes as overlapping buffers indicate that a
functional connection is already present, (3) identify the number of overlapping dispersal
buffers giving top priority to the areas with the highest degree of overlap between dunes
(in this case, where the separating distance between dunes is less than two times the
halved maximum dispersal distance of 3.2 km), (4) in these overlap areas, use aerial
imagery to determine if potential stepping stones are present (will appear as crescentshaped landforms). For my study I did not consider the geomorphological characteristics
of the dune, however they should also be considered before labeling that dune as a future
40
stepping stone because some dunes may sustain erosion and resist re-stabilization better
than others. This is an important consideration if this algorithm is to be used in the future.
But for the purposes of my study, if a stabilized dune is found in the overlap area, move
on to step 5. If no potential stepping stones are observed, look at the next highest area of
overlap and continue until one is located, then proceed to step 5, (5) break ties by
determining the functional connectivity of the dune network as a whole by counting the
total number of potential connections formed (both primary and secondary) through the
addition of a potential stepping stone habitat in each of the areas of highest overlap. In
some cases, this may involve removing the ‘dissolve’ used to merge buffers so that each
individual dispersal buffer can be observed, (6) if ties still exist after counting the
functional connections, priority will be given to the location with the largest area of
buffer overlap. This is an iterative heuristic process where every time a stepping stone
location is given top priority, it is added to the dune network and the algorithm is
repeated again, with the previously selected dune acting as a permanent fixture in the
landscape (Figure 2.5). The process is complete once all potential locations are
exhausted.
I used this algorithm to both determine potential stepping stone locations and
prioritize them in the Amiens region of Suffield. The algorithm produced four potential
stepping stone locations. The use of GIS was integral in determining stepping stone
locations but it could not be used to assess habitat quality. Therefore, once these locations
were identified, they were visited in person to determine the presence or absence of
stabilized dunes. If they were present, I qualitatively assessed them for vegetation cover,
shape, height, and exposed sand. Using GIS in combination with ground-truthing allowed
41
for a more comprehensive analysis of the prospective habitat restoration locations.
42
Figure 2.5 This flow chart depicts the stepping stone algorithm.
43
= Dune
= Dispersal Buffers
Figure 2.6 Diagram of functional connections. ‘Site A’ is functionally connected to ‘Site
B’ through a primary functional connection. ‘Site B’ is also functionally connected to
‘Site C’ by a primary functional connection. ‘Site A’ is functionally connected to ‘Site C’
through a secondary functional connection.
44
2.3 Results
The maximum observed distance travelled by a kangaroo rat in the recapture
database was by a female that was found 9.5 km from her original capture location. She
moved along a flat, sandy fireguard in CFB Suffield (Double Wide Scrape, Figure 2.3).
The maximum recapture distance between sand dunes (i.e., through natural habitat and
not along a road feature) was by a male that moved 3.2 km to Butler’s Dune from
Suffield National Wildlife Area (SNWA) 1, a river valley habitat (see Figure 2.3). I used
1.6 km as the buffer size, which I believe to likely be more representative of the
metapopulation as a whole, therefore benefiting more individuals. With this new distance,
all three river valley sites (SNWA1, 2 and 3) were isolated, as well as the two Carbine
Dunes, and Mounted Rifle Blowout.
I used Thiessen polygons to identify neighbouring dunes. I investigated the
percentage of inter-dune gaps that could be theoretically traversed and based these
calculations on the distance between neighbouring dunes (primary connections) and the
observed recapture distances. The closest dunes in the Amiens region are within 0.6 km
of each other, well within the maximum movement distance observed. This connection is
between the Carbine Dune and the Carbine South Blowouts. At the time of writing,
neither of them showed evidence of being occupied. The distances between many other
dunes greatly exceed the estimated dispersal ability of kangaroo rats in Alberta through
natural grassland habitat (Table 1.3). The average distance between neighbouring dunes
in the Amiens region is 2.66 km. Only 26% of the gaps between neighbouring dunes are
1.6 km or less in length. Only the best dispersers (3.2 km) observed can span the distance
between many neighbouring dunes, with 74% of the gaps between the Amiens dunes
being theoretically traversable for those individuals.
45
The stepping stone location with the highest priority (Stepping stone 1) was
determined to fall between Butler’s Dune and Dejean’s Dune, SNWA3 and SNWA1,
serving to connect the four sites through primary functional connections (Figure 2.7). The
UTM coordinates for this stepping stone were 12U 547190 5606518.
46
Figure 2.7 Stepping Stone 1 with a 1.6 km buffer added to the dune network.
47
Stepping Stone 2 yielded five primary functional connections with Woodhouse
Dune, Bagnold’s Dune, Dejean’s Dune, and Butler’s Dune, as well as Stepping Stone 1
(Figure 2.8). Through those sites, other dunes were secondarily connected. The UTM
coordinates for this stepping stone were 12U 547032 5608082.
48
Figure 2.8 Stepping Stone 2 with a 1.6 km buffer added to the dune network.
49
Stepping Stone 3 functionally connected SNWA2, SNWA1, Dejean’s Dune, and
Stepping Stone 1 through four primary functional connections (Figure 2.9). The UTM
coordinates for this stepping stone were 12U 548510 5607028.
50
Figure 2.9 Stepping Stone 3 with a 1.6 km buffer added to the dune network.
51
The fourth location, Stepping Stone 4, provided a corridor between Mounted Rifle
Blowout and Aurora Dune yielding two primary functional connections (Figure 2.10).
The UTM coordinates for this stepping stone were 12U 546121 5611076.
52
Figure 2.10 Stepping Stone 4 with a 1.6 km buffer added to the dune network.
53
The primary functional connections formed are summarized in Figure 2.11 and
Table 2.4. I did not add any more stepping stone locations because at this point, all the
dunes that could be connected by the addition of one stepping stone were now connected.
Carbine Dune and Carbine South Blowouts would require the addition of more than one
stepping stone to become functionally connected with the rest of the dunes in the Amiens
region (as can be seen by the lack of overlapping buffers) and were therefore not
considered in this particular analysis. Stepping stone creation was not evaluated for areas
between dune clusters, as the distance is too far to be effective. For example, the Empress
and Dune Point dunefields are more than 30 km away from the Amiens Dunefield (Figure
2.12). Furthermore, the Empress Dunefield and Dune Point Dunefield are roughly 26 km
away from each other. Even within CFB Suffield, large distances separate dunefields. For
example, the Ypres Dunefield is approximately 12 km away from the closest Amiens site,
SNWA 3 (Figure 2.12). In such circumstances, stepping stones are not practical and were
not considered.
54
55
stepping stone).
55
Figure 2.11 Graph depicting the primary functional connections formed through the addition of stepping stone habitat patches (SS =
Table 2.4 Table summarizing the number of primary connections formed after all four
stepping stones had been added to the dune network.
Stepping Stone
Number of Primary Connections Formed
1
2
3
4
6
5
4
2
56
Figure 2.12 Dunefields in the species range in Alberta. Source: R. Dzenkiw.
57
When looking at the dunes that are currently active, one should note that there are
habitat patches that are, or will become, very important to the functional connectivity of
the dune network. For example, before the addition of stepping stone habitats,
Woodhouse Dune contributes the most to the network connectivity with three primary
functional connections, linking Aurora Dune, Butler’s Dune, and Dejean’s Dune. With
the addition of the four stepping stones, Dejean’s Dune will also become quite important
with five primary functional connections between itself and Butler’s Dune, Woodhouse
Dune, and Stepping Stones 1, 2, and 3. They are important because they provide a link
between dunes, facilitating dispersal and ultimately the rescue and recolonization of
multiple dunes. I will also note that many of these dunes, including the highly connected
ones, had few to no kangaroo rats occupying them at the time of surveying.
I had to confirm if these potential stepping stone locations had viable habitat (i.e.,
stabilized or semi-stabilized sand dunes that could be restored to suitable habitat) that had
the potential for restoration to kangaroo rat habitat, so I visited each of the four potential
sites in the summer of 2015 to make sure restorable habitat was present in each location
and then performed a qualitative assessment. I walked the perimeter of each location
looking at the amount and type of vegetation (grass, shrubs, trees, etc.), and determined if
there was any exposed sand. I expected to find relatively sandy, but mostly grassed,
crescent shaped hills, perhaps with some blowouts still eroding. These would be ideal,
because essentially only the grass would need to be removed. If the sites did not have
dunes (stabilized or semi-stabilized), I would have to reconsider those stepping stone
locations. If the site contained stabilized dunes (highly vegetated), I would check if there
were any higher quality, semi-stabilized dunes (some exposed sand) nearby. If the sites
58
were treed or covered in shrubs, they may require more effort to restore than sites that
contained bare, sandy ground.
The potential location for Stepping Stone 1 was a stabilized sand dune. It was
completely covered in vegetation with no bare ground exposed. However, another
stabilized dune was within site of Stepping Stone 1. I visited that dune and it had areas of
exposed sand with sparse vegetation. Upon initial assessment it appeared more suitable
than the location found using aerial imagery. This location was at UTM coordinates 12U
547693 5606760. I looked at this location using GIS, and determined that although it was
higher quality habitat, it was not in an optimal location because it was not within the
buffer overlap where it would be accessible via dispersal. Therefore, theoretically it
would not be very useful as a stepping stone. Having a habitat that is reachable through
dispersal takes priority over habitat quality, as long as it is able to provide adequate
habitat once it is restored. The location for Stepping Stone 2 was adequate. It had
extensive sandy patches with areas of dense vegetation, and very few shrubs, and with
some adjustments to remove vegetation, could serve as suitable kangaroo rat habitat. The
location for Stepping Stone 3 was also quite vegetated, but like the Stepping Stone 1
location, it was within sight of a more suitable, partially stabilized dune; one that had the
potential to already act as a stepping stone due to the amount of exposed sand. This new
location was also within 200 m of the original location. The UTM coordinates of this
higher quality dune were 12U 548399 5607202. Again, I looked at this location using
GIS and determined that it also did not satisfy the location requirements, as it was not
within 1.6 km of adjacent occupied dunes. The location for Stepping Stone 4 did not have
any sandy patches remaining and had a large amount of shrubs and trees growing. I could
59
not see any other dunes in the vicinity that would better serve the purpose of a stepping
stone. Therefore, Stepping Stone 4 should remain at the original location, but this site
may take a greater effort to restore because it was more vegetated. After verifying the
stepping stone locations in the field, it is evident that the four locations found using GIS
are viable and should be considered for restoration.
2.4 Discussion
To increase the likelihood of Ord’s kangaroo rat metapopulation persistence in
Canada, management methods such as the restoration of habitat to connect isolated subpopulations, are key (Environment Canada, 2012). My study investigated kangaroo rat
recapture distances in Alberta and looked at the potential for using stepping stones to
functionally connect isolated habitats. This information may have the potential to help
reverse the decline of the Ord’s kangaroo rat in Alberta.
Based on my recapture analysis, kangaroo rats in Alberta were estimated to have
limited dispersal abilities relative to the distances separating dune habitats, with
movement distances of 1.6 km being insufficient to reach most neighbouring dunes. If
kangaroo rats could all disperse as far as the maximum observed movement of 3.2 km,
many more dunes could become accessible. But because the majority of kangaroo rats
observed moved much shorter distances, many dunes remain isolated. Being a smallbodied animal, their dispersal abilities are not predicted to be extensive (Sutherland et al.,
2000), and it does not come as a surprise that the Ord’s kangaroo rat moves relatively
short distances with respect to inter-dune distances (Figure 2.4; Table 2.3).
60
Observations from the kangaroo rat monitoring database indicate that many highquality, actively eroding dune sites were found to be minimally occupied or completely
unoccupied. In fact, by 2015, most dune sites on CFB Suffield had less than 5 individuals
each (Bender, unpublished data). These were sites that had large areas of sparsely
vegetated sand, prime habitat for kangaroo rats. I did not directly research the reasons
behind these small numbers, although I suspect that the relative isolation of the dunes is
preventing dispersal and recolonization. This is precisely why stepping stones have the
potential to be so advantageous. Although some sites may theoretically be accessible by
the best dispersers, there are likely many kangaroo rats that do not move as far (see
Figure 2.4), and even when they do they may not find habitat. Rescue and recolonization
is not likely to occur if kangaroo rats cannot reach adjacent habitats through dispersal.
