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Gray Ratsnake

Gray Ratsnake

(also known as the Eastern Ratsnake and the Black Ratsnake)

Scientific name: Elaphe obsoleta spiloides
Status Carolinian population (COSEWIC): endangered Great Lakes/St. Lawrence population (COSEWIC): threatened (Note: -there are two genetically distinct populations within Ontario: the Carolinian population and the Great Lakes/St. Lawrence population)


Did You Know? The gray ratsnake is Canada’s longest snake. Reaching lengths of up to 2 meters (6.5 feet), this snake looks intimidating. It also has the ability to sound intimidating! When threatened, the gray ratsnake vibrates its tail, making other species (including humans) think it’s a venomous rattlesnake. But nothing could be further from the truth: This snake is completely harmless to humans.

Would you believe? This snake climbs trees. The gray ratsnake is an excellent climber, perfectly adapted for hunting birds and eggs high up in the tree tops. The gray ratsnake also takes cover in cavities in dead trees and likes to sunbathe on exposed branches.

Measuring Up

  • gray ratsnakes have a lifespan of up to 25 years
  • hatchlings (newborns ) are approximately 30 cm (12 inches)
  • adults may reach 2 meters (6.5 feet)


  • adults are black, dark gray or dark brown with a white throat and chin
  • juveniles are lighter with dark blotches


  • gray ratsnakes are constrictors meaning they suffocate their prey and then swallow it whole
  • their prey includes: small rodents, birds and eggs


  • in Canada, gray ratsnakes are found only in Ontario
  • gray ratsnakes prefer “edge habitat” – where field and forest meet
  • they use exposed rocks for sun-bathing
  • they also sunbathe high up in tree branches
  • gray ratsnakes hibernate in the winter in underground sites (hibernacula) –as many as 100 snakes share will share a single hibernaculum


  • gray ratsnakes are gentle creatures
  • they’re excellent tree climbers
  • they’ll swim, if necessary
  • to help regulate their body temperature, they sunbathe on roads, exposed rocks and tree branches


  • nesting sites include: piles of forest debris and compost piles
  • nesting sites are often used by groups of females
  • females lay an average of 14 eggs every other year or every three years
  • hatchlings (the newborn snakes) must fend for themselves as soon as they’re born


  • humans are the main threat to this species
  • humans kill gray ratsnakes intentionally and unintentionally
  • many snakes, crossing roads or basking on roads are killed by cars
  • habitat destruction –particularly the destruction of hibernacula (underground, communal hibernation sites) – is a major threat
  • racoons prey on eggs; hawks attack young snakes
  • other threats to adults include: raccoon, fisher, mink, red-tailed hawk, osprey

How to Help:

  • you can let other people know gray ratsnakes are gentle and harmless
  • you can create compost piles (good nesting sites); just remember not to “turn” piles between July and October (otherwise eggs might be harmed)
  • keep an eye out for snakes on the road; drive slowly and when safe to do so, stop and allow them to pass

Video Credits:

    • Writer: Susan Terrill
    • Camera: Douglas and Franziska von Rosen
    • Editor: Douglas von Rosen
    • Music: Peter Kiesewalter
    • Additional footage: Courtesy of the Friends of Murphys Point Park
      John and Janet Foster

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