Seed Dispersal by Toucans in Amazonia Ecuador
Kimberly M. Holbrook
Department of Biology, University of Missouri-St. Louis
St. Louis, MO 63121-4499 USA
FINAL REPORT – AUGUST 2003
Many-banded Aracari
Summary
Seed dispersal contributes significantly to tropical forest
regeneration and maintenance, influencing processes, such
as metapopulation dynamics, colonization probabilities,
and population persistence. Since large avian frugivores,
such as toucans, have the ability to travel across
fragmented forest areas, they may improve chances of
gene flow throughout tropical forests helping to maintain plant genetic diversity. Loss of
important seed dispersers may not only affect the demographic and spatial patterns of the trees
they disperse, but may also affect gene flow patterns and consequently population genetic
structure. Few studies have examined how hunting activities affect seed dispersal and very little
information exists concerning population genetic consequences of avian seed dispersal in tropical
forests. This project outlines an extensive study on tropical seed dispersal that combines aspects
of vertebrate dispersal behavior with plant population dynamics. With the support of The St.
Louis Zoo Field Research and Conservation grant program and other grant agencies, I will use a
combination of ecological and genetic methods to contribute to our understanding of seed
dispersal and forest regeneration, which has historically been complicated by the difficulties in
tracking seeds from their origin. My overall objective is to examine the impact of animalmediated dispersal processes on recruitment patterns of a tropical tree. My research will address
hypotheses that toucan seed dispersal behavior
influences the population structure of a
Neotropical nutmeg, Virola flexuosa, and
furthermore, that hunting will impact frugivore
densities, movements, and subsequent seed and
seedling shadows. To test these hypotheses, I plan
to estimate seed shadows (i.e. spatial dispersion of
seeds relative to parent trees) from the disperser
perspective, as well as the actual seed and seedling
shadows of V. flexuosa.
This study is conducted in Amazonia
Ecuador at Tiputini Biodiversity Station (TBS; protected from hunting) and Yasuní Research
Station (YRS; subject to hunting). I will conduct toucan censuses at both sites over two 8-month
field seasons. To determine toucan movement patterns I will capture and radio track 7-10
individuals of the many-banded araçari, Pteroglossus pluricinctus, and the white-throated toucan,
Ramphastos tucanus, at TBS and YRS. Bird locations will be entered into a Geographical
Information System (GIS), allowing me to accurately model toucan movements. I will also
experimentally determine seed passage rates with captured individuals and will use these data in
combination with movement data to estimate toucan-generated seed shadows. For genetic
analyses, I will collect fresh leaf tissue from all V. flexuosa trees within a 50-ha area at both TBS
and YRS. At each site I will also sample V. flexuosa seedlings (along transects) and seeds (using
seed traps). I will extract DNA and use PCR for amplification. Then, using microsatellite
markers I will determine the population structure of V. flexuosa at TBS and YBS, as well as
identify individuals and assign maternity.
KM Holbrook
St. Louis Zoo Final Report, August 2003
2
Introduction
Much of the world’s tropical forests will likely disappear within our lifetime, as they continue to
be cleared, burned, fragmented, logged, and overhunted at staggering rates (Terborgh 1999). We
must focus our efforts not only towards conserving tropical forests, but also towards
understanding and protecting important ecological processes, such as seed dispersal, that may
contribute to forest regeneration. Animal-mediated seed dispersal plays a significant role in plant
recruitment and thus in determining tropical forest composition (Willson 1992). Although the
majority of tropical trees depend on vertebrate dispersers to move their seeds (Howe and
Smallwood 1982, Jordano 1992), we still know very little about the effectiveness of fruit-eating
vertebrates in dispersing tropical seeds. An important step to understanding the role of
frugivores in the regeneration of tropical forests is to study their seed dispersal ecology and
movement patterns, on both temporal and spatial scales. This proposal outlines an extensive
study of how hunting impacts seed dispersal by toucans in an effort to further understand how
avian seed dispersers affect tropical forest structure and regeneration.
A seed disperser’s effectiveness, measured as its contribution to plant fitness, has both
qualitative and quantitative components (Schupp 1993). One way to compare the effectiveness
of a disperser is to estimate its contribution to a particular tree’s seed shadow, which is defined as
the spatial dispersion of seeds relative to parent trees and other con-specifics (Janzen 1970).
Seed dispersal and resultant seed shadows influence many key processes, such as metapopulation
dynamics, colonization probabilities, population persistence, and plant community diversity
(Ouborg et al. 1999, Cain et al. 2000). Movement patterns of frugivores are directly related to
seed shadow patterns. For example, frugivores that remain for long periods in fruiting trees will
drop seeds beneath the parent tree, thus influencing the seed shadow differently than frugivores
that fly away and deposit seeds at another site. Since large avian frugivores, such as hornbills
and toucans, have the ability to travel across different habitat types including degraded and
fragmented forest areas (Graham 1999, Holbrook et al. 2002), they may improve chances of gene
flow and help maintain genetic diversity of plant
populations (Hamilton 1999). (photo left: canopy
walkway)
Anthropogenic impacts, such as logging,
agriculture, ranching, and/or hunting, are thought
to affect frugivore movements and abundances
(Redford 1992, Peres 2000). For example, in
Ecuadorian Amazon, toucans have been hunted
extensively at a site in the Yasuní Biosphere
Reserve, where as much as 23% (total of 264
individuals of Ramphastos cuvieri (tucanus), R.
culminatus (vitellinus), and Pteroglossus
flavirostris (azara)) of the biomass of hunted
birds was removed in an 11 month period (Mena et al. 2000). Moreover, at nearby Yasuní
Research Station (YRS), it is suggested that hunting pressures have increased severely since 1994
causing several terrestrial avian frugivores to become extremely rare at that site (English 1998).
