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2009 SOUTHEASTERN NATURALIST 8(2):335–346
Wet-season Food Habits and Intersexual Dietary Overlap
of Florida Box Turtles (Terrapene carolina bauri) on
National Key Deer Wildlife Refuge, Florida
Steven G. Platt1,*, Clint Hall1, Hong Liu2, and Christopher K. Borg3,4
Abstract - We studied the wet-season food habits of adult Terrapene carolina bauri
(Florida Box Turtles) on National Key Deer Wildlife Refuge, Big Pine Key, FL.
Feces were collected from 112 Box Turtles (64 females, 48 males) and analyzed to
determine diet. Based on percent occurrence (number of samples in which a particular
dietary item occurs divided by the sample size), terrestrial gastropods and fl eshy
fruits were the principal foods consumed. Lesser amounts of leafy vegetation were
recovered, whereas insects and other invertebrates, vertebrates (most likely consumed
as carrion), and fungi composed a minor portion of the diet. The occurrence
of deer feces in a single scat constitutes the first report of coprophagy by box turtles.
Our fecal analysis provided little evidence of dietary specialization by either sex,
which is consistent with earlier descriptions of box turtles as generalist omnivores.
Male Florida Box Turtles were significantly larger than females, but there was no
indication that larger body size in males provides access to an expanded resource
base; the near-complete dietary overlap between the sexes suggests they consume
the same foods.
Terrapene carolina bauri Taylor (Florida Box Turtle), one of six extant
subspecies of T. carolina in North America, occurs from extreme southeastern
Georgia, southward throughout peninsular Florida, and into the Florida Keys
(Dodd 2001). Within this distribution, Florida Box Turtles occupy a variety
of habitats (Carr 1952), often at high densities (to 16.3 adults/ha) (Dodd 2001,
Langtimm et al. 1996, Pilgrim et al. 1997, Verdon and Donnelly 2005). Surprisingly
few studies have been conducted on the ecology of Florida Box Turtles
(Dodd 1997a, Dodd et al. 1994, Pilgrim et al. 1997, Verdon and Donnelly 2005)
despite its widespread distribution and high abundance in many areas, and in
particular, little is known regarding its diet. Anecdotal observations on foraging
have been reported (Carr 1952, Dodd et al. 1994), but otherwise there is a
notable paucity of dietary information in the literature (Dodd 2001).
Studies of diet are fundamental to understanding the ecology of an
organism (Rosenberg and Cooper 1990), and among turtles, diet directly
affects energy allocation, which in turn determines survival, growth, and
1Sul Ross State University, Department of Biology, Box C-64, Alpine, TX 79832.
2Department of Earth and Environment, ECS 343, Florida International University,
11200 SW 8th Street, Miami, FL 33199. 3Department of Biological Sciences, Florida
International University, 11200 SW 8th Street, Miami, FL 33199. 4Current address -
Tall Timbers Research Station, 13093 Henry Beadel Drive, Tallahassee, FL 32312.
*Corresponding author - email@example.com.
336 Southeastern Naturalist Vol. 8, No. 2
reproductive rates (Ford and Moll 2004, Sloan et al. 1996). Indeed, annual
variation in the availability of food resources may limit clutch size and
reproductive frequency of Florida Box Turtles (Dodd 1997b). Information
on diet is also a necessary prerequisite for the study of complex ecological
relationships such as seed-dispersal mutualisms between plants and animals
(Liu et al. 2004). Moreover, dietary studies can provide information on
potential pathways of exposure to environmental contaminants, which may
be responsible for a high incidence of aural abscesses observed among box
turtles (Brown et al. 2003, Holladay et al. 2001). From the standpoint of conservation,
knowledge of diet is essential for assessing the potential impacts
of urbanization and land-management practices on box turtle populations
(Budischak et al. 2006). This need for greater understanding of dietary habits
is especially relevant in south Florida, where Florida Box Turtle populations
are thought to be declining (Dodd and Franz 1993), and habitat is being
modified or destroyed by human activities at an increasingly rapid rate (Pilgrim
et al. 1997, Snyder et al. 1990, Verdon and Donnelly 2005).