According to Bascompte & Sole (1996), neighbouring patches of available habitat may
become so isolated that recolonization becomes quite challenging following a local
extirpation event. Curtis (1956) stated that immigrants from unaffected areas could
quickly heal extirpated sub-populations but also that patch isolation could effectively
remove that possibility, leaving isolated patches unoccupied. It is also possible that,
although a dune might be highly connected, the dunes to which it is connected are
otherwise isolated. If a dune is not connected to occupied dunes, there is no potential for
immigration from those habitats. Predation might also play a role in the lack of occupants
with kangaroo rats being prey for a large variety of species (Gummer, 1997a; Johnson &
Hansen, 1979; Smith & Murphy, 1973). Finally, there is also a stochastic component.
There can be large fluctuations in sub-population sizes at dunes and the causes of these
fluctuations remain unknown. For example, Woodhouse Dune has had productive years
61
but at the time of writing, I only observed one individual. These are all suppositions that
may help explain why I observed high-quality habitats that were unoccupied.
2.4.1 Dispersal distance
The majority of kangaroo rats that moved through natural grassland habitat were
found to move distances that would be insufficient to reach other dune habitats, should
they attempt to disperse (Figure 2.4; Table 2.3). The results of this study indicated that
stepping stones would be necessary to facilitate natural dispersal within dunefields. With
the space between dune habitats likely exceeding the dispersal ability of the majority of
kangaroo rats, it is particularly crucial that such methods of habitat management be
implemented to prevent or mitigate further dune loss, isolation, and fragmentation.
The maximum distances that kangaroo rats were observed to move in Alberta (3.2
km through grassland and 9.5 km along a road) exceed the dispersal distances reported
for other species of kangaroo rats (See Appendix B, Table B1, Table B2, and detailed text
below). Many studies have been conducted on the dispersal ability of multiple kangaroo
rat species (Gummer, 1997a; Jones, 1989; Price, Kelly, & Goldingay, 1994; Skvarla et
al., 2004; Waser & Elliot, 2001; Williams, unpublished data).
The dispersal ability of the Stephen’s kangaroo rat (Dipodomys stephensi) has
been estimated based on the recapture of individuals surviving >2 months, displaying
movement distances up to 323 m for males and 351 m for females (Price et al., 1994).
However, the study area consisted of continuous kangaroo rat habitat (2 km long and 0.5
km wide), making long-distance dispersal unnecessary. The giant kangaroo rat
(Dipodomys ingens) shows dispersal distances up to 99 m for males and 122 m for
females and occasionally long distance dispersal events up to 700 m have been observed
62
(Williams, unpublished data). The dispersal distances in Merriam’s kangaroo rat
(Dipodomys merriami) were estimated using two different proxies (Jones, 1989).
Merriam’s kangaroo rats were found to disperse up to 250 m and 158 m for males and
females respectively when the distance between first and last capture was used as a
proxy, while the maximum dispersal distance was 265 m and 158 m for males and
females respectively when using home range centers as a proxy. The largest site
examined by Jones (1989) was only 0.8 km x 0.8 km, which may be why comparable
dispersal distances were not seen. Both Jones (1989) and O’Farrell (1980) attribute these
dispersal events to changes in resource distribution and social pressures. Zeng & Borwn
(1987) also studied dispersal in Merriam’s kangaroo rat, and although they did not give
specific distances, they claim to have observed movements of more than 350 m in adults
of both sexes. Eight sub-populations of banner-tailed kangaroo rats were studied within a
2 km x 3 km area in Arizona, with populated habitat patches being separated by a few
hundred meters of unsuitable vegetation. Kangaroo rats in this area were shown to move
under 50 m for most dispersal events (Skvarla et al., 2004). Few individuals were
observed dispersing, even when adjacent habitats were only a few hundred meters away.
They concluded that neighbouring patches were likely genetically separated because
approximately one individual from one sub-population dispersed to a neighbouring subpopulation every two generations. Season is believed to influence their dispersal, with
dispersal events maximizing breeding opportunities and seed availability. The lack of
habitat isolation is also interesting to note. Dispersal distances did not have to be as great
as those in Alberta, because the habitat patches were all relatively close to one another.
According to Waser and Elliot (2001), the dispersal distances of banner-tailed kangaroo
63
rats increased when sub-populations were at low densities. This is because habitats had
more vacancies and were open to immigration. Alberta kangaroo rat sub-population
densities are also quite low, which may help explain one of the reasons why longdistance movements are observed. With my study taking place over a large expanse of
land and over many years, I had the ability to recapture individuals at relatively large
distances away from their first capture site. This may explain why I am reporting longer
recapture distances, even though most previous recapture data indicate that most
movements do not exceed 500 m (COSEWIC, 2006; Gummer, 1997a). It has become
evident that kangaroo rats in Alberta are displaying longer recapture distances than those
of other species in other areas.
Many of the dunes in the Middle Sand Hills are not situated within 500 m from
one another (Table 2.3). Thus, isolated sub-populations require multiple areas of
interconnected suitable habitat to allow for dispersal between dunes (Gummer, 1997a). In
certain circumstances, the presence of roads may contribute to long-distance dispersal
events, such as the 9.5 km dispersal event observed on Double Wide Scrape. This is
possible because sandy roads have minimal ground cover and are linear, facilitating
highly directed movement. In other cases, roads might act as both a barrier and an
attractive sink. If a road runs between two natural habitats (i.e. eroding sand dunes) and
does not connect them, it can serve as an attractive sink because dispersing kangaroo rats
gravitate towards its open, often sandy, habitat (COSEWIC, 2006; Heinrichs et al., 2010;
Teucher, 2007) even though roads are low quality (Heinrichs et al., 2010; Teucher, 2007).
They have greater soil compaction than dunes, increased predation (Teucher, 2007), and
poor seed quality (Gelbard & Belnap, 2003; Gummer et al., 2005). But, because kangaroo
64
rats do not recognize them as low-quality, they may stop dispersing after encountering
sandy roads and will not continue on to higher quality dune habitats (Heins et al., 2004).
In fact, according to a model performed by Heinrichs et al. (2010), the removal of road
sink habitats could actually improve kangaroo rat metapopulation persistence. Roads may
also re-direct dispersing kangaroo rats so that they never reach any sand dunes (Henirichs
et al., 2010). In this way, roads can act as barriers and corridors, depending on the source
location of dispersing kangaroo rats.
With an estimated maximum dispersal distance of 3.2 km through natural habitat,
there is potential for kangaroo rats to have access to more than one habitat in areas where
dunes (or other natural sites) are in higher densities, such as within the Amiens region of
CFB Suffield. However, the maximum distances observed were not typical for most
individuals, with most recapture distances falling well below 3.2 km, averaging 40.1 m.
The isolation of dunes increases the susceptibility of dispersing kangaroo rats to
predation because they lack the knowledge of the area, and therefore have difficulty
finding escape routes, and they are exposing themselves for longer periods of time
(Gummer, 1997a; Metzgar, 1967). Reducing the isolation of habitat patches through the
addition of stepping stones can facilitate dispersal as well as limit exposure of kangaroo
rats to predation, and increase the number of successful dispersal events.
2.4.2 Stepping stones
The results of my analysis indicate that only four stepping stones are necessary to
functionally connect the majority of dunes in the Amiens region, with the exception of
the Carbine dunes, which would require more than one stepping stone to make dispersal
possible between them and the other dunes in the area. Thus, six or more stepping stones
65
would likely facilitate dispersal between all of the dunes in the Amiens region, but my
goal was to determine the areas that only required one stepping stone to functionally
connect two or more dunes. Furthermore, the majority of dunes in the Amiens region will
be accessible through dispersal with the addition of the four strategically placed stepping
stones.
My algorithm was successful in theoretically determining where stepping stones
were required to functionally connect dunes. However, after visiting each stepping stone
site in person, I realized that one site in particular might not be as vital as originally
thought. Stepping Stone 3 was located in close proximity to a semi-stabilized dune. This
dune was higher in quality than the stepping stone as there were multiple patches of
exposed sand. Even though it was only 200 m away from the stepping stone, it was not
within the buffer overlap zone and therefore it was theoretically unreachable through
dispersal. Considering that some aspects of my estimates of maximum dispersal were
arbitrarily defined, it is possible that some kangaroo rats do have the ability to reach the
alternate stepping stone location through dispersal. It is also possible that the alternate
location already has the potential to serve as a stepping stone without alteration.
Therefore, I suggest that before any stepping stones are created at the Stepping Stone 3
location, further research is conducted to determine if restoration is truly required at the
site. Such research will involve more detailed observations of dispersal and monitoring of
the alternate site to see if kangaroo rats are using it, even if only briefly. If it is
determined that the original Stepping Stone 3 location is still optimal, habitat restoration
can proceed at that site.
66
All of the stepping stone sites were within 1 km of a grassy trail, allowing for
wheeled vehicles to come relatively close to each site. Being able to easily access the
stepping stones is not necessary but is beneficial, as it is easier to perform the measures
required to restore and maintain them. Bender (2009) performed controlled burns in the
Middle Sand Hills with reported success. Dunes had suitable habitat for 3-5 years postburn, and then began to vegetate once again. This indicates that controlled burns can be
used to temporarily increase the habitat quality at dunes. However, to maintain this
increased quality, the burns must be repeated periodically. Bender (2009) also tested the
use of rubbing posts and mineralized salt licks to attract ungulates and stimulate erosion.
He found that when used alone, they did not have a significant effect, but when used in
combination with controlled burns the treatment resulted in a 100% success rate for
kangaroo rat establishment. More extreme methods such as mechanical or herbicidal
removal of vegetation need further investigation (Alberta Environmental and Sustainable
Resource Development, 2013), although they should be addressed with caution as they
have greater potential for harm. If mechanical methods are studied, it may be better to
conduct research in less vulnerable areas outside of the National Wildlife Area (Bender,
personal communication, 2015). It is important to thoroughly research each restoration
method to minimize potentially negative consequences for kangaroo rats or other species.
Environmental assessments can be used to identify the consequences of restoration and
how to maximize the benefits (Parks Canada & Canadian Parks Council, 2008). Adaptive
management trials can be performed on smaller scales, testing different restoration
techniques, and monitoring the results (Clarke, Stokes, & Wallace, 2010).
67
2.4.3 Limitations of this study
Although this study was effective at using recapture distances to estimate
kangaroo rat dispersal ability and at determining where stepping stones could be the most
valuable, there were a few limitations. I had to make a number of assumptions in my
study because there remains some uncertainty in our knowledge of kangaroo rats and
because of logistical constraints. I was unable to directly measure kangaroo rat dispersal
and was therefore limited to using recapture distances as proxies for dispersal
movements. I assumed that at least some of the movements observed between the capture
and recapture of kangaroo rats included dispersal. It is likely that most of the recapture
distances were not dispersal events at all. However, given that most kangaroo rats do not
typically venture far from their burrows (Behrends et al., 1986; Schroder, 1979), it is
unlikely that the long-distance movements in the recapture database were daily
movements, so they probably represent dispersal events.
I also assumed that the observed distances were representative of the
metapopulation as a whole and that the maximum recapture distances observed in the
database reflect the maximum distances kangaroo rats could disperse. A potential
limitation resulting from this assumption is that dispersal could have been
underrepresented. If juveniles are more likely to disperse (Bender et al., 2010; Gummer,
1997a) then there is only a narrow window within which to capture the individuals before
they leave their natal site, making it difficult to capture them all. There are at least three
reasons dispersal could have been underrepresented: (1) I did not capture the individual
before the dispersal event, (2) I did not capture the individual after the dispersal event, or
(3) I did not capture the dispersing individual at all. Therefore, it is possible that some
68
kangaroo rats can and did move longer distances but were not recorded. This would mean
that inter-dune gaps exceeding 3.2 km might actually be traversable by some individuals,
making such dunes less isolated than I predicted.
