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2007 SOUTHEASTERN NATURALIST 6(3):435–448
Ecology and Morphology of Chelydra serpentina in
Matthew J. Aresco1,2,* and Margaret S. Gunzburger1,2
Abstract - Chelydra serpentina (Common Snapping Turtle) is a wide-ranging and
often abundant turtle species in the eastern United States, but relatively little is
known of its basic ecology in the Southeast. The objective of our study was to
examine the ecology and population biology of and describe the morphology of
Common Snapping Turtles in northwestern Florida. We intensively sampled five
localities in Leon County, Fl using traps and hand collection (n = 111), and we
also opportunistically collected Common Snapping Turtles as we encountered them
through the course of other studies (n = 11). Analysis of seven morphological
characters from a subset of individuals indicated that the Common Snapping Turtle
in this study is an intergrade between C. s. serpentina and C. s. osceola. Estimated
early growth rates were 20 mm carapace length (CL)/year, and females matured at
about 220 mm CL (156 mm PL, approximately 6–8 years). Male Common Snapping
Turtles (CL mean = 299 ± 6 mm) were larger than females (CL mean = 270 ± 5
mm), and the overall adult sex ratio was 1:1. Diet consisted primarily of aquatic
plants (n = 4). Nesting females were found from early April through mid-May, and
clutch size ranged from 5 to 49 eggs (n = 3). Common Snapping Turtle abundance
varied over the five sites, but was highest (an average density of 16 individuals/ha)
in small suburban ponds with abundant aquatic vegetation, a thick layer of organic
sediment, and no alligators. In northwestern Florida, predation by alligators and
humans and primary productivity appear to be the factors that influence the distribution
and abundance of Common Snapping Turtles.
Chelydra serpentina (Linnaeus) (Common Snapping Turtle) is one of the
largest and most widely distributed turtles in North America (Ernst et al.
1994). This species occurs in lakes, ponds, streams, and slow-flowing rivers
throughout southern Canada and the entire eastern and central United States
(Ernst et al. 1994). A disjunct population occurs from Mexico through Central
America and northern South America (Ernst and Barbour 1992). Four subspecies
are currently recognized, two of which occur in the United States, C. s.
osceola Stejneger (peninsular Florida) and C. s. serpentina (Linnaeus) (remainder
of the US/Canadian geographic range), which are distinguished by
several morphological characteristics (Ernst et al. 1994, Feuer 1971,
Stejneger 1918). Intergradation has been documented between these subspecies
in the Okefenokee Swamp area of southern Georgia (Feuer 1971). Recent
research suggests that there is no genetic distinction between C. s. serpentina
1Department of Biological Science, Florida State University, Tallahassee, Fl 32306-
1100. 2Current address - Nokuse Plantation, 13292 County Highway 3280, Bruce, FL
32455. *Corresponding author - email@example.com.
436 Southeastern Naturalist Vol. 6, No. 3
and C. s. osceola (Walker et al. 1998), and use of morphological characteristics
may not allow diagnosis to subspecies (Phillips et al. 1996). The Common
Snapping Turtle is not currently considered endangered in any part of its
range, but threats to the Common Snapping Turtle that may result in local
population declines include habitat destruction and alteration, pollution, and
harvest (Aresco et al. 2006, Ernst et al. 1994, Gibbons 2003).
Life history and demography of the Common Snapping Turtle are relatively
well-studied in some areas in the northern portion of its range, such as
the E.S. George Reserve in Michigan (Congdon et al. 1987, 1994) and
Algonquin Provincial Park in Ontario (Galbraith and Brooks 1987a, Loncke
and Obbard 1977). Demographic research on Common Snapping Turtles in
the northern portion of its range indicates that this species has a typical life
history of a long-lived, ectothermic vertebrate: slow growth rates, low recruitment,
and high adult survivorship (Galbraith and Brooks 1987a,
Galbraith et al. 1989, Yntema 1976). This species can reach high abundances
in some habitats, but significant variation in density (0–66 adults/ha) and
biomass (9–340 kg/ha) of Common Snapping Turtles has been documented
in the northern and central portions of its range (Congdon and Gibbons 1989,
Froese and Burghardt 1975, Galbraith et al. 1988, Iverson 1982, Iverson et
al. 2000, Major 1975). However, no detailed ecological research has been
published for Common Snapping Turtles in the southern portion of its North
American range. A study at Lake Conway in central Florida found that
snapping turtles (n = 21) were most commonly captured in shallow water
areas with abundant aquatic vegetation and mud substrates (Bancroft et al.
