(Schneider, 1783)
Painted turtle
Recognition
The carapace (to 25 cm) is smooth, oval, flattened, and keelless; the highest and widest points are at the center; and the posterior margin is without serrations. Vertebrals are usually broader than long (although, the 1st may be as long as broad or slightly longer than broad), and the underlying neurals are six sided and shortest anteriorly. The carapace is olive to black, with yellow or red borders along the seams and red bars or crescents on the marginals. Some individuals have a well-developed medial stripe, which is red or yellow. The bridge and hingeless plastron are yellow; often there is a black or reddish brown plastral blotch of varying size and shape. The entoplastron lies anterior to the humero-pectoral seam. The plastral hindlobe bears only a slight posterior notch, and the plastral formula is: abd >< an > gul > pect > fem > hum. Axillary and inguinal buttresses are moderate in length. The head is moderate in size with a slightly projecting snout, and the upper jaw bears a terminal notch bordered on each side by a cusp. The broad triturating surface of the maxilla bears a weak median ridge. Both the palatine and pterygoid contribute to the upper triturating surface. The temporal arch is complete, and the orbito-nasal foramen is larger than the posterior palatine foramen. The lower parietal process does not always touch the palatine, and the pterygoid does not extend backward to the level of the exoccipital. Skin is black to olive. Neck, legs, and tail are striped with red and yellow; the head is striped with yellow. A yellow line extends posteriorly from below the eye and may meet a similar line from the lower jaw. There is a large, yellow dorsolateral spot and a yellow streak on each side of the head behind the eye. The chin is marked with two wide yellow lines, which meet at the tip of the jaw and enclose a narrow yellow stripe. The 5th toe has only two phalanges; the toes are webbed.
The karyotype is 2n = 50: 26 macrochromosomes (16 metacentric, 6 submetacentric, and 4 telocentric) and 24 microchromosomes (Stock, 1972; Killebrew, 1977a); however, DeSmet (1978) reported 24 macrochromosomes and 26 microchromosomes.
Males have elongated foreclaws and long, thick tails, with the vent posterior to the carapacial margin. Females are larger in all shell dimensions.
Distribution
This is the only North American turtle that ranges across the continent. It occurs across southern Canada, from Nova Scotia to British Columbia, and south to Georgia, Alabama, Mississippi, Louisiana, Oklahoma, Colorado, Wyoming, Idaho, and Oregon; it is also found in scattered localities in Texas, New Mexico, Arizona, Utah, and Chihuahua, Mexico. According to Stebbins (1985) it has been introduced in California.
Geographic Variation
Four subspecies are recognized. The eastern painted turtle, Chrysemys picta picta (Schneider, 1783) ranges from southeastern Canada through New England and the Atlantic coastal states to Georgia and thence west into eastern Alabama. This subspecies has the vertebral and pleural carapacial seams aligned, light borders along the carapacial seams, and a plain yellow plastron. The medial carapacial stripe is narrow; it may be poorly developed or absent. The Midland painted turtle, C. p. marginata Agassiz, 1857 ranges from southern Quebec to Ontario and south in the central United States to Tennessee and northern Alabama. Its range is east of the Mississippi River, and extends eastward into New England, Pennsylvania, West Virginia, Maryland, and Virginia. It has alternating vertebral and pleural seams, dark borders along the carapacial seams, and a variable dark figure on the plastron. This figure is usually no more than half the width of the plastron, and it does not extend out along the seams. The medial stripe is normally absent or poorly developed. The southern painted turtle, C. p. dorsalis Agassiz, 1857, is found from southern Illinois and Missouri southward along both sides of the Mississippi River to the Gulf coast of Louisiana and eastward through the northern part of Mississippi into Alabama; there is a relict population in southeastern Oklahoma. It has a conspicuous red or yellow medial stripe, alternating vertebral and pleural seams, and a plain yellow plastron. C. p. bellii (Gray, 1831b), the western painted turtle, ranges from western Ontario across southern Canada to British Columbia and south to Missouri, northern Oklahoma, eastern Colorado, Wyoming, Idaho, and northern Oregon; it is also found in many scattered localities in the southwestern United States and in one area in Chihuahua. This is the largest of the painted turtles; it has alternating vertebral and pleural seams; a reticulate pattern of lines on the carapace; and a large, dark plastral figure, which branches out along the seams and occupies most of the plastral surface. Its medial stripe is absent or poorly developed.