With the extirpation of other game animals at YRS, one might expect hunting pressures on
toucans to increase as hunters switch efforts towards large arboreal birds. As anthropogenic
KM Holbrook
St. Louis Zoo Final Report, August 2003
3
activities, such as hunting and deforestation increase, the chance of seeds being dispersed may
decline simply due to lowered numbers of dispersers or because altered habitats are no longer
conducive to animal movement. For example, a recent study from Bolivia suggests that the
extinction of important seed dispersers may result in pronounced changes in the demographic and
genetic structure of tree species (Pacheco and Simonetti 2000). Therefore, loss of important seed
dispersers may not only affect the demographic and spatial patterns of the trees they disperse, but
may also affect gene flow patterns and consequently population genetic structure. In light of ongoing rapid and pervasive changes to tropical forests, there is an emerging need to understand
processes, such as seed dispersal, that influence forest regeneration.
My research will address hypotheses that there are species-specific differences in seed
dispersal behavior and ecology among toucans, and that hunting will impact frugivore densities,
movements, and subsequent seed and seedling shadows. To test these hypotheses, I plan to
estimate seed shadows generated by toucans (the ‘frugivore perspective’), as well as the actual
seed and seedling shadows of Virola flexuosa (the ‘plant perspective’). My objectives
specifically are to: 1) estimate seed shadows generated by two species of toucans (P. pluricinctus
and R. tucanus) using radio telemetry and seed passage trials, which will generate a probability
model of the spatial distribution of seeds based only on toucan dispersal, and 2) estimate seed
and seedling shadows of V. flexuosa using microsatellite markers, which will allow me to create
a spatial distribution map of where seeds and seedlings are dispersed. Although the geneticbased model includes dispersal by other frugivores, I expect the primary dispersers of V. flexuosa
to be toucans; and therefore, my expectation is that these models will be comparable. Ultimately,
I will compare toucan-generated seed shadows (from radio telemetry and gut passage rates) with
seed and seedling shadows specific to V. flexuosa (using microsatellites). Moreover, I will
compare seed dispersal between hunted and non-hunted sites to determine if hunting activities
are influencing seed dispersal by toucans.
Methods
Study Area – Research is conducted at Tiputini
Biodiversity Station (TBS) and Yasuní Research Station
(YRS) in the Orellanos Province, Ecuador (Figure 1).
Ecuador is extremely rich in biodiversity hosting 6% of
the world’s vascular plant species (more than 16,000;
(Jørgensen and Leòn-Yánez 1999) and 15% of the
world’s bird species (more than 1,500; (Parker et al.
1996). Tiputini Biodiversity Station is protected from
hunting activities, while YRS is subject to hunting by
indigenous Huaorani (Mena et al. 2000). Both stations
(approximately 40 km apart) are floristically similar and
are located in the Yasuní Biosphere Reserve (1.5 million
ha) in equatorial western Amazonia. The vegetation is
described as evergreen lowland rain forest and the area
receives more than 3,000 mm of rainfall per year
(Jørgensen and Leòn-Yánez 1999). The presence of
canopy towers at TBS and YRS, access to Huaorani
Rio Napo
Coca #
Rio
TBS %
Rio Tiputini
Napo
YRS %
Rio
Tipu
tini
20
0
20
40 Kilometers
Figure 1. Location of TBS and
YRS in Ecuador.
KM Holbrook
St. Louis Zoo Final Report, August 2003
4
hunting information at YRS, a highly diverse regional bird and plant community, and existing
trail systems at both sites all provide an excellent setting for this study. Additionally, TBS and
YRS have two 100-ha plots and one 50-ha plot, respectively. In the YRS plot all tree species
greater than 1 cm dbh have been identified and accurately mapped, which will facilitate this
project greatly. In the 50-ha TBS plot (one half of one of the existing 100-ha plots), all V.
flexuosa individuals greater than 1 cm dbh have been identified, mapped, and leaf material
collected (see Preliminary Results and Figure 3).
Study Species – I focus this study on toucans (Ramphastidae) because they are important
members of seed disperser communities and are found throughout the Neotropics. Moreover,
although toucans are large conspicuous members of the canopy and subcanopy bird community,
their ecology has been relatively little studied. The many-banded araçari (P. pluricinctus; ~250
g) and white-throated toucan (R. tucanus; ~700 g) are ideal species to study because both are
abundant in Amazonia and present an opportunity to compare seed dispersal by toucans that
differ in size and likely differ in diet, movement patterns, and seed dispersal ecology.
Virola flexuosa (Rol.) Warb. (Myristicaceae) is a widespread dioecious species
throughout South America (Lambright 1981) and is likely to be important in toucan diet, as are
other species in the genus (Howe et al. 1985). For example, Howe et al. (1985) found that
dispersers of V. sebifera were restricted to a small, specialized group of frugivores, of which
toucans were found to disperse the majority of seeds away from the parent tree. Primates likely
play a more important role in dispersing Virola species in Amazonia than in Central America;
however, preliminary studies indicate toucans to be the primary visitors to V. flexuosa (K.
Holbrook pers. obs.). Furthermore, V. flexuosa is relatively easy to identify in the field in both
fertile and sterile condition and, because it is a large-seeded species, it is expected to be
disproportionately affected by the depletion of large-bodied frugivores. The fruit of V. flexuosa
is distinctive with a bright red aril enclosed by a capsule, which is expected to dehisce during
early and midmorning hours (Howe and Kerckhove 1981).