I had to make assumptions about how kangaroo rats move through the landscape
with its various types of land cover, which I assumed to be homogeneous in Alberta. It is
possible that kangaroo rats could perform better or worse than expected when dispersing
through different varieties of land cover, which affect the estimated dispersal distances
and ultimately the optimal locations for stepping stones. For example, if I underestimated the impact of landscape heterogeneity on kangaroo rat dispersal, then it would
not necessarily be accurate to represent the area over which kangaroo rats can disperse
using a circular buffer. By assuming the matrix was homogeneous from the perspective
of a kangaroo rat when it was in fact heterogeneous, the optimal stepping stone locations
may not functionally connect isolated habitat patches and natural dispersal would not be
facilitated, especially in areas where vegetation is dense.
I also assumed that not every individual could move 3.2 km so I decreased the
radius of the dispersal buffer I created to better reflect the ability of the species in
Alberta. I chose a value of 50%. Had I used a larger percentage, more dunes would have
appeared as accessible and perhaps would not have required stepping stones to facilitate
dispersal. If I had used a smaller percentage more dunes would have appeared as
inaccessible through dispersal, which would have likely resulted in a greater number of
stepping stones required to facilitate dispersal. The number of stepping stones required to
facilitate dispersal depends on the dispersal buffer radius used in the algorithm.
69
There could also be some disadvantages to creating stepping stones, which should
be considered before implementation. If a dune is chosen for restoration and it is does not
remain active, then the area of usable habitat could shrink and habitat quality could
decrease. If this happens, they could end up acting as population sinks where the rate of
mortality and emigration exceeds the rate of birth and immigration. In some cases,
habitats can act as both sources and sinks, maintaining a high rate of population growth in
some situations while displaying high mortality rates in others (Heinrichs et al., 2010). If
a stepping stone does turn out to be a sink, the metapopulation would be more stable
without it (Heinrichs et al., 2010). This is why it is important to make sure the
prospective stepping stone sites are geomorphologically appropriate, large enough to
sustain a stable sub-population, and have native plants and open sand to meet the needs of
the kangaroo rat. In my algorithm, I made the assumption that as long as the dunes
targeted for restoration were similar in size to other occupied dunes and had evidence of a
sandy composition, they would all be suitable for restoration. However, this may not be
the case. If this algorithm is used in future studies, I would recommend consultation with
a geomorphologist to assess if the dunes at the selected locations are in fact restorable.
Stepping stones may also function as sinks if they are created before adequately
assessing the surrounding area. For example, if they are created in the vicinity of badger
burrows, coyote dens, or any other potential predators, they may be subjected to higher
rates of predation. Therefore the location of stepping stones should be assessed not only
for their accessibility via dispersal, but also for their proximity to potential threats.
As briefly mentioned earlier, the creation of stepping stones may also have the
potential to negatively affect other species in the area. Not every organism is adapted to
70
sand hill habitats and the restoration of a stabilized dune may have adverse effects on
species that currently live or rely on the stabilized dune habitat. Pre-restoration studies
should be performed to determine if dune stabilization could result in significantly
negative consequences for other species occupying the habitat.
I would recommend that future studies continue to investigate kangaroo rat
dispersal abilities and movement patterns using direct measurements and frequent
observations starting in early spring because this is when kangaroo rats are expected to
begin dispersing (Bender et al., 2010). Tracking devices such as radio collars can be used
to assess the dispersal ability of adult kangaroo rats. They can be used to obtain frequent
location information, which will both allow for direct distance measurements and a
greater understanding of how well individuals move through various land cover types.
Although radio collars should not be used on juvenile individuals as they are still
growing, research focussing on the capture of young individuals at natal sites before
dispersal occurs could also be informative. As mentioned earlier, it is expected that
juveniles are more likely to disperse (Bender et al., 2010; Gummer, 1997a), so if they can
be captured before they potentially disperse from their natal territory, it is more likely
that we will obtain information on successful dispersal events.
2.5 Conclusion
In summary, the current distance between many habitat patches in the Amiens
region of CFB Suffield likely exceeds the estimated dispersal ability of Ord’s kangaroo
rats in Alberta. This is based on recapture data and subsequent generalizations about the
metapopulation as a whole. With the metapopulation heading towards extirpation, it is
71
critical that individual sub-populations have the ability to rescue and recolonize
neighbouring dunes through dispersal. I was able to use GIS to create an algorithm that
could determine and prioritize potential locations for future stepping stone habitat
patches. The restoration of these stabilized dunes through methods such as controlled
burns has the potential to facilitate kangaroo rat dispersal. Following further research, the
addition of stepping stone patches should be considered as a method of metapopulation
management.
72
Chapter Three: Translocations
3.1 Introduction
With high rates of extinctions occurring worldwide (Fahrig, 2003), management
tools need to be developed and implemented to curb the continued loss of species. Many
conservation efforts have been studied and implemented in an attempt to mitigate these
problems (Rudnick et al., 2012). This study will focus on one tool in particular,
translocations. A translocation is the intentional movement of a wild animal by a human
from one location to another (IUCN, 1987; IUCN/SSC, 2013). Translocations have been
proposed as one of the methods to mitigate the effects of habitat loss and fragmentation.
Conservation translocations aim to improve the conservation status of a species and/or
restore natural ecosystem functions (IUCN/SSC, 2013). Translocations can be used to
temporarily treat the symptoms of habitat isolation and, with continued use, can increase
sub-population sizes and aid in genetic restoration by decreasing inbreeding depression,
maintaining local adaptation, increasing the population size, and restoring historical
levels of genetic diversity (Bouzat et al., 2009; IUCN/SSC, 2013). Translocations can
also create satellite sub-populations that serve as a reservoir of individuals that can
recolonize nearby sites, should local extirpation take place (Ewans, Brockwell, Gani, &
Resnick, 1987; Greipsson, 2011). Having local sub-populations throughout the landscape
distributes the threat of unpredictable demographic and environmental impacts over many
sub-populations as well as provides genetic rescue, which increases the fitness and
genetic diversity of a sub-population by introducing new alleles (Thrall, Richards,
McCauley, & Antonovics, 1998). Demographic rescue increases the number of
individuals in a sub-population, which decreases the risk of local extirpation due to
73
variation in survival and reproduction (Morrison, Marcot, & Mannan, 2006). Immigration
from other patches in the metapopulation can provide such a rescue effect (Brown &
Kodric-Brown, 1977), especially in small sub-populations (Stacey & Taper, 1992). If
inter-patch dispersal is increased, local extirpation may be prevented (Harrison, 1991).
My study investigated whether translocations are an effective conservation tool for
rescuing and recolonizing Ord’s kangaroo rat habitat patches that had few to no kangaroo
rats occupying them.
3.1.1 The benefits of using translocations in the Alberta kangaroo rat metapopulation
Many dune habitats have become isolated following dune stabilization and
landscape fragmentation, with the extent of open sand in the Middle Sand Hills
decreasing by up to 40% on average per decade between 1949 – 2005 (COSEWIC, 2006;
Hugenholtz et al., 2010). With the loss of so many dunes, habitats have become more
isolated and functional connectivity has decreased.
The Alberta metapopulation of Ord’s kangaroo rat may benefit from a successful
program of translocations to rescue sub-populations or recolonize habitats (Alberta
Environment and Sustainable Resource Development, 2013; Environment Canada, 2012).
With kangaroo rats heading towards extirpation in Canada, successful translocations can
be used to facilitate both rescue and recolonization by moving kangaroo rats from
productive source patches to declining sub-populations or recently extirpated patches.
This can increase the likelihood of survival for the translocated individual as well as
introduce new alleles to the population into which they are released. However, there is
very little information on whether or not translocations can be performed successfully in
the Alberta Ord’s kangaroo rat. Translocations have been performed with limited success
74
in other kangaroo rat species, such as the Tipton’s kangaroo rat (Dipodomys nitratoides
nitratoides)(Germano, 2001), Stephen’s kangaroo rat (Dipodomys stephensi) (Baker,
2014; Shier & Swaisgood, 2010), San Bernadino kangaroo rat (Dipodomys merriami
parvus) (O’Farrell, 1999), and the giant kangaroo rat (Dipodomys ingens) (Williams et
al., 1993). These translocations had varied results ranging from great successes and high
survival rates to translocations yielding high mortality rates. For example, Williams et al.
(1993) translocated 30 giant kangaroo rats to an unoccupied site and reported higher rates
of reproduction than the source sub-population, witnessing population growth at the
release site for two years post-release. In the same study, when 30 other kangaroo rats
were translocated to areas that had a higher number of predators, high mortality rates
were observed with only one individual remaining by the end of the year. O’Farrell
(1999) translocated San Bernadino kangaroo rats, resulting in a 40% survival rate at the
release site. Of those that survived, all were shown to be reproductively active and new
offspring were observed. Germano (2001) conducted a number of successful
translocations of Tipton’s kangaroo rats, but he also conducted translocations that
resulted in high mortality rates caused by random unpredictable events. For example, one
translocation of 33 kangaroo rats resulted in only one survivor due to extensive rain
(which caused artificial burrow collapses) and site destruction by cattle. Furthermore,
some studies yielded inconclusive results, where individuals observed at the release sites
were not conclusively identified as translocated kangaroo rats or where causes of
mortality were unknown (Germano, 2001). These examples highlight the need for
translocation research across different species as results vary greatly between studies.
Translocations have not yet been performed on Ord’s kangaroo rats in Alberta, so the
75
feasibility of using translocations successfully remains unclear. The goal of my research
is to fill this gap in knowledge by determining if experimental translocations can be used
with success. Before implementing such measures, a variety of considerations must be
taken into account.
3.1.2 Design considerations
Bender et al. (2010) developed the Translocation Protocol for the Ord’s Kangaroo
Rat (Dipodmys ordii), which outlines important translocation considerations and
summarizes the methods that are most likely to result in successful translocations. Most
of the factors I discuss and use are outlined in the protocol and I considered them when
performing my translocations. By doing so, I sought to maximize the benefits of the
translocations and increase the chances for success.
The Ord’s kangaroo rat translocation protocol (Bender et al., 2010) states that
when trying to facilitate rescue and recolonization, ideal source sites are those that are
lower in habitat quality such as roads or habitats that exhibit high seasonal densities that
could lead to resource depletion. When possible, road sites with higher densities should
be targeted for kangaroo rat extraction because the removal of individuals from lowdensity sites can limit breeding opportunities for those that remain (Bender et al., 2010).
Natural dune sites that have high densities should be targeted as well considering that
juveniles are already likely to disperse (Bender et al., 2010) and the removal of
individuals from such productive sites is unlikely to negatively impact the population
dynamics of the source site.
The quality of the habitat to which the translocated animal is being released can
determine the success or failure of a translocation (Greipsson, 2011; Griffith, Scott,
76
Carpenter, & Reed, 1989; IUCN/SSC, 2013; 1989; Kleiman, 1989). If chosen
thoughtfully, the target sites will fulfill the ecological requirements of the organism,
providing suitable habitat both in area and quality (Greipsson, 2011; IUCN/SSC, 2013).
Such requirements include food, shelter, and foraging areas. For kangaroo rats, dune sites
are higher in quality and are less susceptible to predation and parasitism than linear
anthropogenic features such as roads and trails (Robertson, 2007; Teucher, 2007), which
are believed to act as metapopulation sinks (Henirichs et al., 2010). Road habitats are also
subject to soil compression, which increases heat loss through thermal conduction
(Teucher, 2007; Liddle & Moore, 1974). Soil compaction has also shown to decrease
burrow depths in other studies, further increasing heat loss (Germano & Rhodehamel,
1995). Because dune sites offer loose, sandy soils, kangaroo rats have warmer burrow
temperatures (Teucher, 2007). They also have the option of burrowing on the south
facing slopes of dunes, which receive higher solar radiation, warming the burrows
(Teucher, 2007). This means kangaroo rat translocations have the potential to decrease
hypothermia in those that are moved from road sites to natural dune sites. This is a clear
advantage to translocations because a significant cause of individual over-winter
mortality is hypothermia (Gummer, 1997a). Habitat quality aside, dune sites are also
more likely to have forage that is both higher in quality than road sites (i.e. more nonnative seeds) and more plentiful than at high-density dune sites (Gelbard & Belnap, 2003;
Gummer et al., 2005, Teucher, 2007). Furthermore, Germano (2010) reported that
mortality due to intraspecific aggression at release sites often occurred if there were
resident kangaroo rats present. By translocating to high-density sites, kangaroo rats
would end up expending more energy negotiating relationships at the new site, rather
77
than foraging and performing other necessary duties (Randall, 1989; Shier & Swaisgood,
2010). Goldingay, Kelly, & Williams (1997) reported negative interactions between
translocated Tipton’s kangaroo rats (Dipodomys nitroides nitroides) and resident
kangaroo rats, while Randall (1989) stated that Merriam’s kangaroo rats displayed more
aggression towards unfamiliar individuals. Thus, optimal release sites would be those that
are higher quality and have few to no kangaroo rats present. This minimizes competition
and territorial aggression, allowing for more opportunities to explore the site and settle in.