1983), similar to the preferred habitat reported in other portions of its range
(Ernst et al. 1994). As an ectothermic organism, demographic characteristics
such as growth rate and age at maturity of Common Snapping Turtles are
likely to be strongly influenced by the warmer climate and longer growing
season in northern Florida compared to north temperate populations.
The objective of this study was to collect a range of ecological and
population data for Common Snapping Turtles in northwestern Florida. To
accomplish this goal, we intensively sampled Common Snapping Turtles at
five sites in Leon County, FL, and also collected data on other Common
Snapping Turtles we opportunistically collected dead on roads and during
the course of other research. Our results provide baseline ecological and
population data for this species in the southern portion of its range
and allow for comparisons to data from northern populations. We also
examined several morphological characters of Common Snapping Turtles
that have been used to discriminate subspecies in order to determine
whether individuals in northwestern Florida are either intergrades or can be
clearly assigned to one subspecies.
We sampled Common Snapping Turtle populations at five sites in Leon
County, FL: McCord Pond, Harriman Pond, Chapman Pond, San Luis
2007 M.J. Aresco and M.S. Gunzburger 437
Pond, and Lake Jackson. Our sampling techniques and effort varied across
these sites (Table 1) and included trapping, hand-collection, and drift
fences. McCord Pond, Harriman Pond, Chapman Pond, and San Luis Pond
are small ponds (< 3 ha) located within suburban parks in Tallahassee, FL,
and we collected Common Snapping Turtles before and during drawdown
and sediment-removal operations at these sites (Aresco and Gunzburger
2004). Prior to sediment removal, the substrate of these ponds was a thick
layer of organic sediment that supported an abundance of aquatic macrophytes.
Lake Jackson is a large (1620 ha), shallow lake with sand and
organic substrate and abundant aquatic macrophytes. Water level is controlled
naturally by variation in rainfall and by two sinkholes. During
drought conditions, a lowering of the water table causes leakage into the
groundwater through the sinkholes and most of the lake bottom dries, an
event that has occurred 9 times during the last 100 years, drying on average
every 12 years (Wagner 1984).
We collected Common Snapping Turtles using several sampling
techniques. At McCord Pond and Chapman Pond, we first used two doublethroated
1-m diameter hoop traps baited with sardines that we checked daily.
Second, at these sites and at San Luis Pond and Harriman Pond, we surveyed
each site daily during the drawdown and sediment removal operations and
collected any Common Snapping Turtles we encountered. Turtles were
detected and captured in each drying pool by walking transects and moving
both hands up and down and from side to side in the shallow water and mud
until the entire area was covered several times. Buried turtles of all sizes
were easily detected in soft mud by following tracks and, in most cases,
observing disturbed mud and/or a small snout-opening at the surface. We
collected turtles in this manner from muddy areas surrounding drying pools
of water, sediment piles, and from the sediment being actively excavated by
machinery (Aresco and Gunzburger 2004). We feel confident that we collected
every Common Snapping Turtle present at McCord Pond and
Harriman Pond because the entire pond area was subjected to sediment
removal, and we were present throughout the entire operation at these sites
(Aresco and Gunzburger 2004). Our sampling effort at these sites was
correlated with the length of time required for the drydown and sedimentremoval
Our sampling methods at Lake Jackson differed significantly from the
other sites. A large migration of turtles occurred during this study in response
to the natural drydown of Lake Jackson in 2000 and the subsequent
refilling of the lake in 2001. As Lake Jackson dried, turtles and other
herpetofauna emigrated to the west towards Little Lake Jackson, which held
water throughout the drought. We collected Common Snapping Turtles
migrating between these two lakes at a 700-m drift fence along the road
separating these lakes (Aresco 2005). During the drydown in 2000, we also
performed regular surveys of the drying lakebed and collected any turtles
found in the soft mud of drying pools (Aresco 2005). Since virtually all
438 Southeastern Naturalist Vol. 6, No. 3
Table 2. Variation in morphological features associated with subspecies distinction (Ernst et al. 1994, Feuer 1971, Stejneger 1918) of Chelydra serpentina
serpentina and Chelydra serpentina osceola from a population at McCord Pond, Tallahassee, Leon County, Fl (n = 35).