Frugivore Surveys – I will conduct line-transect surveys to document the abundance of the six
toucan species found at both TBS and YRS (R. tucanus, R. vitellinus, P. pluricinctus, P.
inscriptus, P. azara, and Selenidera reinwardtii) with the prediction that toucan numbers,
especially Ramphastos spp., will be higher at TBS than YRS because of hunting pressure at the
latter site (English 1998). Surveys will be based on distance sampling methods of Buckland et
al. (1993). I will also count other non-hunted frugivores (see Mena et al. 2000 for a list of avian
species not considered to be useful by hunters) with the prediction that their numbers will not be
significantly different between the two sites. A line-transect method is appropriate for toucans
and other conspicuous avian frugivores as they are readily recorded by vocalization and/or sight.
Two observers, from 0600-1100 hrs, will survey toucans over ten 1-km transects once/week,
resulting in a total of 40 km surveyed per month. Other studies have successfully estimated
densities of large avian frugivores using a similar methodology (Kinnaird et al. 1996, Whitney et
al. 1998, Robinson et al. 2000). Numbers of toucans and other selected frugivores will be
estimated using the program DISTANCE (Laake et al. 1993). Abundance data can be evaluated
using three models to fit detection-probability functions: uniform, half-normal, and hazard
(Laake et al. 1993). For example, Kinnaird et al. (1996) found a uniform density function to
produce the best fit for hornbill monthly abundances.
KM Holbrook
St. Louis Zoo Final Report, August 2003
5
Fruit and Diet Studies – Tree watches will be conducted throughout the fruiting season to
determine the relative role toucans play in dispersing the fruit of V. flexuosa. My expectation,
based on prior studies of Virola species (Howe and Kerckhove 1981; Howe et al. 1985), is that
toucans will serve as the major dispersers of V. flexuosa, which will be important in attributing
differences in population structure of V. flexuosa to toucans. Preliminary results from
observations at fruiting trees suggest R. tucanus and P. pluricinctus are the primary visitors to V.
flexuosa (K. Holbrook pers. obs.); however further data are needed to understand their role in
dispersal away from fruiting trees. Important variables in terms of dispersal will be the number
of visits, total number of fruit eaten and removed by toucans per visit, and time spent foraging.
Ten focal female trees in each of the 50-ha plots at TBS and YRS will be located and observed
from 0600-1100 hrs with a minimum of eight replications per tree. If the
plots do not contain ten reproductive female trees, the remaining
individuals will be located outside the plots. Although it is expected that
the majority of frugivore activity will be concentrated in the early morning
hours, focal trees will also be observed for visiting frugivores throughout
the fruiting season between 1100-1800 hrs when seeds from traps are
collected. All visiting frugivores will be identified with additional
information gathered such as fruit removal rates and amount of time spent
foraging. For each frugivore species, I will attempt to record the number
of seeds eaten, regurgitated, or knocked down. Fruit removal is defined as
the number of seeds swallowed and taken away. When activity at the tree is very high, I will
concentrate observations on toucans. One-way ANOVAs will be used to compare fruit removal
rate among toucan species and other observed frugivores (fruit removal rate as the dependent
variable and species as treatment), and to test differences in amount of time spent foraging
among toucan species, as well as between toucans and other observed frugivores (time spent
foraging as the dependent variable and species as treatment). Seed traps (1 m 2) made of PVC
tubing and mosquito netting, as part of a larger sampling regime for seed shadow studies, will be
placed underneath the canopy of each focal tree to allow estimates of crop size. For description
of complete seed trap design, see Virola Sampling section below. One seed trap will be
positioned along each of four transects radiating out at 90° intervals (i.e. 0°, 90°, 180°, and 270°).
The four traps will be placed at randomly selected points between the tree bole and the edge of
the crown (Laman 1996). To estimate crop size, I will count the number of capsules collected in
seed traps and divide by the proportion of the canopy area sampled by traps. Each fruit consists
of a capsule and one arillate seed, with the arillate seed the unit of dispersal (Howe and
Kerckhove 1981). Following a similar design as (Howe and Kerckhove 1981), capsules
collected in the traps should give an adequate estimate of the total crop matured.
Finally, during frugivore surveys and radio telemetry sessions all observations of foraging
toucans will be recorded. These data will provide important information on toucan-diet, of
which little is known. To facilitate identification of fleshy-fruited species, all fruit species will be
collected on an opportunistic basis and photographed to establish a fruit and seed collection at
TBS. In addition, Drs. Bette Loiselle and John Blake of the University of Missouri-St. Louis will
contribute to the fruit and seed reference collection while conducting other research projects at
TBS. (A community-wide fruit/seed collection already exists at YRS.) Digital photographs will
be downloaded onto a computer at TBS to create an electronic database of toucan-dispersed
KM Holbrook
St. Louis Zoo Final Report, August 2003
6
fruits and seeds. Unidentified collections (including fruits and leaves) will be identified at the
National Herbarium in Quito.
Toucan Movements – To determine toucan movement
patterns through the various seasons (e.g. rainy, dry,
breeding, non-breeding) I will radio track two species of
toucans during two 8-month field seasons. These data
will be used in combination with seed passage times to
generate species-specific models of toucan seed dispersal.
