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.


Characteristic features 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 (ie, have a heat-sensing pit on either side of the face).

Distribution and Habitat

Four species are native to Canada: the western rattlesnake (C. oreganous) occurs in arid grasslands of BC; the prairie rattlesnake (C. viridus) lives in similar habitats in Saskatchewan, Alberta and BC; the timber rattlesnake (C. horridus; extirpated in Canada) and the massasauga rattlesnake (S. catenatus) are restricted to southern Ontario. Rattlesnakes often hibernate communally in rocky outcrops.


Although massasauga rattlesnakes may mate in spring, mating in other species occurs in late summer; fertilization takes place the following spring. In early fall 2-10 (may be more in 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 2% of all snakebites in North America are fatal if given medical attention. The incidence of snakebite in Canada is low.