Timing is also important. Translocations should be conducted in the spring to
allow time to accumulate seed caches that will sustain the kangaroo rats through the
winter at the new site, and to minimize the spread of bot fly parasitism, which intensifies
in the summer with infection typically beginning in late June to early July (Robertson,
2007; see also Bender et al., 2010).
The type of release must also be considered. There are two types of releases:
(1) hard-releases, and (2) soft-releases. A hard-release would involve releasing
translocated kangaroo rats into the new environment without any provisions. Softreleases entail the provision of food and shelter for the individual at the site of release,
and they occasionally include temporary confinement (Bender et al., 2010; Bright &
Morris, 1994). There has been reported success with soft-release methods, including a
study performed by Davis (1983) comparing the success of soft and hard releases in
translocated marten. There are three potential reasons for this: (1) food is provided and
individuals do not have to travel as far to forage, (2) the attachment to a particular area
helps to decrease disorientation, and (3) territorial pressure is minimized (Bright &
Morris, 1994).
78
3.1.3 Objectives
The purpose of the research presented in this chapter is to evaluate the feasibility
of kangaroo rat translocations in Alberta by assessing the success of experimental
translocations. The duration of site occupancy (short-, intermediate-, or long-term; see
definitions below) is used as an indicator of success. In the broader sense, I am interested
in the potential for applying translocations to manage the Alberta metapopulation. If
translocations can be performed successfully, they could be used to rescue declining subpopulations and recolonize unoccupied habitat patches. I also address translocation
potential in mitigating habitat loss due to anthropogenic development.
3.2 Translocation methods
3.2.1 Study area
Ord’s kangaroo rat translocations were conducted at various locations within the
species’ range in Alberta (Figure 1.2) between 2012 and 2014. The source and release
sites used can be seen in Figure 3.1. Further details about the study area can be reviewed
in Chapter 1.
79
Figure 3.1 Sites involved in the translocations performed between 2012 and 2014.
80
3.2.2 Performing translocations
Between 2012 and 2014, I translocated sixteen individuals: ten from productive,
high-density dune habitats and six from low-quality road habitats (Figure 3.1; Table 3.1).
All were all translocated to low-density, high-quality natural habitats. In total, four of the
sixteen kangaroo rats were radio collared.
81
Table 3.1 Translocations performed between 2012 and 2014 in the Middle Sand Hills of
southern Alberta (M= Male; F=Female). Empress Huge, Empress Big, Ypres West,
Bagnold’s, and Mounted Rifle are natural dune sites. Pipeline is a sandy river valley site.
Year
Source Site
Release Site
Age
Sex
2012
Empress Huge
Pipeline
Juvenile
F
2012
Empress Huge
Pipeline
Juvenile
F
2012
Empress Huge
Pipeline
Juvenile
M
2012
Empress Huge
Pipeline
Juvenile
M
2012
Empress Huge
Pipeline
Juvenile
M
2012
Empress Huge
Pipeline
Adult
F
2013
Empress Big
Empress Huge
Adult
F
2013
Empress Big
Empress Huge
Adult
F
2013
Empress Big
Empress Huge
Adult
M
2013
Empress Big
Empress Huge
Adult
M
2013
Mule Deer Rd.
Ypres West
Adult
F
2013
Double Wide
Ypres West
Adult
M
2013
Double Wide
Ypres West
Adult
M
2014
Butler's Tr.
Bagnold's
Adult
M
2014
Dugway Tr.
Mounted Rifle
Adult
M
2014
Dugway Tr.
Mounted Rifle
Adult
M
82
Translocations were performed in the spring of each study year. My intention was
to follow the translocation recommendations (Bender et al., 2010) and translocate
primarily from lower quality road sites. However, the number of kangaroo rats proved to
be a limiting factor and translocations were conducted more on an opportunistic basis.
Despite the small number of individuals from which to choose, I still only conducted
translocations that would increase the quality of habitat in which they were living. All
sixteen of the individuals were relocated to natural sites that had few to no resident
kangaroo rats present (Figure 3.1). All translocations took place during the night because
light causes stress in kangaroo rats (O’Farrell, 1974).
Translocated kangaroo rats were captured using identical methods for the
population surveys outlined in Chapter 2. I translocated adult and juvenile males and
females. I did not translocate reproductive females. This includes estrous, pregnant, or
lactating females. I avoided estrous females because I did not want to interrupt valuable
breeding opportunities. Removing kangaroo rats during the breeding periods can decrease
reproductive success (Tennant et al., 2013). I did not translocate pregnant females
because I did not want to cause them stress, and relocating them would force them to
have to create a new food cache, which would increase their exposure to predators and
use valuable energy. Lactating females were not considered because their young would
likely die if their mother were removed (Bender et al., 2010). I also targeted individuals
in a 50:50 sex ratio (Bender et al., 2010, Williams et al., 1993) to mimic that of nature
(Fisher, 1930). Although the goal was to find equal numbers of each sex, I was restricted
to translocating somewhat opportunistically because there were so few kangaroo rats to
select from. Therefore, I located and captured juveniles, reproductively inactive adult
83
females, and adult males at the source location.
The kangaroo rats were then placed in separate hard-cased, small-animal carriers
fitted with food and bedding and transported by vehicle to the new location. Distances
between locations varied, with the shortest translocations requiring roughly 20 minutes of
driving (2.5 km) and the longest taking approximately 1 hour to reach (47 km). Once I
arrived at the release site, the animal carriers were placed on the ground while I
constructed artificial burrows.
3.2.3 Radio collaring
Before releasing the individuals into their new burrows, some individuals were
radio collared. Radio collars can be useful for monitoring kangaroo rat movements,
which is a technique previously used to monitor Ord’s kangaroo rats in Alberta
(Gummer, 2005; Gummer & Robertson, 2003) and also used to monitor the Stephen’s
kangaroo rat (Dipodomys stephensi Merriam) (Behrends et al., 1986; Price et al., 1994),
Tipton kangaroo rats, and Heermann’s kangaroo rats (Germano, 2010). The collars were
used to assist me in locating the kangaroo rats upon my return to the site. Considering the
delicate nature of kangaroo rats and the fact that I had not used radio collars before, I
wanted to be cautious in my use of the collars so I only intended to apply a small number.
Another reason for not radio collaring every individual was because I wanted to be able
to separate the effect of the radio collar on the success of the translocation from the effect
of the translocation itself.
The radio collars were used opportunistically on adult kangaroo rats that did not
display outward indicators of stress (i.e. biting, thrashing, vocalization, loss of
responsiveness, etc.). This resulted in four kangaroo rats being fitted with 1.4 g VHF
84
radio collars (model BD-2CT, Holohil Systems Ltd., Carp, ON). Three were administered
in 2013 and one was administered in 2014. I did not radio collar juveniles because the
collar would become tight as they grew. Calm kangaroo rats were selected because
collars were administered without sedation, and struggling individuals were difficult to
collar. A quick collaring procedure was also less stressful for the kangaroo rat. The wire
that rested around the neck of the kangaroo rat was inserted into flexible, plastic Tygon®
tubing to decrease potentially painful friction, following the method previously used by
Gummer, 1997a, 2005). The collar was then slipped over the neck of the kangaroo rat and
using a small metal crimp it was fastened in place tight enough to ensure it could not slip
above the head but loose enough to allow for adequate movement and breathing
(Gummer, 1997a). I used R-1000 Telemetry receivers (150 MHz range) with RA-150
directional yagi antennae to locate the individuals after release and to eventually find and
recapture them to remove their collars before the end of the season or before their battery
life was exhausted (approximately 10 weeks).
3.2.4 Release of kangaroo rats
Kangaroo rats remained in their containers while I constructed artificial burrows
for a soft-release. I used this method of release in an attempt to allow the individuals to
become accustomed to their new environment, and to minimize stress and exposure to
predators immediately after release.
To construct the burrow, I dug a hole large enough to fit a small, biodegradable
cardboard box along with food (rolled oats) and cotton bedding in which to nest, as well
as a biodegradable cardboard tube that led from the chamber (box) to the surface
(Germano, 2001; Germano, 2010; Williams et al., 1993). The chamber was set back
85
roughly a meter from the tube opening at a depth of approximately 30 cm (Germano,
2001; Germano, 2010). I then covered the burrow with sand so only the opening of the
tube remained exposed. This would serve as the burrow entrance. The burrows were
located on south-facing sandy slopes where they would receive the most solar radiation
(Teucher, 2007). I aimed to have them in their newly constructed burrows before sunrise
so that they were not stressed further by the increasing light. In an attempt to minimize
intraspecific aggression, none of the artificial burrows were constructed within 50 m of
one another.
Once artificial nests were constructed and radio collars were attached (if
applicable), translocated kangaroo rats were then released into the artificial burrows.
Using a plastic plug, the entrance of each artificial burrow was temporarily sealed until
dawn. This prevented kangaroo rats from attempting to escape immediately upon release,
thwarting any chance for successful establishment. Escape of kangaroo rats immediately
following release has occurred in some translocations of the giant kangaroo rat, with
individuals having to be recaptured and placed back into the burrows (Williams et al.,
1993). Ambient light makes it easier for predators to capture kangaroo rats, so they tend
to avoid surface activity during the daylight hours (Lockard & Owings, 1974; Kaufman
& Kaufman, 1982). Therefore, the plug was only removed from the entrance once the sun
had risen and illuminated the dune. Ideally, this would discourage premature emergence
from the burrow and help the individual to become adjusted to their new environment.
The release sites were checked between two to seven days following release,
depending on environmental conditions, to determine if the translocated individuals had
remained up to that point. A minimum of two days was an arbitrary amount of time I felt
86
was necessary to minimize stress on the animal, given my knowledge of the species and
the fact that guidance from the literature was extremely limited. The locations were
monitored two to three times per month following the initial check, for the remainder of
the field season (two-three months). I continued monitoring the release sites in the
following field seasons with surveys conducted 1-3 times per month, depending on where
in the month the two-week survey period fell.
3.2.5 Evaluating the success of translocations
Ideally, to evaluate success one should compare the survival of a group of
translocated kangaroo rats to that of resident kangaroo rats. If the survival rates were
comparable, then this could be an indicator of a successful translocation. The success of a
translocation program should not necessarily be assessed at the individual level, but at a
sample/sub-population level, particularly for Ord’s kangaroo rats in Alberta where
underlying rates of mortality are high (COSEWIC, 2006). However, this requires a large
sample size and strong population information and if such information is not available,
then other methods must be considered, as described below. In this case, the sample size
of translocated kangaroo rats was quite small. By analyzing the population survey data I
could gain a general sense of what survival and typical activity was like for resident
kangaroo rats, and this could help me to establish increments of time upon which to base
translocation success.
I used the duration of site occupancy as an indicator of success for each
individual. The criteria for success was broken into four categories: (1) no evidence of
success, (2) short-term success, (3) intermediate-term success, and (4) long-term success.
The timeframes used to create the criteria for success were based on typical kangaroo rat
87
activity patterns (see Chapter 2), comparing the above ground activity of the translocated
kangaroo rats to the activity normally observed in resident kangaroo rats. A primary
indicator of occupancy was obtained if I recaptured the translocated individuals.
Secondary evidence of occupancy was obtained if I observed footprints and/or signs of
digging near the artificial burrows.
The indicator of success labeled ‘no evidence of success’ occurs when no
evidence can be found during monitoring to indicate the translocated individual remained
at the release site following translocation. This means there are no tracks, signs of
digging, or kangaroo rat sightings. This does not necessarily mean the translocation was
unsuccessful; it may be that the translocated individuals established at the release site but
were not detected, or that signs of occupancy did not point directly to that individual.
