University of Massachusetts Amherst

Massachusetts North American Amphibian Program

Bog Turtle

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Herp Atlas 1992-1998 Survey

  • The map below shows the distribution of the Bog Turtle in Massachusetts based on the original intensive volunteer survey that took place from 1992-1998.
  • Download pdf of map

Updated Distribution Map

Glyptemys muhlenbergii (3-4”)
Federal Status: “Threatened”; MA Status: "Endangered." Illegal to harass, kill, collect or possess.


The Bog Turtle is a small turtle, 3-4 inches, with a mahogany, dull brown oblong carapace (upper shell), most with a faint yellowish or reddish starburst shaped pattern centered in each scute. The plastron (lower shell) is mostly brown or black, irregularly marked with yellow. The black head bears the most striking feature of this species, a large bright orange patch behind each ear (the patch may be yellow or red on some individuals). The neck is brown and the tail and legs are brownish yellow or dark brown. In males the tail is longer and thicker than in females, and the plastron is concave.

Massachusetts populations lie on the northern periphery of the range. Bog Turtles in Massachusetts inhabit low-lying open calcareous wetlands, notably fens. Bog Turtles occur in small patches of optimal habitat within a dynamic wetland system. These patches typically include early successional stages of wet meadow or fens, surrounded by advanced successional stages of freshwater marsh or wooded swamp.

This secretive turtle overwinters from about mid October to late March, in subterranean seepage areas with a continual source of flowing water. On warm sunny days in the spring they come up to bask and feed. The Bog Turtle typically confines its wanderings to wetland locations and is more agile in the water. It is often found with its’ “feet wet and its back dry”. When alarmed, the Bog Turtle digs rapidly into the mucky substrate. This species has occasionally been found in upland habitat adjacent to the wetland.

On cold days of spring and fall individuals may remain completely sheltered or burrowed in mud. Bog Turtles often aestivate (dormancy or reduced activity during the summer) during the dry summer months of July and August. Most activity occurs in late April, May, June, and September. This turtle maintains a small home range of approximately 3 acres.

The Bog Turtle is an opportunistic omnivore and forages both on land and underwater. The diet consists primarily of invertebrates. Favorites include slugs, beetles, millipedes, insect larvae, earthworms, pondweed, sedge seeds and other plant material. Sexual maturity occurs around year ten for females.

Mating takes place early May through early June. Gravid (egg carrying) females usually begin to nest at dusk. Clutches of 2-5 white, elliptical eggs are laid on the tops of tussock sedge during midsummer; they incubate for 7-8 weeks and hatch in late summer. In Massachusetts, hatchlings may overwinter in the nest. Bog Turtles are thought to live 60 or more years.

Adapted from the MA Natural Heritage and Endangered Species Program’s Bog Turtle fact sheet. 2007



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