Blanding’s turtle (Emydoidea blandingii) and Snapping turtle (Chelydra serpentina) habitat use and
movements in the Oakland Swamp wetland complex, Ontario, Canada, and their response to the
Provincial Highway 24 exclusion fence and aquatic culvert ecopassage from 2010-2011
Brennan Caverhill, Bob Johnson, Julia Phillips, Erin Nadeau, Magda Kula & Roger Holmes
December 2011
Toronto Zoo, Adopt-A-Pond Programme, 361A Old Finch Ave, Toronto, ON, M1B 5K7, Canada
Table of Contents
Table of Contents ...................................................................................................................................... 2
In Brief ...................................................................................................................................................... 5
Numbers ................................................................................................................................................ 5
Photos .................................................................................................................................................... 5
Summary ................................................................................................................................................... 6
Introduction ............................................................................................................................................. 10
Toronto Zoo’s Adopt-A-Pond Programme and Ontario Turtle Tally Project .................................... 10
Highway 24 project background ......................................................................................................... 10
Blanding’s turtles ................................................................................................................................ 13
Snapping turtles................................................................................................................................... 15
Wetland habitat ................................................................................................................................... 16
Turtle road mortality ........................................................................................................................... 17
Road ecology, ecopassages, and turtles .............................................................................................. 19
Landowner stewardship, stakeholder engagement, and public outreach ............................................ 20
Materials and Methods ............................................................................................................................ 22
Study site ............................................................................................................................................. 22
Data collection .................................................................................................................................... 23
Field methodology .............................................................................................................................. 25
Road surveys ................................................................................................................................... 25
Wetland surveys .............................................................................................................................. 26
Trapping .......................................................................................................................................... 27
Turtle processing (morphometrics, samples, etc.) .......................................................................... 27
Radio-telemetry (active hand-held) ................................................................................................ 28
Nesting surveys & artificial nest site construction.......................................................................... 28
Radio-telemetry (passive data-logging) .......................................................................................... 29
Culvert measurements ......................................................................................................................... 30
Water quality measurements ........................................................................................................... 33
Light & sound measurement ........................................................................................................... 33
Turtle fence cameras ....................................................................................................................... 33
Highway 24 traffic and turtle-vehicle collision probability ................................................................ 34
Other wildlife & roadkill at the HWY 24 Mount Pleasant Creek culvert crossing ............................ 36
Landowner stewardship, stakeholder engagement, and public outreach ............................................ 37
Results ..................................................................................................................................................... 38
Habitat descriptions............................................................................................................................. 38
2
Turtle occurrence, abundance, distribution, and population size estimate ......................................... 40
Movements and home range ............................................................................................................... 44
Mating ................................................................................................................................................. 47
Nesting ................................................................................................................................................ 48
Overwintering ..................................................................................................................................... 50
Water quality ....................................................................................................................................... 51
Fence camera....................................................................................................................................... 52
Turtle culvert use ................................................................................................................................ 54
HWY 24 traffic and the probability of a turtle being killed on the road............................................. 55
Other roadkill at the HWY 24 Mount Pleasant Creek culvert crossing .............................................. 56
Other wildlife using the HWY 24 Mount Pleasant Creek culvert crossing ........................................ 57
Landowner stewardship, stakeholder engagement, and public outreach ............................................ 57
Discussion ............................................................................................................................................... 63
Habitat ................................................................................................................................................. 63
Occurrence, abundance, and distribution ............................................................................................ 63
Movements & home range .................................................................................................................. 64
Nesting ................................................................................................................................................ 65
Overwintering ..................................................................................................................................... 66
Culvert measurements ......................................................................................................................... 66
Culvert use .......................................................................................................................................... 67
Highway 24 turtle road mortality ........................................................................................................ 69
Other roadkill and wildlife at the HWY 24 Mount Pleasant Creek culvert crossing.......................... 70
Landowner stewardship, stakeholder engagement, and public outreach ............................................ 71
RECOMMENDATIONS .................................................................................................................... 72
Acknowledgements ............................................................................................................................. 73
Select References .................................................................................................................................... 74
Literature Cited ................................................................................................................................... 74
Personal Communications................................................................................................................... 76
Appendix ................................................................................................................................................. 77
Data ..................................................................................................................................................... 77
Turtle occurrence, abundance, and distribution .............................................................................. 77
Habitat ............................................................................................................................................. 78
Movements ...................................................................................................................................... 79
Data Collection ................................................................................................................................... 80
Cards ............................................................................................................................................... 80
Measurements ................................................................................................................................. 84
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Notch Codes .................................................................................................................................... 85
Definitions ........................................................................................................................................... 85
Habitat descriptions......................................................................................................................... 85
Population Structure........................................................................................................................ 86
Scale ................................................................................................................................................ 86
Photos .................................................................................................................................................. 87
Stewardship Documents ...................................................................................................................... 89
Digital Appendix ................................................................................................................................. 92
4
In Brief
Numbers
 >1210 – Person hours surveying, trapping, and tracking turtles from April 2010 to September 2011
 63 – Total number of Blanding’s turtles marked in and around the Oakland Swamp in 2010-2011
 >120 – Estimated number of Blanding’s turtles thought to be living in the Oakland Swamp
 403 – Average # of vehicles per hour that drive on HWY 24 daily between 6 am & 8 pm (via MTO)
 93% - Average chance of a turtle being killed when trying to cross over HWY 24 on the road
 13 – Number of times one male Blanding’s turtle, 0-1 (Frank), crossed under HWY 24 in 2010
 8 & 0 – Road-killed Blanding’s found at study site in 2008 (pre-fence) & 2010-2011 (post-fence)
 12 of 19 - Radio-tagged Blanding’s turtles that crossed the road at least once in 2010 & 2011
 5.3 – Kilometers travelled by one male Blanding’s turtle, 0-3 (Vamos), in 2010
 >200,000 – Square meter home range of one female Blanding’s turtle, 0-10 in 2010-2011 (Grace)
 22 – Landowners, representing 10 families, involved in our project in 2010 & 2011
Photos
Clockwise from top left, then center: 1) Landowners observing wetland habitat; 2) Snapping turtle; 3) Radio tracking; 4)
Radio transmitter; 5) Nest site construction; 6) Blanding’s turtle plastron; 7) Exclusion fence along HWY 24; 8) Aquatic
hoop-net trap; 9) Mount Pleasant Creek and HWY 24 culvert crossing (photos © Brennan Caverhill – Toronto Zoo)
5
Summary
Blanding's turtle (Emydoidea blandingii) and Snapping turtle (Chelydra serpentina) populations are
declining in Ontario. Their wetland habitat has dwindled in the province throughout the past 100 years, by as
much as 80% according to certain research (Findlay 1996). Both turtles are listed as species at risk in Ontario
and throughout Canada. There are few published studies of Blanding’s turtle habitat use and movements in
southern Ontario. Management of this species is often based on data from central Ontario Blanding’s turtle
populations (ie. From Algonquin Park). These data from less impacted anthropogenically (edge) locations may
differ from the urbanized southern Ontario landscape.
Next to habitat loss and degradation, road mortality is one of the biggest threats to remaining
populations of Blanding’s and Snapping turtles, and those of most other freshwater turtle populations in North
America. Roadways constructed through wetlands destroy, degrade, and fragment turtle habitat, and create
barriers to migration and dispersal. Vehicles driving on roads injure and kill individual turtles, primarily gravid
females searching for nesting sites, reducing population sizes and skewing sex ratios. Fortunately, the field of
road ecology, which studies the impact of roads on the environment, is beginning to contribute to the knowledge
and practice of mitigating the effects of roads on wildlife. Public education campaigns are informing motorists
with wildlife crossing signage and speed limits. Exclusion fencing and wildlife crossings, or ecopassages, are
being used to successfully prevent wildlife-vehicle collisions, while facilitating safe road crossings and
improving habitat connectivity.
Provincial Highway 24 (HWY 24) runs south from Cambridge through Brant and Norfolk Counties to
Lake Erie in Ontario. It bisects the provincially significant Oakland Swamp wetland complex, which is prime
turtle habitat. Blanding's turtle and Snapping turtle populations in the area have been adversely affected by the
400+ vehicles/hr that travel at speeds of 80+ km/hr on the two-lane highway. A single event reported to the
Toronto Zoo’s Ontario Turtle Tally documented eight dead Blanding’s turtles and two Snapping turtles roadkilled in one day at the Mount Pleasant Creek crossing in April 2008. After contact between the Toronto Zoo and
Ontario`s Ministry of Transportation (MTO) a temporary wildlife mortality mitigation fence was installed by
MTO in August 2008, then a permanent structure in March 2010, to prevent turtles from crossing over the road
and encourage them to travel under it through a 25 m long, 1.8 m diameter corrugated steel culvert. From April
2010 to September 2011 researchers from the Toronto Zoo`s Adopt-A-Pond Wetland Conservation Programme
studied habitat use and movements of resident turtle populations and their response to the ecopassage.
With 1210 person hours of effort in the field and 2200 trap nights, 63 Blanding's turtles and 25
Snapping turtles were captured and marked in and around the study site in 2010 and 2011. Nineteen Blanding’s
and three Snapping turtles were radio-tagged, which provided more than 1000 turtle observations for analysis.
Fewer were tracked in 2010 because it was the first year of the study, and no females were captured until after
nesting season, therefore no nesting movement was captured for females in that year. In 2011 tracking stopped in
6
July, after which point the majority of radio transmitters were removed from the turtles. Preferred turtle habitat
included willow swamps, shallow open waters, marshes, and pond shorelines. Blanding’s turtle habitat selection
and movements varied seasonally, with aggregations occurring following nesting (July-August) and during
wintering (November-March), and dispersal in the spring (April-June) and fall (August-September). In 2010,
radio-tagged Blanding’s turtles moved 18 m per day, and 75 m between subsequent captures on average. Males (
= 5.2 km total straight line movements, N = 4 individuals) moved more than females (
= 1.9 km, N = 9
turtles), who moved more than juveniles (x = 0.5 km, N = 1). Male and female Snapping turtles moved about the
same distance on average throughout the season (
= 2 km, N = 3) in 2010. Total movements, represented by
the number of movements between wetland sections within the study area, peaked in early June and early August
in 2010. Movements in 2011 peaked in late June when females returned from their nesting sites, but data from
August onwards was not included in this report. Using Percent Volume Contour (PVC) and Minimum Convex
Polygon (MCP) calculations, male Blanding’s turtles (
females (
= 1.5 & 11.4 ha, N=4) had larger home ranges than
= 1.1 & 6.2 ha, N=9), who had larger home ranges than juveniles (x = 0.5 & 1.6 ha, N=1) in 2010.
However, including nesting data from 2011 generated female MCP home range sizes (
doubled male MCP home range sizes (
= 21 ha, N=14) that
= 10 ha, N=4). Overall, the average 95% PVC home range for all
Blanding`s turtles was an underestimate at 11730 m2 (1.2 ha), while the average MCP home range was an
overestimate at 73582 m2 (7.4 ha) using data from 2010 only. Using all data from 2010 and 2011, and only the
MCP calculation, the average home range size for Blanding’s turtles at the Oakland Swamp was 18 ha, including
data from 19 individuals and almost 1000 capture points.
Two artificial nesting sites were constructed in the study site, the first in December 2010 and the second
in October 2011. With 156 hours of effort directed at nesting surveys, six Blanding’s turtle nests were
discovered and another 14 gravid females were found on land in June at suspected or potential nesting sites.
Female Blanding’s turtles tended to stay within 100 m of the wetland margin during their nesting forays in 2011,
which occurred primarily in agricultural fields, including those planted with corn, millet, rye, soy, and tobacco.
Selected substrates were sandy and fine. Two nests were relocated to an artificial nesting site to avoid
destruction; four nests were left in-situ, two of which were protected with nest cages, and two of which were left
unprotected. No predation of known Blanding’s turtle nests occurred, but many Snapping turtle and Painted
turtle nests were found predated, especially along the south-facing north shore of Possum Pond (PP).
In 2010 7 radio-tagged Blanding’s turtles overwintered within a 100 m radius of one another in the
western end of West Marsh (WM); two females wintered in the Ellis Avenue Pond (EA), and one male in
Possum Pond (PP). Overwintering sites exhibited various physical characteristics, but typically occurred in
shallow (10-50 cm) water depths, among willow clusters or along pond shorelines. Turtles entered their
wintering sites from September to October, and exited in mid April.
Zero roadkill turtles were observed at or near the fence and culvert ecopassage in 2010, despite the fact
that radio telemetry work recorded 46 successful turtle crossings of HWY 24 in 2010. In 2011, one hatchling
7
Snapping turtle and one mid-sized Painted turtle were found dead on the road; the former was at the northeast
edge of the fence and likely walked around, while the latter may have slid under the fence through a gap likely
created by a muskrat, which was later repaired and closed. From April to July 2011 another 12 successful
Blanding’s turtle crossings of HWY 24 were recorded. Considering the high calculated probability of mortality
(Pkilled = 93%) during a single attempted crossing over HWY 24 on the road, we assumed that turtles crossed
back and forth under the road through the aquatic culvert. Radio-tagged individual Blanding’s turtles crossed
from zero to 13 times (
= 1.5 and 8.0 for females and males respectively) throughout the year in 2010. Twelve
turtles crossed under HWY 24 one time each in 2011. Like total movements, road crossing movements peaked in
early June and August in 2010, and late June in 2011. We confirmed that Blanding’s turtles travelled through the
culvert using visual observations (N = 3 crossing events) and a passive data-logging radio receiver (N = 7 in
2010, N = 7 in 2011), which was installed in the culvert from June to November 2010, and April to September
2011. We also observed one individual Blanding’s turtle within 1 m of the fence, apparently attempting to cross
the road, but unable to because of the fence. Overall, the culvert and wildlife mortality mitigation fence provided
an effective mitigation tool to prevent turtle road mortality and facilitated crossings to habitat on either side of
the highway. Although ~75 individuals (the majority frogs) from 11 vertebrate species were found dead on
HWY 24 between the two exclusion fences bordering the wetland on either side of the causeway in each of 2010
and 2011, visual observations indicated the culvert ecopassage did provide a road crossing option and cover to
other wildlife, including fish, amphibians, birds, and mammals.
During and after the field season we engaged landowners, stakeholders, and other target audiences in
education and stewardship endeavors throughout 2010 and 2011. With over 20 presentations, three displays, four
focus groups, and half a dozen news articles and radio interviews, we reached well over 1000 individuals
directly. We personally met and informed all landowners with property on or adjacent to the study area about the
Toronto Zoo’s Ontario Turtle Tally and HWY 24 Blanding’s turtle project. All landowners allowed us access to
their property to conduct our research, while some were extremely helpful in providing their time, knowledge,
and resources for the project. The Ontario Ministries of Transportation (MTO) and Natural Resources (MNR)
were fully engaged in the project, providing not only assistance in the field, but also helpful and informative
advice throughout the duration of the project. Several Girl Guide groups, eco-schools, conservation authorities,
MTO staff, and the general public were also educated about Toronto Zoo`s Ontario Turtle Tally and the HWY
24 project through our informative presentations and displays.
This report provides critical information on turtle movement and habitat use for turtles living in a rural
agricultural landscape in southern Ontario. These data indicate the importance of the Oakland Swamp wetland
complex to an inland population of Blanding’s turtles, and the key role that land stewardship plays in an
agricultural landscape. A key item of interest if that we confirmed Blanding’s turtle and Snapping turtle
movements through an aquatic culvert, and determined that the culvert allowed them to access habitat on either
side of a road. A retrofit turtle fence provided an effective barrier to turtle road mortality, and facilitated turtle
8
access to the culvert. The Toronto Zoo’s Turtle Tally generated additional informative sightings during the
course of the study, and this meant that follow-up research and management continued to prevent further road
mortalities. We are encouraged to continue to partner with MTO to locate turtle mortality hotspots along roads,
and construct similar exclusion fencing and culvert passageways to enhance habitat connectivity and road
permeability for turtles and other wildlife. Protection of the Oakland Swamp wetland complex is encouraged as
it represents an important turtle habitat with mitigated road mortality threat. Landowners can contribute greatly
to turtle conservation in Ontario by submitting turtle sightings and by preserving, enhancing, or creating turtle
habitat on their properties, and removing turtles from the road (or preventing their access to it) wherever
possible.
9
Introduction
Toronto Zoo’s Adopt-A-Pond Programme and Ontario Turtle Tally Project
The Toronto Zoo’s mission is to be a dynamic and exciting action centre that inspires people to love,
respect and protect wildlife and wild spaces. The Adopt-A-Pond (AAP) Wetland Conservation Programme and
Urban Turtle Initiative (UTI) is directed by the Toronto Zoo’s Curator of Reptiles and Amphibians and
coordinated by a full time manager. Its specific mission is to provide individuals and organizations with
information, resources, and educational opportunities to conserve, restore, create, and link wetland habitats. The
Ontario Turtle Tally (OTT) is an AAP/UTI initiative, which aims to gather turtle sightings from the public and
organize and submit them to the province’s Natural Heritage Information Center (NHIC). This information is
then used to better document turtle population distribution and protect turtle populations in Ontario. Currently,
over 1400 individuals report over 1600 turtle sightings to OTT annually. Funding is provided by the Toronto
Zoo, Environment Canada’s Habitat Stewardship Program, and the Ontario Ministry of Natural Resources’
Species at Risk Stewardship Fund (Figure 1).