Subspecies description McCord Pond, northwest Florida
Character C. s. osceola C. s. serpentina Mean ± SD (range) % with C. s. osceola trait
Width 3rd vertebral/total length of vertebrals > 0.33 < 0.33 0.32 ± 0.02 (0.30–0.37) 12%
Plastral forelobe length/carapace length > 0.4 < 0.4 0.40 ± 0.02 (0.36–0.47) 66%
Width 3rd vertebral/ height 2nd pleural > 0.9 < 0.9 0.88 ± 0.06 (0.78–1.07) 31%
Number of pairs of chin barbels Two One 9%
Prominence of lateral caudal tubercules Moderate Well-developed 11%
Dorsal keel knobs Center of scute Rear of scute 0%
Neck tubercles Long, pointed Round, wart-like *
*100% of individuals had moderately pointed (intermediate) neck tubercules.
Table 1. Variation in density, biomass, and percent composition in the Chelydra serpentina (Common Snapping Turtle) community among five sites in Leon
County, FL. Sampling effort includes trap hours and visual-encounter surveys (see methods for description of sampling methods at each site). Percent
composition is the percent of Common Snapping Turtles in the overall turtle community at each site.
Sampling Number collected Density Biomass Percent
Locality Area (ha) Sampling dates effort (hr) Juv M F total (#/ha) (kg/ha) composition
McCord Pond 2.0 1 Aug 1999–Mar 2000 1182 9 25 30 64 32 128 18.0%
Harriman Pond 0.5 1 Oct 2000–30 Oct 2000 154 2 5 4 11 22 69.5 10.0%
San Luis Pond 2.2 13 Mar 2004–24 Apr 2004 102 1 10 5 16 7.3 32.0 na
Chapman Pond 1.0 1 Jul 2003–30 Jul 2003, 1476 1 1 1 3 3.0 11.0 3.5%
16 Sept 2003–27 Sept 2003
Lake Jackson 405.0 22 Feb 2000–1 Nov 2005 6204 9 4 4 17 0.04 0.07 0.2%
2007 M.J. Aresco and M.S. Gunzburger 439
individuals of all turtle species were migrating overland west from the north
part of the drying Lake Jackson in 2000, we were able to estimate absolute
abundance and population structure of each species, including Common
In addition to the five sites in which we intensively sampled Common
Snapping Turtle populations, we also opportunistically collected
Common Snapping Turtles at other localities in Leon County, Fl as we
encountered them dead on roads (DOR) or during other research projects
(Aresco and James 2005).
For each Common Snapping Turtle collected, we recorded maximum
carapace length (CL) and plastron length (PL) in mm, weight (g), and sex.
We used secondary sex characteristics including tail size and location of
cloacal opening (Ernst et al. 1994) to determine sex of individuals larger
than the minimum size at maturity for females, which we confirmed through
dissection of a gravid DOR female that measured 225 mm CL, 162 mm PL.
We did not confirm size at maturity of male Common Snapping Turtles
through dissection, so we classified individuals less than 220 mm CL as
juveniles. It is possible that males mature at a larger size than females, and
individuals greater than 220-mm CL with male secondary sex characteristics
are subadult males. We counted lines of arrested growth (LAGs) for those
Common Snapping Turtles with clearly visible LAGs on the 2nd pleural scute
(n = 21). We did not verify that LAGs are deposited annually using markrecapture
of known-age animals, thus the age estimates based on counts of
LAGs may be inaccurate (Galbraith and Brooks 1987b). We measured seven
morphological characters from a subsample of 35 Common Snapping
Turtles from McCord Pond to identify subspecies (Table 2). We collected
clutch-size data from three Common Snapping Turtles: we dissected one
female found DOR and we radiographed two females hand-collected on
land. We obtained diet data by collecting fecal samples from two Common
Snapping Turtles and dissecting the stomach of two others (one that became
entangled and drowned in a trap at McCord Pond and one found DOR). In
some cases, we were unable to measure or sex turtles due to time constraints
or degradation of specimens collected DOR; thus, not all data were collected
from each individual. We also counted individuals of all other species of
turtles captured during our sampling at all five sites except San Luis Pond.