When the sexes differ in body size, they often exploit different food
resources, possibly as a means of reducing the potential for intraspecific
competition (Slatkin 1984). Florida Box Turtles exhibit pronounced sexual
size dimorphism, with males attaining a larger average body size and growing
to greater maximum sizes than females (Dodd 1997a, Ernst et al. 1998,
Verdon and Donnelly 2005). However, with the exception of Stuart and Miller
(1987), intersexual dietary differences among Box Turtles have received
little attention. Here we present the results of a dietary study of Florida Box
Turtles in pine rockland forests on Big Pine Key, FL. In this study, we characterize
the wet-season diet, estimate dietary specialization, quantify sexual
size dimorphism, and measure dietary overlap between the sexes.
Study Area and Methods
This study was conducted on National Key Deer Wildlife Refuge
(NKDWR; 24°42'N, 81°22'W), Big Pine Key, Monroe County, FL. NKDWR
(3110 ha) was established for the protection of Odocoileus virginianus
clavium Barbour and Allen (Key Deer), an endangered subspecies of Whitetailed
Deer endemic to the Lower Florida Keys. The refuge is characterized
by extensive pine rockland forest with smaller areas of hardwood hammocks
and coastal mangrove forests. Pine rockland forest is a fire-dependent
ecosystem that occurs on limestone outcrops in extreme southern Florida
(Snyder et al. 1990). This ecosystem is dominated by a relatively open
canopy of Pinus elliottii Engelm. (Slash Pine) with a diverse and often dense
understory of shrubs, vines, herbs, and several species of palms (Snyder et
al. 1990). The climate of the region is considered tropical with pronounced
wet (May to October) and dry (November to April) seasons. Wet- and dryseason
rainfall averages 743 and 265 mm, respectively, while the average
dry-season temperature (22 °C) is considerably less than that of the wet
season (29 °C) (Verdon and Donnelly 2005).
2009 S.G. Platt, C. Hall, H. Liu, and C.K. Borg 337
Florida Box Turtles were collected from June through October 1999 and
July through November 2000 as part of a larger study on seed dispersal (Liu
et al. 2004). We searched for turtles in the morning (0730–1000 h) and late
afternoon (1700–1930 h). During both years, we found Florida Box Turtles
by visually searching suitable microhabitats and through opportunistic encounters.
A trained dog augmented our search efforts in 1999. Additionally,
we searched for dead turtles in the wake of prescribed burns on NKDWR,
conducted as part of a study to assess the effects of fire on pine rockland
vegetation (Snyder et al. 2005). Straight-line carapace and plastron lengths
(CL and PL, respectively) of each turtle were measured with calipers (± 0.1
cm). Following Dodd et al. (1994), only turtles with a CL >11.0 cm were
considered adults. The sex of adult turtles was determined based on plastral
morphology; males exhibit a deep concavity that is absent in females (Dodd
2001). Each captured turtle was permanently marked by notching a unique
series of marginal scutes (Cagle 1939) and released at the capture site within
We used a one-tailed Student’s t-test (Zar 1996) to test the hypothesis that
the CL of adult male Box Turtles was greater than that of adult females. The
degree of size dimorphism (defined as a statistically significant difference in
mean length of sexually mature organisms) among the sexes was quantified
with a compressed sexual size dimorphism index (SDI; Lovich and Gibbons
1992). SDI is a dimensionless number that is calculated by dividing the mean
size of the larger sex by the mean size of the smaller sex, then adding or
subtracting one from this value depending on whether males or females, respectively,
are the larger sex (Lovich and Gibbons 1992). Although SDI may
be based on mass or some measure of body length (CL or PL), we selected
CL as the appropriate variable because body mass can exhibit considerable
variation among turtles of similar length due to the presence of eggs in
gravid females, recent ingestion of large meals, and overall body condition
(Lovich and Gibbons 1992). Mean values are presented as ± 1 SE, and results
considered significant at P ≤ 0.05.