Figure 1. The HWY 24 Oakland Swamp Blanding’s turtle project funding partners
Highway 24 project background
Provincial Highway 24 (HWY 24) runs south from Cambridge through Brant and Norfolk Counties to
Lake Erie in Ontario, Canada (Figure 2). It bisects the provincially significant ~800 ha Oakland Swamp wetland
complex at several locations along its eastern margin. At one point, a short ~200 m causeway crosses the
northeastern extent of the swamp, where it drains into Mount Pleasant Creek under the road through a 25 m
culvert. The current 1.8 m diameter circular corrugated steel culvert that runs underneath HWY 24 replaced a 23
m long 2.2 m wide 1.6 m tall oval pipe in 2006. The road experienced other upgrades at the time, which included
new asphalt, shoulder repair, and ditch cleanouts (Adele Mochrie, pers comm.).
A single event reported to the Toronto Zoo’s Ontario Turtle Tally documented eight Blanding’s turtles
and two Snapping turtles road-killed at the Mount Pleasant Creek crossing in April 2008 (Figure 3). Two
additional Blanding’s turtles were found alive at the site, and helped across the road by Don Scallen, a local
naturalist who reported the sightings. Due to accumulated shell and scale fragments, it was suspected that
additional turtle road mortality had likely occurred at this location in the past, and it was deemed a hotspot for
turtle road mortality.
10
Figure 2. HWY 24, highlighted in blue, stretching from Cambridge (A) to Simcoe (B) in southwestern Ontario,
with the study area (HWY 24 Mount Pleasant Creek crossing) highlighted in yellow (map © Google Maps)
Figure 3. Recently road-killed Blanding’s turtles, and older turtle fragments, at the HWY 24 Mount Pleasant
Creek Crossing in spring 2008 (photos © Don Scallen)
11
The AAP team at the Toronto Zoo partnered with the Ontario Ministry of Transportation (MTO) and
acted quickly to install a temporary turtle exclusion fence in August 2008, within four months of the initial
report. Following winter damage, the temporary fence was repaired in spring 2009. No turtles were found roadkilled at the site throughout 2009. Given the apparent success of the trial exclusion fencing, a permanent 1 m tall
chain link fence with a 45o 0.5 m overhang was installed in February and March 2010 (Figure 4).
Figure 4. Temporary (black) and permanent (chain link) exclusion fence along HWY 24 (photos © MTO)
From April 2010 to September 2011 researchers from the Toronto Zoo conducted field studies primarily
to monitor movements and habitat use in an unstudied southern Ontario Blanding’s turtle population, and also to
monitor turtle movements in response to recently installed fencing. Specifically, we wanted to: 1) provide
recovery experts [Ontario Multi Species Turtle at Risk Recovery Team (OMSTARRT) and MNR] and
Environmental Planners (MTO) with information that would help mitigate SAR turtle road mortality, and define
patterns of SAR turtle habitat use and movements in wetlands intersected by roadways; 2) increase partnership
opportunities with MTO by recognizing the significance of the installation of a SAR turtle road crossing and
mortality prevention structure on HWY 24; 3) maintain and reinforce positive relationships with landowners
living adjacent to the Oakland Swamp near HWY 24 to ensure the protection of a regionally significant habitat
for turtles; 4) increase opportunities for other members of the local Oakland Swamp community to participate in
landowner habitat management projects to benefit SAR and collaborate with agencies such as MTO and MNR to
engage in SAR turtle stewardship activities; and 5) educate landowners, schools, and other community groups
throughout the area (including Brant and Norfolk counties) about SAR turtles and turtle habitat, and the actions
that will help protect them. These objectives are specific to this project, but they also represent one component of
a larger Toronto Zoo programme to engage Ontarions in SAR stewardship activities.
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Blanding’s turtles
The Blanding’s turtle (Emydoidea blandingii) is a freshwater turtle found only in North America (Carr
1995). Adults are 20 – 25 cm in length with a slate grey or black high domed shell with yellow flecks. Its throat
and chin are bright yellow, and its plastron (belly shell) is yellow with unique patterns of black blotches. To
some First Nations communities it is known as the “turtle with the sun under its chin”, and in French it is
“la tortue mouchetée” which means “speckled turtle”. Its main range, which is one of the most restricted ranges
of all freshwater turtles found in North America, is centered just south of the Great Lakes region of Canada and
the United States (Herman et al. 1995) (Figure 5). Small, disjunct populations exist on the continent’s eastern
seaboard, as far east as Nova Scotia, where the species is listed as endangered by COSEWIC (Mockford 1999).
The species as a whole has been designated as “Near Threatened” by the International Union for the
Conservation of Nature (IUCN 2.3), meaning it is threatened with extinction in the near future, although it does
not currently qualify for the “Threatened” status (Baillie et al. 2004).
Figure 5. Blanding’s turtle species distribution (map © Brennan Caverhill – Toronto Zoo 2011)
The southern region of Ontario supports a widespread, but scattered distribution of the species extending
from Georgian Bay to Quebec in the north and east, to Lake Ontario and Erie in the south and west (Figure 6).
Blanding’s turtles in Ontario are listed as provincially and nationally threatened by the Committee on the Status
13
of Species at Risk in Ontario (COSSARO) and the Committee on the Status of Endangered Wildlife in Canada
(COSEWIC), respectively. Habitat varies throughout its range, but often includes shallow waters, muck
substrates, and abundant vegetation (Hartwig 2007).
Very little is known about Blanding’s turtle habitat
selection in Ontario, but selection does appear to occur at the home range scale, with little difference among
seasons (Edge 2008). Nesting females return to the same general area to lay their eggs every year (Arata et al.
2007, Caverhill 2006, Congdon et al. 1983), but are known to change nesting areas when environmental
conditions require it. Individuals can live over 75 years, and perhaps up to 100 (Congdon et al. 2001).
Blanding’s turtles are often considered a “landscape turtle” because they are known to travel great distances
throughout various wetland and upland environments (Bob Johnson, pers comm.). This makes them an excellent
turtle to study when dealing with landscape management issues and asking questions about landscape
connectivity.
Figure 6. Blanding’s turtle distribution in Ontario (map © Ontario Nature 2010)
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Snapping turtles
The Snapping Turtle (Chelydra serpentina) is a large-bodied North American freshwater turtle (Carr
1995). Adults grow to be up to 45 cm in length and have a grey/brown shell with a jagged rear perimeter, and a
spiky tail. Turtles in the genus Chelydra are widely referred to as “Snappers” because of their inclination to bite
defensively when disturbed on land. The species’ main range occurs throughout central and eastern Canada and
the United States, extending from the Rocky Mountains to the eastern seaboard, south to Florida and Texas
(Figure 7). Although designated in the category of “Least Concern” by the IUCN, the species is listed as
“Special Concern” in Canada by COSEWIC because of apparently declining populations and public persecution
(Brooks 2009). Several jurisdictions in the United States have placed restrictions on hunting in the late 1990s, as
harvests from single states were known to exceed 10 tonnes annually (Congdon et al. 1994).
Figure 7. Snapping turtle species distribution (map © Brennan Caverhill – Toronto Zoo 2011)
Southern Ontario supports a large and well distributed population of Snapping turtles (Figure 8).
Snapping turtles in Ontario are listed provincially and nationally as a species of Special Concern under
COSSARO and COSEWIC. Their habitat includes shallow ponds, lakes, streams, and other wetlands. Snappers
are versatile in their ability to inhabit a variety of wetland habitats. Most animals tend to use the same home
range year after year (Arata et al. 2007, Obbard & Brooks 1981). They are diurnal, and primarily active during
15
the morning and evening. Females lay between 10 and 50 eggs, and reach sexual maturity at age 15. It is
believed that snapping turtles can live for over 100 years in the wild (Brooks 1990).
Figure 8. Snapping turtle distribution in Ontario (map © Ontario Nature 2010)
Wetland habitat
Wetlands are seasonally waterlogged areas, covered or saturated by water for at least part of the year
(Newmaster et al. 1997). Wetlands can include lakes, ponds, and rivers, but are typically designated within the
following five categories, according to The Canadian Wetland Classification System: 1) bog, 2) fen, 3) marsh, 4)
swamp, and 5) shallow open water (National Wetlands Working Group 1988). Each of these wetland types can
be further classified by its physical features, hydrology, and vegetation into subcategories such as open or treed
bogs and fens, hardwood or thicket swamps, and so on (Newmaster et al. 1997). In the field, turtle habitat often
exhibits features of several wetland types simultaneously, making absolute categorization difficult and somewhat
16
subjective. Definitions and descriptions of the wetland habitat found in our study area are described in the
methods and results sections of this paper.
Figure 9. Wetland habitat, including shallow open water, swamp, marsh, and pond (photos © BC)
Wetlands are an integral part of the southern Ontario landscape, for humans and nature alike. They
buffer against floods and drought, store carbon, filter water, and harbour great biodiversity including all forms of
life (Woodward & Wui 2001). All turtle species in Ontario depend upon wetland habitat. Unfortunately, some
estimates suggest 75-90% of the wetland habitat in southern Ontario has been lost to development (Findlay
1997). This loss of habitat, in combination with the destructive repercussions of roads, endangers turtle
populations throughout the province.
Turtle road mortality
Road mortality is one of the biggest threats to freshwater turtles in North America (Beaudry et al. 2008,
Gibbs & Schriver 2002). It is well documented that roads destroy, degrade, and fragment habitat (Andrews et al.
2006). Roads also disrupt movements and alter population demographics and genetics due to increased adult
mortality as a result of turtle-vehicle collisions (Aresco 2005). Turtle populations are more adversely affected by
17
roads than most other species (Beaudry et al 2008). Individuals can live for over 100 years and older turtles
reproduce more effectively (Gibbons 1988, Congdon 2001). Older individuals tend to lay more eggs, which also
exhibit higher hatching success (Caverhill 2006, Congdon et al. 1994). Most of the turtles that get killed on
roads are gravid females going to lay their eggs (Gibbs 2001). These females are often attracted to the roadside
itself as a nesting site (Szerlag & McRobert 2006). Losing just one reproductive female turtle has an equally
detrimental population level impact to losing dozens of males, hundreds of hatchlings, or perhaps thousands of
eggs (Caverhill 2006). Because turtles are long-lived, late to mature, and have low reproductive output, the
impact that roads have on turtle populations is enormous (Congdon et al. 2003).
Figure 10. Turtle roadkill found along the HWY 24 corridor between Cambridge and Simcoe in 2010, including
Blanding’s, Snapping, and Painted turtles (photos © BC)
As a “landscape species” Blanding’s turtles are known to travel great distances, not only within wetlands
but also throughout dry upland habitat. This elevates their risk of encountering roads, and enduring subsequent
mortality. Females will travel over two kilometres to nest (Arata et al. 2007, Congdon et al. 1983; Joyal et al.
2001), and males are known for terrestrial movements upwards of five to ten kilometres in the active season
between overwintering and summer foraging areas (Beaudry et al. 2010; Power 1989). Blanding’s turtle
demographics, including their late maturity (~20 years), long generation time (~40 years), low recruitment, and
18
long life (~80 years) exacerbate the negative effects adult mortality poses to dwindling populations (Congdon et
al. 2001; Herman et al. 2003). As a result, conservation efforts have recently become more focused on this
primary threat.
Road ecology, ecopassages, and turtles
The field of road ecology studies the interaction between road networks and the natural environment. An
increase in research and scientific inquiry has contributed to more on-the-ground mitigation measures with
transportation planners and other stakeholders. Mitigation typically involves two separate approaches: the
modification of motorist behaviour and/or the modification of animal behaviour (Glista et al. 2009). Motorist
behaviour is modified with awareness and education including public campaigns and in situ speed limits, speed
bumps, lights, and signs (Figure 11). Animal behaviour modification is encouraged with habitat alterations
and/or installation of wildlife crossing systems (Ashley et al. 2007, Clevenger et al. 2001, OREG 2010).
Figure 11. Driver awareness and motorist behavior-change campaigns, including speed bumps in Nova Scotia,
temporary signage and speed limit reductions, and permanent wildlife crossing signs in Ontario (photos © BC)
Effective wildlife crossing systems, or ecopassages, include two components: exclusion fences and
crossing structures (Andrews et al. 2006). Exclusion fencing prevents animals from accessing the paved surface
of roadways where the majority of wildlife-vehicle collisions (WVCs) occur. Individuals are guided along an
impermeable barrier, which requires different materials and dimensions depending on the target species, to a
road crossing structure. Crossing structures allow animal passage from one side of the road to the other through
under-road or over-road terrestrial or aquatic passages. These structures may have been constructed specifically
to facilitate wildlife passage or for other purposes (drainage, water flow, etc). Ideally, all ecopassages are
designed to allow safe passage for animals, promote habitat connectivity, be accessible, and encourage natural
movements (Glista et al. 2009). The type of road, passage, fencing, habitat, and species all factor in to determine
19
how successful an ecopassage will be at preventing WVCs while facilitating movement and connectivity
(Ascensao & Mira 2006, Boarman & Sazaki 1996, Cramer & Bissonette 2005).
Several studies have now addressed how well different ecopassage designs prevent WVCs (Clevenger et
al. 2001, Dodd et al. 2003), while fewer focus on the utility of these structures for maintaining habitat
connectivity by confirming actual crossings by given study species, movement patterns relative to the structures,
and population persistence over time. For turtles, researchers have confirmed spotted turtle culvert crossings in
Massachusetts with thread-bobbins and visual observation (Kaye et al. 2005); several species were catalogued
using terrestrial culverts in Florida with hand-held photographs and track identification (Aresco 2005); passive
integrated transponders (PIT tags) and a magnetic coil reader were used to monitor desert tortoise use of storm
drain culverts in California (Boarman et al. 1998). More work needs to be done to understand the response of
turtles and other wildlife to ecopassages, and the effects that roads and mitigation measures have on dwindling
populations.
Figure 12. Turtle crossing structures in Algonquin Park, Ontario (left), Lake Jackson, Florida (center), and
Caledon, Ontario (right), each showing different barrier wall / exclusion fence and culvert elements, which
constitute effective ecopassages (photos © MTO, MA)
Landowner stewardship, stakeholder engagement, and public outreach
To supplement the research and monitoring conducted in the Highway 24 Blanding’s turtle project,
landowner stewardship, stakeholder engagement, and public outreach were a top priority. It has been shown that
education and stewardship can generate conservation actions that contribute to the recovery of turtle populations
(Caverhill 2006). Through the process of Community-Based Social Marketing (CBSM) several key audiences
have been identified by the Adopt-A-Pond Programme as having the potential to play a critical and impactful
20
role in the conservation of turtle Species at Risk across the province. The audiences selected are those whose
changes in behaviour can directly address the primary threats to turtles, either through actions taken on their
property, in their community, or on their local roads. The audience of waterfront property owners has been
identified as one of the most important. This group includes not only those on river or lake front properties but
also landowners with wetland habitat. In some cases, such as along HWY 24, many of these landowners own
agricultural properties with wetland area and make regular management decisions that have the capacity to either
positively or negatively impact turtles and other species of wildlife. The decisions and actions they take are
influenced by a variety of factors and it is possible to influence these decisions by way of education, creation of
social norms, provision of incentives or benefits, and/or the reduction of barriers to conservation action.
In order to increase local interest and engagement in turtle conservation and to learn more about the
values and behaviours of property owners in the Hwy 24 area a focus group session was conducted (for details,
see the methods section of this paper) in 2010. This was an opportunity to better understand this particular
audience and use the information obtained to develop an appropriate communication strategy for rural
landowners in Brantford and also in other areas of the province. Several keen landowners identified at this
meeting were engaged in habitat restoration projects, including nest site construction, in 2011. Details can be
found in the methods and results sections of this paper. In addition to this, turtle outreach presentations were
delivered to youth involved in two other target audiences: guide and scout groups, and eco-schools. These two
audiences were selected as targets because they represent groups of youth that are involved in environmental
education and have the capacity to become involved in turtle conservation by way of small scale behaviour
changes.
21
Materials and Methods
Study site
The Oakland Swamp is a provincially significant wetland complex in Brant County, Ontario, Canada. It
is drained in the north by Mount Pleasant Creek, which flows from west to east under HWY 24 at LAT
43.09872°N and LONG -80.35111°W, Zone 17T, Datum NAD83. A 25 m long, 1.8 m diameter circular
corrugated steel pipe funnels the water that flows from the swamp in the west to the stillwaters of Mount
Pleasant Creek in the East. The ~20 ha northeast region of the Oakland Swamp, which lies to the west of HWY
24, and the ~10 ha Mount Pleasant Creek wetland complex, which lies to the east of HWY 24, together comprise
the Highway Culvert area, which is the focal point of the study area (Figure 13).
