Deirochelys reticularia

(Latreille, in Sonnini and Latreille, 1802)
Chicken turtle

Deirochelys reticularia is a small to medium-sized (to 25 cm) turtle with an extremely long neck and a reticulate pattern of yellow lines on the tan to olive, oval carapace. The long, narrow, and somewhat depressed carapace is widest behind the middle, and in adults is neither keeled nor posteriorly serrated. Its surface is somewhat rough and sculptured with small longitudinal ridges. Vertebrals are broader than long. The 1st is in contact with four marginals and the cervical, and the undersides of the marginals are yellow and may have a dark blotch at the seam. One or two black blotches may also occur on the bridge. The hingeless plastron is yellow, and in the western race may have a dark pattern bordering the seams. The plastral formula is: abd > an > gul > fem > hum >< pect; the entoplastron is usually slightly anterior to the humero-pectoral seam. Plastral buttresses are moderate. The head is long and narrow with a pointed snout; the upper jaw bears neither a hook nor notch. The narrow triturating surfaces are ridgeless, and the palatine and pterygoid bones do not contribute to the upper surface. The orbito-nasal foramen is small, but the posterior palatine foramen is large. The inferior process of the parietal touches the palatine. The skin is olive to brown, with yellow or white stripes. There is a characteristic pattern of vertical light stripes on the rump, and the foreleg stripe is very wide. Length of the head and neck, measured from the snout to shoulder, is approximately equal to the plastron length and about 75-80% of the carapace length. Cervical vertebrae II to VII are much longer than VIII, and elongation of the neck is probably responsible for modifications to the rib heads for expanded inserts of the retractor neck muscles (McDowell, 1964). Thoracic rib heads are long, slender, and ventrally bowed. The toes are webbed.
The diploid chromosome number is 50: 26 macrochromosomes and 24 microchromosomes with a total of 80 arms. Chromosome types, according to centromere placement, include 20 metacentric and submetacentric, 10 subtelocentric, and 20 acrocentric and telocentric configurations (Stock, 1972; Killebrew, 1977a).
Adult males have long, thick tails, with the vent posterior to the carapacial margin. Females are larger than males.

Deirochelys occurs in southeastern Virginia and from southern North Carolina south along the Atlantic Coastal Plain to the Florida Keys, west along the Gulf Coastal Plain to Texas, and northward west of the Mississippi River to southeastern Oklahoma and southeastern Missouri. It has also been found in northwestern Mississippi. There are few records of this species from above the fall line.

Geographic Variation
Three subspecies are recognized. The eastern chicken turtle, Deirochelys reticularia reticularia (Latreille, in Sonnini and Latreille, 1802), occurs along the Atlantic and Gulf Coastal Plains from southeastern Virginia to the Mississippi River. This subspecies has narrow, netlike lines on the olive to brown carapace, a narrow yellow carapacial rim, and often a spot at the juncture of the femoral and anal scutes. Black spots are present on the ventral surface of the marginals at the level of the bridge in about 72% of individuals (Schwartz, 1956a). D. r. chrysea Schwartz, 1956a, the Florida chicken turtle, is restricted to peninsular Florida. This race has a network of broad, bright, orange or yellow lines on the carapace and a wide, orange carapacial rim. Black spots are present on the ventral surface of the marginals at the level of the bridge in about 43% of individuals (Schwartz, 1956a). D. r. miaria Schwartz, 1956a, the western chicken turtle, occurs west of the Mississippi River from southeastern Missouri and central Oklahoma south to the Gulf, and there is a record from western Mississippi. It is flattened, has a network of broad, faint lines on the carapace, and has a plastral pattern of dark markings along the seams. Adults have unstreaked chins and throats.

The chicken turtle is fairly common in still-water habitats, such as ponds, lakes, ditches, and cypress swamps; sometimes large aggregations can be found in temporary pools. Apparently it does not live in moving-water habitats.

Natural History
Male chicken turtles attain sexual maturity at plastron lengths of 7.5-8.5 cm during years 2-3 (Gibbons, 1969; Jackson, 1988). Females may come into breeding condition when as small as 14.1 cm plastron length (Gibbons and Greene, 1978), but most mature at a of about 16.0 cm (Gibbons, 1969). During courtship the male vibrates his foreclaws against the female's face (Fritz, 1991).
Deirochelys is one of the few North American turtles to have a "winter" nesting pattern (Jackson, 1988). Iverson (1977d) thought the chicken turtle nested throughout the year, but there is no evidence of this. The nesting season is divided into two periods: a late winter and spring period from mid-February to May, and a fall and early winter period from August to November (Gibbons, 1969; Gibbons and Greene, 1978, 1979, 1990). The percentage of nesting females (based on X-ray data) from a single area in South Carolina in various months from 1976 to 1987 was as follows: January 1%, February 14%, March 37%, April 5%, August 13%, September 24%, October 1%, November 2% (Gibbons and Greene, 1990). Further south in Florida the nesting season is continuous from mid-September to March, but may be delayed by cold weather (Jackson, 1988). Females may retain calcified eggs from autumn to spring (Buhlmann et al., 1995). The nest is cylindrical to goblet-shaped and 10.0-16.5 cm deep (Ernst and Barbour, 1972; David, 1975).
At least two clutches are laid a year, usually one each nesting period. Clutches contain about 2-19 eggs (Jackson, 1988). Females lay fewer eggs in the second clutch of any year. The flexible, oblong, white eggs are 28.0-40.0 x 17.0-23.6 mm. Incubation in Florida takes 78-89 days (Iverson, 1977d; Jackson, 1988). The nearly round 28.0-31.6 mm hatchling carapace is keeled and rugose.
During the first year of life chicken turtles are at least partially carnivorous (Jackson, 1978b), but adults are probably more omnivorous. Animal foods eaten are crayfish, aquatic insects, spiders, snails, and tadpoles and adult frogs; plant foods taken include Panicum, and buds of Nuphar (Ernst et al., 1994; Jackson, 1996; Demuth and Buhlmann, 1997). Captive adults will eat romaine lettuce, newborn mice, fish, and commercial trout chow, but juveniles refuse plant materials, feeding instead on fish, newborn mice, earthworms, and trout chow.

Baur (1889b) first proposed a close relationship of Deirochelys and Emydoidea on the basis of similar skull and rib specializations, and this was accepted by Loveridge and Williams (1957), McDowell (1964), and Ernst and Barbour (1972), among others. Most authors also noted Deirochelys has a close resemblance to Chrysemys, Pseudemys, and Trachemys in its shell features. Bramble (1974) in his study of shell kinesis and other osteological and myological characters indicated that Emydoidea is more closely related to Emys and Terrapene than to Deirochelys, and that Deirochelys is more closely related to Chrysemys and Pseudemys. This has been further corroborated by Jackson's (1978b) findings on fossil Deirochelys.

IUCN Red List Status (1996)
Not listed.