Binghamton Zoo Animals

False Map Turtle

(Graptemys pseudographica)
Order: Testudines
Family: Emydidae
Genus: Graptemys
Species: Graptemys pseudographica

HABITAT AND RANGE: Found primarily in large streams of the Missouri and Mississippi River systems from Ohio, Indiana, Illinois, Wisconsin, Minnesota and the Dakotas southward. They may also range from extreme southwestern Alabama, southern and western Mississippi, Louisiana and eastern Texas. Typically found in large rivers and their backwaters, but the False Map Turtle also occupies lakes, ponds, sloughs, bayous, oxbows and occasionally marshes. The False Map Turtle prefers water with abundant aquatic vegetation, places to bask and slow currents, but can be found in swiftly flowing channels of large rivers.

PHYSICAL CHARACTERISTICS: This is a medium to large sized turtle that grows 5 to 10 inches carapace length. The shell is dark brown, olive or black. This turtle gets its name from the light yellow lines that form a reticulated or map-like pattern on the back, but this pattern is usually obscure on adults. Old females have dark blotches on the back and plastron. There is a vertebral keel on the back that is rather prominent even in adults. The marginals on the rear of the carapace are serrated. The plastron is dull yellow with black lines and swirls. The head and limbs are black or dark olive. There are light yellow lines on the head and limbs. A backwards L is present behind each eye. There are no large blotches or spots found on the head and three lines reach the eye. This distinguishes False Map Turtles from all other Map Turtles. Females grow much larger than the males. Adult males have long claws on the front feet and a long, thick tail with the cloacal opening past the edge of the carapace. The young have brighter shells and markings, a dark pattern on the plastron and a pronounced vertebral keel.

ADAPTATIONS: Activity varies geographically, but generally ranges from late March to mid-October. Emergence from overwintering (observed in Wisconsin) occurs in April when the water temperatures are 4-7 degrees Celsius. Overwintering sites typically include muskrat lodges or bank burrows. It is not uncommon for the False Map Turtle to be seen basking during winter days in its more southerly range. It spends the majority of its day basking in muskrat lodges, logs, rock piles, sandbars or stumps. Basking rarely occurs on or near shore. Basking turtles stretch their hind limbs, spread the webbing between the toes and extend the head and forelimbs. While basking, they are extremely wary and difficult to approach. Entrance into the water by one turtle is usually followed by all those basking in the general vicinity. Movement data of this turtle is sparse. In summer months, most males move into quiet backwaters to forage. Females also move into backwaters to forage after laying their first clutch of eggs.

DIET: The False Map Turtle is omnivorous, feeding on mollusks, insects, insect larvae and plant material. In addition to consuming the same insects as females, the males also eat beetles, flies and fish carrion. In its southern range, mollusks are the principal component of the diet.

REPRODUCTION AND DEVELOPMENT: Mating probably occurs in April and again in October and November, but has been observed in a captive male in July. The nesting season in Wisconsin lasts from mid-May to late July. First clutches are usually laid by mid-May to mid-June. Nests are located in open sand areas or in areas dominated by low shrubs. Nests are flask-shaped and dug with the hind limbs. Two and possibly three clutches, with 8-22 eggs (varies with subspecies), are laid per year. Natural incubation lasts from 60 to 82 days. Gender determination correlates with incubation temperature.

STATUS IN WILD: Declining populations in Missouri are attributed to several factors, including water pollution, river channelization, reduction of suitable nesting sites, siltation and unlawful shooting. In the past, the pet trade has also influenced population stability. Commercial fishermen reported that the species was more abundant 25 years earlier in the Missouri and Mississippi Rivers, but has now become uncommon and all but eradicated for several river miles below Kansas City and St. Louis. They attribute this decline to water pollution.