Figure 13. Highway Culvert (HC) study area, including the 11 delineated and surveyed wetland sections within
the Oakland Swamp and Mount Pleasant Creek wetland complex [TP = Tobacco Pond, TE = Tobacco East, WM
= West Marsh, EA = Ellis Ave Ponds, WM = West Marsh, CU = Culvert, EP = East Pond, PP = Possum Pond,
AL = Arthur Lillies, CL = Chapin Lake, ML = Mudford Lillies, CP = Copek Pond]
22
The study area is centered in the Lake Erie Plain, just southwest of Brantford. The landscape is low
lying, gently undulating, and has been largely transformed by human activity. It is dominated by agricultural
fields and farms, including row crops like tobacco, soy, corn, and ginseng. It contains relatively few forests and
wetlands. The Oakland Swamp is the largest natural feature on the landscape, at ~ 800 ha in size. The swamp has
been modified by humans in the past, as evidenced by long, linear trenches and local landowners’ recollections
(Tony Varga, pers comm.). Irrigation ponds and trenches that exist throughout the area are used to bring water to
the agricultural fields. Some cleared land surrounding the Oakland Swamp that was used for agriculture in the
past has reverted to wetland swamp since the 1950’s (Leone Nelson, pers comm.).
The dominant wetland types that exist within the study area include shrub swamps, shallow open water,
and marshes. Within each of these macro-habitats are meso-habitat features like willow thickets, cattail bays,
watermeal and duckweed coves, overhanging shrub shorelines, and cow lily dominated open water. Within these
locations, micro-habitat features including sedge hummocks, willow rooting zones, open water, emergent
vegetation, and muskrat huts are available to the turtles.
Data collection
Data were collected in two main categories: 1) effort (person hours dedicated to road surveys, wetland
surveys, trapping, and radio-telemetry, categorized by delineated wetland sections within the study area); and 2)
observations (of Blanding’s turtles, Snapping turtles, and Painted turtles, categorized by observation type and
location). Effort was expressed in person hours, and can be seen in Tables 1 and Figures 14 & 15 for 2010.
Figure 14 shows that effort was concentrated spatially in wetlands immediately surrounding the culvert and
highway within the study area in 2010. The spatial effort distribution was similar in 2010 and 2011. A summary
of all effort for both years can be found in Table 2. Spatial geography was delineated according to a specific set
of criteria. Data cards used during field work, spatial terminology, and other details can be seen in the Appendix
of this report.
Table 1: Effort (expressed in person hours) by wetland section and activity type in 2010
Survey
Trap
TP
0
2.42
TE
0
0
EA
0
16.16
WM
7.5
36.43
CU
24.77
0.17
EP
8.67
60.08
PP
17.25
25.33
AL
1.75
17.25
CL
3
0
ML
0.75
3
CP
0
1.92
TOTAL
63.69
162.76
Radio
0
2.08
20.42
117.47
6.84
67.93
43.17
6.42
0
0
0
264.33
Other
0
0
0
0
13
0
15
0
0
0
0
28
TOTAL
2.42
2.08
36.58
161.4
44.78
136.68
100.75
25.42
3
3.75
1.92
518.78
23
180
160
140
Other
120
Radio
100
Trap
80
Survey
60
40
20
0
TP
TE
EA
WM
CU
EP
PP
AL
CL
ML
CP
Figure 14: Effort (in person hours) by wetland section and activity in 2010
28
63.69
Survey
Trap
162.76
Radio
264.33
Other
Figure 15: Effort (in person hours) by activity (visual surveys, trapping, radio-tracking, and other) in 2010
24
In addition to the effort hours exerted in the field by researchers tabled above and figured below, a total
of 137 hours and 25 minutes of dedicated road surveys were conducted in search of turtles and turtle crossing
hotspots between April and November 2010. Another 80 hours and 20 minutes of road surveys were conducted
between April and August 2011. Surveys in 2010 covered 7982.3 km of municipal and provincial highway
between Cambridge and Simcoe, and in 2011 they covered 3943.9 km of road throughout the HWY 24 corridor.
Road surveys solicited not only researchers but also volunteers in the surveys. Some stretches of road were
surveyed many times (50+) throughout the season, while others were only surveyed once. Often during a road
survey prime wetland habitat was discovered, and these habitats were surveyed as well.
Table 2: Total effort (expressed in person hours, rounded to the nearest hour) by activity in 2010 & 2011
Field Research
Activity
Visual Survey
Nesting Survey
Trapping
Radio Tracking
Road Surveys
Other
TOTAL
2010
2011
TOTAL
64
*
163
264
137
28
656
71
156
39
200
80
8
554
135
156
202
464
217
36
1210
*In 2010, Nesting Surveys were included in Visual Surveys
Field methodology
Road surveys
Road surveys were conducted almost daily at various times throughout the day from April to November
2010, and April to August 2011. The majority of the surveys occurred between Cambridge in the north and
Simcoe in the south, along the HWY 24 corridor and along surrounding country roads. Most surveys were
conducted by a single driver / observer, driving at ~80 km/hr or the posted speed limit. Several surveys,
specifically those surrounding the HWY 24 Mount Pleasant Creek culvert crossing, were conducted by one to
five observers on foot. Road surveys were conducted primarily by Brennan Caverhill in 2010, but an assembled
team of expert Turtle Tallyers conducted the majority in 2011. Surveys were not conducted in regular intervals
in time or space because it is known that herpetofaunal roadkill is often concentrated at specific hot-spots, during
predictable hot-moments (Beaudry et al. 2010, Langen et al. 2007). It was our goal to discover those areas and
periods as quickly as possible. Timing and location of road surveys were therefore selected to provide the
highest chance of encountering turtles on the road. We selected routes that travelled through areas with high
wetland concentrations, and predicted turtle crossings using Google Maps® and aerial photography (Figure 16).
Once we encountered a road-killed turtle at a specific location, we tended to revisit that location again and more
25
often in subsequent surveys. Information including travel time, distance, start and end locations, route travelled,
method, observers, and findings were recorded for each survey. All road survey data can be found in the digital
appendix of this report.
Figure 16. Most highly traveled road survey routes within the HWY 24 corridor, from Guelph to Long Point;
different routes were colour coded for personal identification; red crosses are potential crossing sites,
exclamation marks are road-killed turtles, and white circles are key turning points along the route
Wetland surveys
Visual surveys by research staff and volunteer stewards for turtles in wetlands were conducted almost
daily between April 20 and September 3, 2010, and April 1 and August 15, 2011, by one to five observers
simultaneously. Surveys were conducted on foot or in canoe, by walking or paddling either directly through the
wetland habitat or around its perimeter, depending on water depth and accessibility. Blanding’s turtle and
Snapping turtles were hand-captured if possible when encountered. Painted turtles were noted, but not captured.
If a captured turtle was un-marked, it was processed on site (see “turtle processing” below) and released as soon
as possible (minimum one hour, maximum 24 hours if radio-tagged) at the capture location. If it was previously
26
marked, an observation was recorded and it was released immediately. If the turtle could not be captured and
identified, species and location were noted, and surveys continued. Effort cards detailing all the information
collected during surveys can be seen in the appendix of this report.
Trapping
Trapping employed aquatic hoop-net funnel traps baited with sardines in soy oil placed in a perforated
sandwich container. We deployed 10 traps that were 16” in diameter, four 24” in diameter, and four 32” in
various configurations throughout wetland habitat within the study area. The number of traps set depended on
site suitability, available time and researchers. Traps were set for a period of one to five nights. A trap-session
consisted of setting a number of traps, checking them daily for a number of days, and removing or moving them
to a new location. In 2010 we conducted approximately 25 trap sessions, for a total of 1693 trap nights (1 trap x
1 night = 1 trap night), and in 2011 we conducted 12 trap sessions for a total of 507 trap nights, equalling 2200
trap nights total for 2010 and 2011. Trap cards showing all the data collected for each trap can be seen in the
appendix.
Turtle processing (morphometrics, samples, etc.)
Captured Blanding’s turtles and Snapping turtles were aged, sexed, measured, weighed, photographed,
blood-sampled, and notched for individual identification. Age was determined by counting the average number
of annuli (growth rings) on each plastral scute, a reasonable estimate for many species (Sexton 1959). Turtles
were sexed based on plastral concavity, pre-cloacal distance (distance between plastron and vent), tail size, and
upper lip colour. Measurements were taken to the nearest tenth of a centimeter with 50 cm calipers and a 30 cm
measuring tape. Weights were recorded to the nearest 10 grams using 250 g and 2000 g Pesola® spring scales or
a 10 kg weigh scale, depending on the size of the turtle. Photographs were taken with a 10 megapixel Nikon D80
digital SLR camera. Blood samples were extracted from the post-cloacal caudal artery or vein in the tail with
sterilized 1.0 mL syringes and 23 gauge needles. Samples were deposited in lysis buffer and stored in a cool dark
place for future analysis. If a blood sample was not acquired within the first three attempts, the process was
postponed until future capture. Some turtles were not sampled, due to the time of capture (eg. nesting). Turtles
were marked by notching marginal scutes in a unique pattern with a triangular file, modified from Cagle (1939).
Between May 2010 and August 2011, 22 turtles [19 Blanding`s turtles (14 female, four male, one juvenile) and
three Snapping turtles (one female, two male)] were also fitted with radio-transmitters, so we could monitor
movements, habitat use, and response to the exclusion-fence and culvert ecopassage.
We used the “Lincoln-Petersen Method” or “Lincoln Index” to estimate the total population size for the
Blanding’s turtle and Snapping turtle populations in the Oakland Swamp, where N=MC/R (N = population size
estimate, M = number of individuals captured and marked in visit one, C = number of individuals captured in
visit two, and R = number of individuals recaptured from visit one in visit two). This estimate assumes only two
visits are made to the study area; we considered each year to be a single visit. Other assumptions include: 1) a
27
closed population (no mortality, birth, emigration, or immigration), 2) tags remain visible so marked individuals
are successfully recognized upon subsequent capture, 3) correct recording of marks and recognition of
individuals by researchers. Although assumption one was likely violated slightly, two and three were met
satisfactorily.
Radio-telemetry (active hand-held)
We used 18 Holohil AI-2 and PD-2 and four Sigma-Eight radio transmitters, which emitted a ~0.6 pulse
per second signal in the 172.000 to 172.999 MHz range. We affixed transmitters to the rear right or left side of
each turtle`s carapace with superglue and PC-7 marine epoxy (two small drops of superglue per tab was used for
short-term adherence while the epoxy dried). Attaching and removing the radios using this method is harmless to
the turtle, and leaves no damage or residue upon removal. We ensured that combined transmitter/epoxy weights
were less than 5% of the weight of the turtle to which the radio was attached. Battery life for the transmitters
varied from 16 months for small juvenile transmitters to 36 months for large adult transmitters.
We tracked radio-tagged turtles using a Wildlife Materials portable receiver and a hand-held Yagi threeelement directional antenna. Radio-tagged turtles were located two to four times per week on average, and
occasionally several times per day (more if the turtle was very near the road and culvert, or nesting) throughout
the active season (May – October 2010 & 2011). Upon each observation, data were recorded including turtle ID,
date, time, weather conditions (air and water temperature, cloud cover, wind speed), sighting method (visual or
pinpoint), observers, location description, UTM or LAT/LON, turtle behavior, position, habitat, and vegetation
cover in a 2.5 m radius. UTMs were obtained from a Garmin Rino 530HCx hand held GPS unit, providing
spatial accuracy of +/- 3 m. Temperatures were recorded in the shade (air) or at 30 cm depths (water) using an
analog thermometer. Observation cards showing all fields for data collection can be seen in the appendix of this
report.
Nesting surveys & artificial nest site construction
Nesting surveys were conducted from May-July in both 2010 and 2011, but nests and nesting females
were only discovered in 2011. Researchers radio-tracked all female Blanding’s turtles every morning between
7AM and 9AM and every evening between 5PM and 10PM from June 1 to July 1, 2011. To search for nesting
turtles that were not radio-tagged, we also walked during these times throughout all potential nesting areas
(exposed sandy/gravely substrates with good drainage and sun exposure) within a 1 km radius of all wetlands
known to contain Blanding’s turtles in the study area. If a turtle was found in the water after dark, we assumed
that turtle would not nest that day. If a female turtle was encountered on land at any time, we monitored it from a
distance with binoculars to allow unhindered behaviors. Turtles that were found digging in one place for
extended periods were quietly approached from behind to check for egg laying. If a nest was laid in a location
prone to predation or destruction, we relocated the eggs within 24 hours to an artificial nesting site. Some nests
28
were protected with 2 x 2’ wire-covered enclosures to prevent predation, while others were left unprotected to
monitor predation risks.
Two artificial nest sites were constructed, one in December 2010 and the second in October 2011.
Locations were chosen with the following in mind: proximity to known wetland habitat, safe location away from
the road, sun exposure, drainage, and support of local landowners. Methodology developed by Adopt-A-Pond
experts was followed for design and construction. Surface vegetation was removed to a depth of ~6” in a 20’ by
40’ area. Landscape cloth was laid to reduce vegetation growth. Layers of pea-gravel and sand were mixed to a
depth of ~12” throughout the area, with a preference for a south-facing slope.
Radio-telemetry (passive data-logging)
From June 30 to November 8, 2010 and April 27 to October 9, 2011 we employed a passive datalogging radio-receiver in and adjacent to the culvert that passes under HWY 24. Its components, functions, and
approximate pricing are listed in the appendix. In addition to the hardware described, a laptop computer, MMC
card reader, USB to analog adapter cable, computer operating system, and OrionTool software were required to
download and view the data collected by the receiver. We stored the water-sensitive electronics in a 50L
Rubbermaid bin, which successfully waterproofed the system throughout its installation periods. Also required
were a number of radio-transmitters attached to turtles of interest.
The ORION receiver was programmed to log signals emitting within the 172.000 – 172.999 MHz range,
a pulse width between 8-50 milliseconds, and a pulse interval of 0.05 to 2.5 seconds per pulse. After several
iterations its noise floor was ultimately set to -120 decibels (any signal below that intensity would not be
recorded), therefore filtering out noise or extraneous signals from the environment. The receiver was broadband
with DSP processing, so it listened to all programmed frequencies simultaneously. It was also programmed to
alternate antennas every five seconds. Any valid detections were recorded with the date, time, frequency,
antenna, signal strength, and pulse rate.
The solar panel was angled due south at 45 degrees and propped up above the shadows on a wooden
frame to maximize solar gain and resulting battery charge. Two antenna cables were cut to the same length
(~50m); one was run to the east end of the culvert (antenna 1) and the other to the west end (antenna 2) through
the culvert. Each antenna was tied to a brick at the end, with a stripped end that acted as an antenna facing up,
and sunk to the bottom of the water column approximately 3 m inside the end of the culvert. The entire
electronic setup, including receiver, antenna switch, charge controller, and battery were stored in a waterproof
bin approximately 20 m from the culvert, and concealed in the bushes to avoid human interference (Figure 17).
29
Figure 17: Passive data-logging radio-receiver setup, showing relative location of road, fence, and receiver
Culvert measurements
We used a 50 m measuring tape to measure the dimensions of the culvert, road, fencing, and surrounding
features. We calculated culvert diameter, length, slope, water levels, flow rate, substrate depths, and several
other parameters including fence height and length, road height and width, and distance to water from each
feature. We also measured water quality and temperature at the culvert, and the light and sound levels within the
culvert (see below). Measurements taken in 2010 are depicted in Table 3 and Figures 18-20. Flow rates varied
throughout the season, and were significantly slower during low-water periods (0.05 m/s) versus high-water
periods (1 m/s).
30
Table 3: Culvert measurements
Culvert
1
CL
25 m
CD
1.8 m
CCS
2
2.5 m
SL
FR
0.3º
0.25m/s
HTP
DFP
CO
eCO
0.8 m
8.5 m
0.1
0.05
2
CL (culvert length), CD (culvert diameter/width), CCS (culvert cross-section area = πr ), SL (slope), FR (Flow Rate), HTP (Height to
Pavement), DFP (Distance From Pavement), CO (culvert openness = ratio of CCS to CL), eCO (effective culvert openness)
Figure 18. HWY 24 culvert cross sections, showing west and east entrances, and average sediment
(soil/rock/organics = brown) and water levels (water = blue, air = white)
We calculated the culvert openness ratio using the formula CO = CCS/CL (culvert openness = crosssectional area divided by its length). The result is 0.1. However, since the culvert was fully aquatic throughout
the entire study period and likely never goes dry, and considering there is substrate accumulation in each end, the
effective opening size is less than the full CO. Therefore, we also estimated the effective culvert openness, eCO.
31
Figure 19. HWY 24 culvert profile, showing length, water depth, and relative human and turtle size
Figure 20. HWY 24 culvert and turtle fence aerial view, showing fence length, culvert placement, guard rails,
and infrared cameras
32
Water quality measurements
We solicited the help of water quality technician Becky Mitchell from the Grand River Conservation
Authority (GRCA) to determine several water quality parameters including pH, DO, conductivity, and
temperature. We used a YSI 650 MDS probe at four wetland locations within the study area, including the
culvert; we also installed two temperature loggers at the study site, one in the water at the culvert and one within
a relocated Blanding’s turtle nest at the artificial nesting site on Frank Dorombozi’s property.