Given that kangaroo rats of various species generally limit their surface activities to short
bursts and sometimes only emerge for a total of 1 – 3 hours per night over a series of
quick excursions (Kenagy & Kenagy, 1976; Tappe, 1941; Schroder, 1979), their
detectability may often be limited. For example, on a particularly large dune like Empress
Huge Dune, it is unlikely every kangaroo rat will be captured and, unless tracks are
leading directly into and out of the artificial burrow, I would have no reason to associate
observed footprints elsewhere on the dune with the translocated individual. Studies have
shown that a high proportion of translocated animals die shortly after release (Short,
2009). Considering this, finding the kangaroo rat at the site (anywhere on the dune upon
which they were translocated) two days after release would indicate an absence of
obvious failure (Short, 2009; i.e., did not immediately abandon the release site), and
therefore, short-term success. If kangaroo rats are located at the release site during the
88
following activity period (i.e., the next new moon lunar period), roughly 3-4 weeks after
release, this is labeled an intermediate-term success. This indicates that the normal
activity pattern of the translocated kangaroo rats was not disrupted and activity did not
differ from what would be expected of resident kangaroo rats throughout the lunar cycle.
Long-term success occurs if a kangaroo rat is located at the release site during the
following spring survey. Observing a long-term success is not likely because of the high
rate of mortality in kangaroo rats. Up to 90 % of residents may not survive the winter
(Gummer, 1997a; Gummer, 2005). Therefore, mortality in translocated kangaroo rats
should also be expected. That being said, finding a translocated individual in the spring
following release signifies that the translocation was definitely successful, as they
survived a season that has been shown to be very difficult for most kangaroo rats.
Another indicator of long-term success would be if a translocated kangaroo rat
reproduced, yielding offspring that were found the following year at the release site.
Thus, not only would the translocated kangaroo rat be contributing the sub-population,
there would be potential for further growth with their offspring. Surviving offspring
could help re-establish sub-populations and ultimately decrease the risk of extirpation.
89
Table 3.2 Criteria for kangaroo rat translocation success in the Middle Sand Hills of
Alberta.
Success
Criteria
No evidence of success
No evidence that individual remained at the release
site but abandonment or mortality inconclusive.
Short-Term
Evidence of occupancy at the release site within 2 days
following the translocation.
Intermediate-Term
Evidence of occupancy at the release site during the
following activity period.
Long-Term
Translocated kangaroo rat or offspring were found at
the release site the following year.
90
3.3 Results
Over three years, 16 kangaroo rats were translocated (Table 3.1). Detailed
translocation observations can be viewed in Tables 3.3 – 3.7, while the translocation
successes are summarized in Table 1.6.
3.3.1 Translocation to the Pipeline site, 2012
Two of the six kangaroo rats translocated from Empress Huge Dune to the
Pipeline site on June 16, 2012 and June 25, 2012 showed signs of activity after release
into July (Table 3.3). They were no longer present in August. One burrow was crushed
shortly after the release date, while two more burrows appear to have been dug up by a
predator in August. No individuals were recaptured. It is possible that the kangaroo rats
moved elsewhere, but being such a large site it cannot be confirmed. Because two
individuals remained for at least a month, encompassing a full activity cycle, these
translocations were considered intermediate-term successes. The other four translocations
displayed no evidence of success.
91
Table 3.3 Translocation observations at the Pipeline site.
Identification
20129170
Release Date Release Site
Observations
June 16, 2012
-Burrow had tracks visible into
Pipeline
July. August 11, site was examined
and I did not find any evidence of
occupancy.
20127207
June 16, 2012
Pipeline
-Burrow had tracks visible into
July. August 11, site was examined
and I did not find any evidence of
occupancy.
20129630
June 16, 2012
Pipeline
-Crushed by ungulate sometime in
June. August 11, site was examined
and I did not find any evidence of
occupancy.
20128241
June 16, 2012
Pipeline
-August 11, site was examined and
I did not find any evidence of
occupancy.
20125077
June 24, 2012
Pipeline
-August 11, site was examined and
I did not find any evidence of
occupancy.
20126707
June 24, 2012
Pipeline
-August 11, site was examined and
I did not find any evidence of
occupancy.
92
3.3.2 Translocation to Empress Huge Dune, 2013
Of the four kangaroo rats that were translocated from Empress Big Dune to
Empress Huge Dune on June 4, 2013 there were two intermediate-term successes and two
that had no evidence of success (Table 3.4).
One female was located again seven days later on June 11, 2013 and outfitted
with a radio collar. She was captured again on July 4, 2013. The radio collar had a very
small area of exposed wire where the plastic tubing met the transmitter. The wire along
with a metal crimp became partially embedded in her neck. This created a skin abrasion
that became infected. She also got her front paw stuck between her neck and the collar
and was unable to remove it. The radio collar was promptly removed. Once the collar
was removed, she was able to stretch her leg out and she quickly regained the use of her
paw. Despite the irritation it caused the kangaroo rat, the radio collar was greatly
beneficial in locating her. She was recaptured again during a survey on August 12, 2013,
and it was determined that she was pregnant and healthy. Her abrasions had healed
completely and she did not appear to suffer any weight loss or other long-lasting negative
effects from the translocation or radio collar. I classified this as an intermediate-term
success because she was located up to 2 months following her translocation, which
encompassed two full activity cycles. I did not return to the site that year, so I was not
able to microchip her offspring. Therefore, I was not able to determine if her young
survived the winter. Although I cannot consider this a long-term success, her pregnancy
is encouraging. It indicates that she was established enough at the new site to invest
valuable energy into reproduction and it shows the potential for re-establishing the subpopulation through breeding.
93
There was evidence that the first translocated male had remained at its release site
on Empress Huge Dune. Six days after release, he was observed to still be using the
artificial burrow into which he was released. There was a well-established runway
leading out from the burrow in the weeks following the translocation. A month later, the
cardboard tubing was no longer visible in the burrow entrance, but the burrow still
appeared to be in use with tracks leading into the entrance. In fact, multiple entrances
were formed and there were dig sites located around the burrow and another burrow had
been constructed approximately 10 m away. Although I was unable to capture him, there
was evidence that the burrow was in continual use at least until July 4, 2013. The original
burrow had collapsed by the end of July and there were no more footprints around the
entrance. This indicated that he was present for a minimum of just over a month, which
encompassed a full activity cycle following release. This translocation was classified as
an intermediate-term success.
The other translocated male and female were not located again and there was no
sign of establishment. There were multiple burrows near the male’s artificial burrow, but
they may have belonged to other individuals. This does not mean that the individuals
abandoned the site or were killed. It only means that their fate is inconclusive. The site
was particularly large, taking many hours to survey, and it is possible that they had
created burrows elsewhere on the dune and we simply did not see them during our
surveys. However, because I was not able to locate them or any sign of their presence, I
labelled this translocation as ‘no evidence of success’.
94
Table 3.4 Translocation observations at Empress Huge Dune.
Identification
20139426
Date
Release Site
Observations
June 4, 2013
Empress Huge
-Observed June 11, recaptured and radio
Dune
collared. Original burrow not in use.
-June 15, radio signal indicated she was in a
new burrow.
-July 6, recaptured and radio collar removed
due to irritation.
-August 12, recaptured and found to be
pregnant and healthy.
20139230
June 4, 2013
Empress Huge
-June 11, no sign of occupancy. Burrow
Dune
had collapsed. Footprints in the vicinity,
but not certain who they belonged to.
-June 15, more sand covered the burrow.
-July 4, remains of burrow collected for
disposal.
-Aug 12, still no signs.
20137426
June 4, 2013
Empress Huge
-Observed June 11, running into burrow.
Dune
Runways were well marked and a new
burrow was found 10 m away.
-June 15, signs of activity around the burrow
entrance.
-July 4, cardboard tube no longer in entrance
but entrance still appeared to be in use.
-August 12, no longer finding signs of
occupancy. Burrow collapsed.
20139531
June 4, 2013
Empress Huge
-June 11, no signs of occupancy and mouse
Dune
found in burrow.
-June 15, burrow still in tact but no signs of
occupancy.
-July 4, burrow collapsed.
-Aug 12, no signs of occupancy.
95
3.3.2 Translocation to Ypres West, 2013
Of the three kangaroo rats translocated from the road sites to Ypres West Dune on
June 11, 2013 one displayed long-term success, one displayed intermediate-term success
and one had ‘no evidence of success’ (Table 3.5).
One of the two translocated males received a radio collar before he was released.
The site was initially surveyed 2 and 5 days after release and his radio collar had fallen
off due to a loose crimp. It was later located in the bowl of the dune. He appeared to have
remained at the site for a period of time after his release with evidence of occupancy up
to July 2, 2014. His artificial burrow had tracks going to and from the entrance up to a
month after his release, and more entrances were created in the vicinity. Considering that
intermediate-term success is defined by finding individuals occupying the release site in
the following active period after the release, the translocation qualifies as an
intermediate-term success. It is possible he remained longer than 1 month, but I did not
see evidence suggesting a longer duration of occupancy.
The single translocated female was given a radio collar, which subsequently
slipped to her abdomen after release and was promptly removed. The sun had started to
rise, so attempts to refasten the collar were not performed. The site was checked again on
June 13, 2013 and then on June 15, 2013. She did not appear to be using the artificial
burrow, and a mouse was found inside it. She was finally recaptured on August 2, 2013
and was followed to her new burrow. She was infected with two botflies but was
otherwise in good condition. The following summer I captured a juvenile male kangaroo
rat, which leads me to believe the translocated female remained long enough to
reproduce. Given that there was only one resident male at this site prior to the
96
translocations and no known females since 2007, it can be inferred, though not
confirmed, that the translocated female mothered the offspring I captured the summer
following her release. I do not believe any other females were present because we
thoroughly searched the entire dune multiple times throughout the four-month field
season, and it is unlikely that a female abandoned her food cache and burrow elsewhere
just before the onset of winter to move to a new site. This translocation was particularly
important because a new generation was established the following summer. This
indicates that there is potential for rescue or recolonization using translocations. As
described earlier, a long-term success is declared if the individual survives the winter or
their offspring is found on the dune. Because offspring were found the following year,
this was considered a long-term success.
The third male was never recaptured. The site was visited 2 and 5 days following
his translocation. The burrow had been stepped on and the entrance had partially
collapsed. Another burrow had been created 18 m from that location, with many
footprints around the entrance. However, I do not know who inhabited the burrow. There
were no definitive signs indicating his continued presence on the dune in subsequent
surveys and therefore the translocation was classified as ‘no evidence of success’.
97
Table 3.5 Translocation observations at Ypres West Dune.
Identification
Release Date
Release Site
Observations
20136687
June 11, 2013
Ypres West
June 13, collar had fallen off and was
collected. Burrow was in tact with signs of
occupancy.
-June 16, still had footprints and activity
around burrow.
-July 2, burrow was still in tact with many
footprints around burrow.
-Aug 2, no more signs of activity.
20138835
June 11, 2013
Ypres West
-June 13, no sign of female or use of burrow.
-June 16, still no sign of female or use of
burrow.
-July 2, mouse in burrow but no sign of
female.
-Aug 2, female recaptured and followed to
new burrow.
-July 27, 2014, offspring found. Juvenile
male.
20139267
June 11, 2013
Ypres West
-June 13, no sign of male or use of burrow.
Burrow entrance had been stepped on and
collapsed.
-June 16, burrows constructed 18 m away.
Not positive it belonged to him, however.
-July 2, many tracks leading to/from the
burrow entrance 18 m away.
98
3.3.3 Translocation to Bagnold’s Dune, 2014
The male kangaroo rat that was relocated from the two-track vehicle trail
(Butler’s Trail) in the Amiens Region of Suffield to Bagnold’s Dune on June 23, 2014
initially did not appear to remain at the dune (Table 3.6). When the site was checked a
few days after release, there were no signs that the kangaroo rat attempted to establish
itself at that location. The following spring, a burrow was located on the dune with active
runways leading from the burrow to the center of the dune. The site was checked again a
week after the active burrow was located, and there were no new signs of activity. In fact,
the burrow entrance had started to fill in with sand. When the site was checked a month
later, the burrow was absent and a kangaroo rat skeleton was located in the bowl of the
dune. Considering that Bagnold’s dune was not known to have any kangaroo rats present
since 2012, it is quite possible that the kangaroo rat occupying the dune was the
translocated individual and simply was not detected. It is also possible that he was living
near the dune for a period of time, before returning to it the following spring. However,
despite numerous attempts to scan the sand with a PIT tag reader, no microchip was
located so the individual could not be conclusively identified. I suspect this was a longterm success, but it cannot be verified. I have no direct evidence that the kangaroo rat
remained, so I must conclude that there was ‘no evidence of success’.