We attempted to return Common Snapping Turtles collected during this
research to their original collection location when possible. For San Luis
Pond, we held all Common Snapping Turtles (n = 16) in large cattle tanks at
the Florida State University greenhouse facility for two months during the
sediment-removal project. These turtles were released back to San Luis
Pond after the project was completed. At Lake Jackson, we returned all
Common Snapping Turtles captured back to Little Lake Jackson, which
retained water throughout the course of this study. At our three remaining
study sites, we were unable to return the turtles we collected to their original
pond for several reasons. At all three sites, the sediment removal operations
440 Southeastern Naturalist Vol. 6, No. 3
resulted in poor habitat quality immediately after completion, with little
organic sediment or aquatic vegetation remaining (Aresco and Gunzburger
2004). At McCord Pond, the extended duration of the sediment removal
operation (nine months) and the large number of Common Snapping Turtles
collected (n = 64) made holding turtles in cattle tanks an unviable option.
Thus, from McCord Pond, we moved all Common Snapping Turtles collected
to Lake Iamonia, Lake Overstreet, and Lake Hall, three large nearby
lakes with similar habitat characteristics to McCord Pond prior to sediment
removal. At Harriman Pond and Chapman Pond, we moved all Common
Snapping Turtles collected to McCord Pond in an effort to reestablish this
population, as the habitat quality had improved over time through growth of
macrophytes and sediment deposition.
Morphological characters and subspecies classification
A sample of 35 Common Snapping Turtles from McCord Pond shared
characteristics of both C. s. serpentina and C. s. osceola, suggesting that
the population consisted of intergrades of characters used to separate these
subspecies (Table 2). The proportion of Common Snapping Turtles with
osceola-like traits varied across traits from 0 to 66% (Table 2). Most traits
could be classified into one of the two subspecies, but for neck tubercles,
all individuals had an intermediate morphology with moderately pointed
tubercles. An examination of variation in plastral forelobe length/carapace
length to third vertebral width/second pleural height showed considerable
overlap in these characters between C. s. serpentina and this population
from northwestern Florida, but little overlap with C. s. osceola (Aresco et
Population and community structure
Abundance and density of Common Snapping Turtles varied over the
five sites in Leon County, Fl from a low of 0.04/ha at Lake Jackson to a
high of 32/ha at McCord Pond (Table 1). Biomass of Common Snapping
Turtles ranged from 128 kg/ha at McCord Pond to 0.07 kg/ha at Lake
Jackson (Table 1). Common Snapping Turtles were very abundant at ponds
in suburban parks; at these four sites, average density was 16/ha and
average biomass was 60 kg/ha (Table 1). Sex ratio of adult males:adult
females was not significantly different from 1:1 at McCord Pond, our
highest density site (28 males:25 females; 2 = 0.08, df = 1, p = 0.78), and
from all five sites pooled (41 males:45 females; 2 = 0.1, df = 1, p = 0.75).
The abundance of Common Snapping Turtles relative to other turtle
species varied strongly across the five sites. Common Snapping Turtles
represented only 0.2% of the turtle community at Lake Jackson, whereas it
represented 18% of the turtle community at the much smaller McCord
Pond (Table 1). Other turtle species found syntopically with Common
Snapping Turtles included Trachemys scripta (Schoepff) (Yellow-bellied
2007 M.J. Aresco and M.S. Gunzburger 441
Slider), Pseudemys floridana (LeConte) (Florida Cooter), Sternotherus
odoratus (Latreille) (Stinkpot), S. minor (Agassiz) (Loggerhead Musk
Turtle), Kinosternon subrubrum (Lacepède) (Mud Turtle), and Apalone
ferox (Schneider) (Florida Softshell).