Light & sound measurement
We used light and sound meters to measure the brightness and noise levels in the culvert at mid-day in
September 2011. Light was measured in Lux units with a Lunasix 3 system exposure meter made by Gossen
Gmbh Erlangen (Germany), and sound was measured in decibels with a GR1565-B Sound-Level Meter made by
General Radio (Massachusetts). All measures were taken in the air above the water in the culvert, about 50 cm
above the water level (Figure 21). The turtles, of course, would have a different experience of the light and
sound in the culvert because they travel through the structure underwater. Because of this, these measures should
mainly be used to compare this culvert to others that are being studied with respect to turtle passage.
Figure 21. Brennan taking light and sound measurements in the culvert (photo © Amy Mui)
Turtle fence cameras
We installed two “Stealth Cam” infrared trail cameras, model number STC-I540IR, along the wetlandside (as opposed to road-side) edge of the HWY 24 turtle fence to determine whether turtles were actually being
funneled along the wetland-side edge of the fence to the culvert (Figure 20). One was fixed on the east fence, 30
m north of the culvert, facing south towards the culvert. The second was fixed to the west fence, 30 m south of
the culvert, facing north towards the culvert (Figure 22). They were angled so they could capture movements
along the fence, and locked to the fence with a bike lock and camouflaged to deter theft.
33
Figure 22. HWY 24 fence cameras, showing (1) researcher installing the camera on the wetland-side edge of the
fence; (2) the position and angle of the infrared camera, tucked under the 45 degree angle of the fence; (3) the
view of the camera from the road, showing camouflage
We monitored the cameras daily from April through June 2011. When the vegetation became too tall,
the pathway along the fence became obscured, and the waving vegetation caused too many photos that captured
plant movement, but no animals, so the cameras were uninstalled.
Highway 24 traffic and turtle-vehicle collision probability
We used the equation ( Pkilled = 1 - e
-Na/v
) to estimate the probability that a turtle would be struck and
killed by a vehicle in one attempted crossing of HWY 24, where Pkilled = the chance of being killed (%), N =
traffic rate (vehicles/minute), a = width of the kill zone, which is 2 tire widths per lane plus four times the
average shell length of a Blanding’s turtle (m), and v = turtle velocity when crossing the road (m/min) (Aresco
2003, Ashley et al. 2007, Beaudry et al. 2010, Gibbs & Schriver 2002, all adapted from Hels & Buchwald 2001).
To calculate “N”, traffic rates, we acquired traffic statistics from analysts at the provincial Ministry of
Transportation (MTO) (Bill Briggs, MTO, 2009 data, personal communication, January 2010). Vehicle counts
were collected in spring, summer, and fall 2009 from permanent stations using magnetic strips embedded in the
asphalt less than one kilometer south of the study site at the junction of Maple Grove Road and provincial
Highway 24 (43.05202°N and -80.36866°W). Since the data collection occurred near to the study site in time
and space we assumed the data suitably reflected the traffic conditions along HWY 24 at our study site.
On average, a total of 403 vehicles drive over the culvert per hour from March to October, including
both northbound and southbound traffic, between the hours of 0600 (6am) and 2000 (8pm) every day. An
average of 6845 vehicles drive over the culvert every day, and 82% of this traffic occurs between 6am and 8pm
(Table 4). We selected the 0600-2000 time interval for our calculations because it best matches the activity
period of Blanding’s turtles and Snapping turtles, which are both diurnal species that are most active during the
day between dawn and dusk. Although similar studies have chosen an activity period of 0600-1800 (Ashley et
34
al. 2007, Beaudry et al. 2010), we often saw turtles active and terrestrial after 6pm, especially females during
nesting season.
Table 4: Traffic measurements for HWY 24 in spring, summer, and fall 2009 (extrapolated to 2010)
average
average
% traffic
average
average
vehicles/day vehicles/6am-8pm 6am-8pm vehicles/hour vehicles/min
season
month
year
spring
March
2009
5722
4782
83%
342
5.7
summer
August
2009
7772
6303
81%
450
7.5
October 2009
7040
5862
83%
419
7.0
6845
5649
82%
403
6.7
fall
TOTAL
To calculate “a”, the width of the kill zone, we needed to know average tire widths of vehicles driving
on HWY 24, the number of lanes, and the average carapace length of Blanding’s turtles and Snapping turtles.
We acquired statistics regarding relative percentages of different vehicle types on HWY 24 from MTO (Bill
Briggs, MTO, 2009 data, personal communication, January 2010). Tire widths were estimated from vehicle
measurements in a gas station parking lot. These data are shown in Table 5, and illustrated in Figure 23.
Figure 23. Illustration of “a”, the kill zone, using a car and Blanding’s turtles (measurements would be larger for
larger tires and turtles)
35
Table 5: Vehicle types on HWY 24, relative percentages, and tire width estimations
vehicle code
1
2
3
4
vehicle type
car
* relative %
85%
7%
2%
6%
100%
avg. tire width
0.25 m
0.3 m
0.75 m
1.25 m
0.6375 m
0.021 m
0.015 m
0.075 m
0.3235 m
pickup or van bus or truck heavy truck
º weighted tire width 0.2125 m
all
*relative % indicates the percentage of vehicles on HWY 24 that are of that type
º weighted tire width takes the relative % times the average tire width, to determine an overall average tire width
HWY 24 consists of two lanes along the sections within the study area, one supporting traffic in each
direction (one northbound, one southbound). For shell length, we used the mean carapace length for all
Blanding’s turtles (N=28, mean carapace length = 20.5 cm) and Snapping turtles (N=21, mean carapace length =
27.2 cm) captured and measured at the Oakland Swamps in this study in 2010. A range of calculations for
parameter “a” are presented in Table 6.
Table 6: Estimates for parameter “a” [(tire width x 2) + (carapace length x 4), times # of lanes)]
estimate
tire width (m) + carapace (m) lanes
result
all cars (Blanding’s)
0.25 x 2
+
0.205 x 4
x2
2.64 m
all cars (Snapping)
0.25 x 2
+
0.272 x 4
x2
3.18 m
weighted (Blanding’s)
0.32 x 2
+
0.205 x 4
x2
2.92 m
weighted (Snapping)
0.32 x 2
+
0.272 x 4
x2
3.46 m
all trucks (Blanding’s)
1.25 x 2
+
0.205 x 4
x2
6.64 m
all trucks (Snapping)
1.25 x 2
+
0.272 x 4
x2
7.18 m
To calculate “v”, turtle velocity, we used a conservative estimate from the literature of 7.5 m/min
(Beaudry et al. 2010, Wren et al. 1998). At full speed, we have clocked turtles at upwards of 15 m/min on land,
but a typical meander is usually much slower.
Other wildlife & roadkill at the HWY 24 Mount Pleasant Creek culvert crossing
From April to November 2010 and April to September 2011 we walked the road shoulder, vegetated
margin, and ditch on either side of the road in search of animals, alive or dead, surrounding the fenced section of
the HWY 24 culvert and Mount Pleasant Creek crossing. We recorded the date, time, species, and approximate
location (east or west shoulder, north or south extent of fence) of all road-killed and live animals found.
36
From April 2010 to August 2011 we searched for signs of other wildlife that might be using the culvert
to cross under HWY 24. Every day we were in the field we would check the culvert, occasionally paddling or
wading through it to physically flush out anything that might be inside. We also searched for tracks in winter.
Results are described below.
Landowner stewardship, stakeholder engagement, and public outreach
Throughout 2010 and 2011 we actively engaged landowners in stewardship activities, promoted
stakeholder awareness and involvement, and educated the public about the Toronto Zoo’s Ontario Turtle Tally
and the HWY 24 project. We methodically approached landowners surrounding the study area at the beginning
of the project in spring 2010, introduced ourselves and provided them with information about the turtles of
Ontario, and our project. We asked permission to access their wetland property, and later invited them to a
landowner focus group held in November. At the end of the project in August 2011 we hosted a “Thank You”
celebration at Frank & Debbie Dorombozi’s property, the most active and engaged of all the landowners, who
also allowed us to construct an artificial nest site on their property. We opportunistically encountered and
engaged these and other landowners throughout the field season, speaking with some on a daily basis. We were
in touch with officials from MTO and MNR on a monthly basis, providing project updates and support. We
advertised our availability to deliver “Turtle Talks” to local guide groups and eco-schools, and provided several
displays at local county fairs and events. Some examples of the outputs produced to engage the public are shown
in the appendix. The outcomes of these objectives are outlined in the results section of this report.
37
Results
Habitat descriptions
Turtles in this study occupied wetland habitat in the Oakland Swamp and Mount Pleasant Creek, which
are situated in the Grand River watershed and Lake Erie Plain. The Ontario Ministry of Natural Resources
(OMNR) completed a wetland evaluation of the Oakland Swamp complex in September 1985, when it was
designated as a “provincially significant wetland”. The total productivity value for the wetland, which includes
indices such as growing degree-days, soils, wetland types, and nutrient status of surface water, received a total
score of 50%. The total diversity value was found to be 73%. This includes the number of wetland types,
vegetation communities, diversity of surrounding habitat, proximity to other wetlands, interspersion, and open
water types. The total biological component ranked 173 out of 250, a relatively high score for the region, hence
its designation as being significant.
The majority of the Blanding’s turtles marked and radio tagged in this study spent the majority of their
time in willow swamps, characterized by 0.15 m to 1.0 m deep water, carpets of floating Duckweed (Lemna spp.
And Wolfia sp.), channels and sink holes, cavernous rooting zones, and muskrat huts. The next most commonly
occupied habitat was shallow open water (0.25 m to 1.5 m deep) with abundant Cow Lily (Nuphar variegata)
and Coontail (Ceratophyllum spp.). The turtles also spent a great deal of time in marsh habitat with abundant
grass, sedge, and cattail, and also irrigation pond shorelines > 2 m deep water with abundant overhanging
vegetation including dogwood, river grape, and willow (Figure 24). Snapping turtles were found in similar and
overlapping habitat, primarily shallow open water and irrigation pond shorelines.
Descriptive features of each wetland section occupied by turtles within the study area can be found in
Table 7. The table includes wetland size, shape, heterogeneity, plant communities, water depth and flow, and
other variables. A second table also includes the most common plant species found in each section of the study
area, and their abundance within each section. This can be found in the appendix. Dominant plants included
willow and dogwood shrubs, yellow water lily, coontail and duckweeds, along with grasses, cattails, and other
aquatic herbs.
Figure 24. Top four turtle occupied habitats: willow swamp, shallow open water, marsh, and pond shoreline.
38
Table 7. Habitat features of 10 wetland sections in the Highway Culvert (HC) study area. Size in hectares,
shape, % of different wetland types within each section, the macro, meso, and micro-habitat heterogeneity
(measured in low, medium, or high), plant diversity, primary vegetation communities, average water depth,
water flow type, surrounding habitat, and relative abundance of Blanding’s and Snapping turtles.
Feature
TE
TP
WM
EA
EP
PP
AL
CL
ML
CP
All
Size (ha)
0.3
0.76
20+
1.04
0.65
1.95
1.85
1.75
0.6
0.5
800+
Shape
oval
oval
amoebic
oval
oblong
oblong
oblong
oblong
oblong
oblong
Type (%)
pond
(95%),
swamp
(5%)
pond
(100%)
marsh
(40%),
s.o.w.
(10%),
swamp
(50%)
s.o.w.
(90%),
marsh
(5%),
swamp
(5%)
s.o.w.
(60%),
pond
(30%),
swamp
(10%)
s.o.w.
(40%),
pond
(50%),
swamp
(10%)
s.o.w.
(60%),
pond
(30%),
swamp
(10%)
pond
(90%),
s.o.w.
(10%)
s.o.w.
(90%),
swamp
(10%)
pond
(80%),
s.o.w.
(20%)
amoebic
with tail
s (85%),
s.o. (5%),
m (5%),
p (5%)
Macro-
low
low
high
low
med
med
med
low
med
med
med
Meso-
med
low
high
med
med
med
med
low
med
low
high
Micro-
med
low
high
med
med
med
med
low
med
med
high
Plant Div.
low
low
high
med
med
high
med
low
med
low
med
Veg. Com
open
water
>2m
open
water
>2m
ct, grass,
willow
50cm
lillies
open
lilies
70cm
70cm
open,
lilies
>2m
ALL
>2m
open
water, dw
>2m
lillies, dw
60cm
open,
lilies
>2m
palus.
palus.
palus.
palus.
palus.
palus.
palus.
palus.
palus.
palus.
palus.
swamp,
forest,
crop
1
swamp,
forest,
crop
50
mowed
lawn
5
row crop,
riparian
buffer
3
row crop,
riparian
buffer
0
row crop,
mowed
lawn,
0
row crop,
riparian
buffer
0
ALL
15
mowed
lawn,
buffer
25
mowed
lawn
Blanding
swamp
forest,
crop
1
Snapping
0
0
10
10
20
20
20
5
10
5
100
Water
Depth
Water
Flow
Surr.
Habitat
1m
100
Wetlands that exhibited more heterogeneity at all levels (micro- meso- and macro-) tended to also have
more turtle diversity. The pie chart below (Figure 25) indicates the proportion of time Blanding’s turtles spent in
each of the four wetland types found in the study area [swamp, marsh, pond, and shallow open water (SOW)] in
2010.
137
28%
145
30%
127
26%
SOW
76
16%
swamp
marsh
pond
Figure 25. Proportion of Blanding’s turtle capture points (of all types) in four wetland types in 2010
In spring 2011 the turtles exhibited similar habitat selection patterns as in 2010 (preferring swamps, then
ponds and shallow open water, followed by marshes). However, due to extreme drought conditions in late June
39
and early July 2011, the WM (West Marsh) swamp and marsh sections dried almost completely, and all turtles
vacated these evaporating habitats for the deep, cool waters of EP, EA, and TE, all of which are used as
irrigation ponds for surrounding agriculture.
Turtle occurrence, abundance, distribution, and population size estimate
Blanding’s turtles, snapping turtles, and painted turtles occurred in most wetlands sampled throughout
the study area. Only Blanding’s turtles and snapping turtles were marked, measured, weighed, and
photographed. Painted turtles were counted and released upon capture. A total of 63 Blanding’s turtles and 25
Snapping turtles were marked during 2010 and 2011 (Table 8). These totals do not include road-killed
individuals of each species (Blanding’s = 7, Snapping = 12) discovered on and around sections of HWY 24. Of
the marked live Blanding’s turtles and Snapping turtles, 19 and three were radio-tagged respectively.
Table 8: Live Blanding’s turtle and Snapping turtle individuals marked in 2010 and 2011 [not including roadkilled turtles in and around the Oakland Swamp.
Blanding’s M
turtles
Snapping M
turtles
F J
Total
F
J
Total
14 11
4
29
2010
10
6
4
20
2011
5
6
34
2011
1
2
2
5
Total
19 34 10
63
Total
11
8
6
25
2010
23
Visual surveys yielded the most new captures of individual Blanding’s turtles, followed by traps, nesting
surveys, and road surveys (Table 9). No Blanding’s turtles were captured using basking traps, although several
painted turtles were captured using this method. By far the most successful method for capturing Snapping
turtles was aquatic hoop-net trapping, followed by road surveys, visual surveys, and nesting surveys.
Table 9: Blanding’s turtle and Snapping turtle capture methods and capture totals for 2010 and 2011 (including
7 roadkilled Blanding’s turtles and 12 roadkilled Snapping turtles found outside the study area)
Capture Method Blanding’s Snapping
Total
Road Survey
9
12
21
Nesting Survey
10
1
11
Visual Survey
27
3
30
Hoop-Net Trap
24
21
45
Basking Trap
0
0
0
Total
70
37
107
40
The Lincoln Index was used to estimate population size, where N=MC/R. For Blanding’s turtles, we
captured 29 individuals in year one (M), and 43 individuals in year two (C), nine of which were recaptures (R).
Therefore N = (29x43)/9 = 138. For Snapping turtles, we captured 20 individuals in year one (M), and five
individuals in year two (C), one of which was a recapture (R). Therefore N = (20x5)/1 = 100. These population
size estimates for both species fit within the range that was intuitively perceived by researchers at the site.
Each captured turtle’s measurements, notch codes, deformities, date and location of first capture, radio
tags, photographs, and additional notes can be found in the digital appendix. Included are all formal photos taken
of all Blanding’s turtles and Snapping turtles, their morphometrics, etc. Additionally, field photos are included of
some turtles in situ, as well as some video footage. Figure 26 shows the initial observation points of all
Blanding’s turtles and Snapping turtles captured in 2010 and 2011. Figure 27 shows all capture locations for
Blanding’s turtles and Snapping turtles throughout 2010 and 2011, representing overall occurrence and
distribution throughout the wetland complex surrounding HWY 24.