99
Table 3.6 Translocation observations at Bagnold’s Dune.
Identification Release Date
Release Site
Observations
20144446
Bagnold’s
-June 26, no sign of occupancy the
Dune
entire field season (until September).
June 23, 2014
-June 15, single active burrow found
on north side of dune. Runways
present.
resent.
-When checked 1 week later, burrow
was no longer in use.
-July 21, no signs of activity.
-August 31, no signs of activity.
-June 16, 2015 burrow found with
tracks and runways.
-June 23, burrow no longer in use and
no signs of activity.
-Kangaroo rat skeleton found in July
12, 2015 but no PIT tag was found.
100
3.3.4 Translocation to Mounted Rifle Blowout, 2014
Two kangaroo rats were translocated to Mounted Rifle Blowout in 2014. One was
a long-term success and the other was considered, ‘no evidence of success’ (Table 3.7).
The first male that was translocated from Dugway Trail to Mounted Rifle
Blowout on June 26, 2014 was a juvenile, and he remained at the dune throughout the
field season up until the end of the field season in late September. I was able to recapture
him to verify his identification. He had created a variety of burrows located on all sides
of the dune. He appeared to be in good health as he was free of parasites, had a silky coat,
and was a healthy weight (> 60 g). I returned to the site in the spring of 2015 and the
burrows were still present and active, with signs of activity throughout the dune including
tracks, digs, high-use trails, and runways at various locations. Considering that the dune
was previously unoccupied and that the site is quite isolated, and given how far most
kangaroo rats can disperse, I am fairly certain that the signs of activity were created by
the translocated individual. Therefore, because he survived the winter, this translocation
can be considered a long-term success.
I also translocated an adult male from Dugway Trail to Mounted Rifle Blowout
and radio collared him. Three days after the release I returned to the site and attempted to
locate the kangaroo rat using both regular survey methods as well radio telemetry. I was
not able to locate the kangaroo rat nor was I able to obtain a signal from his radio collar.
It is possible that the radio collar had failed; however that cannot be verified. I proceeded
to survey the area immediately surrounding the dune as well as all the roads in the
Amiens region, and the grassy habitat within roughly 2 km south, east, and west of the
dune. I surveyed the area north of the dune as well, but I did not survey north of Mounted
101
Rifle road as the vegetation was quite dense and it is unlikely the kangaroo rat would
move very far in that direction. I performed extensive surveys multiple nights throughout
the remainder of the field season but I was unable to determine his location. From the
evidence I gathered, it is unlikely that the individual remained at the site, but I cannot be
certain. Therefore, this translocation was labelled, ‘no evidence of success’.
102
Table 3.7 Translocation observations at Mounted Rifle Blowout.
Identification
Release Date
Release Site
Observations
20145573
June 26, 2014
Mounted Rifle
-June 28, artificial burrow was in use with
Blowout
runway and tracks leading to/from the
entrance.
-July 2, recaptured with more burrows
constructed around the site.
-July 5, evidence of activity such as
runways and footprints around burrows still
present. High-use trails created through
vegetation.
-July 20, more footprints and evidence of
digging.
-August 20, footprints and evidence of
digging.
-September 24, recaptured again. Healthy
with many burrows, runways, and high-use
trails.
-June 9, 2015, burrows still present with
activity.
-June 13, 2015, burrows still present with
activity.
-July 16, 2015, fewer burrows and less
activity.
August 13, 2015, No longer finding
evidence of occupancy.
20148237
July 2, 2014
Mounted Rifle
-July 5, No sign of the radio collared male,
Blowout
and no signal received from collar.
-Upon continued searches throughout the
July – September (see above), no signs of
occupancy were found.
103
3.3.6 Summary of Results
In total, over the three-year study period, five kangaroo rats showed intermediate
success and two showed long-term success. Nine translocations were labeled ‘no
evidence of success’ (Table 3.8).
104
Table 3.8 Kangaroo rat translocation success for individuals translocated between 2012
and 2014. Short-term success was indicated if the kangaroo rat was found at the dune
upon which they were released within two days after release. Intermediate-term success
was indicated if kangaroo rat was found at the dune upon which they were released
during the active period following release. Long-term success was reported if the
translocated kangaroo rats or their offspring were found at the dune upon which they
were released the following year.
Source Site
Release Site
Year
Age
Sex
Success
Empress Huge Pipeline
2012
Juvenile
F
Intermediate-term success
Empress Huge Pipeline
2012
Juvenile
F
Intermediate-term success
Empress Huge Pipeline
2012
Juvenile
M
No evidence of success
Empress Huge Pipeline
2012
Juvenile
M
No evidence of success
Empress Huge Pipeline
2012
Juvenile
M
No evidence of success
Empress Huge Pipeline
2012
Adult
F
No evidence of success
Empress Big
Empress Huge 2013
Adult
F
Intermediate-term
Empress Big
Empress Huge 2013
Adult
F
No evidence of success
Empress Big
Empress Huge 2013
Adult
M
Intermediate-term
Empress Big
Empress Huge 2013
Adult
M
No evidence of success
Mule Deer Rd. Ypres West
2013
Adult
F
Long-term
Double Wide
Ypres West
2013
Adult
M
No evidence of success
Double Wide
Ypres West
2013
Adult
M
Intermediate-term success
Butler's Tr.
Bagnold's
2014
Adult
M
No evidence of success
Dugway Tr.
Mounted Rifle 2014
Adult
M
Long-term
Dugway Tr.
Mounted Rifle 2014
Adult
M
No evidence of success
105
3.4 Discussion
With the Ord’s kangaroo rat in danger of extirpation in Canada, it is becoming
increasingly important to identify ways to manage the declining metapopulation. This
study sought to determine if translocations could be conducted with success and
subsequently be used as a conservation tool to increase metapopulation viability through
enhanced rescue and recolonization of isolated habitat patches with few or no occupants.
My intention was to compare the duration of translocated kangaroo rat occupancy to the
duration of occupancy in non-translocated individuals to see if the survival of
translocated kangaroo rats differed from the baseline rates of survival in resident
kangaroo rats. If there was not a difference, then the translocations could be considered
successful. However, the small sample size restricted my criteria for success, so I used
duration of occupancy of the translocated individual without direct comparison to other
kangaroo rats in the metapopulation. I obtained some clear examples of success, with five
intermediate-term successes and two long-term successes, but the majority of
translocations did not appear to indicate success. Some translocations were determined to
be successful while others did not give any indication that establishment had occurred.
Translocations that persist for at least one activity period (intermediate-term
success) have the potential to rescue and recolonize sub-populations. One of the females
who remained for a full activity period had become pregnant just over a month after her
release at the site. It is possible that some of the males who remained for a full activity
period bred as well, although I do not know if they fathered any offspring.
The long-term successes, where kangaroo rats survived the winter or where
offspring were found the following year, also indicate successful contributions to rescue
106
and recolonization. Translocated animals introduce new genes into the sub-population
and increase the number of individuals in the sub-population. Furthermore, long-term
successes indicate that not only can translocated individuals establish themselves
temporarily and sometimes breed, but they can also thrive. Kangaroo rats often struggle
to survive the harsh Canadian winters, with hypothermia and starvation claiming the lives
of numerous individuals (Gummer, 1997a). They are also a prey species for many
animals (see Chapter 1 for a list of predators). So, to observe a translocated individual
who was able to construct adequately deep burrows, accumulate seed caches, avoid
predators at the site of release (one of the primary reasons for translocation failure
(Germano, 2010; Greipsson, 2011; Short, 2009)), and occasionally breed, is indicative of
a thriving translocation.
This study used quantitative criteria to determine success, but my conclusions
were also supplemented with qualitative data. Therefore, not every ‘no evidence of
success’ necessarily indicates a failed translocation. Translocations that did not have
evidence of success were classified as such because it was unclear what became of the
translocated individuals. It is possible that some of those individuals remained on the
dune upon which they were released, and in some cases signs of activity were found to
suggest this was true. However, if they did not remain near the artificial burrow and I
could not recapture them, I could not determine if the tracks and burrows elsewhere on
the dune belonged to the translocated individual, a resident, or another colonizer. I was
unable to distinguish unoccupied sites from failures to detect kangaroo rats at occupied
release sites. Thus, it is quite possible that some of the translocated kangaroo rats that did
not show signs of occupancy were, in fact, successful. For example, the individual
107
translocated to Bagnold’s Dune was never recaptured, but the dune did have a burrow
located on it the following year with tracks and runways present. I even found a skeleton
of a kangaroo rat on the dune a short time after the burrow collapsed, but because the
microchip was not present I could not confirm the identity of the individual. Given that
the dune was previously unoccupied and the fact that in twenty years researchers have not
found any evidence indicating dispersal to the dune (likely because of its isolation), I
suspect the kangaroo rat was the one I had translocated and therefore a possible long-term
success. In another example, I suspect the last translocation to Mounted Rifle Blowout
was an unsuccessful translocation because the individual was wearing a radio collar and
the dune and surrounding area was searched extensively. If the kangaroo rat was present,
it should have been found. Those animals that disappeared without radio collars were
more difficult to assess because there was no evidence to suggest one result or another.
Assuming that they were no longer at the site, there are a variety of factors that could
have explained their absence.
3.4.1 Reasons why kangaroo rats may not have remained at the release sites
There are a number of reasons why translocated kangaroo rats may have not
established themselves at the release sites. First, kangaroo rats may have abandoned the
release site because of stress. Regardless of the measures taken to limit stress and injury
on the kangaroo rats, translocation are still very taxing events and the impact of increased
anxiety levels could influence whether or not individuals remained at the release sites
(IUCN/SSC, 2013). Stress can cause an increase in the cardiac and respiratory output of
an individual, an increase in blood glucose, a decrease in the production of both growth
and sex hormones, and decreased immunity (Chrousos, Phillip, & Gold, 1992; Padget &
108
Glaser, 2003; Tsigos & Chrousus, 2002). These factors can affect their survival at the
release site (Teixeira et al., 2007). Furthermore, stress can stimulate rapid dispersal from
the release site (IUCN/SSC, 2013).
It is possible that some of the translocated kangaroo rats abandoned the release
site in an attempt to return to their capture location. This is called ‘homing’, where an
animal tries to return to their home range after they have been translocated. Translocated
animals often have a strong drive to return to their home and they often abandon the
release site in an attempt to reach their original capture location (Villasenor et al., 2013).
Translocated kangaroo rats may have also been predated upon. Translocated
individuals are often more exposed to predation, as exploratory movements tend to
increase at the release site (Bright & Morris, 1994; Van Zant & Wooten, 2003; Villasenor
et al., 2013). In a study by Williams et al. (1993), all of the translocations failed when
released into a location where predators were present, while those released in areas
protected from predators survived. Translocated kangaroo rats are unfamiliar with their
surroundings and areas of cover and are more vulnerable to predation, at least until they
increase their familiarity with the site (Germano, 2010). I suspect this might be what
happened to second male translocated to Mounted Rifle Blowout because I was unable to
locate him or obtain a signal from his radio collar. It is unlikely that the kangaroo rat
travelled out of the signal range for the radio antenna in such a short period of time on his
own, which also leads me to believe he was predated upon.
It is also possible that intraspecific aggression resulted in the abandonment or
even mortality at some sites. Kangaroo rats are territorial animals and will often fight
each other, especially if they are unfamiliar with one another (Randall, 1989). Such
109
aggression has been observed to result in mortality in some instances (Germano, 2010). I
targeted low-density release sites, so I believe this outcome to be less likely.
3.4.2 Evaluating quantitative and qualitative approaches to determining translocation
success
As previously mentioned, it is possible that some translocated kangaroo rats did
remain at their release site but were simply not detected. The translocation guidelines that
I followed (see Bender et al., 2010) were created to promote successful translocations.