Growth rates and size relationships
The size distribution of Common Snapping Turtles at these sites was
dominated by large adults, with a few juveniles to indicate low levels of
recruitment (Table 1, Fig. 1). Adults outnumbered juveniles at all sites
except Lake Jackson (Table 1). Estimated early growth (1–6 years) of
Common Snapping Turtles in Leon County, Fl was variable among individuals
and ranged from 20–30 mm CL/year (Fig. 2). Based on estimated
age using LAGs and the minimum size at maturity for females (based on one
dissected DOR individual), we estimate that females matured at about 6–8
years (Fig. 1, Fig. 2). Male Common Snapping Turtles (CL mean = 299 ± 6
mm, PL mean = 216 ± 5 mm, n = 38) were larger than females (CL mean =
270 ± 5 mm, PL mean = 200 ± 4 mm, n = 43) in this study (t-test for CL:
t = -3.81, df = 80, P < 0.001; Fig. 1).
We recorded clutch size for three female Common Snapping Turtles
collected while nesting from 4 April through 16 May (Table 3). Clutch size
ranged from 5–49 eggs. In addition, a Common Snapping Turtle was observed
nesting on 28 Mar 1996 at Wakulla Springs State Park, Wakulla
Figure 1. Size distribution of Chelydra serpentina (Common Snapping Turtles)
collected from five sites (McCord Pond Harriman Pond, San Luis Pond, Chapman
Pond, and Lake Jackson) in Leon County, FL.
442 Southeastern Naturalist Vol. 6, No. 3
County, FL, just south of Leon County (Scott Savery, Wakulla Springs State
Park, Crawfordville, FL, pers. comm.). Thus, we infer that the nesting
season of Common Snapping Turtles in Leon County begins in late March/
early April and probably continues at least through late May.
The diet of four Common Snapping Turtles collected in Leon County
consisted of predominantly aquatic plants, with one aquatic insect (Table 4).
We found no evidence of consumption of fish or other vertebrates by
Common Snapping Turtles.
Subadult and adult males and females (independent of nesting movements)
were observed moving overland in pine flatwoods in the
Apalachicola National Forest, Liberty County, FL, between permanent water
in swamps and ephemeral cypress dome ponds (M.J. Aresco and J.G.
Palis, unpubl. data). At Lake Jackson, two juveniles (40 mm CL) were found
Table 3. Clutch size for three Chelydra serpentina (Common Snapping Turtles) collected in
Leon County, FL. Lines of arrested growth (LAG) were not visible on the two larger females.
Date Locality CL (mm) Weight (g) LAG Clutch size Method
4 Apr 2002 San Luis Pond 225 1920 6 5 Di s sect ion
28 Apr 2003 Lake Jackson 285 4850 - 34 X-ray
16 May 2003 Goose Pond 387 9750 - 49 X-ray
Figure 2. Relationship
of estimated age
and size (CL) of
Turtles) (n = 21) in
Leon County, FL.
Age was estimated
using counts of lines
of arrested growth
(LAG) on the 2nd
pleural scute and included
turtles with complete
sets of clearly visible
2007 M.J. Aresco and M.S. Gunzburger 443
at the drift fence moving directly towards Little Lake Jackson after apparently
migrating at least 0.5 km from the nearest remaining pool on the lake
bottom during the final days of drying. A large male (346 mm CL) migrated
from a drying pool at Lake Jackson on 20 April 2000 to Little Lake Jackson
and was captured migrating back to Lake Jackson on 15 March 2001 as the
lake refilled. During the dry-down of Lake Jackson, under severe drought
conditions, two Common Snapping Turtles, a 140 mm CL juvenile and 268
mm CL adult, were found dead on the dry lake bottom, both probably killed
Common Snapping Turtles in this study in Leon County, Fl were classified
as intergrades because for the first 3 characteristics in Table 2, the
individuals in this population are almost exactly equal to the dividing value
for the two subspecies. In addition, the fact that there is significant variation
in the proportion of individuals with traits characteristic of C. s. osceola (0–
11%, Table 2) suggests that there are not two different morphotypes present
in the population, but rather a mix of morphology consistent with hybridization.
Further research, including analysis of additional portions of the
genome, is needed to clarify the subspecific relationships.
Abundance of Common Snapping Turtles varied considerably over the
five sites sampled in this study in Leon County, FL. Abundance was highest
in small (< 3 ha) suburban ponds and much lower in the one large lake (1620
ha) (Table 1). It is unlikely that this is due to variation in sampling effort, as
the site with the highest sampling effort had the lowest density. This result is
supported by a separate study of turtle communities in northwestern Florida
that included a survey of 14 additional lakes (4–2330 ha) in Leon County
(Aresco and James 2005). In that study, Common Snapping Turtles were
caught in hoop traps at only 2 sites (McCord Pond and Chapman Pond) and
Table 4. Diet of four C. serpentina collected in Leon County, FL.