In 1999, we collected feces from captured Florida Box Turtles and analyzed
the contents to determine diet. Feces were obtained by retaining turtles
overnight (12–18 hours) in plastic buckets containing about 5 cm of water
to stimulate defecation (Platt et al. 2001). The contents of each bucket were
then passed over a sieve (2-mm mesh) and food items recovered, dried,
and later identified to the lowest possible taxonomic level. We calculated
the percent occurrence of each food item recovered from the feces following
Rosenberg and Cooper (1990), who defined percent occurrence as the
number of samples in which a particular item occurs divided by the sample
size. Although often considered synonymous with frequency of occurrence,
percent occurrence differs slightly and is a more appropriate metric when
the number of individual food items cannot be quantified (Rosenberg and
338 Southeastern Naturalist Vol. 8, No. 2
We used the Shannon-Wiener diversity index (H') to estimate dietary
niche breadth and determine the degree of dietary specialization of each sex
(Schoener 1968). The Shannon-Wiener index is calculated as:
H' = – Σ pj log pj,
where pj is the proportion of individuals using resource j (category of food
items). Because H' may range from 0 to ∞, we standardized the index on a
scale of 0 to 1 using the evenness measure J' calculated as
J' = H' (log n) –1,
where n is the number of categories of dietary items (Krebs 1989). The lower
the value of J', the more specialized the feeding habits of a particular sex, i.e.,
low J' values indicate little diversity in the resources consumed, and hence a
greater degree of dietary specialization (Krebs 1989, Schoener 1968).
Dietary niche overlap between the sexes was determined using percent
overlap (P), which measures the area of overlap of the resource utilization
curves of males (m) and females (f) (Krebs 1989). P is estimated by
Σ (minimum pim, pif) x 100, where pim and pif are the proportion of food item
(i) used by males and females, respectively, and ranges from 0 (no overlap)
to 1 (complete overlap) (Krebs 1989).
We found 207 adult Florida Box Turtles on NKDWR, including 194
living turtles and 13 (7 females, 6 males) killed by prescribed burns. Our
sample consisted of 120 females and 87 males. Mean CL values for adult
male and female Box Turtles were 15.3 ± 0.09 cm (range = 12.8 to 17.3 cm),
and 14.1 ± 0.07 cm (range = 12.1 to 15.8 cm), respectively. Male CL was
significantly greater than female CL (t = 10.4, df = 205; P < 0.001), and we
calculated a SDI of 2.08 for the NKDWR sample.
We obtained feces from 112 adult (64 female and 48 male) Florida Box
Turtles from which we identified 24 dietary items (Table 1). Gastropod
remains and seeds of plants producing fl eshy fruits were the items most
frequently recovered from turtle feces. We identified several intact and
partially intact gastropod shells as Chondropoma dentatum Say (Crenulate
Horn) and Helicina clappi Pilsbry (Rainbow Drop), but most remains consisted
of little more than small pieces of unidentifiable crushed shells. The
most frequently recovered seeds were Byrsonima lucida (Mill.) DC. (Long
Key Locustberry), Mosiera longipes (O. Berg) Small (Mangroveberry),
and Thrinax morrisii H. Wendel (Key Thatch Palm). Seven other species of
fl eshy fruits were recovered, but occurred in <10% of fecal samples. Seeds
were from the dominant components of the shrub (Long Key Locustberry,
Key Thatch Palm, and Coccothrinax argentata (Jacq.) L.H. Bailey [Florida
Silver Palm]) and herbaceous (Morinda royoc L. [Redgal]) layers of pine
rockland forest (Snyder et al. 1990). Leafy vegetation was recovered from
the feces of 30 (26.7%) Florida Box Turtles, whereas insects, crustaceans,
vertebrate remains, fecal pellets of Key Deer, and fungi each occurred in the
2009 S.G. Platt, C. Hall, H. Liu, and C.K. Borg 339
feces of nine (8.0%) or fewer turtles. Dietary diversity (H') and evenness (J')
values were similar for males and females, and evenness values approached
1 for both sexes, indicating little dietary specialization (Table 1). We calculated
an 88.3% overlap in the diet between the sexes.