Figures 26. Blanding’s turtle (yellow) and Snapping turtle (green) initial capture locations for 2010 (circles) &
2011 (triangles); N = 63 Blanding’s turtles and 25 Snapping turtles (NB - many points overlap and obscure one
another, so it may not appear as if all 88 points are present on the map)
41
Figure 27. All Blanding’s turtle (yellow) and Snapping turtle (green) capture locations for 2010 (circles) & 2011
(triangles); N = 63 individual Blanding’s turtles and 25 Snapping turtles, captured 1100+ times throughout the
study period
Blanding’s turtles were also confirmed to occupy wetland habitat north and south of the Oakland
Swamp. Five confirmed individual Blanding’s turtle observations from two trusted stewards (Georg Hentsch and
Don Scallen), which were accompanied by photo proof, were reported from ~20 km north of the study site in the
area surrounding Bannister Lake (Figure 28). Three additional sightings, supported by photos, were recorded by
Ruth Ann Logan from ~15 km south of the study site, in and around Vivian’s Pond. These reports from 2010 and
2011 add to several interspersed Blanding’s turtle sightings from the area in MNR’s NHIC database. These
observations confirm that Blanding’s turtle individuals occupy many wetlands throughout the HWY 24 corridor,
from Cambridge to Simcoe west of Brantford. It could be that the densely population Oakland Swamp is a
source for these more widely distributed satellite populations.
42
Figure 28. Confirmed Blanding’s turtle sightings from stewards in 2010 and 2011 in areas surrounding the study
site; yellow balloons are Blanding’s turtle individual locations, and the yellow square indicates the Oakland
Swamp study site
In the Oakland Swamp, there was a seasonal component to habitat use by Blanding’s turtles, as indicated
by their changing locations within the wetlands by month in 2010 and 2011. In both years, Blanding’s turtles
tended disperse in spring (April-June) as they basked, foraged, and mated. The most massive dispersal occurred
during nesting, when females made large forays into surrounding agricultural fields, sometimes travelling as far
as 2 km straight-line from the center of their home-range. Following nesting, a period of aggregation occurred in
the summer (July-August), especially in 2011 when water levels dropped tremendously and only deep-water
irrigation ponds were occupied. Fall dispersal occurred in 2010 (September-October), as turtles moved towards
their overwintering locations, which were relatively aggregated in winter (November 2010 – March 2011).
Below are two maps, on depicting the dispersal event during nesting in June 2011, the second showing
aggregation in deep irrigation pools during the drought of July 2011 (Figure 29).
43
Figure 29. Blanding’s turtle capture points during periods of dispersal (June 2011), and aggregation (July 2011);
in both maps, N=19 radiotagged Blanding’s turtles were being tracked for a total of 100-200 captures
Movements and home range
Radio-tagged Blanding’s turtles and snapping turtles were located several times per week throughout the
active season (May to September 2010 & 2011) and several times per month as they entered their overwintering
sites (October to December 2010). As depicted in Figure 30, inter-wetland movements peaked in early June, then
again in early August in 2010. An “inter-wetland movement” occurs when a turtle is captured in one discrete
wetland section of the study site on one occasion, then in a separate discrete section on the next occasion. The
date of the movement was considered to be the date of capture in the new wetland section. The majority of interwetland movements in 2011 once again occurred in June. Due to drought conditions in July and August, most
turtles stayed in deep irrigation ponds for the remainder of the summer.
Figure 30. Blanding’s turtle inter-wetland movements in 2010 (left) and 2011 (right); NB – 4 males and 14
females are represented, so there were more than 3x as many females than males being tracked
44
Figure 31 shows the capture locations and movements of one Blanding’s turtle, male 0-1 (Frank), who
was captured 53 times in 2010; during a six month active season, he moved back and forth across the road 13
times, and had a total path distance of 6292 m (sum of distances between subsequent capture points, which
provides a minimum estimate of his total straight line movements) between June and October 2010. Path
distances and corresponding maps were not calculated or created in 2011. However, his 8 ha MCP home range
was calculated using all capture points from 2010 and 2011 (Figure 32). Corresponding maps for all other radio
tagged turtles are provided in the digital appendix.
Figure 31. Blanding’s turtle male 0-1 (Frank) capture locations (N = 53) and movement pathways from May to
November 2010, showing his first and last (overwintering) locations
On average, radio-tagged Blanding’s turtles moved 18 m per day, and 75 m between subsequent
captures in 2010. Males (~5.2 km total movements per turtle) moved more than females (~1.9 km), who moved
more than juveniles (0.5 km), for Blanding’s turtles in 2010. Path distance calculations were not made for 2011
data. Male and female snapping turtles moved about the same distance (~2 km total) in 2010.
Figure 32 shows the home range of Blanding’s turtle, male 0-1 (Frank), who had an MCP of 79187 m2
(7.9 ha) and a 95% PVC of 15457 m2 (1.5 ha) in 2010. Using data from both years, his MCP home range
remained unchanged, at ~8 ha (Figure 33). Corresponding maps and data for all other radio tagged turtles can
found in the digital appendix.
45
Figure 32. Blanding’s turtle male 0-1 (Frank) MCP and PVC home range estimate visualizations, derived from
capture points (N = 53) between May and November 2010
Figure 33. Blanding’s turtle male 0-1 (Frank) MCP home range and capture points (N = 67) using all data from
June 2010 to July 2011
46
Using both the Minimum Convex Polygon (MCP) and Percent Volume Contour (PVC) calculation
methods with data from 2010, male Blanding’s turtles (1.5 to 11.4 ha) had larger home ranges than females (1.1
to 6.2 ha), who had larger home ranges than juveniles (0.5 to 1.6 ha). MCP home ranges for Blanding’s and
Snapping turtles for 2010 are depicted in Figure 34. However, when incorporating all spring nesting movements
for females and males in 2011, the average of 14 individual female home range sizes (
of four male home range sizes (
= 21 ha) doubled that
= 10 ha), using the MCP method only. In fact, one female Blanding’s turtle
had a home range of over 78 ha! Overall, the average 95% PVC home range was an underestimate at 11730 m2
(1.2 ha), while the average MCP home range for all Blanding’s turtles was an overestimate at 73582 m2 (7.3 ha)
in 2010. Only MCP calculations were made for home range in 2011.
Figure 34. All radio tagged snapping turtle MCP in 2010 (left), including two males (green) and one female
(yellow) - note how male ranges do not overlap; all radio tagged Blanding’s turtle Minimum Convex Polygons
(MCP) in 2010 (right), with juveniles (N=1) in orange, females (N=9) in yellow, and males (N=4) in green
Mating
Blanding’s turtles were observed mating on five occasions during the last week of April and first two
weeks in May 2011. All mating events occurred in water 30 to 60 cm in depth. Mating waters were relatively
open with algae and some floating plants at the surface. The coupled pair often circled a willow cluster while
engaged. Often, the male and female turtle in coitus were unaware of our presence, and we were able to take
underwater photos and video footage of the affair (Figure 35). Often, the male turtle would sweep his head and
neck back and forth in front of the female, while grasping her carapace tightly with his four feet. Knocking her
head into her shell like this would cause her tail to protrude. He would also often bang his plastron against her
carapace repeatedly, knocking her deep into the substrate, at which point they would no longer be visible.
47
Figure 35. Blanding’s turtle male 0-3 (top) and female 2-4 (bottom) mating; in these photos, from May 4, 2011,
both turtles were radio-tagged
Nesting
Researchers conducted 156 hours of survey effort dedicated to nesting and discovered six Blanding’s
turtle nests and another 14 different individual gravid females at suspected nesting sites in June 2011. Blanding’s
turtles laid eggs primarily in agricultural fields surrounding the West Marsh (WM) to the north and south of the
wetland (Figure 36). Female Blanding’s turtles tended to stay within 100 m of the wetland margin during their
nesting forays in 2011, which occurred primarily fields recently planted with corn, millet, rye, soy, and tobacco
(Table 10). Selected substrates were sandy and fine. Two nests were relocated to the first artificial nesting site
and protected with wire nest cages; four nests were left in-situ, two of which were protected with nest cages, and
the other two were left unprotected. No predation of known Blanding’s turtle nests occurred, but many snapping
turtle and painted turtle nests were found predated, especially along the south-facing north shore of Possum Pond
(PP).
Table 10: Female Blanding’s turtle nests observed in June 2011
Turtle
ID &
Name
Date
Laid
Date
Hatched
#
eggs
#
hatch
Habitat
& Status
1-9
Amanda
June 9
< Sep 7
9
7
corn field
(no cage)
0-10
Grace
Jun 15
Sep 5
13
13
1-3
Speedy
Jun 15
Sep 7
11
11
4-4
Jun 15
NA
NA
NA
millet
field
(moved)
millet
field
(caged)
millet
Notes
Emergence hole discovered Sep 2 – two
eggs did not develop (likely
unfertilized); 7 empty shells
Relocated from WM to PP on June 15;
partial hatching of nest on Sep 5, full by
Sep 7
Four hatchlings discovered within 5 m
radius of nest, two observed emerging
from eggs; synchronous emergence
Nest could not be found due to mowing
48
Tota
8-1
Mini
Jun 21
~ Oct 1
5
4
3-0
Debbie
Jun 23
NA
NA
0
field (no
cage)
millet
field
(moved)
corn field
(no cage)
in millet field
Relocated from WM to PP on Jun 22; 4
normal sized eggs hatched, one egg was
pea-sized and empty!
Nest located this fall; no hatching as of
Sep 10
Figure 36. Blanding’s turtle nests (orange squares) and nest search/attempts (yellow triangles) in June 2011
Two artificial nesting sites were constructed, the first in December 2010 on the north shore of Possum
Pond (PP) and the second in October 2011 along the south field margin of West Marsh nesting field south (WM
(s)). We followed nest site design and construction protocols developed by the Adopt-A-Pond Programme, and
hired local residents to assist in construction. The first was constructed on Frank Dorombozi’s property (Figure
37a), and the second on the border of Tony Varga and Mike Biggin’s properties. All landowners involved were
extremely helpful, and are committed to maintaining and monitoring their nesting sites. Although neither has
49
been used by a Blanding’s turtle yet, one was used as a relocation site for nests considered to be in danger of
destruction or predation, and we hope to receive reports in the future of additional success.
Figure 37a. Artificial nest site constructed on Frank Dorombozi’s property in December 2011.
Overwintering
Most radio-tagged Blanding’s turtle overwintered within a 100 m radius of one another in the western
end of West Marsh (WM); two females wintered in the Ellis Avenue Pond (EA), and one male in PP (Figure
37b). Overwintering site water levels were between 10 cm and 150 cm in depth (approximately). Individual
turtles were usually along an undercut shoreline, or among rooting zones of willow clusters. Water froze solid to
an unknown exact depth of at least 15 cm (enough to support the weight of a gear-clad researcher). Turtles
entered their overwintering sites from September to October 2010, and departed in late April 2011.
Figure 37b. Overwintering locations for 14 radio-tagged Blanding’s turtles and 2 Snappers in 2010-2011.
50
Water quality
We measured several water quality parameters from the wetland, including temperature, acidity,
dissolved oxygen content, turbidity, and conductivity. All measurements were taken on June 6, 2011 between
11:00AM and 1:00PM. Results are shown in Table 11, and sample locations are mapped in Figure 38.
Table 11: Water quality measurements from the Oakland Swamp wetland from June 6, 2011
Water Quality
Parameter
Temperature
Unit
o
C
Site 1
Site 2
(HCPP) (HCEP)
20.09
20.46
Site 3
(HCCU)
21.0
Site 4a
Site 4b
(HCWM) (HCWM)
20.6
24.5
Acidity
pH
7.33
7.24
7.0
6.98
7.42
Oxygen
DO%
64.4
38.2
40.0
12.4
63.0
Oxygen
mg/L
5.84
3.44
3.50
1.11
5.24
Turbidity
g/L
0.249
0.263
0.250
0.251
0.247
Conductivity
µS/cm
382
404
200
387
380
The location of the probe in the water column can impact the readings greatly. To illustrate this, we held
the probe at site 4a in the loose organic substrate, while readings from 4b were from the water column. Note the
difference in DO and pH. Note also how much cooler it was in the substrate, than in the water column.
Figure 38: Sample site locations for water quality measures
We also installed a temperature logger on the bottom of the water column at the outflow of the culvert,
at its east end. Below is the profile of the temperature over time, from June 6 to August 11, 2011 (Figure 39).
51
35
30
25
20
15
10
5
0
06/06/2011…
06/08/2011…
06/10/2011…
06/12/2011…
06/15/11…
06/17/11…
06/19/11…
06/21/11…
06/23/11…
06/25/11…
06/27/11…
06/29/11…
07/01/2011…
07/04/2011…
07/06/2011…
07/08/2011…
07/10/2011…
07/12/2011…
07/14/11…
07/16/11…
07/18/11…
07/20/11…
07/22/11…
07/25/11…
07/27/11…
07/29/11…
07/31/11…
08/02/2011…
08/04/2011…
08/06/2011…
08/08/2011…
08/10/2011…
Temperature (oC)
Water temperature at east end outflow of HWY
24 culvert (HCCU)
Figure 39: Water temperature at the culvert from June 6 to August 11, 2011 – max 34oC, min 14 oC – note the
greater fluctuations in temperature from night to day in June versus July and August
On September 7, 2011 we measured light and sound levels in and around the culvert. Outside the culvert
light levels were approximately 18 Lux, while inside they ranged from 10 at the edge to four in the very center.
Sound levels outside the culvert reached 90 decibels with a passing truck, and 75 decibels with passing cars.
Inside the culvert, sound levels were between 55 and 75 decibels, while filtering for high, medium, or low
pitched sounds.
Fence camera
The infrared cameras did not capture the movements of any turtles along the fence. However, in April
2011 researchers did find a male turtle sitting in the grass facing the fence on the wetland side, suggesting he
was attempting to cross the road and was stopped by the fence (Figure 40).
Figure 40. Photos showing Blanding’s turtle male against the fence on May 4, 2011, and his location relative to
the fence and culvert (photo closeup at left, progressively further back to the right)
52
Although no turtles were photographed by the infrared cameras along the fence, several other animals,
including raccoons (N=5), Canada Geese (N=3), wood ducks (1 mother and her brood), several bird species, and
researchers were all captured (Figure 41).
Figure 41. Images captured by the infrared camera stationed on the west fence, facing north, showing
researchers, song birds, raccoons, and Canada geese (clockwise from top left)
53
Turtle culvert use
Blanding’s turtles and Snapping turtles were both found to travel through the culvert and safely pass
under HWY 24 on numerous occasions throughout the active season. Three sets of evidence, both indirect and
direct, were used to come to this conclusion: 1) the observation that Blanding’s turtles and Snapping turtles
crossed back and forth between habitat on the east and west sides of the highway many (50+) times throughout
the season, and despite a very high Pkilled, none were roadkilled; 2) the passive data-logging radio receiver
installed in the culvert recorded the passage of four Blanding’s turtles on seven occasions through the culvert
(Table 12); and 3) Blanding’s turtles were observed swimming into the culvert (N=3) (Figure 42)
Table 12: Turtle crossings through the culvert that were recorded by the data logging receiver in 2010
#
1
2
3
4
5
6
7
Turtle
9-0
0-1
0-12
0-1
0-1
0-3
0-3
Sex
F
M
F
M
M
M
M
Avg.
Date
Jul. 4, 2010
Jul. 28, 2010
Sep. 1, 2010
Sep. 29, 2010
Sep. 30, 2010
Oct. 7, 2010
Oct. 9, 2010
Jul – Oct 2010
Enter
21:07
12:24
09:27
13:38
08:26
12:30
15:15
13:15
Exit
10:54
14:30
08:36
15:23
15:26
Duration
NA
NA
1 hr 27 min
0 hr 52 min
0 hr 10 min
2 hr 53 min
0 hr 11 min
1 hr 6 min
Notes
only one hit – confirmed crossing
only one hit – confirmed crossing
experimental test – confirmed crossing
experimental test – confirmed crossing
many hits – confirmed crossing
many hits – observer present – no crossing
many hits – confirmed crossing
Blanding’s turtles safely crossed HWY 24 on 46 occasions throughout the active season in 2010, while
none were killed on the highway within or near (within 1 km) the exclusion fence (Figure 43). Radio tagged
females crossed on average 1.5 times (N = 9, range 0 to 7), while radio tagged males crossed on average 8 times
(N = 4, range 3 to 13). Two snapping turtles each crossed the road three times (one male, one female). In 2011
another 14 Blanding’s turtle crossings were recorded, one for each of 11 turtles, and three for notorious Frank.
This was a unique situation in that habitat on the west side of the road dried up, so all turtles escaped to the
deeper waters of the irrigation pond on the east side of the road, and stayed there. Had water levels stayed up on
the west side, we suspect there would have been more movement back and forth across the road. However, this
does demonstrate the importance of water refuge accessed by road crossing.
Figure 42. Underwater photograph of Blanding’s turtle male 2-3 (Henry) swimming towards the culvert, and inair photograph of him swimming into the culvert seconds later (photos © BC)
54
Figure 43. Blanding’s turtle road crossings in 2010 (left) and 2011 (right); males in blue, females in red, broken
up by two week sections through the year (June 1 to November 30 for 2010, and April 1 to July 31 for 2011)
Figure 44. Blanding’s turtle road crossings for 2010 and 2011 combined
HWY 24 traffic and the probability of a turtle being killed on the road
For Blanding’s turtles, solving the equation ( Pkilled = 1 - e
-Na/v
) conservatively (best case scenario for
turtles) results in a 63 percent probability of a turtle being killed in one attempted crossing, while solving it
liberally (worst case scenario for turtles) results in a 99 percent probability of becoming roadkill. For snapping
turtles, 70% and 99% were the conservative and liberal estimates. The average probabilities of a turtle being
55
killed during one attempted crossing of HWY 24 were 93% and 95% for Blanding’s and Snapping turtles
respectively (Table 13).
