Pseudemys concinnaEastern River Cooter

Geographic Range

The river cooter occurs in the east and southeast part of the United States. The range covers an area from eastern Virginia south to Florida, west to eastern Texas, north to southeast Nebraska, and east back to the origin. Isolated populations can be found in neighboring states, including West Virginia, Kentucky, and Tennessee (Stebbins 1966)(Ernst et al., 1994).

Habitat

The river cooter is primarily a river turtle, but can be found in ditches and saltwater areas near river mouths. Rivers with slow to moderate currents, abundant aquatic vegetation, and rocky bottoms are preferred. Other less frequently used habitats include lakes, ponds, deep springs, floodplain river pools, and swamps. Moll et al. (1991) concluded that optimal habitat in Illinois appeared to be sloughs and oxbows with abundant macrophytes, located on the floodplains of major river systems (Ernst et al., 1994).

Physical Description

Adult river cooters average 9 to 12 inches (carapace length). The head and neck have numerous thin, yellow stripes. The olive or brown colored carapace is often highlighted with lighter markings and slightly flared posteriorly. Carapace scutes are usually with well-developed concentric rings. A distinguishing characteristic is the faint "C" shaped marking visible on the second costal scute. This marking may be difficult to see when the shell is dry. The plastron is marked with dark spots along the scute margins. These markings usually fade with age. The upper jaw is notched in front and flanked by a cusp on each side. There is some sexual dimorphism. Male specimens have elongated toenails on the forelimbs. Females are typically larger and more domed than males (Conant et al. 1975).

Reproduction

The river cooter usually mates in the spring. The male will pursue the female, first sniffing her tail, then moving to a position dorsal to her. He will then extend his neck and head downward and outward over hers, position his elongated foreclaws just anterior to her snout, and vibrate them rapidly in front of her face. If the female is receptive, she will sink to the bottom and allow the male to slide backward and mount her. If not receptive, the female will try to outswim the male or duck under a submerged object to displace him (Ernst et al., 1994). Nesting normally occurs in late May or June, but some clutches may come as late as July to late summer. Nest locations are typically sandy or friable loam soils, within 30 meters of the water. Nest cavities are dug entirely with the hind feet. Green and Pauley (1987) described a nest dug by a 30.5 cm female as 12.7 cm deep with an opening 6.8 cm in diameter. The eggs are pink to white in color and ellipsoidal in shape, bearing many fine nodules. Clutches range from 9 to 29 eggs, although 19 to 20 eggs/clutch are most common. Most hatchlings emerge from the nest in August or September after an incubation period of 80-150 days, dependent on soil temperatures. In some northern populations, hatchlings may overwinter in the nest cavity and emerge the following spring. Hatchlings have green shells with brighter light markings than do adults. The carapace is rounded with a medial keel present. Typical hatchlings weigh 10 to 14 grams (Ernst et al., 1994).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    2190 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1277 days
    AnAge

Lifespan/Longevity

  • Average lifespan
    Status: captivity
    44 years
    AnAge

Behavior

The river cooter is active from April to October over most of its range, but some remain active all year in Florida and the lower Gulf Coastal Plain streams. Winter months are spent in the mud or on the bottom of some body of water (Ernst et al., 1994). Most activity is diurnal, although some females may nest after dark. This species forages in the early morning and late afternoon, with most time between spent basking in the sun. The river cooter is a shy species, leaving the water only to bask or nest, and will return to the water at the first indication of danger. Minton (1972) reported some specimens might occasionally make overland trips to other bodies of water. Buhlmann and Vaughn (1991) reported the average home range for two radio-collared adults to be 1.2 and 1.6 hectares. This species spends a majority of time submerged in water 1.0 to 1.5 meters deep, either resting on the bottom or searching for food. Periods of breathing at the surface range from 30 seconds to four minutes. Belkin (1964) found the time of submergence to be 50 times longer than that of the breathing periods (on average).

Food Habits

The river cooter is primarily herbivorous, although specimens of all ages will consume animal foods. Preferred plants include eelgrass (Vallisneria americana), elodea (Elodea canadensis), and various algae (Buhlmann and Vaughn, 1991). Animal foods include crayfish, tadpoles, small fish, snails, and many small insects. In saltwater habitats, this species feeds largely on turtle grass (Ernst et al., 1994).

Economic Importance for Humans: Positive

Humans sometimes consume river cooters as food. They are also a useful biological control of water hyacinth (family Pontederiaceae) in some locations (Harding, personal communication).

Conservation Status

Although still locally abundant, the river cooter has been greatly reduced in numbers throughout its range. This species is now listed as endangered in Illinois and threatened in Florida. While nest and hatchling predation can reduce population size, human activity appears to have the greatest detrimental impact. Adults are eaten, crushed by automobiles, and driven from their habitats by pollution. Buhlmann and Vaughn (1991) report that management actions increasing the number of basking sites would be beneficial, and should be done where an increase in population is deemed appropriate.

Other Comments

There are five subspecies of Pseudemys concinna recognized. These include P. c. concinna (Eastern river cooter), P.c. suwanniensis (Suwannee River cooter), P. c. mobilensis (Mobile Bay cooter), P. c. heiroglyphica (hieroglyphic river cooter), and P. c. metteri (Missouri River cooter). There is currently debate on whether or not this species should be placed within the genus Chrysemys (Ernst et al., 1994).

Contributors

Kevin Gardiner (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

References

Belkin, D. 1964. Variations in heart rate during voluntary diving in the turtle, Pseudemys concinna. Copeia, 1964: 321-330.

Buhlmann, K., M. Vaughan. 1991. Ecology of the turtle Pseudemys concinna in the New River, West Virginia. Journal of Herpetology, 25(1): 72-78.

Conant, R., J. Collins. 1975. Peterson Field Guides: Reptiles and Amphibians of Eastern and Central North America.. New York: Houghton Mifflin Company.

Ernst, C., R. Barbour, J. Lovich. 1994. Turtles of the United States and Canada. Washington and London: Smithsonian Institute Press.

Green, N., T. Pauley. 1987. Amphibians and Reptiles in West Virginia. Pittsburgh, Pennsylvania: University of Pittsburgh Press.

Minton, S. 1972. Amphibians and Reptiles of Indiana. Indiana Acad. Sci. Monogr., 3: 1-346.

Moll, E., M. Morris. 1991. Status of the River Cooter, Pseudemys concinna, in Illinois. Transactions of the Illinois State Academy of Science, 84(1): 77-83.

Stebbins, R. 1966. A Field Guide to Western Reptiles and Amphibians. Boston: Houghton Mifflin Company.