Following a methodology employed in Cameroon by
Holbrook and Smith (2000), I will capture 7-10
individuals of P. pluricinctus and R. tucanus at each site
using canopy nets at roost sites and/or fruiting trees. I
will attach radio transmitters at the base of one of the central tail feathers (Holbrook and Smith
2000). Toucan locations will be measured by triangulation using receivers and hand-held 3element Yagi antennas (White and Garrott 1990). Tracking stations will be located on currently
existing canopy platforms and additional temporary stations will be built at suitable sites
allowing for minimal error in location data. Station positions will be determined using a Global
Positioning System. Three observers, using two-way radios, will collect simultaneous bearings 2
days per week at each site over a period of 8 months. Tracking periods will last 4-6 daylight
hours with individual birds located every 15 minutes. These data should result in 7-10
individuals of each species at each site tracked over a
minimum of 68 days (2 days/week x 34 weeks),
allowing us to collect approximately 344 locations per
individual (assuming a minimum 5-6 locations/day)
each field season. A sample size of 20-50 locations is
considered sufficient for estimating seasonal home
ranges (White and Garrott 1990); therefore, a sample
of 344 will be enough to confidently estimate home
range movements. In addition, I will dedicate several
tracking days to following individually tagged birds in
order to collect more detailed movement and location data (e.g. tree to tree movements, cavity
roost locations). These detailed movement data will complement location data collected through
triangulation and will be used for future calculation of toucan-generated seed shadows. Bird
locations will be estimated through triangulation using the program LOAS 2.03 (Ecological
Software Solutions). I will map locations and analyze movement patterns using the Animal
Movement Extension (Hooge and Eichenlaub 2000) in the program ArcView GIS 3.2 (ESRI,
Inc.). Home ranges will be estimated using Kernel methods, which assign a probability of area
use based on number and spatial arrangement of locations (Worton 1989). Kernel Home Range
analyses will afford estimates of maximum dispersal distance as well as data on spatially
clumped patterns of seed dispersal. Movement analyses over time may also provide evidence for
any potential temporal patterns of dispersal. Comparisons between sites among toucan species
will be analyzed using ANOVA (home range as dependent variable with site and species as
factors).
KM Holbrook
St. Louis Zoo Final Report, August 2003
7
Seed Passage Trials – I will experimentally determine seed passage rates with captive
individuals and will use these data in combination with movement data to estimate toucangenerated seed shadows. Seed passage trials will be conducted both in the field in Ecuador and
with captive toucans in U.S. zoos. For field trials, 2-3 individuals of each species will be held
captive up to 6 days in experimental cages (7 x 4 x 4 m) constructed of flexible nylon mesh
(Santana et al. 1986). Ripe fruits of V. flexuosa will be provided in the morning and each bird
will be observed continuously from 0600-1800 hrs from a blind near the cage. Seeds will be
noted immediately after regurgitation or defecation and passage time will be recorded. For zoo
trials, I will use seeds of V. flexuosa (collected and dried or frozen in the field) with an artificial
aril attached to mimic as closely as possible fruits used in the field. I will collaborate with
researchers at the Saint Louis Zoo and Cleveland Metroparks Zoo and expect to initiate zoo trials
upon return from the field.
Seed Shadows – Following Murray (1988), toucan-generated seed shadows will be calculated
using seed passage times and movement data from radio telemetry. From seed passage trials,
time categories (e.g. 30, 60, and 90 minutes) will be chosen for the model. Within each of these
time categories, distances (e.g. 50 m, 100 m, 150 m) moved by toucans will be grouped with the
probability of movements made within each distance category, within each time category,
calculated. The final calculation is:
p = Σ (a*b)
where p = probability of a seed being deposited at a particular distance from the parent tree, a =
probability of a bird being at a particular distance in a time interval, and b = probability of a seed
being passed in that time interval; p is then plotted against distance to give a probability of seed
deposition at various distances. These probabablistic seed shadows will be integrated with the V.
flexuosa plot data. Using a spatially implicit model, adult female trees (located by x,y
coordinates and entered in a GIS database) will serve as the origin for calculations in the model.
Virola Sampling – I will use DNA microsatellites to determine the population structure and
identify relatedness between seeds and seedlings with source maternal trees of V. flexuosa at TBS
and YRS. These genetic relatedness data will be used to create a model of dispersal of V.
flexuosa for comparison of the spatial distribution among seeds, seedlings, and saplings.
I will collect fresh leaf tissue from all saplings and adult trees within a 50-ha area at both
TBS and YRS. All V. flexuosa individuals at both TBS and YRS will be mapped and their
locations recorded in a GIS database. I will also sample V. flexuosa seeds (in traps) and
seedlings (in plots) along transects established at the same ten focal trees described earlier. Four
transects will be arranged at 90° intervals originating from the tree base, and will radiate out to a
distance of 60 m from the focal tree following a method similar to Laman (1996). Seed traps (1
m2) will be placed along each of the four transects prior to fruit maturation in the following
manner: one each under the canopy as described earlier, one each at 10 m, two each at 25 m, two
each at 40 m, and three each at 60 m. (A total of 36 traps will sample each focal tree.) Larger
numbers of traps at greater distances help keep the sampling rate in proportion to the increased
area with distance. This design will allow me to sample below the canopy (estimated diameter of
10-15 m) and out to a maximum distance of 60 m beyond the tree canopy. I will collect all V.
flexuosa seeds that arrive in the traps approximately once per week throughout the fruiting
season. Near the end of the fruiting season, I will sample a small amount of leaf material from
KM Holbrook
St. Louis Zoo Final Report, August 2003
8
all V. flexuosa seedlings in 1 m2 plots that will be located adjacent to each of the 36 seed traps.
