Species Description
A small and exceptionally handsome freshwater turtle that fits comfortably in the palm, adult Spotted Turtles are from 3.5 to 4.5 inches (9 to 11.5 cm) long. This makes Clemmys guttata the second-smallest turtle species, after the Bog Turtle (Glyptemys muhlenbergii), in the eastern United States.
Hatchlings emerge with but one spot per each scute, but as they age and grow, they develop additional spots. The black heads and necks of these turtles are also decorated with yellow and/or orange spots. The plastron (lower shell) is yellow-orange with black pigment along the edge of each scute. Unlike the familiar Eastern Box Turtle (Terrapene carolina), the plastron lacks a hinge, meaning Spotted Turtles can’t fully close their shells (like Box Turtles). There are a number of differences between the sexes. Adult male Spotted Turtles have brown eyes, concave plastrons and longer tails than females. Adult females have orange eyes, flat plastrons and slightly greater shell heights than males. The Spotted Turtle has a much flatter and more stream-lined profile compared to the higher, domed shell of the Box Turtle.
Taxonomy
The Spotted Turtle was described in 1792 as Testudo guttatai by Johann Gottlob Schneider, a German classicist and naturalist. Of course, taxonomy is ever-changing. Specimens in the United States National Museum (Washington, D.C.) herpetology collection, found on a south Georgia rice plantation 100 years later in 1892, were labeled “Chelopus guttatus,” meaning speckled terrapin—a reference to the species’ sprinkling of yellow spots. Eventually, the Spotted Turtle became reclassified as Clemmys guttata. Currently, it is the only species in the genus Clemmys.
A member of the structurally-diverse and species-rich Family Emydidae, the closest relatives of the Spotted Turtle include the Eastern Box Turtle (Terrapene carolina) and members of the genus Glyptemys (the Wood Turtle, G. insculpta, and the Bog Turtle, G. muhlenbergii).
Distribution
The Spotted Turtle ranges from Maine and southeastern Ontario south along the Atlantic Coastal Plain to central Florida, and westward across New York, Pennsylvania, Ohio, northern Indiana and Michigan to northeastern Illinois. The species is rare and locally distributed in Florida and portions of southern Georgia. There are isolated populations in the western Carolinas and south-central Vermont. Formerly, the species occurred in southern Quebec.
Habitat
Spotted turtles occur in a variety of freshwater wetland habitats including marshes, swamps, wet meadows, bogs and vernal ponds. Clean, slow-moving or still-water wetlands are required to support turtle populations. Spotted Turtle sites are typically vegetated with aquatic plants and have soft, mucky substrates. Sometimes the bottoms of pools used by turtles are blanketed with thick accumulations of leaf litter. These turtles have a penchant for burying themselves and hiding, typically underwater, beneath soft mud and debris.
In the southeastern Coastal Plain, populations of these turtles are often associated with blackwater creek swamps, Carolina bays, ponds in pine flatwoods and ditches. Semi-permanent wetlands seem the norm, although many sites occupied by Spotted Turtles are wetlands that experience dramatic seasonal fluctuations in water levels. When foraging, turtles prefer shallow water around two feet (60 cm) or less in depth.
Movement and Home Range
This mostly diurnal species is especially active during late winter and spring (February to June), with turtles comprising more southerly populations (i.e., Georgia, South Carolina) initiating activity earlier (late February to March) than their counterparts farther north (e.g., northeastern U.S. and in southern Ontario). Turtle activity has been documented in surprisingly chilly water (ca. 40°F)!
Adult Spotted Turtles congregate to breed in the spring. At this time they are habitual, communal “baskers,” and it’s common to observe three to five or more adults lined up on a sun-bathed log. Turtles may also bask on small hummocks (e.g., tree islands), on grass tussocks and on the ground at the water’s edge.
A typical day in the life of an adult Spotted Turtle would include waking early, emerging from where it slept—buried underwater in the mud of the pond bottom—and then puddling and swimming about in the shallows while moving all of about 70 feet (21 m) to and from basking and foraging sites.
