Pennsylvania Field Office
Northeast Region

Eastern Massasauga Rattlesnake
Life History and Biology

eastern massasauga rattlesnake Sistrurus catenatus catenatus

Information derived from Pennsylvania Angler & BoaterNovember-December 2007 – by Andrew Shiels

STATUS: Candidate

DESCRIPTION: E. Massasaugas range from 24 to 30 inches. Their body is a grayish color with a series of dark-brown, irregularly shaped blotches along the top of the back. Along the sides of the body are two to three rows of smaller, more rounded spots. Massasaugas are pit vipers, which means there is a heat-sensing pit on the side of the head between the eye and nostril. Massasaugas have vertically elliptical pupils and a single row of scales on the underside of the tail. The body is very stout compared to the length.

RANGE AND POPULATION LEVEL: Eastern massasaugas live in an area that extends from western New York and southern Ontario to southern Iowa and a narrow band in northeastern Missouri. Historically, the snake's range covered this same area, but within this large area the number of populations and the number of snakes within populations have steadily shrunk. The eastern massasauga is generally found in small, isolated populations throughout its range. HABITAT: Massasaugas are habitat specialists. They require swamps and bottomland wetlands near upland meadows, old-field or grassland habitats. The wetlands are needed for over-wintering. To avoid death from freezing, massasaugas descend under ground through small mammal or crayfish burrows to reach the water table where they spend the winter, often partially submerged. Thus, their health and survival depends on the presence of other organisms such as crayfish. Upland habitats are used for basking and foraging. Massasaugas travel back and forth between these habitat types depending on the season. Unless both habitats are present, massasaugas can’t survive.

REASONS FOR CURRENT STATUS: Never common in Pennsylvania, massasaugas now may be found in only half their historic sites, due to dam building, highway construction, urbanization, forest succession, surface mining and agricultural activity. When we drain wetlands and develop in natural areas, we push species into ever smaller isolated islands of habitat where it is difficult for them to survive. By conserving massasaugas, we conserve natural systems that support many species of plants and animals.

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Last updated: May 4, 2011
All images by FWS unless otherwise noted.