Description
This large turtle can reach up to 27 cm carapace length. The carapace is oval with a distinct low keel and
serrations along the back edge. It is olive green in colour with
a pattern of fine yellow lines on the carapace, vaguely resembling a map. Both the
head and legs have an intricate pattern of bright yellow lines.
The plastron is cream to yellow in adults
but in juveniles there are dark lines along the seams.
Confusing Species
Painted Turtles have similar
colouring on the head and neck but also have red markings on the
margin of the carapace and lack both the
serrations and keel. Blanding's Turtles have yellow markings on
the carapace but lack the serrations, and
keel, as well as the marking on the head.
Distribution
In Canada, Common Map Turtles are found in southern
Ontario, east along the St. Lawrence River and into Quebec. They
range through the central United States south to Oklahoma and
Alabama.
Habitat
Map Turtles inhabit larger rivers and lakes with slow
moving water and a soft bottom. They require high quality water
which supports their mollusc prey. Individuals may congregate in
areas with abundant basking sites.
Reproduction
Females may require more than 10 years to reach
maturity. Nesting occurs from June through July. A single clutch
of up to 17 eggs is laid. Hatching occurs in fall although in cool
years eggs may not hatch at all. It is possible that in some cases
hatchlings overwinter in the nest. The gender of hatchlings is
determined by incubation temperature of the eggs.
Natural history
Map Turtles are known for their communal basking and
many individuals may be found piled up together. Basking is
particularly important for females prior to egg laying and in the
fall prior to hibernation. Map Turtles have very strong jaws and
specialize in eating molluscs such as snails and clams although
crayfish, other invertebrates and even some fish are also eaten.
Individuals can live more than 20 years.
Conservation Concerns
Populations may be large, however they are vulnerable
to water pollution which reduces mollusc populations. In addition,
shoreline development destroys nesting habitat. Adult females are
also vulnerable to traffic mortality as they wander in search of
nest sites.
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