BOG TURTLES

Scientific Name: Clemmys muhlenbergii

Range: The historic bog turtle range runs from southern New England to northern Georgia. A 250-mile gap in Virginia separates the species into distinct northern and southern populations. In Pennsylvania, the turtle is found mostly in the rapidly developing southeastern portion of the state. Turtle populations once found in the western part of the state are gone.

Appearance: The bog turtle is one of the smallest North American turtles with the adult shell measuring 3 to 4.5 inches in length. It is easily distinguished from other turtles by the large, conspicuous bright orange, yellow or red blotch on each side of its head. The upper shell is dark brown with yellow to orange markings and covered with ridged plates that are eventually worn smooth; the lower shell is dark brown or black, sometimes with scattered light markings.

Biology-Natural History: Bog turtles are active from spring to fall, and hibernate during the winter. They are most difficult to find in midsummer, leading to speculation that they are inactive during the hottest part of the year. When danger threatens, the turtle burrows rapidly into the mucky bottom. They eat a diet of beetles, insect larvae, snails, seeds and millipedes. Female bog turtles mature at 5 to 8 years of age. They mate in May and June, and in June or July the females deposit two to six white eggs on sphagnum moss or sedge tussocks that are exposed to sunlight. The eggs hatch after an incubation period of 42 to 56 days, and the young emerge in August or early September. Infertile eggs are common, and not all females produce egg clutches each year.

Preferred Habitat: Bog turtles live in shallow, spring-fed fen; sphagnum bogs; and swamps, marshy meadows and pastures with soft, muddy bottoms, slow-flowing water and open canopies. The wetlands are usually mosaics of micro-habitats which include dry pockets, saturated areas and areas that are periodically flooded. They depend on this hydrologic mosaic, using shallow water in the spring, and mud during winter hibernation. These wetlands, unless disrupted by fire, beaver activity, grazing or periodic wet years, are slowly invaded by trees and other types of woody vegetation. This causes the wetland to gradually undergo a transition and become a closed-canopy, wooded swamps unsuitable for bog turtle habitation. Historically, bog turtles probably moved from one open-canopy wetland patch to another, as succession closed wetland canopies in some areas and natural processes, such as fire, opened canopies in other areas.

Threats: The primary reason for the bog turtle's status is the draining or other destruction of its habitat. Bog turtles have always been considered the rarest of North American turtles and are highly valued by turtle fanciers in this country, and possibly twice as much overseas. Many, therefore, have been illegally removed for commercial purposes. Because their habitats are widely separated, other turtles are not likely to move in and replace those removed.

State status: Endangered

Federal status: Under consideration for listing as a threatened species

- Sources: U.S. Fish and Wildlife Service,
Pennsylvania Fish and Boat Commission