Ringed Map Turtle

Graptemys oculifera

Description

The ringed map turtle, Graptemys oculifera, is a small, dark, olive brown turtle with a yellow ring on each shield of the upper shell (carapace). The carapace has a spiny, sawtooth ridge down the center. The undershell (plastron) is yellow. The head has two yellow stripes and a large yellow spot behind the eye. A yellow stripe covers the entire lower jaw. Females attain a shell length of 7 in (17 cm), and males average about 4 in (10 cm) in length. The species is also known by the common name ringed sawback turtle.

Behavior

This species feeds primarily on snails and other small crustaceans found in and beside the river. It characteristically spends many hours on floating logs or other debris basking in the sun. The nesting season is from mid-May to early August. The female digs a nest in sand and deposits from four to eight eggs. Egg mortality is very high, nearly 90%.

Habitat

The ringed map turtle inhabits a riverine habitat where the river channel is narrow, and currents are moderate. Nesting habitat is on wide, flat sandy beaches or gravel bars. This turtle requires high water quality to support its main food sources.

Distribution

The turtle is endemic and restricted to the main channels of the Pearl and Bogue Chitto Rivers in Mississippi and Louisiana. This species is found in most reaches of the Pearl River from its mouth to Neshoba County in east-central Mississippi. It is found in the Bogue Chitto River from its mouth upstream to Franklinton in Washington Parish, Louisiana. While it is still relatively abundant at some localities, the population shows an overall decline in numbers along these rivers, and it has disappeared altogether from many historic sites. The highest densities in the Pearl River are above the Ross Barnett Reservoir and below the confluence with the Strong River in Simpson County. There is no current population estimate.

Threats

Much of the turtle's habitat along the Pearl River has been modified by construction of dams, dikes, and reservoirs. Currently, many remaining habitat sites are being threatened by proposed flood control projects and ongoing maintenance of river channels. Navigational and flood control maintenance requires the removal of debris from sand and gravel bars, and dredging of river channels, depriving the turtle of basking and nesting sites. These activities have increased the water turbidity and siltation, which has significantly decreased the numbers of aquatic snails and mollusks on which the turtle feeds. Water quality has been degraded throughout these river basins. Projects planned or currently authorized by the Army Corps of Engineers would further impact nearly 30% of the remaining Pearl River habitat. These projects include a navigation channel in the East Pearl near Picayune, a navigation channel from Jackson to Carthage, a drainage channel from Carthage to Edinburg, and construction of the Shoccoe Dam. Channel modification and flood control studies are also planned for the Bogue Chitto River. The federal Soil Conservation Service has planned at least ten watershed projects within the Pearl River basin.

Conservation and Recovery

These federal agencies will be required to study the impact of proposed and ongoing projects on the ringed map turtle. Formal consultation with the U. S. Fish and Wildlife Service (FWS) will determine whether permits for the projects should be approved or denied.

The FWS Recovery Plan outlines three objectives for the recovery of the ringed map turtle: to protect 150 mi (240 km) of river habitat in two stretches above and below the Ross Barnett Reservoir; to attain stable or increasing populations in both protected stretches; and to periodically monitor population trends and habitat quality.

Contact

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
http://southeast.fws.gov/

References

Cagle, F. R. 1953. "The Status of the Turtle Graptemys oculifera." Zoologica 83: 137-144.

Cliburn, J. W. 1971. "The Ranges of Four Species of Graptemys in Mississippi." Journal of the Mississippi Academy of Sciences 16: 16-19.

McCoy, C. J., and R. C. Vogt. 1980. "Distribution and Population Status of the Ringed Sawback in Mississippi and Louisiana." Report. U. S. Fish and Wildlife Service, Atlanta.

U. S. Fish and Wildlife Service. 1988. "Recovery Plan for the Ringed Sawback Turtle." U. S. Fish and Wildlife Service, Atlanta.