Table 13: Results for Pkilled, given various parameter estimates ranging from conservative (best case scenario for
the turtle) to liberal (worst case scenario for the turtle).
N
a
v
traffic volume kill zone turtle velocity
(vehicles/min)
(m)
(m/min)
estimate
species
Pkilled
best
Blanding’s
5.7
2.64
15
0.633296
average
Blanding’s
6.7
2.92
7.5
0.926392
worst
Blanding’s
7.5
6.64
5
0.999953
best
Snapping
5.7
3.18
15
0.701325
average
Snapping
6.7
3.46
7.5
0.954539
worst
Snapping
7.5
7.18
5
0.999979
Calculations vary depending on estimated values for given parameters, such as traffic, tire width, turtle
speed, and other variables. Driver behaviour, including turtle rescue or avoidance and intentional strikes, was not
factored into the equation.
Other roadkill at the HWY 24 Mount Pleasant Creek culvert crossing
From April to November 2010 we discovered 76 individuals of 10 vertebrate species dead on the road at
the HWY 24 Mount Pleasant Creek Crossing, within the fenced section of the road (Table 14). The majority of
these were Northern Leopard Frogs (N = 50). A very similar pattern of roadkilled animals occurred in 2011, with
over 50 frogs, several mammals (a deer and two raccoons), and a few birds. In 2011 two turtles were found dead
on the road between the turtle fences: one snapping turtle at the northeast end, who was small enough (2”) to
crawl through the mesh of the fence, and a medium sized (4”) painted turtle, who likely crawled under the fence
through a hole created by a muskrat. This hole, and others, were patched regularly throughout the field seasons
to prevent further similar incidents.
Table 14. Animals found on HWY 24 between or near the exclusion fence at the Mount Pleasant Creek crossing
From April to November 2010
species
common name
Painted turtle
Northern Leopard Frog
latin name
Chrysemys picta
Rana pipiens
reptile
1
individual tally
amphibian
bird
mammal
50
56
Bullfrog
Green Frog
unidentified anurans
Red-winged blackbird
Green Heron
Woodcock
White-tailed deer
Raccoon
Virginia Opossum
TOTAL
Rana catesbeiana
Rana clamitans
2
5
10
Agelaius phoeniceus
Butorides virescens
Scolopax sp.
Odocoileus virginianus
Procyon lotor
Didelphis virginiana
2
1
1
1
67
4
1
2
1
4
Other wildlife using the HWY 24 Mount Pleasant Creek culvert crossing
From April 2010 to September 2011 we found evidence that fish, amphibians, birds, mammals, and
insects also use the culvert to cross under HWY 24 to habitat on either side of the road, or to seek refuge from
heat or predators under the cover of the culvert (Figure 45).
Figure 45. Small mammal tracks heading into the culvert entrance (photo © BC – Toronto Zoo); a female woodduck and her brood swimming out of the east end of the culvert, having just safely crossed from the west
Landowner stewardship, stakeholder engagement, and public outreach
Throughout the duration of the two field seasons we met and informed all landowners with property on
or adjacent to the study area about the Toronto Zoo’s Ontario Turtle Tally (OTT) and HWY 24 Blanding’s turtle
project. We were committed to an informed community around lands and aquatic environments on which turtles
depend. We distributed OTT brochures, magnets, and stickers to interested individuals. All landowners allowed
us access to their property to conduct our research. Certain individuals preferred that we keep our activities to a
57
minimum, while others were extremely helpful in providing their time, knowledge, and resources to the project.
Two families, the Dorombozis and Biggins/Woods, also helped us create artificial nesting sites on their property
(photos in appendix). Several key landowners with property connected to the HWY 24 and Mount Pleasant
Creek crossing, including Frank Dorombozi, were visited and updated at least monthly if not weekly or daily.
Individual turtles were named after key landowners in the area (see poster in appendix), who were provided with
a photo of “their turtle” and a note thanking them for their participation (Figure 46). This helped to provide a
sense of involvement in the project and to increase the level of support for the activities occurring throughout the
area.
Figure 46. A poster showing the plastron (belly shell) pattern of all individual Blanding’s turtles captured during
the study; beside each shell is written the turtle’s notch code, name, sex, and radio frequency (ex. Frank)
In November 2010, a focus groups session was hosted at a local community hall to gather feedback for
local landowners and contribute to the CBSM initiative of Adopt-A-Pond. The session was advertised locally
and seventeen adults and five children, representing 10 families, were in attendance. Throughout the session
landowners were asked questions pertaining to their values and behaviours towards wildlife in general, and
towards turtles and wetlands in particular.
58
Overall, the focus group indicated an enjoyment at having species of wetland wildlife such as turtles,
frogs, and birds on their property. There were however several comments made regarding uneasiness around
snapping turtles, both due to issues around personal safety as well as to the consumption of other animals such as
fish and small birds by this particular species. Despite this, there was agreement amongst the group that
regardless of concerns about moving snapping turtles on roads, there is a local support in favor of taking this
positive action. While landowners recognized lost economic opportunities as a result of maintaining wetlands on
their land they did admit that the natural formation of wetlands in low lying areas is inevitable and that several of
them have been able to benefit financially through government-run tax incentive programs. Others admitted to
hearing of tax programs and being willing and interested in maintaining their wetland property if they could
receive these benefits.
As many of the landowners already have a significant volume of wetland on their property there was no
interest in becoming involved in projects to construct wetlands. There was however a high level of interest in the
concept of turtle nest site construction. In some cases landowners were simply interested in obtaining
information on the construction process and costs such that they could take on a project themselves, while in
other cases landowners were interested in volunteering their time and/or equipment to construction of a site
either on their own property or on a nearby property.
In terms of communication, landowners admitted to having few places to go to find appropriate
information on agricultural or land management practices. Many stated that resources and organizations that
were at one time helpful are no longer available and they now see the internet as a primary source of information
despite the fact that much of the information they find is too vague. To actually engage and inform landowners
about projects occurring in their community (as with the Hwy 24 project), landowners suggested phone calls and
newsletters mailed to their home as the most effective means of distributing information.
We also administered a small survey focused on potential activities that can be undertaken by
landowners. Results from this survey are displayed in Table 15 and Figure 47.
Table 15. Statements provided to landowners indicating a behaviour that could affect turtles on their property;
they were asked to rank the likelihood they would engage in that behaviour from one (not likely) to 7 (likely).
#
1
2
3
4
5
6
7
8
9
Statement
Allowing turtle research to happen on my property
Allowing someone else to pay for and build a turtle nesting beach on my property
Improve existing wetlands on my property (ex. Put basking logs in irrigation pond)
Protecting turtle nests by placing cages over the nests that I find
Stopping my vehicle and assisting a turtle across the road
Slowing down and driving around turtles on the road
Avoiding chemical use on certain sections of my property
Allowing natural vegetation to grow along shorelines on my property
Putting signage on my property advertising information about turtles
59
10
11
12
13
14
15
16
17
Donating money to fund a turtle conservation project
Volunteering time to be part of a wetland construction project
Paying for and building a turtle nesting beach on my property
Storing equipment, like canoes, traps, and other gear, in one of my buildings
Forgoing farming on a less than a 1/4 acre section of my property ... for wildlife
Forgoing farming on a 1/4 to 1/2 acre to leave a place for wildlife
Forgoing farming on a larger than 1/2 acre section of my property to leave space for wildlife
Allowing people interested in turtle conservation to visit my property
Landowner Behaviour Statement Responses
Average
Response
Value
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Question #
Figure 47. Landowner responses to the statements in Table 10, ranking the likelihood they would be willing to
do that behaviour, where 1 is not likely and 7 is very likely; 11 people filled out the survey.
As evidenced by the graph above, landowners were most likely to slow down and drive around turtles on
the road, and allow people interested in turtle conservation to visit their property. They were least likely to pay
for and build a turtle nest on their property. For most, it is also very likely they would allow turtle research to
happen on their property. This information is helpful not only in determining potential behaviours to promote to
landowners in the Brantford area but also for landowners in other areas of the province where AAP is focused.
We also created a guide to stewardship actions for landowners of wetland turtle habitat (Figure 48). The
guide was written in winter 2010-2011, and printed in spring 2011. It was delivered to all landowners
surrounding the Oakland Swamp in spring and summer 2011, and feedback was incorporated in the fall.
Revisions were made according to user comments and feedback, and the final version was printed in fall 2011.
This guide will serve as a source of information specific to landowners and with a level of detail that will enable
them to take actions on their own properties that can provide benefit to turtles.
60
Figure 48. “Turtles On Your Property” guide (cover & page 3); full version in the “digital appendix”
In response to information gathered at the focus group session several projects were initiated. To meet
the need for agricultural property owners to understand the programs available to receive financial benefits for
the maintenance of wetlands on their property a short brochure was drafted. Information from this brochure will
be integrated into the "Turtles on your Property Guide" and will be distributed to landowners. As some
individuals at the focus group session indicated an interest in assisting in the construction of a turtle nesting
beach on their rural property we opted to pursue this as a project. Sites were identified, landowners showed
support for the conservation initiative, and construction took place in Dec 2010 and Oct 2011.
The Ontario Ministries of Transportation (MTO) and Natural Resources (MNR) were fully engaged in
the project in 2010 and 2011, providing not only help in the field, but also other assistance throughout the
duration of the project. Adele Mochrie at MTO spent several days in the field and countless hours in the office
providing us with useful data and contacts to enhance the project. She was a primary contact in the construction
of the turtle exclusion fence. Adele co-presented with Toronto Zoo staff to provincial government officials and
their school high-school aged children about the HWY 24 project. She also created a turtle display in her London
MTO office, which included a poster about turtles and roads created by the AAP team. Karine Beriault at MNR
assisted with radio tracking in the field and provided maps and air photos to researchers (Figure 49).
Figure 49. Karine Beriault (MNR) helping in the field, and Adele Mochrie (MTO) next to her turtle display, and
holding the poster we created for her and other MTO offices in southern Ontario.
61
Several guide groups, eco-schools, and the general public were all informed of threats to turtles and their
status in Ontario through informative presentations and displays (Figure 35). Over 20 presentations and four
displays were conducted between April 2010 and September 2011, reaching over 800 and 1000 individual
audience members respectively. An excel file representing all outreach activities and volunteer support, which
totals over 500 hours contributed, can be found in the digital appendix. Additionally, we posted advertisements
in several local newspapers for the Turtle Tally, and researchers were interviewed for several radio programs,
newspaper articles, and newsletter articles throughout the study period from April 2010 to September 2011.
Figure 50. Outreach
activities, including
landowner engagement
on their wetland
property, a presentation
to a group of girl guides,
and a turtles of Ontario
display at the Norfolk
county fair.
To encourage reporting of turtle sightings to Ontario Turtle Tally print ads promoting the program were
placed in five local papers (Brantford Expositor, Paris Star, Simcoe Reformer, Brant Connection, Tuesday Times
Reformer). Ads were run in the days just prior to or during the May long weekend as this is just prior to the
prime season for turtle movement and also a popular weekend for road travel. These ads reached approximately
99,684 households in Brant County. Across Ontario newspaper advertising is responsible for approximately 18%
of all new Turtle Tally submissions. Since the onset of this research project reports to Ontario Turtle Tally from
Brant County total 75. This is a substantial increase from the two years preceding the project where the total
number of submissions was less than 5.
62
Discussion
The Oakland Swamp Blanding’s turtle population is significant in Ontario, and southern Ontario
agricultural landscapes in particular. With over 63 individuals captured and marked (including over 30
reproductive females), and an estimated population size of over 100 individuals, this is one of the larger
documented populations in the province. There is a healthy population size, sex ratio, and recruitment at the
study site. This, in combination with the reduced (but not eliminated) threat of road mortality (thanks to the
fencing and ecopassage) and low probability of habitat loss due to development, makes this population very
important for the continued survival and conservation of the species in Ontario.
Habitat
The habitat occupied by Blanding’s and Snapping turtles in this study is consistent with features found
throughout their range in Ontario (COSEWIC 2005). Slow moving, shallow, and highly vegetated wetland
waters were preferred by Blanding’s turtles, including willow swamp, shallow open water, marsh, and pond
shoreline habitat types. The turtles were often found tucked under the rooting zones of willow shrubs during
warmer weather in the summer, and basking on collapsed muskrat huts among open patches of willow thickets in
the cooler weather of the spring. Turtles were rarely seen basking on open logs or shorelines.
Nesting habitat consisted primarily of agricultural fields, including those surrounding the swamp and
planted with millet, corn, soy, and tobacco. Substrates were fine and sandy, with little clay or organic content.
Several Blanding’s turtles were found on gravelly roads during nesting, but only one nest attempt was made
along roads. Nest sites were within 100 m of the nearest wetland.
Amy Mui, a doctoral candidate at the University of Toronto, will be conducting research over the next
two years to determine if wetland habitat utilized by Blanding's turtles can be identified and mapped using
hyperspectral remotely sensed imagery. This will allow large scale mapping of critical habitat, which can aid in
conservation measures beyond the local scale.
Occurrence, abundance, and distribution
Blanding’s turtles occurred throughout the study area, and were concentrated in the wetlands
immediately adjacent to the highway. We were surprised at the dense abundance of Blanding’s turtles occupying
the Oakland Swamp wetland complex (N = 63 captured and tagged individuals, and N = 138 estimated
population size). Given the high incidence of road mortality at the HWY 24 Mount Pleasant Creek crossing
before the fence installation in 2008, we expected the worst and were pleasantly surprised by the population size
and demographics of the resident turtle populations, including the high number of females and presence of
juveniles and hatchlings for both Blanding’s and Snapping turtles. Blanding’s turtles were distributed throughout
63
the study area, and showed some seasonal patterns (concentrations in mid-summer and winter, dispersal in late
spring and late summer).
Home ranges were between five and 78 ha in size, using the Mimimum Convex Polygon (MCP) method.
Female Blanding’s turtle home ranges averaged 21 ha, while males averaged only 10 ha. These home ranges
were much smaller than those calculated from a similar number of radio-tagged Blanding’s turtles in Algonquin
Park, where male and female home ranges did not differ and averaged ~60 ha in size. Perhaps the fragmented
and limited habitat in the Oakland Swamp limited the turtles home range sizes.
The MCP home range calculation is an over estimate of the habitat area used by the turtles, because it
includes tracts of agricultural field and forest not visited by the turtles. The Percent Volume Contour (PVC) is an
underestimate of home range, because it only includes areas around capture points and neglects travel routes
between points. It should be noted that the PVC calculation is not the same as the simple contours that are
typically produced in tools like Spatial Analyst. A simple contour represents only the boundary of a specific
value of the raster data, and does not relate to probability, while a percent volume contour represents the
boundary of the area that contains x% of the volume of a probability density distribution. For applications like
animal home range delineation it is the percent volume contour that is required. The 95% volume contour would
therefore on average contain 95% of the points that were used to generate the kernel density estimate.
Movements & home range
Blanding’s turtles moved often throughout the season, but within a limited area, and without any
enormous unexpected forays outside of the primary study area. The overall distances travelled (
= 2 and 5 km
for females and males in 2010) were lower than expected. Blanding’s turtles are known to occupy extents of
greater than 10 km during the active season (Caverhill 2006) and travel upwards of 6000 m (COSEWIC 2005),
while most turtles in this study kept within a relatively small extent (
= 1.5 km). This could be because turtles
living in large interconnected wetland systems (like in Nova Scotia and Algonquin Park) have access to more
habitat, while those in smaller closed systems (like the Oakland Swamp) have less available habitat, therefore
move shorter distances within a limited habitat. Snapping turtles tended to move less and stay in one place for
extended (two weeks or more) periods of time, then move a moderate distance and stay there for an extended
period, indicating punctuated movements.
The number of times turtles switched wetland sections within the study area is considered to be a
relative indicator of movements (Bowne et al. 2006). Using this measure, turtle movements peaked in June and
August 2010, then again in June 2011. Turtles did move back and forth across the road much more often than we
expected. We assumed there would be a single spring migration across the road in April, then another fall
migration to wintering sites in September. Turtles crossed the road many times throughout the entire active
season. For the Oakland study sites road work and culvert maintenance should occur in the winter months, when
turtles and their movements are less likely to be affected. If maintenance is required during the active season,
July or November would be the best times of year to do work, as turtle movement is limited during these times.
64
We suggest that requests for information on seasonal turtle movement and habitat use be made prior to
construction along roadsides near wetlands in this area.
Nesting
Blanding’s turtles nested in a variety of agricultural fields surrounding the study site. They used fields
recently planted with corn, soy, and millet primarily. All substrates were sandy and fine, with good drainage and
sun exposure. Turtles travelled upwards of 1-3 km as the crow flies from the center of their summer range to
their nesting sites, and usually stayed within 100 m of the wetland margin. Female turtles did cross roads to get
to their nesting sites, and some were found on the road. This, in combination with the use of tractors, tillers, and
other heavy-equipment on the fields in which the turtles were nesting makes this time of year (June) very
dangerous for nesting turtles. That being said, only one female Blanding’s turtle was found dead on the road in
the two years of field studies. No radio-tagged turtles were found dead or injured due to their nesting forays.
