Systematics: Described originally as Testudo scripta by Johann David Schoepff in 1792; type locality not stated, but designated as Charleston, South Carolina, by Schmidt (1953). The genus Trachemys was first used for this species by Agassiz (1857), but the generic status remained uncertain until recently (see "Remarks"). Sixteen subspecies are recognized throughout its range. There appear to be two evolutionary lineages, one in the neotropics and one in the temperate zone (Iverson, 1992). The latter includes T. s. scripta (Schoepff), T. s. elegans (Wied), and T. s. troostii (Holbrook). Ernst (1990) and Conant and Collins (1991) illustrated the distributions of these subspecies. Of these, T. s. scripta, the nominate subspecies, and T. s. troostii are native to Virginia. The latter was first described as Emys Troostii by John Edwards Holbrook in 1836 based on specimens from the Cumberland River, Tennessee. It was first recognized as a subspecies of Pseudemys (= Trachemys) scripta by Carr (1937). Other names applied to this species in the Virginia literature are Emys serrata (Holbrook, 1836), Emys cumberlandensis (= T. s. troosth) (Holbrook, 1836), Pseudemys scripta (Hoffman, 1949b; Schmidt, 1953; Burger, 1958; Conant, 1958), and Chrysemys scripta (e.g., Ernst and Barbour, 1972; Conant, 1975; Mitchell, 1976a, 1981a; Tobey, 1985; Delzell, 1979).

Description: A large freshwater turtle reaching a maximum carapace length (CL) of 289 mm (11.4 inches) (Conant and Collins, 1991) in the United States. In Virginia, known maximum straight-line CL is 309 mm, maximum plastron length (PL) is 294 mm, and maximum body mass is 3,200 g.

Morphology: Carapace oval-shaped with a weak middorsal keel; midpoint of each marginal scute on the posterior margin of carapace indented (serrated) causing 2 blunt, rounded projections; carapace rugose in adults; marginals 12/12, pleurals 5/5, and vertebrals 5; hingeless plastron 86-95% of CL.

Coloration and Pattern: Carapace olive to brown with yellow markings; usually single, yellow, vertical line present on each pleural scute; short yellow bars may be present on marginals over bridge that outline a dark blotch; ventral side of each marginal bears a black spot; old individuals may be completely black; yellow bridge usually unpatterned except for a black spot in inguinal scute; plastron yellow with black spots in 2 or more scutes-spots are either solid black or are hollow; skin greenish to olive-brown with yellow stripes; behind each eye on head is either a wide, vertical yellow bar or a narrow yellow to reddish oblique stripe; several thin stripes on neck and limbs; vertical, alternating yellow and brown to black stripes occur on the rear of each thigh.

Subspecies: Trachemys s. troostii differs from the nominate subspecies by having a yellow oblique patch behind each eye, fewer and wider stripes on the limbs and neck, hollow black spots on most of the scutes of the plastron, and horizontal lines of yellow and black on the rear of the thighs. It also occurs in a different geographic location (see "Geographic Distribution"). Trachemys s. scripta has the vertical yellow bar behind each eye, thin stripes on the limbs and neck, usually 2 solid black spots on the anterior plastron, and vertical lines of yellow and black on the rear of the thighs. Intergradation does not occur between these two forms. Introduced T. s. elegans has a distinct, elongated red patch behind each eye, dark (usually hollow) spots on each of the plastral scutes, and vertical markings on the rear of the thighs. See below for additional comments.

Sexual Dimorphism: Sexual size dimorphism is pronounced in sliders. Adult males averaged 158.4 ± 25.4 mm CL (115.8-227.5, n = 110), 143.6 ± 23.1 mm PL (100.3-209.0, n = 110), and 596.1 ± 278.1 g body mass (190-1,350, n = 95). Adult females averaged 246.3 ±15.4 mm CL (220.5-309.0, n = 136), 229.4 ± 15.1 mm PL (191.0-294.0, n = 134), and 2,199.5 ± 421.5 g body mass (1,360- 3,200, n = 123). Sexual dimorphism index was 0.55. Males possess elongated foreclaws (ave. = 16.0 ± 2.3 mm, 10.8-21.8, n = 31) and an elongated tail in which the anal opening is posterior to the edge of the carapace (precloacal distance was 13-38 mm, ave. = 26.9 ± 5.6, n = 53). Females have higher domed shells, shorter foreclaws (ave. = 10.1 ± 1.3 mm, 8.1-13.3, n = 22), and shorter tails (precloacal distance was 0-22 mm, ave. = 10.5 ± 4.7, n = 57).

Juveniles: In hatchlings, the carapace is green with yellow markings and the plastron is yellow with a variable number of spots. Head markings are as described above for adults. The carapace darkens with age, but other patterns remain unchanged. Hatchlings from Virginia were 28.5- 35.3 mm CL (ave. = 31.6 ± 1.2, n = 259) and 25.9-32.6 mm PL (ave. = 29.3 ± 1.5), and weighed 6.0- 11.0 g (ave. = 8.1 ± 1.0).

