Prairie Rattlesnake (Crotalus viridis)

Description
Prairie Rattlesnake

Size

  • Body is large and heavy, with a length that ranges from 80 centimetres to 1.4 metres (32 inches to 5 feet).
  • In general, male rattlesnakes are larger than the females.

Appearance

  • Head is broad and heart-shaped.
  • Rough scales sit above the eyes, which are cat-like with vertical pupils.
  • Body colour ranges from yellow-green to brown, with dark brown, irregular blotches and spots down the back and sides.
  • Tail is tipped by a rattle that, when vibrated, makes a distinct buzzing sound to warn larger animals of the snake’s presence.
Distribution
  • In Alberta, this snake ranges in Alberta’s Grassland Natural Region, south of the Red Deer River and east of Lethbridge.
Natural History

Habitat

  • Habitat for this species includes:
    • Drier areas of native grassland and sagebrush, often close to a river valley or coulee
    • Farm fields and pastures
    • Rocky outcrops
    • Sandy soil near rock piles or flat boulders
    • Stony canyons

Food

  • Prey includes warm-blooded animals, including:
    • Juvenile ground squirrels
    • Mice
    • Songbirds
    • Voles
  • Adult rattlesnakes will also take amphibians and other reptiles if the opportunity presents itself.
  • Juvenile rattlesnakes feed mainly on invertebrates.
  • Adult rattlesnakes subdue or kill prey by striking and delivering venom through two elongated hollow fangs. Prey is consumed whole, starting with the head.

When Active

  • In Alberta, prairie rattlesnakes are active from mid-April to October. Winters are spent in dens, or hibernacula.
  • Are most active in the mornings and evenings of sunshine-filled days.
  • At night, rattlesnakes can be found on roads, where they are attracted to the heat.
Reproduction and Growth

Breeding Behaviour

  • Mating occurs during mid- to late summer and the young are born a year later. Breeding occurs every two to three years.
  • Female rattlesnakes carry their developing embryos in specialized membranes within their bodies, later giving birth to live young between late August and mid-October.
  • Rattlesnake litters consist of anywhere from 4 to 12 young.
  • Rattlesnakes are about 28 centimetres (11 inches) long at birth.
  • Young snakes reach sexual maturity at between three to seven years of age.
Conservation and Management

Status

The prairie rattlesnake is classified as May Be At Risk in the General Status of Alberta Wild Species report. See:

Also see the Status of the Prairie Rattlesnake in Alberta report at:

In a subsequent detailed status assessment, Alberta’s Endangered Species Conservation Committee identified the Prairie Rattlesnake as a Species of Special Concern—a species that without human intervention may soon become threatened with extinction. See information on the Endangered Species Conservation Committee and Species of Special Concern at:

Issues

  • Intentional killing of rattlesnakes by humans, road and pipeline construction, and increased agricultural activities within the traditional range for this species have contributed to declines in population in various localities in Alberta.
  • Rattlesnakes are drawn to the heat of road pavement at night, making them more vulnerable to being killed by traffic, or more likely to be found by those who wish to harm them intentionally.

Current Management

  • The prairie rattlesnake is designated as a non-game animal in the Province of Alberta. It is illegal to kill, possess, buy or sell rattlesnakes in Alberta. Anyone who is concerned about having this species on their property should contact their local Fish and Wildlife office.

Nature's Heat Seekers

Adult rattlesnakes locate warm-blooded prey through the use of two heat-sensing organs called facial pits, situated between the snake’s eyes and nostrils.

 

Page Information

Updated: Mar 12, 2014