Leaf samples will be dried immediately after collection on silica gel until transport to a
laboratory at the University of Missouri-St. Louis, USA. Seeds will be dried at 20-25°C in a
drying oven and stored in paper bags for future DNA extractions (P. Jordano pers. comm.). DNA
will be extracted from leaf and seed tissues (Cheung et al. 1993, Godoy and Jordano 2001) and
PCR (Polymerase Chain Reaction) will be used to amplify the DNA with amplified products
separated on polyacrylamide gels.
Microsatellites should allow me to determine the population structure of V. flexuosa at
TBS and YBS, as well as identify individuals and assign maternity (Dow and Ashley 1996,
Godoy and Jordano 2001). The relationship between individually dispersed seeds sampled in
seed traps and the focal suspected maternal tree will be examined by comparing their multi-locus
microsatellite profiles (Jordano and Godoy 2002). Significance can be tested using software
packages Kinship, ver. 1.3 and Relatedness, ver. 5.0.5 (Queller and Goodnight 1989). Using
categorical statistics, I will compare the ratio of non-related seeds and seedlings (i.e. not
offspring of focal tree) to related seeds and seedlings at each site to minimize problems
associated with differences in fruit crop size of the focal tree.
Microsatellite Protocol – Microsatellite regions in DNA are not generally subject to selection
pressures (Schlotterer and Pemberton 1998, Scribner and Pearce 2000), and because of their high
degree of variability, they are appropriate for population level studies (Parker et al. 1998). All
laboratory work will be conducted in Dr. Patricia Parker’s lab at the University of Missouri-St.
Louis. I will initially develop primers for four to five polymorphic microsatellite regions, adding
more primers if additional resolution is required to reduce parental ambiguity. An enriched
microsatellite library for V. flexuosa has been developed and a resulting 75 positive clones have
been isolated and sequenced. Sequences of microsatellite regions are variable and I am currently
developing primers. While using allozyme techniques would be both efficient and less
expensive, the increased ambiguity of working with such a large number of individuals and the
necessity of a high degree of resolution requires the use of microsatellites.
Many banded Aracari (adult and juvenile)
Field worker with captured Cuvier’s Toucan
Tiputini Biodiversity Station
Preliminary Results
Fruit and Diet Studies – I collected foraging and behavioral data on R. tucanus and P.
pluricinctus at TBS and YRS. My preliminary diet list consists of 54 species represented in 20
plant families (Table 1). In addition, I have initiated a fruit and seed collection at TBS and have
installed a digital library of all the collected fruits in the study.
Plot and perimeter searches have yielded enough female trees to reach the goal of 10 focal
trees at each study site. Four adult female trees have been identified in the TBS 50-ha plot at
KM Holbrook
St. Louis Zoo Final Report, August 2003
9
TBS and three female trees in the plot at YRS with eight and seven additional female trees
located in the area immediately surrounding the plots at TBS and YRS, respectively. Preliminary
results from observations at fruiting trees suggest R. tucanus and P. pluricinctus to be primary
visitors to V. flexuosa; however further data are needed to understand their role in dispersal away
from fruiting trees. Future tree watches are planned for the fruiting season of 2003-2004.
Table 1. Preliminary toucan diet list based on present study and Galetti (2000). a Toucan species: RADI = R.
dicolorus; RATU = R. tucanus; RAVI = R. vitellinus; BABA = Bailonius bailloni; PTAZ = P. azara; PTPL = P.
pluricinctus; SEMA = S. maculirostris; SERE = S. reinwardtii. b From Galetti 2000; these tree species occur in
Yasuní National Park and are expected to be included in toucan diet in my study area.
Plant family
Plant species
Toucan species a
Anacardiaceae
Tapirira cf. guianensis b
RADI
Annonaceae
Rollinia pittieri
RAVI, PTPL
Unonopsis veneficiorum
PTPL
b
SEMA
Araceae
Heteropsis oblongifolia
Anthurium clavigerum
PTPL, PTAZ, SERE
Anthurium sp.
RATU, PTPL
Araliaceae
Schefflera morototoni
RATU, RAVI, PTPL, PTAZ
Dendropanax grande
RAVE
RATU, PTPL
Arecaceae
Iriartea deltoidea
RATU, RAVI, PTPL, PTAZ
Cecropiaceae
Cecropia sp.
Coussapoa orthoneura
RATU, RAVI, PTAZ, PTPL
Porouma minor
PTPL
Clusiaceae
Clusia parviflora b
SEMA
RATU
Elaeocarpaceae
Sloanea sp.
KM Holbrook 10
St. Louis Zoo Final Report, August 2003
Table 1 cont. Preliminary toucan diet list based on present study and Galetti (2000). a Toucan species: RADI = R.
dicolorus; RATU = R. tucanus; RAVI = R. vitellinus; BABA = Bailonius bailloni; PTPA = P. azara; PTIN = P.
inscriptus; PTPL = P. pluricinctus; SEMA = S. maculirostris; SERE = S. reinwardtii. b From Galetti 2000; these
tree species occur in Yasuní National Park and are expected to be included in toucan diet in my study area.
Plant family
Plant species
Toucan species a
b
Euphorbiaceae
Alchornea glandulosa
BABA, SEMA
b
Hyeronima alchorneoides
RAVI, BABA, SEMA
RAVI
Margaritaria nobilis b
Ilex inundata cf.