Confusing Species: This species may be confused with Pseudemys rubriventris, which has red pigment on the carapace and plastron, a dark figure following the plastral seams, and cusps on the upper jaw. Pseudemys concinna has a backwards C-shaped pattern on the 2d pleural scute and a dark figure on the anterior plastral seams. Pseudemys c. floridana has yellowish vertical lines on the carapace with an immaculate yellowish plastron. Chrysemys picta has reddish markings along the margin of the carapace, red lines on the limbs and tail, and 2 pairs of yellow spots on the head.

Geographic Variation: Body size varies among populations. Average CL for adult females was 251.6 ± 23.3 mm (n = 35) in Dismal Swamp National Wildlife Refuge, 246.8 ± 13.8 mm (n = 70) in Back Bay National Wildlife Refuge and False Cape State Park, and 199.9 ± 22.8 mm (n = 48) in Game Refuge Lake, Sussex County. The largest known slider in Virginia (309 mm CL) is a female from the Dismal Swamp.

Geographic variation in pattern occurs in two ways: within the two subspecies naturally occurring in Virginia, and through intergradation with the introduced subspecies T. s. elegans in southeastern Virginia. The former are described in the "Description" section and the latter is described below. For many years before 1972, juveniles of the Red-Eared Slider (T. s. elegans) were sold in pet stores throughout the United States. Many were released in local waters such that there are now numerous established populations around Virginia, especially in the larger urban areas. The effect of these releases has been to introduce elegans genes into natural populations of T. s. scripta. Established populations of T. s. elegans are known from several counties and cities. Populations in the cities of Chesapeake, Norfolk, Virginia Beach, Suffolk, Newport News, and Chesterfield Co. have been found to be comprised of intergrades between these two forms. Turtles in these populations possess characters typical of natural T. s. scripta, characters typical of the introduced T. s. elegans, and various combinations of these two sets of characters. Red-Eared Sliders have an enlarged, oblique reddish patch behind each eye, narrow chin stripes, a yellowish-green carapace with the distinct yellow streak on the pleural scutes, black blotches on most of the plastral scutes, and horizontal yellow and black stripes on the rear of the thighs. Intergrades have the reddish (or yellowish) patch behind the eyes or have both the red streak and a reduced, vertical yellow bar. They also have black blotches of highly variable size on several of the plastral scutes, and a mottled pattern or set of horizontal lines on the rear of the thighs. The carapace is greenish with a narrow yellow line in each of the pleural scutes. See "Conservation and Management" for additional discussion.

Biology: Yellow-Bellied Sliders inhabit all manner of freshwater habitats in southeastern Virginia, from lakes and ponds to rivers, ditches, marshes, bays, and swamps. The Cumberland Slider has been found only in the Holston River. Trachemys s. scripta occasionally enters brackish water or saltwater, as evidenced by several specimens found in False Cape State Park in 1986 that had barnacles encrusted on the shells. Preferred habitat has an organic substrate, aquatic vegetation, and basking sites. The activity period is April through October. Of the known captures, 95.7% of 468 were within this period. These turtles overwinter in water in soft organic substrate, in muskrat burrows, and by simply sitting on the bottom.

This species is omnivorous as adults and mostly carnivorous as juveniles. The following items have been found in their feces: unidentified plant stems and leaves, tulip tree (Nyssa spp.) seeds, muscadine grapes (Vitis rotundafolia), the freshwater mollusk Oxytrema catenaria, and beetles. Other prey include algae, seeds and stems of numerous vascular plants, gastropods, insects, other arthropods, crayfish, crustaceans, tadpoles, fish, and vertebrate carrion (Parmenter and Avery, 1990). Predators of adults are raccoons (Procyon lotor) and humans, who shoot them while basking, kill them on roads, and fracture shells with boat propellers. Hatchlings and juveniles are eaten by large fish, some snakes, raccoons, and wading birds. Eggs in nests are eaten by raccoons, striped skunks (Mephitis mephitis), crows (Corvus spp.), and foxes (Vulpes, Urocyon). In 1980, A. C. Hundley (pers. comm.) observed a red fox (Vulpes vulpes) eating the eggs of a nesting female in Back Bay National Wildlife Refuge as they were being dropped into the nest cavity.

