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Northern Map Turtle

Northern Map Turtle
   Photo: ROM

Features: Seen up close, the fine light lines on the carapace of the Northern Map Turtle (Graptemys geographica) look like contour lines on a topographic map. But more likely, your view of this species will be brief and distant, since it is extremely wary and will dive at the slightest provocation.

Females are much larger than males and have powerful jaws that they use to crush molluscs with. The smaller males eat mostly aquatic insect larvae.

This gregarious species lives in large rivers and lakes, and individuals from a wide area will often congregate at favoured sites to bask together. They also congregate in favourable locations to hibernate.

Status: Special Concern Provincially and Nationally

Range: The Northern Map Turtle's range extends from the Great Lakes region west to Oklahoma and Kansas, south to Louisiana and east to the Adirondack and Appalachian mountain barrier. There are isolated populations in New Jersey and New York states. In Canada, it is found in southwestern Quebec and southern Ontario. In southern Ontario, it is found primarily on the shores of Georgian Bay, Lake St. Clair, Lake Erie and Lake Ontario, and along larger rivers including the Thames, Grand and Ottawa.

Threats: The Northern Map Turtle is an elusive species, and is not well studied in Ontario. Accordingly, we have little data on historic distribution, or much direct evidence for widespread declines. Nevertheless it seems reasonable that with increased shoreline development such as cottages, the decline in habitat quality and increased human disturbance has caused population declines over much of southwestern Ontario in particular.

The invasion of zebra mussels into the Great Lakes region has caused declines in traditional prey species of the Map turtle. While they will eat Zebra Mussels, it is not a preferred food source and likely not as nutient-rich. Biologists have speculated that over the long-term, the loss of major prey species may cause declines in Northern Map Turtle populations.

The pet trade may also be unwittingly contributing to declines in the United States and perhaps Canada. The Northern Map Turtle resembles several popular pet trade species, and illegal capture and export may be occurring.

Protection: Two of the largest populations are in provincial parks on Lake Erie, where the habitat is protected. Turtles are protected in Ontario under the Fish and Wildlife Conservation Act, which makes it illegal to hunt, trap, keep, sell or purchase live specimens without a government permit.

Text Sources: Roche 2000; MacCulloch 2002

Last Modified Date: February 2005

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