Rattlesnake is the common name for about 30 species of venomous, viperid snakes in the genera Crotalus and Sistrurus, found from southern Canada to South America. Three species of rattlesnake are found in Canada: the Western rattlesnake (Crotalus oreganous), the prairie rattlesnake (Crotalus viridus) and the Eastern massasauga rattlesnake (Sistrurus catenatus). Another species, the timber rattlesnake (Crotalus horridus) is extirpated, meaning the species no longer exists in the wild in Canada, but lives elsewhere.
Features characteristic of rattlesnakes include a broad, triangular head with movable fangs, a stout body and a “rattle” made of modified scales, each of which once capped the tip of the tail. The buzzing sound produced by rapidly vibrating the tail is believed to act as a defensive warning to intruders. Rattlesnakes are pit vipers, meaning they have a heat-sensing pits on either side of their face.
Distribution and Habitat
Three species of rattlesnake are found in Canada: the Western rattlesnake (Crotalus oreganous) lives in the arid grasslands of British Columbia; the prairie rattlesnake (Crotalus viridus) lives in similar habitats in Saskatchewan and Alberta; and the Eastern massasauga rattlesnake (Sistrurus catenatus) lives in southern Ontario. A fourth species, the timber rattlesnake (Crotalus horridus), is also native to Canada, but is extirpated. Rattlesnakes often hibernate communally in rocky outcrops.
Mating typically occurs in late summer and fertilization takes place the following spring. In early fall 2–10 (may be more in Eastern massasaugas) live young are born. Females reproduce only every 2–3 years. Diet consists mainly of rodents, other small mammals and birds.
The venom used to kill prey is a mixture of neurotoxins and hemotoxins (affecting nerve and blood tissues, respectively) delivered through the fangs. Rattlesnakes rarely strike humans, unless provoked or accidentally stepped on. The bite can cause painful swelling, muscular paralysis and tissue destruction, and may result in death. Less than 1 per cent of all snakebites in North America are fatal. The incidence of snakebite in Canada is low.