Bleakney (1958) offered an explanation for the present distribution of the subspecies of C. picta. He suggested that at the time of the latest retreat of the glaciers, the painted turtles were divided into three separate populations, which may well have been separate incipient species: C. picta in the southeastern Atlantic coastal region, C. dorsalis in the lower Mississippi River region, and C. bellii in the southwest. However, the populations did not develop complete reproductive isolation. The retreat of the glaciers was accompanied by northward extensions of the three populations. According to Bleakney, C. dorsalis spread up the Mississippi River and met C. bellii near the mouth of the Missouri River; hybridization of these two forms produced C. marginata, which spread up the Ohio River valley into the eastern Great Lakes Region. Meanwhile C. picta spread northward along the Atlantic Coastal Plain and westward along the Gulf Coastal Plain, eventually meeting C. marginata in the north and C. dorsalis in the west. Wherever these forms met, they eventually interbred, indicating that the whole complex consists of a single species with four subspecies. Intergradation between the subspecies has been well-studied in several regions (Bishop and Schmidt, 1931; Johnson, 1954; Hartman, 1958; Waters, 1964, 1969; Ernst, 1967a, 1970a; Ernst and Ernst, 1971; Ernst and Fowler, 1977; Pough and Pough, 1968; and Groves, 1983).
Habitat
Chrysemys picta prefers slow-moving shallow water, as in ponds, marshes, lakes, and creeks. A soft bottom, basking sites, and aquatic vegetation are preferred. Along the Atlantic coast it sometimes enters brackish waters.
Natural History
The painted turtles is the most widespread turtle in North America, and one of the best studied of all freshwater turtles. Life history parameters vary among the four subspecies, probably as function of both latitude and body size (Moll, 1973; Lindeman, 1996b). Variance in some parameter may be so great between the large C p. bellii and the others that it seems to act almost as a different species.
Attainment of sexual maturity in male C. picta seems more correlated to body size than age. Males mature at plastron lengths of 7.0-9.5 cm plastron length, usually in their third or fourth year, but possibly as late as year 5 in some northern populations (Cagle, 1954b; Ernst, 1971b; Ernst and Ernst, 1973; Callard et al., 1976; Tucker, 1978; Licht et al., 1985a; Mitchell, 1985a, 1988). If growth is enhanced, maturity is attained earlier (Ernst and McDonald, 1989; Lindeman, 1996a). Females normally mature at plastron lengths of 9.0-16.5 cm in 5-10 years (Ernst, 1971b; Ernst and Ernst, 1973; Tucker, 1978; Mitchell, 1985c, 1988; Iverson and Smith, 1993; Lindeman, 1996a). Enhanced growth does not necessarily result in early maturity (Ernst and McDonald, 1989).
Spermatogenesis begins in March and reaches peaks in July and August. The cycle is completed in September when the sperm pass into the epididymides (Ernst, 1971b; Mitchell, 1985a, 1988). Body temperatures above 17°C are required for the initiation of testis growth, spermatogenesis, and testosterone secretion (Ganzhorn and Licht, 1983; Licht and Porter, 1985). The ovarian cycle begins with vitellogenesis in July or August. Yolking continues into the fall, but ceases when the female stops feeding and becomes dormant, and then begins again the next spring (Ernst, 1971b; Callard et al., 1978; Congdon and Tinkle, 1982; Mitchell, 1985c, 1988). Ovulation occurs in May after a further spring period of follicular growth. Photoperiod seems to be a major triggering cue of various events in the female sexual cycle (Whillans and Crossman, 1977), although environmental temperatures probably also play an important role (Ganzhorn and Licht, 1983). Maximum ovarian growth and ovulation occur only in spring in females kept at a constant 17°C or 17°C with several hours of daily basking (Ganzhorn and Licht, 1983). Follicles grow at lower temperatures (13°C), but ovulation does not occur. Ovarian activity alternates: in any one season, one ovary will produce more eggs than the other.
Courtship and mating usually occur from March to mid-June but Ernst (1971c) has observed courtship activity in August and September, and Gist et al. (1990) recovered large quantities of sperm from female oviducts in October (much more than from spring females). Courtship observed in Pennsylvania by Ernst (1971b) always took place in water at temperatures of 10.0-27.8°C. Courtship begins with a slow pursuit of the female; when at last she is overtaken the male passes and turns to face her. He then strokes her head and neck with the backs of his elongated foreclaws. A receptive female responds by stroking his out stretched forelimbs with the bottoms of her foreclaws (Ernst, 1971b). Between the periods of stroking, the male swims away, seemingly trying to entice the female to follow. After this behavior has been repeated several times the female sinks to the bottom, the male swims behind and mounts her, and copulation begins.
