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Monograph 22
2006 NORTHEASTERN NATURALIST 13(1):39–42
Predation of Spotted Turtle (Clemmys guttata) Hatchling by
Green Frog (Rana clamitans)
James D. DeGraaf
1,* and Daniel G. Nein1
Abstract - Predation of Clemmys guttata (Spotted Turtle) hatchlings by Rana clamitans
(Green Frog) has not previously been reported. During Spotted Turtle nesting surveys in urban
Massachusetts, a Spotted Turtle hatchling was radio-tagged and tracked to determine initial
movement patterns. Fifteen days post-tagging, the Spotted Turtle hatchling was located in the
gut of an adult female Green Frog. Given the abundance of Green Frogs in semi-permanent
wetlands, they may be important predators on turtle hatchlings. Further studies are required
to determine the frequency of Green Frog predation on turtle hatchlings and to evaluate total
predation pressure on and survival of Spotted Turtle hatchlings.
Introduction. Chelonian hatchlings are vulnerable to the effects of desiccation
and are preyed on by a variety of animals, including snakes, birds, ants, small mammals,
and frogs (Ernst and Lovich 2009, Finkler 2001). Adult Rana catesbeiana
Shaw (Bullfrog) are aggressive predators and feed on a wide variety of prey including
young turtles (Hunter et al. 1999). Prey of the similarly sized Rana clamitans
Latreille (Green Frog) includes aquatic and terrestrial insects, small fish, molluscs,
and small frogs (DeGraaf and Yamasaki 2001, Hamilton 1948, Hunter et al.
1999, Rappole 2007); however, predation on turtles, specifically Clemmys guttata
Schneider (Spotted Turtle) hatchlings, has not been documented to date.
Methods. Spotted Turtle nesting surveys were conducted in Cohasset, MA, during
the months of May and June, 2002 through 2009. The identification and location
of nests followed thread-bobbin tracking methodology described by Wilson (1994).
On 22 June 2007, a Spotted Turtle nest containing five eggs was located in coarse
soil along a driveway 2 m from the edge of water in a semi-permanent wetland. On
13 September 2007, four hatchlings successfully emerged from the nest. One egg was
fertilized, but did not hatch for unknown reasons. As part of a preliminary evaluation
to track initial Spotted Turtle hatchling movements, one hatchling was tagged with
a transmitter (Holohil Systems, Ltd., model BD-2N; 0.5 g) (Fig. 1). The remaining
three hatchlings were released. The hatchling weighed 3.5 g, had a carapace length
of 24.7 mm, a plastron length of 21.0 mm, and a plastron width of 14.0 mm. The
transmitter had an approximate 21-d battery life and was attached to a posterior costal
scute of the hatchling using a small amount of superglue. The trailing transmitter
antenna was trimmed to a length of 7 cm, reducing total transmitter weight to 0.45 g.
Although the transmitter equaled approximately 15 percent of hatchling body mass,
the transmitter did not appear to limit hatchling mobility. The tagged hatchling was
observed to be as mobile (i.e., crawled properly and at similar speed) as untagged
individuals upon release. The tagged hatchling was monitored twice daily (early
mornings and evenings) for 14 d; twenty-seven total locations were recorded. Locations
were marked with pin flags and later recorded with a Wide Area Augmentation
System (WAAS)-enabled global positioning system receiver.
Results. Total linear movement of the tagged Spotted Turtle hatchling from the
nest was 21.0 m (mean = 2.35 m/d). The hatchling moved in a northeastern direction
from the nest directly into a semi-permanent wetland. On 28 September 2007,
Notes of the Northeastern Nat u ral ist, Issue 17/4, 2010
667
1Stantec Consulting Services Inc., 30 Park Drive, Topsham, ME 04086. *Corresponding author
- dana.degraaf@stantec.com.
668 Northeastern Naturalist Notes Vol. 17, No. 4
Figure 1. A Clemmys guttata (Spotted Turtle) hatchling was tagged with a radio transmitter
(Holohil Systems, Ltd., model BD-2N; 0.5 g) on 13 September 2007 in Cohasset, MA. The
transmitter was attached to the posterior costal scute using superglue. Photograph © Daniel
Nein, Stantec Consulting Services Inc.
2010 Northeastern Naturalist Notes 669
rapid transmitter movement was detected during early morning telemetry surveys.
The transmitter signal was confirmed to come from an adult female Green Frog
(100.0 mm snout–vent length [SVL]) which was captured in the water adjacent to
the former Spotted Turtle nest. The Green Frog, identified through observation of a
prominent dorso-lateral ridge (Hunter et al. 1999, Rappole 2007), was euthanized
(i.e., double pithed) and quickly dissected. The slightly digested hatchling was
found along with vegetation in the gut of the Green Frog with the transmitter still
attached. Based on tracking frequency and condition of the hatchling, the hatchling
was likely subjected to digestive processes for ≤24 h.
Discussion. To our knowledge, this is the first confirmed documentation of Green
Frog predation on Spotted Turtle hatchlings. Our data indicates that adult Green Frog
and Bullfrog diets may overlap more than previously described (Werner et al. 1995)
and provides further insight into predation pressure on Spotted Turtle hatchlings.
Bullfrog and Green Frog distributions overlap; however, Bullfrogs are highly
aquatic and distribution is skewed to larger permanent water bodies; Green Frogs inhabit
shallow permanent and semi-permanent freshwater habitats and are often found
on land and close to water (DeGraaf and Yamasaki 2001, Hunter et al. 1999, Werner
et al. 1995). Green Frogs and Spotted Turtles inhabit small shallow-water bodies,
including isolated vernal pools in Massachusetts (Ernst and Lovich 2009, Milam and
Melvin 2001). Our study area contained semi-permanent wetland habitats in an urban
area. Green Frogs may persist in small semi-permanent wetlands where Bullfrogs
cannot, and therefore may be an important predator of Spotted Turtles in these areas.
Green Frog diets reflect habitat use and can vary between sites (Hunter et al. 1999). In
our study area, Green Frog diet may shift more to terrestrial prey as semi-permanent
wetlands experience seasonal drying during summer and early fall months. The
maximum size range for Green Frogs is 90–100 mm SVL (Rappole 2007, Werner et
al. 1995). The female Green Frog that depredated the Spotted Turtle hatchling in our
study was large and at the size limit of this species. Large adult Green Frogs may
forage on larger prey as evidenced by this observation. Further studies are required to
determine the frequency of Green Frog predation on turtle hatchlings and to evaluate
total predation pressure and survival of Spotted Turtle hatchlings.
Acknowledgments. We thank Steve C. Soldan for assistance with field work, Jessica
Griffin, Richard M. DeGraaf, and Steven K. Pelletier for their reviews, and two
anonymous reviewers for their thoughtful comments. Collection, handling, and tagging
procedures followed Massachusetts Division of Fisheries and Wildlife Scientific
Collection Permit conditions and accepted tagging methods. The Massachusetts Bay
Transportation Authority provided funding for this study.
Literature Cited
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670 Northeastern Naturalist Notes Vol. 17, No. 4
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