Florida Box Turtles on NKDWR are generalist omnivores that consume
a variety of animal and plant foods, a profile similar to other studies of box
turtles (Klimstra and Newsome 1960, Stuart and Miller 1987). Terrestrial
Table 1. Dietary items recovered from the feces of adult Terrapene carolina bauri (Florida Box
Turtle) collected on National Key Deer Wildlife Refuge, Big Pine Key, FL from June through
October 1999. Number of turtles from which a specific dietary item was recovered is followed
by percent occurrence (%) in parentheses. Percentages do not sum to 100 because multiple items
were often found in the feces of a single turtle.
Dietary item Females (n = 64) Males (n = 48) All turtles (n = 112)
Annona glabra L. (Pond Apple)A 2 (3.1) 0 2 (1.7)
Brysonima lucidaA 44 (68.7) 31 (64.5) 75 (67.0)
Coccoloba uviferaA 0 3 (6.2) 3 (2.6)
Coccothrinax argentataA 6 (9.3) 2 (4.1) 8 (7.1)
Ficus sp.A 0 1 (2.0) 1 (0.9)
Fabaceae (unidentified) 2 (3.1) 0 2 (1.7)
Morinda royocA 4 (6.2) 6 (12.5) 10 (9.0)
Mosiera longipesA 23 (36.0) 15 (31.2) 38 (34.0)
Smilax havanensis Jacq.A 2 (3.1) 0 2 (1.7)
Thrinax morrisiiA 14 (21.8) 9 (18.7) 23 (20.5)
Foliage (unidentified) 15 (23.4) 7 (14.5) 22 (19.6)
Mosiera longipes 4 (6.2) 3 (6.2) 7 (6.2)
Tillandsia sp. 0 1 (2.0) 1 (0.9)
Bone 1 (1.5) 0 1 (0.9)
Crustacean 1 (1.5) 0 1 (0.9)
Fish 0 1 (2.0) 1 (0.9)
Insects 4 (6.2) 5 (10.4)
Gastropods 60 (93.7) 44 (91.6) 104 (92.8)
Snake (shed skin) 2 (3.1) 0 2 (1.7)
Terrapene carolina 2 (3.1) 2 (4.1) 4 (3.5)
Feces (Odocoileus virginianus) 0 1 (2.0) 1 (0.9)
Fungus 1 (1.5) 1 (2.0) 2 (1.7)
PaperB 2 (3.1) 0 2 (1.7)
StonesB 0 1 (2.0) 1 (0.9)
Diversity (H') 1.21 1.17 1.16
Evenness (J') 0.91 0.90 0.89
ASpecies with fl eshy fruits.
BDietary categories not included in calculations of H'.
340 Southeastern Naturalist Vol. 8, No. 2
gastropods were the most frequently occurring food item that we observed.
Gastropods (snails and slugs) are common prey for other subspecies of box
turtles, occurring in the diet at frequencies as high as 72% (Barbour 1950,
Bush 1959, Klimstra and Newsome 1960, Stuart and Miller 1987). However,
the percent occurrence (92.8%) we observed for NKDWR is the highest yet
reported anywhere. In addition to being consumed as food, snails could be an
important source of calcium for eggshell formation in reproductive female
box turtles (Beasom and Pattee 1978, Esque and Peters 1994).
In contrast to studies in which insects and invertebrates other than gastropods
comprise much of the diet (Klimstra and Newsome 1960, Stickel 1950,
Strang 1983, Stuart and Miller 1987), these prey appear relatively unimportant
for Florida Box Turtles on NKDWR. The diet of Florida Box Turtles on
Egmont Key is thought to be composed primarily of cockroaches (Dodd et
al. 1994), a prey item that we did not detect among the feces of turtles from
NKDWR. Little is known about prey selection in box turtles (Dodd 2001),
but the occurrence of gastropods, insects, and other invertebrates in the diet
probably refl ects their relative availability to foraging turtles.