RATU, PTPL
Flacourtaceae
Casearia arborea
PTPL
Lauraceae
Cryptocarya aschersoniana b
SEMA
‘Laurita’
RATU, RAVI, PTAZ, PTPL
‘Lisagroovy’
RATU
Ocotea alamembra
RATU, RAVI, PTAZ, PTPL, SERE
Ocotea ‘luis’
RATU, PTPL
Ocotea sp. 1
RAVI
Ocotea sp. 2
RATU, RAVI, PTPL, PTAZ
Ocotea jabitensis
RATU, PTPL
Persea pseudofasiculata
RATU
Rhodostemonodaphe sp. 1
RATU, RAVI, PTPL
Rhodostemonodaphe sp. 2
PTPL
Maracgraviaceae
Marcgraviastrum sp. 1
PTAZ, PTPL
Marcgraviastrum sp. 2
PTAZ, PTPL
Melastomataceae
Miconia zubenetana cf.
PTPL
Meliaceae
Cabralea canjerana
RADI, PTPL, SEMA
Guarea ‘gomma’
RATU, PTAZ, SERE
Guarea kunthiana
RATU, PTAZ, PTPL, SERE
Guarea macrophylla #2
PTAZ, PTIN, PTPL
Guarea silvatica
RATU, PTPL
Trichilia “minirachis”
RATU, RAVI, PTPL, PTAZ, SERE
Moraceae
Ficus sp. 1
PTAZ, PTPL
Ficus sp. 2
PTPL
Ficus sp. 3
RATU, RAVI, PTPL
Sorocea steinbachii
PTAZ, PTPL
PTPL, SERE
Myristicaceae
Iryanthera juruensis
Virola dixonii
RATU
Virola duckei
RATU, PTPL
Virola flexuosa
RATU, RAVI, PTPL
Virola ‘microfuzzy’ (elongata)
RATU, RAVI, PTPL
Myrtaceae
Unknown sp. 1
PTPL
RATU, PTPL
Unknown sp. 2
Passifloraceae
Passiflora auriculata
PTPL
PTPL
Rhamnaceae
Rhamnidium elaecocarpum
PTPL
Rubiaceae
Palicourea guinensis
b
Psychotria astrellantha
SEMA
KM Holbrook 11
St. Louis Zoo Final Report, August 2003
Frugivore Surveys – I conducted line-transect surveys to document the abundance of the six
toucan species found at both TBS and YRS (R. tucanus, R. vitellinus, P. pluricinctus, P.
inscriptus, P. azara, and S. reinwardtii) with the prediction that toucan numbers, especially
Ramphastos spp., will be higher at TBS than YRS because of hunting pressure at the latter site.
In addition, I counted other non-hunted frugivores with the prediction that their numbers will not
be significantly different between the two sites. Numbers of toucans and other selected
frugivores will be estimated using the program DISTANCE in the summer 2003.
Toucan Movements – I used canopy nets to capture nine P. pluricinctus and one R. tucanus for
radio telemetry studies at TBS and YRS. Radios were attached to the tail feathers and toucans
were radio-tracked from two to six months. Home ranges and movement analyses will be
analyzed in the summer 2003. During a prior field season (summer 2001), I captured and radio
tracked four P. pluricinctus; estimated home ranges were 142-270 ha (using 95% KHR in
ArcView GIS 3.2, ESRI, Inc) (Table 2). Home ranges are presented for three birds only, as there
were not enough locations for the fourth individual to estimate home range
Table 2. Home range estimates for P. pluricinctus in 2001. KHR=Kernel Home Range. Sex based on weight
and size of birds (M=male, F=female, and U=unknown).
Bird
Sex (wt.)
No. days
detected
20
KHR (ha)
50%
30
KHR (ha) 95%
Tracking period
M (255 g)
No.
locations
101
1
270
7/5 – 8/22
2
3
F (195 g)
U (235 g)
109
55
19
15
48
29
286
142
7/5 – 8/22
7/22 – 8/22
Seed Shadows – Movement data from the summer of 2001 were combined with hypothetical
seed passage times to estimate seed shadows for P. pluricinctus. Estimated seed passage times
were based on current studies of similar sized frugivores (Sun et al. 1997, Holbrook and Smith
2000). Seed shadow models indicate that up to 90% of seeds may be moved farther than 100 m
away from the origin (‘parent plant’) (Figure 2). The origin in these models is always the first
location of the day. Future analyses will use experimentally determined seed passage times and
data collected during summer 2001 and the current field season. Seed shadow models use
movements from the three individuals for which I present home range analyses.
KM Holbrook 12
St. Louis Zoo Final Report, August 2003
0.25
(a)
0.25
0.2
(b)
Probability of deposition
0.2
0.15
0.15
0.1
0.1
0.05
0.05
0
0
<100
0.25
200
300
400
500
600
700
800
900
1000
1200
1500 >1500
(c)
<100
0.25
0.2
0.2
0.15
0.15
0.1
0.1
0.05
0.05
200
300
400
500
600
700
800
900
1000
1200
1500 >1500
(d)
0
0
<100
200
300
400
500
600
700
800
900
1000 1200
Distance from origin
1500 >1500
<100
200
300
400
500
600
700
800
900
1000 1200
1500 >1500
Distance from origin
Figure 2. Estimated seed shadows for P. pluricinctus using hypothetical seed passage times. (a) All seeds
passed in 30 minutes. (b) 50% seeds passed in 30 min, 50% in 60 min. (c) 33% seeds passed in 30 min, 33%
in 60 min, and 33% in 90 min. (d) 25% seeds passed in 30, 60, 90, and 120 min, respectively.
