Eastern Massasauga

Eastern Massasauga Joe Crowley

Eastern Massasauga (Sistrurus catenatus)

Other names: massasauga, massasauga rattlesnake


The eastern massasauga is a pygmy rattlesnake; most adults are only 60 to 75 centimetres long. It is brownish with saddle- or butterfly-shaped darker brown blotches on the back that alternate with smaller blotches on the sides. The belly is black with scattered light markings. The scales are keeled (ridged down the centre), which gives the snake a rough appearance). The massasauga has a vertical pupil (unlike all other snakes in Ontario, which have round pupils) and a triangular head with three dark stripes running down each side. This snake is most easily identified by its rattle, which is made up of interlocking segments that are added one by one when the snake sheds its skin, one to three times a year. The rattle can break off, however, so the absence of a rattle does not indicate that a snake is not a massasauga.

Similar Species

No other rattlesnakes are left in Ontario. The eastern foxsnake, eastern hog-nosed snake, eastern milksnake and northern watersnake superficially resemble the massasauga. Unlike these species, the massasauga has a rattle, vertical pupils and saddle- or butterfly-shaped blotches down its back. The eastern foxsnake and eastern milksnake vibrate their tails when threatened, mimicking the massasauga. The milksnake has smooth scales, and those of the foxsnake are only weakly keeled.


Massasaugas generally are associated with water, are rarely found more than 50 kilometres from the Great Lakes, and often inhabit wetlands near rivers. In Ojibwa, the word “massasauga” means “great river mouth.” The massasauga is a habitat generalist and can be found in forests, meadows, shoreline habitats, wetlands, rock barrens, grasslands and old fields. The species requires very specific microhabitat features within these habitats for mating, hunting and especially thermoregulation.


Massasaugas breed in the spring, and females give birth to live young in late summer. A brood consists of two to 19 young but generally averages about six to 10. At birth, the young are 16 to 24 centimetres in length. Females may require three or more years to mature. Like all rattlesnakes, the massasuaga is a pit viper and can see thermal images of its environment using two heat-sensitive pits between its eyes and nostrils. Its heat-sensitive pits, venom and camouflage make the massasauga a very effective predator of small mammals, this species’ primary prey.

Researchers have observed that massasaugas will remain alert but motionless if approached. Even experienced observers who search for the massasauga as part of a test find a very small percentage of those in a search area; most hikers would walk right by a massasauga, unaware of its presence. This snake is a very docile one. When threatened, it rattles or retreats under nearby cover. The massasauga bites only as a last resort, and its striking range is under 30 centimetres (about a third to a half of its body length).

Threats & Trends

Unfortunately, people frequently kill rattlesnakes on sight, out of fear. Only two people, however, have ever died in Ontario from a massasauga bite, both more than 40 years ago. In comparison, six to 12 people die from lightning strikes each year in Canada. Obviously, the odds of being endangered by one of these snakes are negligible. Loss and fragmentation of massasauga habitat in southwestern Ontario continue to threaten this species throughout its current range. Road mortality is also a serious threat to this slow-moving snake and is probably the most severe threat to this species in protected areas.

The massasauga has been extirpated from much of its previous range in southwestern Ontario and is now restricted to the eastern shore of Georgian Bay, the northern Bruce Peninsula, a tiny population on the Niagara Peninsula and a tiny (no longer viable) population near the city of Windsor.

Current Status & Protection

The eastern massasauga is currently listed as Threatened under the Ontario Endangered Species Act, 2007 and Threatened under the federal Species at Risk Act. The species has also been designated as a Specially Protected Reptile under the Ontario Fish and Wildlife Conservation Act. These acts offer protection to individuals and their habitat. The habitat of this species is further protected in Ontario by the Provincial Policy Statement under the Planning Act. The International Union for Conservation of Nature lists the global status of the eastern massasauga as Least Concern. The species’ status was last confirmed in January 2010. Additional detail about legal protection for species at risk in Ontario is available on our Legal Protection page.

Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Amphibian Stewardship page.

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Eastern Massasauga Range Map

Ontario range (click to enlarge)

In Canada, the massasauga occurs only in Ontario. To the south, this species is found in a diagonal swath from the Great Lakes to Texas and farther south into Mexico, although it has become rare in many of the states in which it is found. The map shows the Ontario range of the massasauga.

Massasauga with neonates
A massasauga with her neonates (newly born snakes). A mother massasauga will stay with her young for a week or two after giving birth.

Massasauga camouflaged on the forest floor
Amongst the pine needles and dead leaves, these snakes are so well camoflauged on the forest floor that people often step over them without even noticing!

A young massasauga
A young massasauga, only a few days old, has one "button" (or segment) on its rattle. Despite just having been born, the bite of a neonate massasauga is just as serious as that of a fully grown adult.

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