The vertebrate remains we recovered in turtle feces were most likely
consumed as carrion. Scavenging of vertebrate carrion by Box Turtles is
well documented (Carr 1952, Dodd 2001, Klimstra and Newsome 1960),
and when available, carrion provides an energetically rich food source that
can be safely obtained without the cost of capturing and subduing prey
(DeVault and Krochmal 2002). Similar to carrion, shed snake skins represent
a protein source for Box Turtles (Weldon et al. 1993). Interestingly,
the most common vertebrate remains we observed were carapacial bones
of other box turtles. Osteophagy is widespread among terrestrial chelonians
(Walde et al. 2007), and bones are an excellent source of calcium and
phosphorus (Esque and Peters 1994)—nutrients that are poorly represented
in the shallow, leached sandy soils typical of pine rockland forest (Snyder
et al. 1990). The large size of most carapacial bones indicated they were
from adult turtles and almost certainly consumed as carrion; however, one
scat contained costal bones from a hatchling or small juvenile. Although
there is no way to determine if this juvenile was scavenged as carrion, our
observation raises the possibility that Florida Box Turtles may occasionally
engage in cannibalism.
Seeds from fleshy-fruited species were the principal plant material that
we found in turtle scats. Most fruits consumed by Florida Box Turtles were
either those that readily dropped to the ground at maturity (Long Key Locustberry,
Key Thatch Palm, and Florida Silver Palm) or occurred on plants
with prostrate growth forms (Redgal). The fruits most frequently found in
turtle feces were drupes with a covering of sugar- or lipid-rich mesocarp,
but berries and aggregate fruits (e.g., Ficus sp. (figs) and Mangroveberry)
were also represented. Most species of fruit found in scats were dark colored
(blue/purple/black), although there was no significant difference
between the color of fruits available on NKDWR and those consumed by
2009 S.G. Platt, C. Hall, H. Liu, and C.K. Borg 341
turtles (Liu et al. 2004). Other studies of box turtles have likewise noted
an abundance of fleshy fruits in the diet (Braun and Brooks 1983, Dodd et
al. 1994, Klimstra and Newsome 1960). Fleshy fruits are high in calories,
offer a rich energetic reward (Golley 1961), and may also be an important
source of moisture in xeric pine rockland habitats, especially during the dry
season (Dodd et al. 1994). The seeds of non-fleshy fruits rarely occurred
among turtle feces from NKDWR.
Dodd et al. (1994) observed Florida Box Turtles on Egmont Key
consuming the fruits of Coccoloba uvifera L. (Seagrape), Opuntia sp.
(cactus), Scaevola plumieri (L.) Vahl. (Half-Flower), and Sabal palmetto
(Walter) Lodd. Ex Schult & Schult f. (Cabbage Palm), and found Schinus
terebinthifolius Raddi. (Brazilian Pepper) seeds in turtle feces. With the
exception of Seagrape, which is a minor component of the diet on NKDWR,
seeds of these plants were absent from our samples. Such differences are
not unexpected, as most of these species are rare or absent in our study area,
or produce fruit primarily during the dry season (e.g., Brazilian Pepper), a
period in which we did not sample. Nor did we observe large (30–40) aggregations
of Florida Box Turtles foraging beneath fruiting trees as described
by Dodd et al. (1994) on Egmont Key. The largest group of feeding Florida
Box Turtles that we encountered was three individuals beneath a single
Long Key Locustberry shrub. In contrast to Egmont Key, where box turtles
from throughout the island converge on clumps of fruiting trees (Dodd et al.
1994), the principal fruiting species used on NKDWR are widespread and
abundant; consequently it is unnecessary for turtles to congregate in large
groups to exploit this food resource.
