ODNR Division of Wildlife - A to Z Species Guide - Northern Map Turtle

 Northern Map Turtle

northern map turtle
This species is usually seen in groups, basking on logs or rocks. In the winter, they spend most of their time underwater beneath submered logs or buried in the mud.

Northern Map Turtle
Graptemys geographica

At-a-Glance

• Peak Breeding Activity: spring and fall

• Nesting period: May-July

• Incubation: 50-70 days

• Clutch Size: 12-14 eggs

• Typical Foods: snails, crayfish, and clams
Description
The female of this species attains a carapace length of about 10 inches, while the male's seldom exceeds five inches. The map turtle's name is derived from the network of fine yellow lines that crisscross the carapace and vaguely resemble the line on a road map. These lines are very noticeable on young specimens, but they fade with age.

Habitat and Habits
Map turtles are extremely wary and show a marked preference for sizable bodies of deep water, such as large rivers and lakes, where they can dive to the safety of the depths. The broad, flat crushing surfaces of their powerful jaws are will suited for consuming snails, crayfish, and clams, which form the bulk of the diet. It is not unusual to see these turtles walking around under the ice, for they are among the very last turtles to go into hibernation--if they go at all--and among the earliest to reappear in spring.

Reproduction and Care of the Young
The reproductive biology of turtles is fascinating. With the exception of softshell turtles, the sex of all species of Ohio turtles is dependent on the temperature at which the eggs develop. For instance, snapping turtle eggs that develop at about 77 degrees Fahrenheit will all hatch out as males, while eggs that develop at much higher or lower temperatures will all hatch out as females. In the wild, warmer eggs at the top of a nest may all hatch out as females, while cooler eggs at the bottom hatch out as males.