The majority of nesting activity occurred between June 2 and June 22, 2011. Because of a cold wet
spring, nesting occurred relatively late this year, compared to other years (several turtle researchers, pers
comm.). Some individual females were seen making nesting forays and attempts for up to seven nights
consecutively, while others were only seen on land once. Females laid between five and 13 eggs in six known
nests. Hatching began on September 2, and was likely to continue at the time this report was written.
Surprisingly, two nests that were left unprotected in agricultural fields (one core, one millet) both yielded healthy
hatchlings. One nest (in millet) completely hatched (all 11 eggs), while the other (in corn) had seven of nine eggs
produce hatchlings (the two that didn’t hatch were likely unfertilized). This surprised us because we assumed the
nests would be harmed by at least one of three threats: 1) dense vegetation growing over the eggs that would
shade the nest and delay incubation; 2) rooting zones that would either suffocate or trap the eggs; 3) harvesting
equipment that would crush the eggs. Despite these threats, the nests survived and produced healthy hatchlings!
To encourage turtles to nest away from roads and (what we considered to be) dangerous agricultural
fields, we constructed two artificial nesting sites for Blanding’s turtles, one in December 2010 and the second in
October 2011. Although no Blanding’s turtles were known to nest in either site, we did relocate two nests at risk
from agricultural fields to the first artificial in June 2011. Only time will tell whether these artificial sites will be
used naturally by turtles for nesting, but the abundance of available bare soil in the region each spring
preferentially attracts nesting turtles. However, these sites will be useful for developing stewardship and
monitoring roles in the local community with engaged landowners.
Despite a significant body of research from Nova Scotia and the United States, very little is published
about the nesting habitats and behaviours of Blanding’s turtles in Ontario. More work needs to be done to make
this information available to researchers and managers who are working to recover this species in the province.
65
Overwintering
We expected some aggregation in winter, and that was the case for seven radio tagged turtles who
gathered in the western extent of West Marsh for the winter. Several other radio tagged individuals overwintered
in isolated environments, apparently without the presence of other turtles. Fortunately all turtles overwintered far
from the road, indicating that construction and maintenance work on fencing and roads near wetlands would be
best suited for the winter months. However, if this work requires the alteration of water levels, we would suggest
that the work take place during the active season, when turtles are able to respond accordingly.
Culvert measurements
We calculated the CO or “Culvert Openness Ratio” to be 0.1 and the eCO or “Effective Culvert
Openness Ratio” for the HWY 24 culvert to be 0.05. Water levels fluctuated throughout the season but usually
filled about half of the culvert, while organic muck and rocky substrate filled about one third of either opening.
As a result, the eCO would be different for various taxa, depending on their mode of travel through the culvert.
For hydrophobic small mammals that only walk on dry land, the eCO would be 0.00. For flying bats and birds it
would be 0.05, because half of the CCS is available for flight passage. The inverse is true for turtles, which are
only capable of swimming through the culvert or walking along the bottom. Taking into account the water depth
at the entrance (water height minus substrate height), the eCO would drop to 0.025.
The temperatures, DO levels, pH, conductivity, and other water quality variables at the culvert were not
unusual. They all fell within expected ranges for similar waters in the landscape. Light levels in the culvert were
low, but present. The noise levels were also low, but the underwater experience for turtles may be different.
Perhaps they can sense the rumble of trucks passing overhead more sensitively than the sound meter, which was
held in the air and used to record noise readings. Subjectively speaking, it was relatively bright and relatively
quiet in the culvert compared to the surrounding environment, and fortunately a potentially enticing passageway
for turtles.
The culvert has an openness ratio of 0.1 and an effective openness ratio of between 0.05 and 0.07,
depending on the consideration that water and substrate partially block or obscure both openings at either end.
These ratios are under the recommended openness ratio of 0.25 for new crossing structures in the United States
(Geoff Gartshore, Ecoplans, personal communication, February 2010), but are above a culvert openness ratio of
0.03, which was found to have good culvert use by a variety of vertebrates (Ecoplans 2006) .
Dimensions of the culvert that was installed at the study site prior to 2006 were provided by the Ontario
Ministry of Transportation (Adele Mochrie, pers comm.). We hoped to hypothesize whether the change in
culvert size and other variables may have resulted in a change in turtle response, and hence road mortality levels.
However, since the old culvert was a similar size to the new one, and since we have no data concerning turtle use
of the culvert prior to 2010, we unfortunately cannot make any conclusions in this regard.
66
Culvert use
We confirmed that turtles used the aquatic culvert to cross under HWY 24 and access habitat on either
side of the road. We made this confirmation with visual observation, and the data logging radio receiver. Major
advantages of using the receiver included proof of passage, and the additional data provided including dates and
times of crossings by identified individuals. This allows researchers and managers to better understand the time
of year and time of day turtles cross roads most often.
Turtle culvert crossings peaked in June and August, and occurred diurnally between 0826 h and 2107 h
(mean = 1315 h). It is interesting to note that uninterrupted (no observers present) culvert crossings were
approximately 10 minutes in duration. However, when researchers were present during an observed culvert
crossing, turtles spent a significantly longer period of time within the structure, an average of one hour and 44
minutes. Despite due diligence, this could be a result of the noise and disturbance caused by observers on or near
the culvert, watching for or tracking the turtles.
Radio telemetry data from our study showing individual turtles on subsequent days on both sides of the
highway proved the turtles crossed the road, but not how. Direct observations of turtles in the culvert were rare,
and despite abundant field effort (500+ person hours) we were fortunate to make the observations we did. In
comparison to chance direct observation and energy intensive daily radio tracking, the passive data logging radio
receiver provided efficient, informative, and verifiable proof of passage through the culvert.
We experienced some difficulty fine tuning the equipment in 2010, but most problems were resolved in
2011. We adjusted the noise floor to -115, fine tuned the pulse width setting, and purchased a new chargecontroller that allowed the unit to stay powered for over a month at a time. The passive data-logging radioreceiver system compliments other field studies like ours, which already employs radio transmitters in
examining turtle habitat use and movement patterns. It adds a highly informative set of data to that which is
already acquired actively by researchers during their work with aquatic turtles.
There are other methods besides the data logging radio receiver that could also confirm culvert passage
by turtles, including but not limited to those listed in Table 16. Pros and cons are described below, along with
estimates of time and cost to conduct, invasiveness to turtles, alteration of their behaviour, and the certainty with
which crossing can be confirmed.
Table 16: Advantages and disadvantages of several methods used to confirm turtle crossings through culverts,
showing person hours of effort required to initiate (time), cost to implement (cost), invasiveness to the turtles
(inv), the degree to which natural turtle behavior is altered (alt), and the certainty with which turtle crossing can
be confirmed (cer).
Method
Data logging
radio receiver
Advantages
operates continuously; does not
influence turtle movement;
supplement to radio tracking
studies; works in fully aquatic
Disadvantages
battery dependent; requires
technical expertise for fine
tuning; expensive electronics;
only records x-ings of radio
time cost inv alt cer
low med med low high
67
culverts;
can track at any time or date;
pinpoints exact locations of
individual turtles
Motion sensing visual confirmation; provides
camera / video interesting images;
camera
Hand held
radio receiver
Traps
Thread trails
Tracks
Observation
tagged turtles;
only works with radio tagged
turtles; does not record
continuously;
does not work as well
underwater; hard to install
perfectly; cannot confirm
individual turtle identity;
may artificially attract turtles;
may harm turtles;
proof that turtles use culvert;
species and individual
identification
shows exact path through culvert; only records travel route for
length of thread; adds bulk to
turtle’s shell;
confirms entry into culvert
does not work in aquatic culverts;
certainty of species / individual
identification is low; does not
record time or date
“see it to believe it”
only works while observers
present; people could spook
turtles or alter behaviour;
high med med low
low
low med med med high
med low med high high
med low med low high
low
low
high low
low
low med
low med high
The assigned scores in the low-med-high ranking scheme shown in Table 3 would be project dependent.
For example, if the project had a healthy budget, the weight of the cost would be much lower than if there was an
extremely limited budget. The following criteria were used for our specific study, but others may want to use
different weights depending on their specific limitations. Low time investments are less than an hour per day
over the duration of the study (including setup, monitoring, and analysis), medium between one and five hours,
and high five hours plus. Low costs are considered to be less than $1000, medium between $1000–$5000, and
high $5000 plus. Low invasiveness to the turtle means no equipment is attached to the turtle or interrupts the
turtle in the field, medium involves one of the two, and high both. Low turtle behaviour alteration means there is
no effect of the equipment on the turtle, medium there is some, and high a large amount. Low certainty means
there is no direct proof the turtle crossed through the culvert, medium there is some, and high indicates 100%
certainty.
Other criteria could also be used to measure the advantages and disadvantages of certain methods,
including whether it identifies the turtle to species, or individual, and whether it provides extra information, like
time of crossing, time spent in the culvert, or route taken. Other beneficial factors would include continuous
recording, and whether all turtle crossings are recorded, as opposed to only those fitted with PIT tags or radio
transmitters. Finally, methods that are highly likely to confirm crossings (receivers) would be favourable to those
that are less likely to provide confirmation (observation).
Ideally the method used has many advantages and few disadvantages, and confers a high degree of
certainty in confirming turtle crossings, as well as other informative data such as time and route of crossing.
Ideal methods also involve low turtle behavior change, invasiveness, cost, and time to implement. Depending on
the specific circumstances involved in different projects, there will be tradeoffs among the various methods. For
68
example, in a study where no turtles are radio-tagged and the culvert crossing is dry, motion-sensing cameras
and track-pads could be employed. If only a day can be spared for research, direct observation will have to
suffice. In practice, a combination of several methods can provide the most informative set of data.
Highway 24 turtle road mortality
Nearly 8000 km of road were surveyed over 137 hours of driving during 2010. All survey routes,
suspected crossings, turtle roadkill locations, and other notes, can be found in the digital appendix (and linked
google maps). It is suggested that walking surveys yield more accurate results for amphibians, but reptiles and
turtles in particular are effectively sampled from a vehicle (Langen et al. 2006). During our road surveys we
were able to identify even hatchling turtles from the vehicle. We stopped the car, considering traffic, the road,
and our safety first, for every item that looked even remotely like a turtle. Surveyors should note that many
articles look like turtle remains, including but not limited to banana peels, plastic bags, work gloves, etc. About
half of our “pullovers” were for turtles, and half were for articles that looked like crushed turtle remains, which
can be very inconspicuous.
Although no turtles were killed at the HWY 24 and Mount Pleasant Creek crossing in 2010, we did find
several road killed turtles along other stretches of HWY 24 and the surrounding country roads. Five Blanding’s
turtles, six Snapping turtles, one Map turtle, and 10+ painted turtles were found road-killed between Cambridge
and Simcoe (maps can be found in the digital appendix). Turtle road mortality showed seasonal patterns
consistent with life history phenology, which is consistent with findings from other studies (Ashley & Robinson
1996). Mortality peaked in early June for both Blanding’s turtles and Snapping turtles, with another small peak
in late August and early September, corresponding with movements to overwintering sites. Other studies also
suggest that turtle road crossings peak in June, with another smaller peak in August and September (MacKinnon
et al. 2005). We plan to continue our road surveys next year in 2011.
Each parameter estimate required to calculate Pkilled varies, depending on several factors. Parameter
“N” (traffic volume) varies depending on the day, time of day, time of year, etc. On the July 1 weekend, many
more vehicles are on the road in transit to Canada Day celebrations. This may also be a prime time for turtle
movements, especially if the nesting season is delayed by cool spring temperatures. Parameter “a” (kill-zone)
varies depending on tire size and turtle shell length. Previous studies assumed an average tire width of 0.25 m,
presumably for cars only, and not taking into account larger vehicles travelling the road (Beaudry et al. 2010).
Another confounding factor would be the presence of low-riding vehicles, whose chassis or fender rides closer to
the ground than the height of a turtle. In these instances, the whole width of the car would be required to
calculate the kill zone, as these vehicles would be unable to straddle a turtle and avoid killing it. Parameter “v”
(turtle velocity) assumes turtles travel with a constant speed when crossing the road. It does not account for
variability in behavioral responses to the road. In reality all turtles are different, and some may stop, speed up,
zig zag, or turn around when encountering roads and oncoming automobiles. It is also possible that some turtles
might freeze in the road or take refuge in their shells in response to traffic, while others might even respond
69
aggressively. Any of these behaviors would greatly increase the time spent crossing a road, and thus the chance
of being hit by a vehicle. Conversely, some turtles might cross roads with as much speed as possible, reducing
the time spent on the road (Beaudry et al. 2008, Gooley 2010). Other confounding factors for the model include
intentional strikes and rescues. Although ~3% of drivers intentionally hit turtles on the road ~3% also rescue
turtles encountered on the road (Ashley et al. 2007). Since an unknown percentage of drivers intentionally avoid
hitting turtles, while an equally unknown percentage accidentally strike them, we can consider all of these
factors to cancel one another, rendering valid the model in its current form.
Other roadkill and wildlife at the HWY 24 Mount Pleasant Creek culvert crossing
Leopard frogs were the most abundant roadkill at culvert crossing in both 2010 and 2011. Perhaps if a
finer mesh layer were added to the lower chain-link fence, amphibian roadkills would be prevented as well.
MTO expressed concern over the risk of debris buildup along the fence, but the benefit of amphibian roadkill
avoidance would be worth the extra maintenance. Other roadkill found at the site, including raccoon, possum,
deer, and birds, are often found along any random stretch of road. However, it is clear that causeways are often a
hotspot for not only turtle mortality, but other animals as well. This should be a primary consideration when
determining survey locations for hotspots for road mortality.
The observations of fish, amphibians, birds, mammals, and insects using the culvert to cross under HWY
24 to habitat on either side of the road is encouraging. Not only does the culvert facilitate turtle movements and
habitat connectivity, but that of other wildlife as well. In the winter, small mammal tracks entered the culvert at
its east and west entrances. It has been noted in other studies that mice, voles and shrews tend to use the
passageways most frequently, followed by lagomorphs (hares and rabbits), canids (fox and coyote), then felids
(Mata et al. 2003). Very little research has been conducted with fully aquatic culverts, because it is more
difficult to prove animal passage without customary track pads and motion sensing cameras (Mata et al. 2005).
Vertebrate crossing is related to various characteristics of the animal in question and the culverts and
their surroundings. Usually the size of the passage and the soil to water ratio determines the size of the animal
that will pass through. The use of different passage types by vertebrate species suggest that mitigation measures
in new roads should focus to the establishment of several passages of different characteristics instead of
investment in a reduced number of large fauna-specific passages (Ascensao & Mira 2007, Mata et al. 2005). The
dimension of the passage is considered to be one of the most important variables in the design of road-crossing
systems for vertebrates. However, this may only be true for small mammals (Yanes 1995). Other groups,
including reptiles, are affected by other variables, including detritus pits, whose presence deters reptiles from
crossing (Yanes 1995).
We did not find any evidence that the exclusion fence and culvert acted as a prey trap for predators. No
animal carcasses, turtle or otherwise, were discovered within the vicinity of the culvert that appeared to have
been predated.
70
Landowner stewardship, stakeholder engagement, and public outreach
An important component of our project was landowner stewardship and public outreach. If we did not
get landowners on board it would have been more difficult to do the work that we did. The landowners in the
region are now much more interested in their resident turtle populations, in no small part due to the fact that
there are now Blanding`s turtles carrying their namesake living in the wetlands on and around their properties.
The main messages we derived from participants at the landowner focus group were the following: 1)
people are interested in turtles and conservation when they become aware of it, and 2) people are willing to help,
but they don't know how! If we focus our efforts on finding interested landowners, informing them how they can
help, then guiding them through that process (whether this takes the form of nest site construction, nest
protection, or simply reporting sightings), that will provide good conservation bang for our funding buck.
However, we do end up with biased audiences at this type of event; most of the folks who attended the meeting
were interested in turtles, and willing to help. That is why they came! It is hard to attract dissenting voices to a
meeting like this. Perhaps the best way to get a less biased group would be to piggy-back on meetings happening
elsewhere, for other reasons, but containing our target audience.
MTO and MNR officials provided valuable support throughout the duration of the project. Close
partnerships with key individuals at these organizations will continue to generate mutually beneficial research
and conservation actions. With any scientific project that generates interesting results comes the responsibility to
share the findings with the public. It was not difficult to deliver 18 formal presentations and set up two
informative displays for people in the surrounding area, which may have helped foster a positive ethos of
conservation among certain circles. Over 500 turtle tally packages were distributed to landowners, presentation
audiences, and interested individuals during 2010 and 2011 (see details in digital appendix).