CL Weight Sample
Date Locality (mm) (g) Sex type Diet item Percent
5 Jul 2003 Chapman Pond 310 5700 M Fecal Spirodela polyrhiza (L.) 95%
Nelumbo lutea (Willd.) 5%
28 Jul 2003 Bradford Road 282 4450 F Stomach Utricularia sp. (L.) 100%
8 Aug 1999 McCord Pond 369 9000 M Stomach Colocasia esculenta (L.) 100%
9 Oct 2003 Waverly Pond 249 2800 M Fecal Lethocerus americanus (Leidy) < 1%
(giant water bug)
Panicum sp. (L.) 1%
Nitella sp. (Agardh) 99%
444 Southeastern Naturalist Vol. 6, No. 3
were not trapped at any large lakes (> 4 ha) (Aresco and James 2005). Other
studies have also demonstrated that Common Snapping Turtles can be very
abundant in small ponds and wetlands, ranging from 61 individuals/ha in a
0.4-ha pond (Major 1975) to 59 individuals/ha at a 0.8-ha pond (Froese and
Burghardt 1975). Population density of Common Snapping Turtles was
correlated with primary productivity across two populations in Ontario
(Galbraith et al. 1988). In Leon County, FL, Aresco and James (2005) found
that overall turtle abundance was highest in lakes with high periphyton
productivity, a mud/organic substrate, and no alligators; however, their
sample size of Common Snapping Turtles was too low to allow for analysis
of specific habitat correlates to abundance of this species.
Size at maturity of Common Snapping Turtles was similar between our
study in northwestern Florida and that in north temperate populations
(Christiansen and Burken 1979, Mosiman and Bider 1960, White and
Murphy 1973). Growth rates are typically greater in turtles at lower latitudes
with a corresponding reduction in age at maturity. We estimated that female
Common Snapping Turtles in our study matured at six to eight years, which
was similar to a population in Iowa (six or more years; Christiansen and
Burken 1979), whereas they require twice that in Michigan (17–20 years;
Congdon et al. 1987) and Ontario (11–16 years; Galbraith et al. 1989).
Clearly, both the length of the growing season and productivity as it relates
to quantity and quality of food resources influences variation in growth rates
and age-at-maturity of Common Snapping Turtles.
In northwestern Florida, Common Snapping Turtles apparently reaches
its highest abundance in small ponds without alligators and with abundant
aquatic vegetation and deep organic sediment (Aresco and Gunzburger
2004, Aresco and James 2005). Similarly, in the St. Croix River in Minnesota
and Wisconsin, abundances of Common Snapping Turtles, Chrysemys
picta (Schneider) (Painted Turtle), and Graptemys geographica (LeSueur)
(Northern Map Turtle) were associated with muck substrates (Wright et al.
1999). In southeastern lakes, survival of Common Snapping Turtle juveniles
may be increased by a muck substrate, which provides a refuge from alligator
predation. During extremes in temperature in shallow ponds, turtles may
also benefit from a soft, deep, mud/muck bottom into which they can bury
into during aestivation or winter dormancy. A muck substrate also provides
optimal microhabitat for diet items of Common Snapping Turtles such as
macroinvertebrates, macrophytes, and macroalgae. Although our analysis of
gut contents suggested that Common Snapping Turtles is primarily herbivorous,
this analysis was limited to four individuals, and the diet of Common
Snapping Turtles is known to be highly variable across individuals within
and among populations (Alexander 1943, Lagler 1943). Trophic position of
Common Snapping Turtles at Lake Jackson based on stable isotope analysis
was 3.5, which reflects a more carnivorous diet at that site (Aresco and
James 2005). This result may also indicate inefficient digestion and assimilation
of plant material.
2007 M.J. Aresco and M.S. Gunzburger 445
This study demonstrates the importance of small wetlands to Common
Snapping Turtle populations. The four small ponds in our study (McCord
Pond, Harriman Pond, San Luis Pond, and Chapman Pond) were once
natural ponds that have been modified over the last two decades to serve as
stormwater retention ponds in city parks (Aresco and Gunzburger 2004).
