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Eastern Massasauga

Carolinian Population – Endangered;

Great Lakes-St.Lawrence – Threatened

Massasauga rattlesnake © Sterling Sztricsko


The eastern Massasauga (Sistrurus catenatus) is a pygmy rattlesnake; most adults are only 55 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.

Massasauga rattlesnake © Joe Crowley

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.

Massasauga rattlesnake © Ryan Wolfe


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.

View an interactive map of the known ranges of Massasauga rattlesnakes in Ontario.


Massasaugas breed in the spring, and females give birth to live young in late summer. A brood consists of nine to 19 young but generally averages about 13. 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.

Tracking Massasuaga rattlesnakes © Peter Ferguson

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 and only bites as a last resort.

Other names: massasauga, massasauga rattlesnake

Juvenile Massasauga rattlesnake © Joe Crowley

Threats and 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. 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.

Massasauga rattlesnake © Amelia Argue

Current Status and Protection

The eastern Massasauga Great Lakes-St.Lawrence population is currently listed as Threatened and the Carolinian population is listed as Endangered under both the Ontario Endangered Species Act, 2007 and 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 some protection to individuals and their habitat. 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 March 2007.

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

Massasauga rattlesnake © Joe Crowley

What You Can Do

Massasauga rattlesnake © Joanne Gui