Virola flexuosa Sampling – During
February and March 2002, I located,
mapped, and collected 157 individuals of
V. flexuosa within the 50-ha plot at TBS;
an additional 19 individuals of V. flexuosa
were mapped and collected in the recent
field season. A further 44 individuals
(adults and seedlings only) were mapped
and collected in the 30 hectares
surrounding the TBS plot. The total
number of plants collected at TBS is
currently 220 (Figure 3). At the YRS site,
110 individuals of V. flexuosa were
collected within a 50-ha plot (a plot census
Figure 3. Location of Virola flexuosa individuals in the
is currently underway and the total number
50-ha plot, nested within existing 100-ha plot at TBS.
is expected to increase). An additional 20
individuals (adults and seedlings) were
collected in the 30 hectares surrounding the YRS plot. Leaf material will be used for
microsatellite analyses and estimation of seed and seedling shadows of V. flexuosa.
Of the 20 female trees identified as focal trees, two produced a sufficient amount of fruit
for seed trap placement and four produced a very small amount of fruit, much of which fell
before maturation. Seed traps were placed under the fruiting individuals and seeds collected for
genetic analyses.
KM Holbrook 13
St. Louis Zoo Final Report, August 2003
Training and Educational Accomplishments
The St. Louis Zoo FRC grant program has helped support Ecuadorian student biologists from the
Universidad San Francisco de Quito (USFQ) and Pontificia Universidad Católica del Ecuador
(PUCE) in current and prior field seasons. In my first field season, I trained and supervised an
Otavaleño student (David Cotacachi) from USFQ; he learned how to mist net and assisted in
radio tagging of toucans, and in addition, learned how to conduct radio telemetry from canopy
towers. David is currently attending an English program on scholarship in the United States with
future plans to take the GRE/TOEFL and apply for graduate programs in biology. I also worked
with a student (Juan Ernesto Guevara) from PUCE on botanical portions of the project; we are
currently collaborating on his undergraduate thesis project examining dispersal limitation of rare
and common tropical tree species. His accomplishments include submission of a paper on prior
work of plant community diversity. Furthermore, Juan Ernesto has recently worked as a field
researcher in Peru and plans collaboration with other botanists studying tropical tree diversity. In
the most recent field season I worked with a student (Andres Reyes) from USFQ and trained him
in line-transect census techniques, mist netting, radio tagging, and telemetry. Andres has
graduated from USFQ and will be working as an assistant manager for Tiputini Biodiversity
Station. Finally, my research has involved some of the field station personnel at TBS and YRS,
who are members of the two local indigenous groups, the Huaorani and the Quechua. I have
been able to work closely with these people, training them in specific skills such use of canopy
nets, radio-tagging birds, and radio tracking.
Other Accomplishments
•
Invitation as a symposium speaker for the 4th International Symposium – Workshop on
Frugivory and Seed Dispersal, Griffith University, Queensland, Australia. July 2005.
•
Awarded a STAR Graduate Fellowship, National Center For Environmental Research,
Environmental Protection Agency, USA. This fellowship will be used for my future
research program and to support myself during dissertation writing.
KM Holbrook 14
St. Louis Zoo Final Report, August 2003
Literature Cited
Buckland, S. T., D. R. Anderson, K. P. Burnham, and J. L. Laake. 1993. Distance sampling:
estimating abundance of biological populations. Chapman & Hall, London.
Cain, M. L., B. G. Milligan, and A. E. Strand. 2000. Long-distance seed dispersal in plant
population. American Journal of Botany 87:1217-1227.
Cheung, W. Y., N. Hubert, and B. S. Landry. 1993. A simple and rapid DNA microextraction
method for plant, animal, and insect suitable for RAPD and PCR analyses. PCR Methods
and Applications 3:69-70.
Dow, B. D., and M. V. Ashley. 1996. Microsatellite analysis of seed dispersal and parentage of
saplings in bur oak, Quercus macrocarpa. Molecular Ecology 5:615-627.
English, P. H. 1998. Ecology of mixed-species understory flocks in Amazonian Ecuador. Ph.D.
Thesis. The University of Texas, Austin, Texas, USA. 182 pp.
Galetti, M. 2000. Frugivory by toucans (Ramphastidae) at two altitudes in the Atlantic forest of
Brazil. Biotropica 32:842-850.
Godoy, J. A., and P. Jordano. 2001. Seed dispersal by animals: Exact identification of source
trees with endocarp DNA microsatellites. Molecular Ecology 10:2275-2283.
Graham, C. H. 1999. Individual, species, and community level responses by birds to forest
fragmentation in southern Mexico. Ph.D. Thesis. The University of Missouri-St. Louis,
St. Louis, MO, USA. 228 pp.
Hamilton, M. B. 1999. Tropical tree gene flow and seed dispersal. Nature 401:129-130.
Holbrook, K. M., and T. B. Smith. 2000. Seed dispersal and movement patterns in two species of
Ceratogymna hornbills in a West African tropical lowland forest. Oecologia 125:245257.
Holbrook, K. M., T. B. Smith, and B. D. Hardesty. 2002. Implications of long-distance
movements of frugivorous rain forest hornbills. Ecography 25:745-749.
Hooge, P. N., and W. M. Eichenlaub. 2000. Animal Movement extension to Arcview. ver. 2.0.
Alaska Science Center, Biological Science Office, U.S. Geological Survey, Anchorage.
Howe, H. F., and G. A. V. Kerckhove. 1981. Removal of wild nutmeg (Virola surinamensis)
crops by birds. Ecology 62:1093-1106.
Howe, H. F., E. W. Schupp, and L. C. Westley. 1985. Early consequences of seed dispersal for a
neotropical tree (Virola surinamensis). Ecology 66:781-791.