Populations of Common Snapping Turtles in suburban ponds in such parks
have been protected from human harvest for several decades. This may be
why large individuals, which were presumably old adults, dominated the
size distribution in the ponds in this study compared to a large lake that is
subjected to intense fishing, including trotlines, and also potential harvest of
turtles (Michael Hill, Florida Fish and Wildlife Conservation Commission,
Tallahassee, FL, pers. comm.). Intensive muck-removal operations, where
entire wetlands are drained and dredged to deepen ponds for stormwater, can
extirpate Common Snapping Turtle populations (Aresco and Gunzburger
2004). Demographic and life-history traits of Common Snapping Turtles,
including long generation times and naturally high rates of egg and juvenile
mortality, limit their annual recruitment (Congdon et al. 1994). They may
not be able to compensate for sudden or chronic losses of large numbers of
breeding adults, and even small increases in annual mortality rates of mature
females (< 10% increase) can lead to long-term declines with little or no
population recovery possible (Brooks et al. 1991, Congdon et al. 1994).
Although the Common Snapping Turtle is an excellent overland disperser,
habitat fragmentation such as roads and development may limit the ability of
Common Snapping Turtles to recolonize ponds, especially with increasing
distance to the nearest unaltered wetland (Gibbs and Shriver 2002). In
addition, habitat alteration resulting from sediment-removal operations
probably reduces the likelihood of population recovery even if some individuals
recolonize the pond. Large-scale sediment-removal operations leave
ponds with a hard, graded sand substrate devoid of any organic material.
Therefore, the conservation of small, vegetated wetlands in suburban and
natural areas should be a priority for the conservation of Common Snapping
Turtles in Florida.
The level of harvest of Common Snapping Turtles in Florida is unknown
because the Florida Fish and Wildlife Conservation Commission
(FFWCC) does not require permits or reporting for turtles harvested for
personal consumption. In addition, most commercial turtle harvest (65–
85%) goes unreported (Enge 1993). Collection for the pet trade apparently
focuses on hatchlings raised from eggs from wild-caught females (Kevin
Enge, FFWCC, Quincy, FL, pers. comm.). Local turtle trappers in north
Florida often capture Common Snapping Turtles on trotlines, set lines, and
bush hooks, both intentionally and as bycatch while trapping fish and
Florida Softshell Turtles. According to trappers, snapping turtle meat is
kept for personal consumption or sold locally. In the 1980s–1990s, baited
trotlines set to catch Florida softshells were prevalent on Lake Jackson,
Leon County, Fl (Michael Hill, FFWCC, Tallahassee, FL, pers. comm.).
446 Southeastern Naturalist Vol. 6, No. 3
Although Common Snapping Turtles may naturally be less abundant in
large lakes, long-term exploitation of Common Snapping Turtles as
bycatch to Florida softshell harvest may at least partially explain the very
low density of this species at Lake Jackson compared to nearby ponds,
which have relatively high densities of Common Snapping Turtles but no
harvest pressure. Therefore, although levels of unreported harvest for personal
consumption or local sales may be relatively low, some Common
Snapping Turtles populations may be adversely affected if population densities
are naturally low and the same populations are exploited over time.
Even low levels of harvest of adult Common Snapping Turtles may result
in dramatic population declines (Congdon et al. 1994). Recent concerns
that increases in harvest of turtles for Asian markets may lead to population
declines have prompted some states to regulate or ban harvest of
Common Snapping Turtles. Harvest bans in some states may lead to an
increase in harvest pressure in states without regulations. Further research
on Common Snapping Turtles should be conducted throughout the southern
portion of its range in order to establish baseline demographic rates and
evaluate population trends in order to better predict the effects of harvest.
We thank the sediment-removal crews, Mike Brezin, Bob Walker, and especially
Dean Hansen for assistance collecting turtles. We thank Michael Hill, Jesse Sasser,
Joseph Daltry, Ray Einarson, and Curtis Watkins for providing access to sedimentremoval
sites. This research was conducted under FSU ACUC Protocol # 0015 and
Florida Fish and Wildlife Conservation Commission Scientific Collecting Permit
WX01666. Our research at San Luis Pond was partially supported by the City of
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