Mating occurs in spring, fall, and winter months (Gibbons and Greene, 1990). Mating has not been recorded in Virginia, but nest records are 18 May to 25 June. Nesting occurs April-July in South Carolina (Gibbons and Greene, 1990). Females construct an oval-shaped nest chamber in a variety of soil types. Nest construction usually occurs at dusk and at night. Clutch size ranged from 6 to 15 (ave. = 10.1 ± 2.1, n = 36). Of 28 females caught in June 1985 and June 1986, 71% produced two clutches (Mitchell and Pague, 1990), The smallest mature female was 204 mm PL and the smallest mature male was 94 mm PL. Females in Back Bay National Wildlife Refuge matured at about 8-9 years and males at 5 years (Mitchell and Pague, 1990). Eggs averaged 34.5 ± 1.9 x 23.2 ± 1.2 mm (length 30.8-38.4; width 20.2-27.3, n = 364) and weighed 7.7-13.8 g (ave. = 10.8 ± 1.4). Egg length, width, and mass are positively related to the size of the female; in general the larger the female the larger the egg. Clutch size is not related to female size in the Virginia sample.

The laboratory incubation period was 69-95 days and hatchlings emerged 19 August to 9 September. One hatchling was found on 25 August at Back Bay National Wildlife Refuge. In South Carolina, hatchlings overwinter in the nest and emerge the following spring (Gibbons and Nelson, 1978). Overwintering in the nest probably occurs in Virginia in some locations and in some years. A pair of newly hatched Siamese twins, joined at the center of the plastron, was found in Dismal Swamp National Wildlife Refuge on 25 September 1985 (Padgett, 1987).

Trachemys scripta is an abundant turtle in many lakes and wetlands in southeastern Virginia and in most ponds and lakes in northern Virginia (C. H. Ernst, pers. comm.), although no population study has been conducted to determine their population size or density. Nothing is known of T. s. troostii populations in southwestern Virginia. Growth of juveniles in Back Bay National Wildlife Refuge from nest emergence until their first winter was 46-71 mm (ave. = 57.4), and growth from age 1 to 6 averaged 13.1 mm per year (Mitchell and Pague, 1990). Sliders may live as long as 30 years in natural populations in South Carolina (Gibbons, 1987). Numerous other aspects of the ecology of Trachemys scripta are evaluated in Gibbons (1990).

Sliders are basking turtles and are frequently seen on logs and banks during the activity season. Body temperatures of adult female sliders on dirt roads seeking nest sites were 18.2-33.6°C (ave. = 25.3 ± 4.3, n = 14), with air temperatures of 20.8- 31.0°C (ave. = 25.2 ± 3.7, n = 12). The body temperature of a single basking juvenile was 27.2°C; the water temperature was 26.5°C.

Remarks: Other common names in Virginia are yellow- bellied terrapin (Hoffman, 1949b; Carroll, 1950) and yellow-bellied turtle (Carr, 1952; Conant, 1975).

The generic status of this species has long been a controversial subject. Seidel and Smith (1986) reviewed the complex history and concluded that the three genera originally proposed by Agassiz in 1857 (Chrysemys, Pseudemys, and Trachemys) should be recognized. The herpetological community has accepted this arrangement.

The sale of pet baby turtles, mostly introduced T. scripta elegans, was prolific in the 1950s and 1960s. Most of these, except those certified free of Salmonella, were banned from sale in 1972 when it was determined that the bacterial disease salmonellosis was contracted by children from the turtles and the aquarium water. Mitchell and McAvoy (1990) found no Salmonella in natural populations of sliders and other freshwater turtles in Virginia. They did find several other genera of bacteria, none seriously harmful to humans.

Turkowski (1972) reported a hatchling T. scripta from Back Bay National Wildlife Refuge through which a stem of broomsedge (Andropogon spp.) had grown. The photos show that the stem penetrated both the carapace and plastron on the left side. This anomaly first appeared in the literature in Virginia Wildlife (April 1948, p. 27). It was noted that both the turtle and grass were living when discovered on 18 September 1947.

The introduced and established populations of T. s. elegans and T. s. scripta in Virginia need further study. The population of the latter subspecies in Fairfax County is assumed to be introduced and not natural, as no natural populations have been found north of the York-James peninsula. To what extent do these two forms interbreed in this area?

Conservation and Management: Natural populations of this turtle appear healthy and are probably not in need of active management. However, the introduction of T. s. elegans genes into formerly natural T. s. scripta populations (see "Geographic Variation") poses an unusual threat to the integrity of Virginia's native sliders. Numerous populations are comprised of intergrades that are obvious crosses between the two subspecies. The natural gene pool of Yellow-Bellied Sliders is being altered in urban areas and potentially elsewhere. The original Virginia yellow-bellied slider with its color and pattern characteristics may not exist in Virginia after a few more decades, except in some isolated populations. Most Virginia populations may eventually be comprised of intergrades. The conservation of the natural gene pool of this subspecies should be approached through a study to determine the extent of the problem and potential of further erosion. Efforts may be needed to minimize the further introduction of nonnative genes. Removal of Red-Eared Sliders may be necessary.

The effects of the introduced populations of T. s. elegans on other turtle species and on wetland ecosystems in Virginia are unknown. Some of these populations are apparently well established and have produced several generations of offspring. A survey of these populations and the associated turtle communities to determine population structure and relative abundance at these sites is warranted.

U.S. Range

---