Studies of box turtles in temperate regions of North America have found
that shoots, buds, and leaves compose a significant portion of the diet (Dodd
2001, Stuart and Miller 1987); however, leafy vegetation was relatively uncommon
in the diet of turtles on NKDWR. Moreover, some of this material
may have been incidentally ingested while turtles were consuming fruits (e.g.,
Mangroveberry). The relative paucity of leafy vegetation in the diet is not
unexpected given the high lignin and cellulose content and low caloric value
of leaves in comparison to the high caloric content and widespread availability
of fruit (Golley 1961). Leafy vegetation may assume greater dietary
importance during the dry season, when most fruits are unavailable (S. Koptur
et al., Florida International University, Miami, FL, unpubl. data).
Box turtles elsewhere in North America reportedly consume large
amounts of fungi (Strang 1983, Stuart and Miller 1987, Surface 1908), an
item that we recovered from only two turtles. These differences may be due
to the bias inherent in different sampling methodologies; two of the studies
that noted a high frequency of fungi were based on an examination of
stomach contents (Stuart and Miller 1987, Surface 1908). In our study, fungi
may have been completely digested and thus would likely have gone undetected
in the feces. We consider the latter unlikely, however, as Moskovits
and Bjorndal (1990) noted that fungi were resistant to digestion and often
342 Southeastern Naturalist Vol. 8, No. 2
defecated intact by Geochelone carbonaria Spix (Red-footed Tortoise) and
G. denticulata (L.) (South American Yellow-footed Tortoise). Likewise, we
have recovered undigested fungi from the feces of Rhinoclemmys areolata
Duméril, Bibron, and Duméril (Furrowed Wood Turtle) in Belize and T.
carolina major Agassiz (Gulf Coast Box Turtles) in Louisiana (S.G. Platt
et al., unpubl. data). More importantly, it is our subjective impression that
fungi are rare in the xeric soils of pine rockland forest and therefore less
available to foraging turtles.
The large number of seeds found in individual fecal samples (Liu et al.
2004), coupled with the high population density (10.2 box turtles/ha; Verdon
and Donnelly 2005), suggests that Florida Box Turtles are significant
dispersers of fl eshy-fruited plant species on NKDWR. In an earlier study, we
planted the seeds of nine fl eshy-fruited species recovered from turtle feces
and all successfully germinated at rates ranging from 10 to 80% (Liu et al.
2004). However, the effects of digestion on the germination performance of
seeds is complex and varied among species; larger-seeded species were more
likely than smaller-seeded species to exhibit a positive response (greater
germination percentage of ingested vs. control seeds) to digestion (Liu et al.
2004). Furthermore, digestion appears to initiate long-term seed dormancy
in Key Thatch Palm, possibly allowing seeds to disperse through time as well
as space (Liu et al. 2004). Similar to our results, Braun and Brooks (1983)
found that passage of seeds through the digestive tract of Terrapene carolina
carolina L. (Eastern Box Turtles) enhanced the germination percentage in 5
of 15 species tested. Although saurochory (dispersal of seeds by reptiles) has
received comparatively little attention from researchers (Traveset 1998) and
previous studies suffer from several serious limitations (reviewed by Liu et
al. 2004), our investigation and others (Braun and Brooks 1983, Carlson et al.
2003, De Lima et al. 1997, Ford and Moll 2004, Iverson 1987, Milton 1992,
Moll and Jansen 1995, Moskovits and Bjorndal 1990, Varela and Bucher
2002) are part of a growing body of literature that strongly suggests turtles are
important seed-dispersal agents in both terrestrial and aquatic ecosystems.
Notably, the consumption of Cabbage Palm (Dodd et al. 1994), Serenoa
repens (Bartr.) Small (Saw Palmetto; Liu et al. 2004), Key Thatch Palm, and
Florida Silver Palm fruits and probable dispersal of their seeds by Florida
Box Turtles are among the few documented cases of palm seed dispersal by
a reptile (see also De Lima et al. 1997, Moskovits and Bjorndal 1990). An
earlier review concluded that reptile-mediated dispersal of palm seeds is
rare and identified only one species of lizard as an important dispersal agent
(Zona 2006, Zona and Henderson 1989).