However, guidelines have not been created to assess what constitutes as a successful
translocation. My criteria for success were quantitative as I used clear-cut time
measurements to indicate short-, intermediate-, or long-term success, although evidence
of occupancy relied on both quantitative and qualitative data. Recapturing a translocated
kangaroo rat would be the best indicator of occupancy, so my primary monitoring goal
was to find and capture them just long enough to scan for their microchip. If I was
unable to recapture a translocated individual, I searched for secondary evidence of
occupancy, such as footprints and signs of digging near the entrance of the artificial
burrow. I could not distinguish if footprints elsewhere on the dune were from the
translocated kangaroo rat or resident kangaroo rats (if the dune had other nontranslocated occupants). Therefore, if kangaroo rats were not recaptured, it was not
possible to conclusively determine if they represented a successful translocation; my
conclusions were inferred based on the available evidence. Despite these uncertainties, I
have still been able to confidently demonstrate that some translocations have the potential
to be successful. In fact, considering the points mentioned above, my study may
underestimate rates of establishment and the degree of success for my translocation trials.
110
3.4.3 Increasing future reliability of translocation assessment
The post-release monitoring program is the means by which translocation success
is measured and is therefore important (IUCN/SSC, 2013). I monitored the kangaroo rats
in the short-, intermediate-, and long-term (days, weeks, months, and 1-2 years post
release), making the study robust. By checking on the release sites at multiple intervals, I
was able to determine if the kangaroo rat remained for days, weeks, months, or even
years. I had to reflect on my own practices in situations where kangaroo rats did not
remain at the release site, to try and determine if the translocation process itself (duration
of confinement, radio collaring, location of burrow on the dune, etc.) could have caused
individuals to leave the site. However, as I was also conducting population surveys at the
same time, I was unable to survey the release sites as frequently as I would have liked to.
To determine exactly how long each kangaroo rat remained at each site as well as
possible reasons for abandonment/mortality, more frequent (perhaps weekly) monitoring
could be beneficial. For example, Germano (2010) monitored radio collared kangaroo
rats once a day for seven days. Those that survived seven days were then tracked every
three days for roughly a month. Any surviving kangaroo rats were recaptured and their
collars removed. Therefore, along with frequent monitoring, radio collars may also
increase certainty of results. Furthermore, I conducted my surveys during the darkest
nights of each month, when kangaroo rat activity is at its peak. Although kangaroo rats
typically avoid activity during the nights surrounding the full moon where they are more
visible to predators, if it was cloudy or if the moon had set, it is possible kangaroo rats
emerged from their burrows to conduct above ground activities (O’Farrell, 1974). To
increase the level of certainty of translocation results, researchers could also survey
111
during nights outside of the prime activity period when the moon is set or cloud cover is
heavy. It is possible that some kangaroo rats will be active during those few extra days.
Establishing a more frequent monitoring program could be beneficial. Wildlife cameras
could also be used for consistent, non-invasive monitoring at the release site. The
addition of wildlife cameras at the release site could increase the certainty regarding the
fate of translocated individuals. They could be placed near burrow entrances as well as
various other locations on the dune to monitor intraspecific interactions, burrow use,
frequency of movement, and predation. The use of cameras could also potentially
decrease the need for frequent post-translocation surveys. Such information could prove
useful in both determining how long individuals remained at the release site and
assessing why some individuals were not observed following the translocation.
Finally, I had a very small sample size, with 16 kangaroo rats translocated over a
three-year period, which limits the extent to which I can form conclusions regarding the
effectiveness of translocations. It would be beneficial to continue research on
translocations, optimally in larger metapopulations where the opportunity to translocate
more individuals is greater. This way the success of translocations can be compared to
the survival of resident kangaroo rats.
3.4.4 Radio collaring kangaroo rats
Many of the translocations yielded inconclusive results, with individuals leaving
little to no evidence of occupancy. This limitation could be minimized with the use of
more radio collars to track the movements of translocated kangaroo rats. I would also
suggest further research into the use of radio collars, which can help to locate individuals
who are on or in the vicinity of the dune. I was cautious in my use of radio collars, as I
112
had little experience and I wanted to ensure the well being of the translocated individuals,
especially because they are an endangered species. Therefore, I only radio collared those
I was most comfortable with (i.e. calm, adult individuals). Although anesthesia has been
used successfully for radio collaring in past studies (see Gummer, 2005), I discovered
that it was also possible to successfully radio collar kangaroo rats without the use of
anesthesia. I could quickly and effectively administer radio collars, slipping the collar
over their head from behind with the transmitter initially behind their head so they could
not see it (adjusting it once it was on), and release individuals into their burrows without
the added risks associated with anesthesia and without requiring a recovery period.
Although the method was improved, I would still make some changes in how the
radio collars are administered in future studies. Of the four radio collars I used in my
study, two came loose and fell off, one was unaccounted for, and one was extremely
useful but had temporary negative side effects on the animal. As mentioned, one of the
translocated individuals experienced abrasions from the collar and got her paw stuck in
the collar. From my observations of the long-term database, although many radio collars
were used with no issues, it was not uncommon to see collars causing irritation, infection,
or immobilized paws resulting from attempts to groom the collar. Fortunately, these
effects were temporary. Upon recapturing the individuals and removing the collars, all
kangaroo rats experienced a full recovery. The metal crimp that held the antenna in place
appeared to be causing the most irritation. Sandi Robertson (personal communication,
2015) used the same collars in the past, and suggested that radio collar antennas be fixed
in place by simply tying a knot in the antenna instead of crimping. I was not aware of this
method until after I had completed my study, but further research could be performed to
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determine if tying the antennae can decrease irritation yet still remain effective in signal
transmission. I would also recommend that radio collars be checked frequently for
negative effects such as abrasions or effects on mobility (e.g. paws temporarily caught in
the collars). With close monitoring and a modified fastening technique, I think radio
collars can be used safely and with great benefit.
3.5 Conclusion
The purpose of this chapter was to assess if translocations could be performed
successfully. Two of the translocations were long-term successes, five were intermediateterm successes, and the remainder of translocations showed no evidence of success. The
results of this study suggest two things: (1) translocations have the potential to be
successful and establishment following translocation is likely more frequent than the data
suggest, and (2) although translocations have the potential to be successful, they should
be implemented with caution because there were also many translocations did not yield
any evidence that they were successful. Therefore, I recommend that translocations be
researched further to obtain more conclusive results before using them for conservation
or mitigation purposes.
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Chapter Four: Conclusions and recommendations
4.1 Synthesis of conclusions
Habitat loss and fragmentation are having negative impacts on the Ord’s kangaroo
rat metapopulation in Alberta, which is at risk of extirpation. The stability of the
metapopulation relies on rescue and recolonization (Brown & Kodric-Brown, 1977;
Fahrig & Paloheimo, 1988; Roff, 1974), which may be facilitated through conservation
tools such as stepping stones and translocations. The purpose of this study was to assess
the feasibility of using such tools to enhance dispersal. It was determined that both
methods could be used to potentially increase the functional connectivity between habitat
patches, but further research is required.
4.1.1 Stepping stones
Most kangaroo rats in Alberta do not appear to have the ability to reach adjacent
dune habitats through dispersal. Even the maximum recapture distance through grassland
habitat (3.2 km) appears insufficient to allow dispersal between many dunes. It was
determined that stepping stones may be a viable method for facilitating natural dispersal
across the landscape. Strategically placed stepping stones have the potential to decrease
inter-dune distances and may help facilitate rescue of sub-populations and recolonization
of habitat patches, while increasing genetic diversity, and distributing the threat of
unpredictable demographic and environmental events. A minimum of four locations was
determined to be necessary to connect the majority of the dunes in the Amiens region of
CFB Suffield. However, the benefits of stepping stones become quite limited in areas
where dune habitats are more isolated. To increase connectivity between other habitat
patches outside of the Amiens region, more stepping stones would be required. Areas
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with a high degree of isolation, such as the Empress Dunes (Figure 1.12; Figure 3.1),
would require the use of many stepping stones to connect them with other habitats, which
would not be efficient or effective (Woodroffe, 2003). Other conservation methods, such
as translocations, can be used to facilitate dispersal to such isolated habitat patches.
4.1.2 Translocations
Translocations have the potential to facilitate inter-patch movement within the
metapopulation. Like stepping stones, successful translocations can facilitate rescue in
declining sub-populations and recolonize vacant habitats. They may be particularly useful
for rescuing or recolonizing isolated habitat patches (i.e., those beyond the natural
dispersal capability of the species) and where stepping stones are insufficient and
infeasible to create. However, there exists uncertainty regarding the ability to
successfully implement translocations. Seven of the sixteen translocated animals in my
study showed evidence of successful establishment, whereas nine did not show any
evidence of establishment. As discussed in Chapter 3, there could be a variety of factors
influencing the success of translocated kangaroo rats, including predation, intraspecific
aggression, stress, and homing. Unfortunately, I was not able to monitor the movements
of every individual after their release. As such, I could not determine why some
individuals did not establish themselves while others did. Further research is necessary to
help increase success and to determine what happens to those that do not display
evidence of site occupancy following release.
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4.2 Using stepping stones and translocations together
Stepping stones and translocations do not have to be used independently of one
another. In fact, they have the potential to complement each other by each serving a
conservation purpose that the other cannot. Stepping stones can facilitate natural dispersal
between habitat patches, while translocations facilitate artificial dispersal between
patches that might otherwise be inaccessible due to isolation (Woodroffe, 2003). One of
the limitations of translocations to isolated habitat patches is that they have to be
performed continually because natural dispersal is not otherwise possible. If stepping
stones are used along with these translocations, then translocations may not have to be
continually performed to sustain the sub-population. Individuals could be translocated to
stepping stone sites as well as surrounding unoccupied dunes to stimulate self-sustaining
natural dispersal among the habitat patches, old and new. For example, Mounted Rifle
Blowout is 2.61 km away from the nearest neighbouring dune. Although the best
dispersers should theoretically be able to reach the dune, the majority of kangaroo rats
observed in Alberta have not been recorded moving such distances. Therefore,
translocations might have to be repeated to sustain a sub-population at this dune.
However, if a stepping stone is placed between Mounted Rifle Blowout and Aurora Dune
(Stepping Stone 4) and kangaroo rats are translocated to both the stepping stone and
Mounted Rifle Blowout, not only is a functional connection likely created and two subpopulations established, but the stepping stone can then become a source of dispersers to
both Mounted Rifle Blowout and Aurora Dune.
Typically, the value of stepping stones comes over multiple generations (Saura et
al., 2014). However, using stepping stones and translocations together could decrease the
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amount of time taken to establish a stepping stone sub-population capable of producing
dispersers, and it might eliminate the need to perform ongoing translocations to isolated
sites. It is in situations such as this, that these tools can complement one another.
When used together, these conservation tools can reduce extirpation risk through
the facilitation of both artificial and natural dispersal, while decreasing the need for
human intervention after the mitigation methods are implemented. It also distributes the
risks associated with environmental and demographic stochasticities over multiple subpopulations rather than one large sub-population (den Boer, 1981). For example, if a
random, localized environmental event occurs, such as a natural disaster like a flood, and
it extirpates an entire sub-population, nearby sub-populatons may remain unaffected. If
individuals do not have the ability to spread themselves out across the landscape and are
aggregated in one locale, they may all be susceptible to a singular event. In an example of
demographic stochasticity, if a sub-population declines due to a random decrease in
reproduction or survival (e.g., skewed sex ratios arising from small sub-population size),
immigrants from other connected sub-populations are able to disperse into the declining
sub-population and increase the number of breeding pairs, which could help re-establish a
stable sub-population.
4.3 Using stepping stones and translocations to mitigate human disturbance
Although I determined that these methods have the potential to be used
successfully in a fragmented environment, they should not be relied upon to mitigate
further habitat destruction from anthropogenic development. Stepping stones, in
particular, will not help rescue kangaroo rats should development occur on occupied
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habitat patches. Stepping stones are used to reduce isolation (Saura et al., 2014) and they
facilitate dispersal by decreasing inter-patch distances, but they are not useful for
protecting individuals from harm or habitat destruction. Stepping stones are beneficial
when used to increase functional connectivity in an already fragmented landscape. The
algorithm I developed could be useful in determining stepping stone locations following
disturbance of the landscape because it aims to maximize functional connectivity.