Nesting occurs from late May until mid-July, with peak activity in June and early July. In northern populations, the beginning of the nesting season is consistently correlated with the mean temperature of the previous year rather than the mean April temperature of the current year (Christens and Bider, 1987). Most nests are dug in late afternoon or early evening, but morning nesting is not uncommon. The flask-shaped nests are dug with the hind feet in loamy or sandy soil in the open. Average dimensions of 14 Pennsylvania nests were as follows: greatest diameter of cavity, 72 mm (65-72); diameter of the neck, 45 mm (41-51); and depth, 104 mm (99-111). The cavity is usually less than 12 cm deep. Nests are usually dug within 200 m of water, but may be as far away as 600 m, and ovipositing females may return to the same site for several seasons (Lindeman, 1992).
Females in some populations only produce one clutch per year (Rhodin and Mittelhauser, 1994; Ernst pers. obs.), but elsewhere females may lay up to four clutches a year, although 2-3 clutches are probably more normal (Tinkle et al., 1981; Congdon and Tinkle, 1982; Iverson and Smith, 1993). Almost half of the females in any population may not reproduce each year. The number of eggs per clutch is 1-23. The number of eggs laid in a clutch differs with the subspecies, and is correlated to female body size (MacCulloch and Secoy, 1983; Iverson and Smith, 1993; Ernst et al., 1994; Lindeman, 1996b). The largest race, C. p. bellii, lays the most eggs per clutch: 4-23. The medium-sized subspecies C. p. picta and C. p. marginata lay 2-13 and 3-14 eggs, respectively. Fifteen clutches of intergrade C. p. picta x C. p. marginata from Pennsylvania averaged 4.73 eggs (4-6). The smallest subspecies, C. p. dorsalis, lays only 1-7 eggs per clutch. In Nebraska, triple-nesting females average 42 eggs per season, about 31% of female body mass (Iverson and Smith, 1993). The eggs normally are elliptical, white to cream in color, and have smooth, slightly pitted surfaces; they are flexible when first laid but become firmer as water is adsorbed. Egg dimensions are 27.9-35.1 mm in length and 15.9-22.6 mm in width. Clutch size, clutch mass, and egg width are positively correlated with female shell length (Congdon and Tinkle, 1982; Congdon and Gibbons, 1987). Artificially incubated eggs in Pennsylvania took 65-80 days (mean 76) to hatch; those naturally incubated in the nest took 72-80 days (mean 76). The earliest natural hatching took place on 14 August, the latest on 29 August (Ernst, 1971d). In many northern populations (Virginia northward, Ernst pers. obs.), young turtles from clutches late in the season often are not ready to emerge from the nest before the onset of cold weather. They apparently hatch and overwinter in the nest until the next April and May. Bull and Vogt (1979) discovered that eggs incubated at high temperatures (30.5°C) produced female hatchlings, but eggs incubated at lower temperatures (25°C) produced males—another case of temperature-controlled sex determination.
The hatchling C. picta is essentially round and has a keeled carapace, usually 24-30 mm long. The head, eyes, and tail are proportionally larger than in the adult. A deep crease exists across the abdominal plate. The pigmentation and patterns of the shell and skin are brighter and more pronounced than in adults. The hatchling has an external yolk sac 10-25 mm in diameter, and a caruncle that usually drops off by the fifth day. Generally, hatchling size is positively correlated to egg size and female body size (Lindeman, 1991; Rowe, 1995; Carl H. Ernst, pers. obs.).
Painted turtles are omnivorous: most species of plants and animals, living or dead, found in their habitat may be eaten as opportunity arises. Of 56 Pennsylvania adults, animal food was found in 64% of the stomachs (61.2% by volume) and plant remains in loom (38.8% by volume). Young painted turtles are carnivorous but become more herbivorous as they mature.
C. picta is diurnal; it spends the night sleeping on the bottom, among vegetation, or on a partially submerged object. It becomes active about sunrise and basks for several hours before beginning to forage in the late morning. Another period of basking follows, and foraging is resumed in the late afternoon, to continue into the early evening. The basking habit is well-developed: as many as 50 painted turtles can be seen on a log at a time. Males and females spend about the same amount of time basking each day, but juveniles bask shorter periods than adults, and Lefevre and Brooks (1995) found no correlation between duration of basking and turtle body size.
IUCN Red List Status (1996)
Not listed.