To our knowledge, the occurrence of deer fecal pellets in a single scat sample
constitutes the first report of coprophagy by box turtles. Coprophagy has
occasionally been observed among other terrestrial and aquatic turtles (Goodman
and Stuart 1998, Mares 1971), which probably derive nutritional benefits
from partially digested food items in the feces (Robbins 2001). Although it is
possible that box turtles secondarily ingest some seeds when consuming deer
2009 S.G. Platt, C. Hall, H. Liu, and C.K. Borg 343
feces (e.g., Gervais et al. 1998), it is unlikely that coprophagy contributes
significantly to the number of seeds we found in scats for two reasons. First,
coprophagy appears rare among box turtles, and second, while Key Deer are
known to consume many of the same fruits as box turtles, their principal dietary
components are forbs and woody browse (Klimstra and Dooley 1990).
Our results on sexual size dimorphism are consistent with Verdon and
Donnelly (2005), who found that the CL of male Florida Box Turtles (14.7 ±
0.2 cm; n = 27) was significantly greater than that of females (13.4 ± 0.1 cm;
n = 47) on Big Pine Key. Using the mean CL for male and female turtles reported
by Verdon and Donnelly (2005), we calculated a SDI of 2.09, a value
very similar to our sample. Although Verdon and Donnelly (2005) did not find
any females with a CL >15.0 cm, 18 females (15%) in our sample had a CL exceeding
this value. The CL of the largest males (to 17.3 cm) found on Big Pine
Key (Verdon and Donnelly 2005, this study) exceeds the maximum of 16.6 cm
reported for other populations of Florida Box Turtles (Dodd 1997a, Ernst et al.
1998). Large body size in male box turtles is thought to confer a mechanical
advantage during copulation; the larger plastron of the male permits the development
of a deeper plastral concavity that meshes with the relatively smaller
carapace of the female, enabling the male to better grasp the front of the female’s
carapace with his claws (Dodd 1997a).
Although male Florida Box Turtles are significantly larger than females,
we saw no indication that larger body size in males provides access to an expanded
resource base. The near-complete overlap in diet suggests that male
and female turtles consume essentially the same foods on NKDWR. Similarly,
Stuart and Miller (1987) found no dietary differences between male and
female Eastern Box Turtles in North Carolina. Dodd (2001) suggested that
intersexual dietary differences are unlikely because both sexes use the same
habitats concurrently, thereby encountering the same food resources. Diversity
values that indicate little dietary specialization by either sex on NKDWR
are consistent with the characterization of box turtles as generalist omnivores
(Allard 1948, Dodd 2001, Stuart and Miller 1987).
Finally, because this dietary study only spanned a single wet season, we
were unable to investigate seasonal patterns of food consumption among
Florida Box Turtles on NKDWR. Given the pronounced wet–dry seasonality
of southern Florida, variation in the diet is expected owing to the seasonal
availability of food resources (Dodd 1997b). Not only do few plants bear fruit
during the dry season (S. Koptur et al., unpubl. data), but drought conditions
probably reduce the availability of snails and insects (Dodd 1997b). Moreover,
annual variation in dietary composition probably also exists, particularly with
regards to mast-fruiting species such as Long Key Locustberry. For example,
in 1999, Long Key Locustberry fruit was abundant, which was refl ected in fecal
samples, but during two subsequent fruiting seasons (2000 and 2001), we
were unable to locate a sufficient number of fruits for germination trials (Liu
et al. 2004). Other food resources likely exhibit similar annual fl uctuations in
availability. Future multi-season studies conducted over several years will be
necessary to address questions of seasonal and annual variation in Florida Box
344 Southeastern Naturalist Vol. 8, No. 2
Support for S.G. Platt was provided by Wildlife Conservation Society and Sul Ross
State University. Hong Liu and Chris Borg were supported by Florida International
University. We are grateful for the assistance of Joanne Springfield Globe, Elizabeth
Birgh, and Trouble (dog) with turtle collections, and Timothy Collins for snail identifi-
cations. Suzanne Koptur kindly provided lab space and logistic assistance. Early drafts
of this manuscript benefited from the comments of Thomas Rainwater, Lewis Medlock,
Trip Lamb, and two anonymous reviewers.
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