Howe, H. F., and J. Smallwood. 1982. Ecology of seed dispersal. Annual Reviews in Ecology
and Systematics 13:201-228.
Janzen, D. H. 1970. Herbivores and the number of tree species in tropical forests. American
Naturalist 104:501-528.
Jordano, P. 1992. Fruits and frugivory. Pages 105-156 in M. Fenner, editor. Seeds: The Ecology
of Regeneration in Plant Communities. CAB International, Wallingford, UK.
Jordano, P., and J. A. Godoy. 2002. Frugivore-generated seed shadows: a landscape view of
demographic and genetic effects. Pages 305-321 in D. J. Levey, W. R. Silva, and M.
Galetti, editors. Seed dispersal and frugivory: Ecology, evolution and conservation. CAB
International, Wallingford, UK.
Jørgensen, P. M., and S. Leòn-Yánez, editors. 1999. Catalogue of the vascular plants of Ecuador.
Missouri Botanical Garden Press, St. Louis.
KM Holbrook 15
St. Louis Zoo Final Report, August 2003
Kinnaird, M. F., T. G. O'Brien, and S. Suryadi. 1996. Population fluctuation in Sulawesi Redknobbed Hornbills: tracking figs in space and time. Auk 113:431-440.
Laake, J. L., S. T. Buckland, D. R. Anderson, and K. P. Burnham. 1993. DISTANCE user's
guide. Colorado Cooperative Fish and Wildlife Research Unit, Colorado State University,
Fort Collins.
Laman, T. G. 1996. Ficus seed shadows in a Bornean rain forest. Oecologia 107:347-355
Lambright, D. D. 1981. The comparative anatomy and morphology of Virola (Myristicaceae).
Ph.D. Thesis. Miami University, Oxford. 93 pp.
Mena, V. P., J. R. Stallings, J. B. Regalado, and R. L. Cueva. 2000. The sustainability of current
hunting practices by the Huaorani. Pages 57-78 in J. G. Robinson and E. L. Bennett,
editors. Hunting for sustainability in tropical forests. Columbia University Press.
Murray, K. G. 1988. Avian seed dispersal of three neotropical gap-dependent plants. Ecological
Monographs 58:271-298.
Ouborg, N. J., Y. Piquot, and J. M. Van Groenendael. 1999. Population genetics, molecular
markers and the study of dispersal in plants. Journal of Ecology 87:551-568.
Pacheco, L. F., and J. A. Simonetti. 2000. Genetic structure of a Mimosoid tree deprived of its
seed disperser, the spider monkey. Conservation Biology 14:1-10.
Parker, P. G., A. A. Snow, M. D. Schug, G. C. Booton, and P. A. Fuerst. 1998. What molecules
can tell us about populations: choosing and using a molecular marker. Ecology 79:361382.
Parker, T. A., D. F. Stotz, and J. W. Fitzpatrick. 1996. Ecological and distributional databases. in
D. F. Stotz, J. W. Fitzpatrick, T. A. P. III, and D. K. Moskovits, editors. Neotropical
birds: ecology and conservation. University of Chicago Press, Chicago.
Peres, C. A. 2000. Effects of subsistence hunting on vertebrate community structure in
Amazonian forests. Conservation Biology 14:240-253.
Queller, D. C., and K. F. Goodnight. 1989. Estimating relatedness using genetic markers.
Evolution 43:258-275.
Redford, K. H. 1992. The empty forest. BioScience 42:412-422.
Robinson, W. D., J. D. Brawn, and S. K. Robinson. 2000. Forest bird community structure in
central Panama: Influence of spatial scale and biogeography. Ecological Monographs
70:209-235.
Santana, E. C., T. C. Moermond, and J. S. Denslow. 1986. Fruit selection in the collared aracari
(Pteroglossus torquatus) and the slaty-tailed trogon (Trogon massena): two birds with
contrasting foraging modes. Brenesia 25-26:279-295.
Schlotterer, C., and J. Pemberton. 1998. The use of microsatellites for genetic analysis of natural
populations - a critical review. in R. DeSalle and B. Schierwater, editors. Molecular
approaches to ecology and evolution. Birkhauser Verlag Basel.
Schupp, E. W. 1993. Quantity, quality and the effectiveness of seed dispersal by animals.
Vegetatio 107/108:15-29.
Scribner, K. T., and J. M. Pearce. 2000. Microsatellites: Evolutionary and methodological
background and empirical applications at individual, population, and phylogenetic levels.
in A. J. Baker, editor. Molecular methods in ecology.
Sun, C., A. R. Ives, H. J. Kraeuter, and T. C. Moermond. 1997. Effectiveness of three turacos as
seed dispersers in a tropical montane forest. Oecologia 112:94-103.
Terborgh, J. 1999. Requiem for nature.
KM Holbrook 16
St. Louis Zoo Final Report, August 2003
White, G. C., and R. A. Garrott. 1990. Analysis of wildlife radiotracking data. Academic Press,
San Diego.
Whitney, K. D., M. F. Fogiel, A. M. Lamperti, K. M. Holbrook, D. J. Stauffer, B. D. Hardesty,
V. T. Parker, and T. B. Smith. 1998. Seed dispersal by Ceratogymna hornbills in the Dja
Reserve, Cameroon. Journal of Tropical Ecology 14:351-371.
Willson, M. F. 1992. The ecology of seed dispersal. Pages 61-85 in M. Fenner, editor. Seeds:
The Ecology of Regeneration in Plant Communities. CAB International, Wallingford,
UK.
Worton, B. J. 1989. Kernel methods for estimating the utilization distribution in home-range
studies. Ecology 70:164-168.
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