Clemmys guttata greatly reduce their activity and become dormant and/or aestivate—buried in the mud, in muskrat burrows or in shallow forms on land—during the heat of summer. These turtle commonly overwinter in aggregations of up to a dozen or more turtles, a facet of their life history that makes them vulnerable to over-collection. Although considered an aquatic, freshwater turtle, Clemmys guttata frequently moves overland. Male turtles may do so in search of mates, females to nest and turtles of either sex in response to drought or in search of better foraging sites.
Herpetologists Carl Ernst, Professor emeritus at George Mason University, and Jacqueline Litzgus, Professor at Laurentian University in Ontario have made vast contributions to our understanding of this species through their respective field studies. Ernst found that the home ranges of male and female spotted turtles in Pennsylvania are not significantly different, with both sexes having mean home ranges of around 0.50 hectares, with daily movements generally less than 65 feet (20 m). The amount of free-standing water at a site influences home range size, and these turtles exhibit site fidelity and possess a homing ability. For a South Carolina population, Litzgus found males to have smaller home ranges (ca. 5 ha) than females (ca. 16 ha).
Diet
The Spotted Turtle is a scavenging omnivore that feeds on a variety of plant and animal life. Its diet is known to include aquatic plants, cranberries, tadpoles, salamander larvae, earthworms and numerous species of aquatic invertebrates including crayfish and snails. Prey is typically consumed underwater.
Reproduction
In the wild, Spotted Turtle females lay one to three clutches of eggs annually. Egg-laying takes place from April to July, with most clutches numbering two to five eggs. Larger females deposit larger eggs and produce a greater complement of eggs. Eggs hatch after an incubation period of 60 to 80 days. The hatchlings, about 1.1 inches (2.8 cm) long when they emerge, have bluish-black shells and heads.
Clemmys guttata is a species with Temperature Sex Determination (TSD)—eggs incubated at 22.5-27°C will produce mostly males, while all eggs incubated at 30°C or greater will hatch into females. Spotted turtles reach sexual maturity at around eight to 12 years of age and commonly live to ages of 20 to 30 or more years in the wild. Jacqueline Litzgus estimated that some individuals that are members of her Ontario study site population may live to be ca. 110 years old. Delayed sexual maturity and a low reproductive potential are traits characteristic of species that experience high annual survivorship of adults.
Conservation Concerns
The Spotted Turtle is a valuable part of our natural heritage and an emblematic component of the vernal pond ecosystem. The enormous popularity of this small inoffensive turtle is due to its exceptional beauty. Clemmys guttata is one of the best known and most beloved of all North American turtles, but it is now imperiled throughout significant portions of its range. The species plays a meaningful role as predator and prey in various types of wetland ecosystems.
As with many species, habitat loss, habitat degradation and habitat fragmentation are the chief causes of Spotted Turtle population declines. Throughout the species’ range, wetlands formerly inhabited by Spotted Turtles have been drained and filled, or they have been rendered unsuitable by pollution, stream channelization, impoundments, eutrophication or other adverse impacts.
At many sites, upland and nesting habitats, as well as forest corridors connecting populations, have been lost to development, agriculture and commercial forestry practices. Urbanization and the accompanying increase in road density and traffic volume results in habitat fragmentation and therefore large numbers of turtles, including C. guttata, being killed when struck by vehicles. As with other plant and animal species, small and fragmented populations of Spotted Turtles are especially susceptible to extinction.
Due to their docile nature and beautiful coloration, Spotted Turtles have long been prized as pets by turtle hobbyists. Over-collection for the pet trade including illegal collection has dramatically reduced the size of some populations, and eliminated others, in portions of the species’ range.
An unnatural, and often human-subsidized, overabundance of raccoons, a predator skilled at catching Spotted Turtle adults as well as finding and depredating nests, poses a serious threat to some populations.