However, following anthropogenic development, sub-populations are likely to become
even smaller because individuals directly affected by the disturbance do not receive any
immediate benefit from stepping stones. Even if stepping stones are created, it remains
unknown if the displaced kangaroo rats will moved to the restored dune. For the reasons
mentioned above, I do not believe stepping stones would prove to be useful tools to
mitigate development on occupied habitat patches. Translocations would be more
appropriate in cases where habitat destruction is imminent because my data suggest that
at least a portion of the translocated kangaroo rats are likely to survive at the release site.
Although translocations have been shown to be very effective in some instances
(see Chapter 3), success is not consistently observed. Considering that translocation from
wild sub-populations to unoccupied patches yields inconsistent establishment rates, it is
not likely that captive breeding programs would be consistently successful either,
especially when successfully breeding kangaroo rats in captivity can be difficult (Chew,
1958; Daly et al., 1984). Translocations may be considered as a last resort, as they would
likely be more effective than stepping stones, but with post-translocation establishment
rates being unpredictable for both wild and captive bred individuals, I would not advise
that they be relied upon to mitigate anthropogenic development.
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4.4 Opportunities for future research
Aside from the specific recommendations to improve this study, which are
already mentioned in Chapters 2 and 3, other future research projects might be beneficial
to the Ord’s kangaroo rat metapopulation in Alberta.
4.4.1 The number and size of patches required to facilitate dispersal
Research has not yet been conducted on the minimum habitat patch size required
to support a stable sub-population of kangaroo rats nor has there been research on the
number of interconnected patches necessary to sustain a kangaroo rat metapopulation in
Alberta. This information is important for two reasons: (1) for a stepping stone to be
useful, it must be large enough to provide adequate shelter and resources for a persistent
sub-population of kangaroo rats (Saura et al., 2014) and (2) metapopulations rely on the
movement of individuals between multiple habitat patches (Hanski, 1991; Kuussaarri,
Saccheri, Camera, & Hanski, 1998; Nelson, 1993; Wright, 1942). I will briefly discuss
the importance of patch size and the number of patches targeted below.
Habitat patch size is an important consideration because larger habitats are better
able to support stable sub-populations (Kramer-Schadt, 2011; Saura et al. 2014) and they
are more likely to be discovered by dispersers (Kramer-Schadt, 2011). Kangaroo rats
require enough space to not only survive, but reproduce as well because it is through
multiple generations that stepping stones become the most effective (Saura et al., 2014).
Colonizers can produce offspring at newly accessed habitat patches. These offspring can
then disperse to the next available habitat patches. There, they can also reproduce,
yielding more dispersing offspring. In this way, dispersers can move across the landscape
accessing more distant patches over multiple generations (Saura et al., 2014). The four
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stepping stone locations that were found using my algorithm were all comparable in size
to dunes that currently support kangaroo rat sub-populations, so I believe they will be
adequate. I did not have any other criteria for patch size. Thus, to benefit future
conservation actions I would suggest research into determining optimal stepping stone
patch sizes so that locations can be selected accordingly.
It may also be important to consider the number of habitat patches in an area
targeted for stepping stones. I only looked for stepping stones in the Amiens region of
CFB Suffield. This area had a cluster of habitat patches that could be functionally
connected by the addition of stepping stones in the proposed locations. Although I
determined that stepping stones were necessary to connect the dunes, my research did not
investigate how many connected dunes would be required to sustain a stable
metapopulation. This could prove to be valuable information as the sub-populations
occupying some dune clusters may not fully benefit from the addition of just one stepping
stone, even if it functionally connects them. Dispersing individuals can decrease the risk
of extirpation when there are multiple functionally connected habitat patches (den Boer,
1981). We do not yet know how many patches are required to maximally benefit the
metapopulation. Such research could help determine where to locate future stepping
stones to increase the likelihood of metapopulation persistence.
4.4.2 Habitat restoration techniques
Habitat restoration also requires further investigation. As I mentioned in Chapter
2, there are a variety of methods that can be used to restore stabilized dunes. Bender
(2009) investigated the use of controlled burns as well as ungulate attractants to promote
disturbance, and therefore destabilization on dunes. The attractants included 8 foot
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rubbing posts and mineralized salt licks. When used alone they did not result in
significant post-restoration establishment, but there was a 100% success rate for
subsequent kangaroo rat colonization when used in combination with controlled burns.
Controlled burns have also been used independently in other studies. The results of a
controlled burn conducted by Price et al. (1995) indicate that stabilized dunes can become
habitable for short periods of time following the burns but the burns must be repeated
every few years to maintain the habitat. Other studies have also looked at the effect of
grazing on dune erosion. Zuo et al. (2008) concluded that grazing decreased the amount
of vegetation on sand dunes in China, which increased the rate of erosion. Partial shrub
removal has also been conducted by Price et al. (1994) to restore Stephen’s kangaroo rat
habitat, with apparent success. There are still other restoration techniques that have not
yet been tested in Alberta. Future research might also include investigating the
effectiveness of mechanical destabilization in Alberta. Mechanical destabilization has
been tested in the Netherlands using rotary cultivators, beach sand cleaners, disc harrows,
and excavators (Riksen & Visser, 2008). The beach sand cleaner was the most effective
at reactivating wind erosion, while the rotary cultivator came in second. Dunes on the
west coast of Vancouver Island have also been restored using backhoes to remove
vegetation and promote soil erosion (Heathfield, & Walker, 2011). However, given the
great diversity of species relying on the sand hill ecosystem (Hugenholtz et al., 2010),
research should include assessments on any potential side effects that may negatively
affect other species residing in the area if intensive, non-natural forms of disturbance are
used to restore habitat quality for Ord’s kangaroo rats.
122
Gaining information on the different approaches to dune restoration may increase
the success of using stepping stones as a conservation method, while minimizing any
potentially negative impacts on other members of the ecosystem. The algorithm I created
can be used to find optimal stepping stone locations, while the information gained from
the proposed study above can be used to effectively restore the stabilized dunes.
4.4.3 Timing of translocations
Translocation techniques may also be improved through future studies. Given that
we still do not fully understand what time of day translocations should be performed to
yield the greatest success (Bender et al., 2010) and the fact that nine translocated
kangaroo rats did not show any indication of establishment, it could be beneficial to study
the timing of translocation further. In fact, there is a lack of consensus regarding the
optimal timing of translocations in the literature: some studies advocate daytime releases
while others suggest that releases should be performed during the night. For example,
Germano (2010) released both Tipton and Heermann’s kangaroo rats into artificial
burrows during the daytime and left the entrances plugged until dusk. Williams et al.
(1993) used the same method with giant kangaroo rats. O’Farrell (1999) translocated San
Bernadino kangaroo rats at sunset and just before sunrise. I followed the translocation
guidelines set forth by Bender et al. (2010), so I released the kangaroo rats during the
dark and unplugged the entrances at dawn. Considering that there is no consensus on
translocation timing and other studies do not specify whether their timing was strategic or
logistic, it would be beneficial to perform research locally to determine when
translocations of Ord’s kangaroo rats in Alberta could be performed to maximize the
likelihood of successful establishment.
123
4.4.4 Which sex and age group should be targeted for translocations?
It could also be useful to determine which sex and age group is most likely to be
successfully translocated. I had intended to translocate a much larger number of
individuals and compare the success of adults, juveniles, males, and females, but I did not
have a sample size large enough to evaluate differences among groups, so it remains
unclear if one sex or age group is more likely to establish than another. I translocated
both adults and juveniles opportunistically and did not observe a pattern of success. That
being said, it may be appropriate to target juveniles because they are more likely to
disperse (Bender et al., 2010; Gummer, 1997a). Future studies could investigate whether
adults or juveniles of each sex show different responses to translocations.
4.4.5 Group translocations
Group translocations have been observed to result in translocation success in a
variety of mammals, including kangaroo rats, on multiple occasions (Germano, 2010;
Randall, 1989; Shier & Swaisgood, 2010; Van Zant & Wooten, 2003). Maintaining social
relationships in solitary, aggressive, territorial species can increase translocation success
(Shier & Swaisgood, 2010), but kangaroo rats translocated in groups have been shown to
quickly settle, survive, and reproduce better than those translocated alone. When
translocated in neighbour groups, individuals traveled shorter distances before settling,
spent more time foraging, and created more burrows (Shier & Swaisgood, 2010).
Neighbours fight less frequently and with less aggression than strangers, as observed in
the banner-tailed kangaroo rat (Randall, 1989; Randall, Hekkala, Cooper, & Barfield,
2002). Germano (2010) translocated 11 Heermann’s kangaroo rats to a site that had
resident kangaroo rats present, and it is believed two were killed as a result of
124
intraspecific aggression. Shier & Swaisgood (2010) have shown that reduced levels of
aggression and fighting among kangaroo rats leads to reduced levels of predation, which
is another reason to consider group translocations. Lastly, group translocations can also
increase site fidelity. Rather than attempting to flee to their original site of capture,
individuals are more inclined to persist near their familiar conspecifics and therefore
remain at the release site (Van Zant & Wooten, 2003).
Because of the small sample size of kangaroo rats with which I had to work, I was
unable to test the use of group translocations. Success has been observed when using
group translocations in other species, so it could be valuable to learn if group
translocations can increase translocation success in the Ord’s kangaroo rat. A site such as
Empress Huge Dune, which sometimes has high densities of kangaroo rats, could be a
good source site for such studies. Further research could also be conducted to determine
if sub-populations in Saskatchewan are large enough to act as sources for either
individual or group translocations, and if kangaroo rats in those sub-populations have the
ability to reproduce with kangaroo rats from Alberta. If so, Saskatchewan subpopulations could also be used as translocation sources to rescue declining subpopulations throughout Alberta.
1.1 Conclusion
In conclusion, the majority of kangaroo rats observed in the Alberta
metapopulation do not move distances sufficient to span the gap between most habitat
patches, which means that the implementation of conservation methods to facilitate
dispersal is necessary to functionally link existing habitat patches and ensure continued
125
dispersal between sub-populations. I created an algorithm that can help determine optimal
stepping stone locations, which if implemented, can decrease inter-dune distances and
potentially aid in facilitating natural dispersal. For habitats that are too isolated to benefit
from the addition of stepping stones, translocations can be considered. Translocations
have the potential to facilitate rescue and recolonization of isolated habitat patches,
although successful establishment at release sites was not consistently observed in my
study. Future research is recommended before translocations are used as a tool for
managing the Alberta metapopulation. Continued research may also help to increase the
ability to identify the most profitable locations for stepping stones. The use of both
stepping stones and translocations independently and in conjunction with one another
have the potential to benefit the Ord’s kangaroo rat metapopulation in Alberta by
increasing the likelihood of metapopulation persistence; therefore they should be
considered as conservation tools both now and in the future.
126
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Appendix A
Figure A 1 Cost-distance map of Aurora Dune.
150
Figure A 2 Cost-distance map of Bagnold’s Dune.
151
Figure A 3 Cost-distance map of Dejean’s Dune.
152
Figure A 4 Cost-distance map of Carbine Dune.
153
Figure A 5 Cost-distance map of Mounted Rifle Blowout.
154
Figure A 6 Cost-distance map of Woodhouse Dune.
155
Figure A 7 Image of cost-distance surface for all Suffield dunes.
156
Figure A 8 Dispersal buffers created using 100% of the maximum kangaroo rat recapture
distance.
157
Figure A 9 Dispersal buffers created using 75% of the maximum kangaroo rat recapture
distance.
158
Appendix B
Table B 1 Recapture distances of Ord’s kangaroo rats in Alberta between natural sites.
Distance Moved (m)
Number of Kangaroo Rats
0-50
1513
50-100
220
100-150
56
150-200
16
200-250
6
250-300
3
300-350
3
350-400
1
400-450
1
450-500
1
950-1000
1
1050-1100
1
1200-1250
1
1300-1350
2
1500-1550
1
1700-1750
1
2500-3000
1
3000-3500
2
159
Table B 2 Maximum observed movements in different kangaroo rat species in natural
habitat.
Species
Author
Movement Distance (m)
Ord’s kangaroo rat
Brands, 2015
3200
Stephen’s kangaroo rat
Price et al., 1994
351
Giant kangaroo rat
Williams, unpublished
700
data
Merriam’s kangaroo rat
Zeng & Brown, 1987
160
>350