71
RECOMMENDATIONS
The Oakland Swamp wetland complex contains abundant turtle habitat where the threat of road
mortality has been mitigated. Critical findings derived from the HWY 24 project include proof that Blanding’s
turtles and Snapping turtles travelled through an aquatic culvert to access habitat on either side of a road, that
these culvert crossings occurred throughout the active season (May – October) and that temporary and
permanent exclusion fencing provided an effective barrier to turtle road mortality. Turtles moved and crossed the
road most often in June in both 2010 and 2011. All confirmed road crossings occurred during the day. The
Toronto Zoo should continue to improve and advertise its Ontario Turtle Tally project to generate more
informative sightings, whereupon followup research and management can mitigate threats to turtles. MTO is
encouraged to continue to partner with conservation organizations to locate turtle mortality hotspots along roads,
and construct similar exclusion fencing and culvert passageways to enhance habitat connectivity and road
permeability for turtles and other wildlife. Constructing exclusion fencing directing animals to existing culverts
is an affordable and effective way to improve existing passages and reduce animal mortality. Landowners and
the general public can contribute greatly to turtle conservation in Ontario by submitting turtle sightings to the
appropriate agencies, and by preserving, enhancing, or creating turtle habitat on their properties, and removing
turtles from the road (or preventing their access to it) wherever possible. Landowner engagement and
stewardship is an effective tool for human behavior change and turtle conservation. Continued research in
partnership with MTO and MNR could be conducted at the HWY 24 field site in one to five year intervals to
determine the continued effectiveness of the fence and culvert ecopassage. Engaged landowners should be
provided with at least yearly updates on newly gathered information and options for actions that contribute to
long term turtle conservation in the area.
Habitat use and movements studies like this one are necessary when wetlands are potentially being
fragmented or altered by human activities, especially roads. Critical information on turtle habitat use and
movement should be collected before, during, and after fragmentation events, and mitigation should be
implemented as often as possible. It takes reasonable amounts of time and money to adequately determine how
to best mitigate for turtles, and considering their state of decline in Ontario, and their ecological and cultural
importance, it is the least we can do.
We recommend follow-up mark and recapture studies perhaps in five-year intervals and any mitigation
methods that might enhance nesting success in the more disturbed agricultural sites.
72
Acknowledgements
Funding was provided by the Ontario Ministry of Natural Resources Species at Risk Stewardship Fund
and Environment Canada Habitat Stewardship Program. The Toronto Zoo supplied radio transmitters and field
researchers. Sigma Eight supplied the data logging radio receiver setup. Warm regards to Adele Mochrie (MTO)
and Karine Beriault (MNR) for their assistance in the field and continued support of the project. Thanks to Cam
Grant and John Grant for help with the installation of the receiver, and for extra time trouble shooting. Kudos to
Jeffie McNeil and Troy Frech for continued help with the database. Hearty regards to Frank Dorobozi for
allowing us to install the equipment on his property, and for all the extra storage space, supplies, time, and
stories. Special thanks to Magda Kula for her work with the maps and data. And thank you to all the field
workers (Roger Holmes, Colleen Middleton, Natosha Fortini, Erin Nadeau, Lynda Ruegg, Shannon Ritchie,
Rava Lee, and Julia Phillips), turtle tally volunteers (Ashley Noto, Peter Caverhill, Jolene Caverhill, Megan
Crowley, Paul van Cedar, Crystal Robertson, Kari Gunson, Don Scallen, Georg Hentsch, Ellen & Jerry Horak),
and landowners (Frank, Tony, Tony, Mike) who helped with the project. Research was conducted under ESA
17(2)(b) permit number GU-B-019-11 and Wildlife Scientific Collectors Authorization number 1062688.
73
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Personal Communications
Beriault, Karine. Ontario Ministry of Natural Resources. Species at Risk Biologist. [email protected]
Gartshore, Geoff. Ecoplans Limited. Senior Ecologist.
[email protected]
McNeil, Jeffie. Parks Canada. Species at Risk Biologist.
[email protected]
Mochrie, Adele. Ontario Ministry of Transportation. Environmental Planner. [email protected]
76
Appendix
Data
Turtle occurrence, abundance, and distribution
Table A1. All Blanding’s turtles captured at the Oakland Swamp and surrounding area during 2010 and 2011
77
Table A2. All Snapping turtles captured at the Oakland Swamp and surrounding area during 2010 and 2011
Habitat
Table A3. Plants lists from 10 wetland sections in the Highway Culvert (HC) study area. Where
0 = absent, 1 = rare (<1%), 2 = sparse (1-10%), 3 = scattered (11-24%), 4 = common (25-50%), 5 = abundant
(51-100% wetland coverage)
Common Name
Water Milfoil
Coontail
Bladderwort
Pondweed
Can. Pondweed
Filamentous
Algae
Knot/Smartweed
Pickerel Weed
Arrowhead
Cattail
Phragmites
W.Water Lily
Y. Pond Lily
Water Shield
Star Duckweed
Duckweed (l)
Duckweed (g)
Watermeal (c)
Watermeal (d)
S. Milkweed
C. Milkweed
M. St. J Wort
M. Cinquefoil
Meadowsweet
Horsetail
Mare's Tail
Marsh Marigold
N. Blue Flag Iris
Sensitive Fern
Moss
Willow
Dogwood
Grass
Sedge
Can. Reed Grass
Joe Pye-Weed
B. Nightshade
Genus species
Myriophyllum spp.
Ceratophyllum spp.
Utricularia spp.
Potamageton spp.
Elodea canadensis
Spirogyra, Anabaena,
Oscillatoria, Lyngbya,
Pithophora spp., etc.
Polygonum spp.
Pontederia cordata
Sagittaria spp.
Typha latifolia
Phragmites spp.
Nymphaea odorata
Nuphar variegata
Brasenia schreberi
Lemna trisulca
Lemna minor
Spirodela polyrhiza
Wolfia arrhiza
Wolfia borealis
Asclepias incarnata
Asclepias syriaca
Triadenum virginicum
Comarum palustre
Spiraea spp.
Equisetum spp.
Hippuris spp.
Caltha palustris
Iris versicolor
Onoclea sensibilis
Sphagnum spp.
Salix spp.
Cornus spp.
Poaceae
Cyperaceae
Phalaris arundinacea
Eutrochium spp.
Solanum dulcamara
Niche
Submerged
Submerged
Submerged
Submerged
Submerged
Submerged
TE
0
0
0
0
0
0
TP
0
0
0
0
0
0
WM
0
1
1
1
0
0
EA
0
5
1
0
0
0
EP
1
2
1
1
0
2
PP
3
3
2
2
1
0
AL
0
4
1
1
0
0
CL
0
1
0
0
0
3
ML
0
1
1
0
0
0
CP
0
1
1
0
0
0
Emergent
Emergent
Emergent
Emergent
Emergent
Floating
Floating
Floating
Floating
Floating
Floating
Floating
Floating
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Shoreline
Terrestrial
Terrestrial
Terrestrial
Terrestrial
Terrestrial
1
0
0
1
1
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
2
2
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
2
2
1
0
0
0
2
0
1
3
1
0
3
0
1
3
1
3
0
1
2
0
2
1
1
0
1
1
2
1
5
4
4
3
3
0
2
2
0
0
1
0
0
5
0
1
3
1
3
0
1
1
0
1
0
0
0
2
0
0
0
2
1
2
2
0
0
0
2
0
1
2
0
0
4
0
2
3
1
3
0
1
2
0
0
0
0
0
1
1
0
0
3
3
2
2
0
0
2
4
0
1
0
0
2
3
0
2
3
2
3
0
1
1
0
1
0
1
0
2
1
0
0
3
2
2
2
0
0
0
4
0
1
1
2
0
5
0
1
4
1
3
0
0
0
0
0
0
0
0
1
1
0
0
3
1
2
1
0
0
0
0
0
0
0
0
0
1
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
2
1
2
1
0
0
0
1
0
0
0
0
1
5
0
0
1
0
2
0
0
0
0
0
0
0
0
1
0
0
0
2
1
2
1
0
0
0
1
0
0
0
0
1
3
0
0
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
2
1
2
1
0
0
0
Notes
45 species
Hi O2 production
200+ species
80+ species
Many Species
forming "scum" on
water suface
100+ species
2 species
30 species
12 sub-families
80+ genera
5 species
78
Water Hemlock
Beggar's Tick
False Nettle
Bedstraw
Goldenrod
Aster
Willow
Maple
Oak
Ash
Elm
Poplar
Riverbank Grape
Virginia Creeper
Cicuta bulbifera
Bidens spp.
Boehmeria spp.
Galium spp.
Solidago spp.
Aster spp.
Salix spp.
Acep spp.
Quercus spp.
Fraxinus spp.
Ulmus spp.
Populus spp.
Vitis riparia
Parthenocissus quinquefolia
Terrestrial
Terrestrial
Terrestrial
Terrestrial
Terrestrial
Terrestrial
Tree
Tree
Tree
Tree
Tree
Tree
Vine
Vine
0
0
0
0
0
0
2
1
0
0
0
1
0
0
0
0
0
0
0
0
2
1
0
0
0
1
0
0
1
2
1
1
1
1
3
3
1
1
1
3
2
0
0
1
0
0
1
1
2
2
1
1
0
1
1
0
0
0
0
0
0
1
3
2
2
1
0
1
3
3
0
0
0
0
0
1
2
2
1
1
0
1
2
0
0
0
0
0
0
0
2
2
1
1
0
1
1
0
0
0
0
0
0
0
2
2
1
1
0
1
0
0
0
0
0
0
0
0
2
2
1
1
0
1
1
0
0
0
0
0
0
0
2
2
1
1
0
1
1
0
Notes
45 species
Movements
Table A4. Home range in (expressed in MCP = Minimum Convex Polygon, and PVC = Percent Volume
Contours), total path distance, dates of first and last captures, total days tracked, and average distance travelled
per day and between captures, for all radio tagged Blanding’s turtles and Snapping turtles in the study area in
2010. Below, home ranges for 2010 and 2011 combined are listed for all radio-tagged turtles.
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Table A5: Passive data-logging radio-receiver components, functions, and approximate prices
#
1
2
Component
ORION Data logging
receiver
Antenna Switch
3
Coaxial Cables
4
12V battery
5
80W Solar Panel
6
Charge Controller /
Display
Multi-Media Card
(MMC)
Total
Function
Records radio-frequencies for which it is programmed to receive
Price
$2500
Takes up to 8 inputs (one from each antenna) and delivers one signal to the
receiver
Two cables, each 50 m in length, stripped (10cm) at receiving end (to act as an
antenna)
Powers Data logging receiver (ideally a deep cycle or marine battery, built to be
drawn down & recharge)
Provides up to 5 Amps of charge at peak sun, and ideally 1-3 amps during nonpeak hours
Takes power from Solar panel and charges 12V battery
$800
Memory card on which the data is recorded
$20
$300
$150
$800
$100
$4670
Data Collection
Cards
All data was collected in the field on a standardized set of data collection cards. These were filled out in
pencil in the field (pen would run when wet). Data were collected on effort, observations, and trapping. All data
cards were photographed with a digital camera once per week as a backup to prevent loss. All cards were then
entered into an online database, developed and coordinated by Jeffie McNeil, MTRI. These data were stored in a
Microsoft Access database, and were extractable to Microsoft Excel xls or csv files, for analysis.
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Figure A1. Effort cards captured observer names, location descriptions, amount and type of work, weather
details, turtle observations, and other comments.
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Figure A2. Observation cards captured standardized information about each turtle sighting, including its
location, behavior, and so on; measurements were recorded for the first capture of all individual turtles
encountered.
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Figure A3. Trap cards captured information about each aquatic hoop net trap that was set to capture turtles
during the study. It included information on location, surrounding habitat, and vegetation.
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Measurements
Figure A4. The above measurements were taken using calipers: maximum carapace length, maximum carapace
width, carapace width at the bridge, maximum plastron length, plastron width on femoral laminae, maximum
plastron width on the femoral scutes, maximum shell height at the bridge, pre-cloacal length, post-cloacal length
and suture length between the anal scutes of the plastron (diagrams (c) Jeffie McNeil).
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Notch Codes
Figure A5. The notching scheme used for Blanding’s turtles in this study. Each turtle was given a unique code
by notching the marginal (perimeter) scutes (sections) of its carapace (back shell). Notches are counted from the
head, starting on the left side, not counting the nuchal (central) scute. Codes are written with commas separating
numbers on the same side and a dash separating sides. In the above example, the ID or notch code would be
2,10-3,9. Snapping turtles were marked in a similar fashion, but spun around 180 degrees – only tail end scutes
were marked, numbered from one to four on left and right sides.
Definitions
Habitat descriptions
When discussing habitat, we use spatial terminology to match the language we use to describe scale.
Micro-habitat exists at the scale of the point, meso-habitat the location, and macro-habitat the section. Outside of
a 100m radius (that of the section, or macro-habitat), the landscape becomes so heterogeneous and patchy that it
invariably occupies many different types of habitat (wetland, forest, agricultural field, etc) rendering a single
nominal description insufficient. Even micro-habitat, for example, can include heterogeneity such as the organic
debris under a willow cluster, in which a turtle is wintering in its roots. There is surprising micro-structure within
a one by one meter landscape, when you stop to look! Meso-habitat would incorporate the hummocky site where
grasses grow up through the edge of a stream bank, and macro-habitat could be described by a homogenous
marsh, including mainly cattail and emergent reeds and rushes. The larger the spatial extent, the greater the
heterogeneity, and therefore the more important the specific language used to describe it.
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Population Structure
We define population structure as the occurrence, abundance, and distribution of turtles on the landscape
at difference scales. Occurrence is the existence of turtles in a defined geographic region; abundance is the
relative number of turtles in a defined geographic region; and distribution is the way in which turtles are spread
across the landscape. All three are qualified by time.
Choosing the most appropriate temporal and spatial scales to examine the occurrence, abundance, and
distribution of turtles depends on the questions being asked, the audience to whom the information will be
presented, and how the information will be used. Here we focus on the extent of the Oakland Swamp wetland
complex and at the grain of the areas and sections within it, including the Highway Culvert area and its 11
wetland sections.
Scale
Scale is a critical concept in our work with the turtles. It includes the spatial and temporal perspectives
from which we observe the population, with respect to the extent and grain of their existence on the landscape
through time. Extent is the total length or area (space) or duration (time) that exists or is observed or analyzed
(Dungan et al. 2002). Grain is the smallest unit of measure (unit size) of any given extent.
We describe turtles in Ontario at five geographic extents: 1- point: an exact position in space represented
by a UTM coordinate [1x1m]; 2- location: particular place represented by the immediate surroundings
[10x10m]; 3- section: a defined geographic region represented by a portion of a lake (cove), stream (stillwater),
river (oxbow), or other delineable wetland component [100x100m]; 4- area; a defined geographic region usually
represented by a lake, stream, river, or other relatively definable water body [1000x1000m]; 5- population: a
defined geographic region that is usually represented by an interconnected system of wetlands [10000x10000m].
Geographic points, locations, sections, areas, and populations are delineated by the presence of turtles,
and the structure of the habitat they occupy. A point is where a turtle is resting. A location includes the
immediate, visible surroundings, as described by obvious landmarks. A section is a discrete portion of the
wetland, with physically discernible boundaries (dams, roads, forests, etc). An area is usually defined by a water
body (lake, stream, or wetland), and a population includes all wetland habitat in which a group of turtles within a
single species are capable of interacting. These spatial extents exist in a nested hierarchy, where larger extents
can include each smaller one as a grain (Figure 2). In the Oakland Swamp population there is one area; this is
composed of several sections, which in turn comprise many locations that encompass thousands of precise
points.
population (~10,000m)
area (~1,000m)
section (~100m)
location (~10m)
. point (~1m)
Figure A6. Nested hierarchy of spatial terms used to describe study site geography, and approximate maximum
length of each extent.
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Photos
Photo A1. Aquatic hoop-net traps used to capture turtles (photos © BC – Toronto Zoo)
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Photo A2. All marked individual turtles were photographed with a digital camera. These photos can aid in
individual identification, aging, sexing, and cataloguing of deformities. Turtles were placed on a piece of white
paper labelled with the turtle ID, date, sex, and location. The following images were recorded: carapace,
plastron, face, side and any deformities. All digital image files are named with the turtle species, ID, date,
locations, and caption using the following naming standard: Species_TurtleID_date _location_caption.jpg.
o Species is single character (B=Blanding’s, S=Snapper)
o TurtleID is the standard naming convention (see section on notching above)
o Date is in format: yyyy-mmm-dd
o Location is the population, area, and section codes (two letters each, for a total of six letters)
o Caption is a text description of the photo
For example: B_0-1_2010-May-24_OSHCEP_plastron.jpg.
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Stewardship Documents
Document A1. Invitation bookmarks (front on left, rear on right) delivered to landowners in Oakland Swamp
area inviting them to the original landowner focus group in November 2010.
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Document A2. Invitation to Girl Guide and Boy Scout leaders to attend focus groups to determine how they can
best contribute to our programs.
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Document A3. Invitation sent to all turtle tally volunteers, soliciting their help for dedicated surveys to the
HWY 24 corridor during spring and summer 2011
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Document A4. Invitation sent to all landowners who made significant contributions to our HWY 24 Blanding’s
turtle project; 11 individuals representing eight families attended the BBQ, plus an additional eight Adopt-APond employees!
Digital Appendix
We have not printed in this report all maps, photos, figures, and graphs produced during this research. We have
stored these digitally and provided this “digital appendix” to funders and stakeholders who received the full final
report. If you are interested in receiving a copy, please contact the staff at Adopt A Pond.
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