What is the Eastern Ratsnake?

Eastern Ratsnake basking in the sunEastern Ratsnake basking in the sun

The Eastern Ratsnake is found in Ontario and is the largest snake in Canada. It is harmless to humans. Habitat loss due to agriculture and urbanization is the main reason for the species' decline. Parks Canada is working with partners to protect this species.

When approached, Eastern Ratsnakes may emit an unpleasant odour or make a rattling sound - even though these snakes do not have rattles!

Adult Eastern Ratsnakes grow to 1.5-1.8 metres long. Although admittedly impressive and somewhat intimidating, they are not venomous.

Adults are most often shiny black with a whitish chin and throat. Juveniles have a blotchy pattern and are paler than adults, becoming darker with age.

Eastern Ratsnakes are good tree climbers. Their diet consists mainly of bird eggs and nestlings, insects and small mammals no larger than a grey squirrel.

The natural predators of ratsnakes include mink, hawks, coyotes and racoons.

In Canada, individual ratsnakes can live as long as 25-30 years. Eastern ratsnakes reproduce at a rather slow rate and, in fact, only reach sexual maturity at 10-12 years of age. Females lay their eggs only every other year.

The species' preferred habitat is woodland edges, where deciduous forest meets open habitat such as fields, clearings and ponds. Ratsnakes are also found in and around abandoned buildings, which provide food and shelter.

The Eastern Ratsnake finds food and shelter in piles of branches on the ground.

Ratsnakes, like all snakes, are cold-blooded animals so many of their habits are geared to finding a suitable temperature. For example:

  • To keep their eggs warm, Eastern Ratsnakes lay their clutch in decaying vegetation or manure piles.
  • To survive the winter, this species gather in underground cavities (hibernacula below the frost line
  • In the spring and fall in particular, Eastern Ratsnakes look for warm, sunny spots such as tree trunks and roads for basking.

Although these habits are essential to the Eastern Ratsnakes's survival, they can also make the species more vulnerable to certain dangers.

Where does the Eastern Ratsnake live?

In Canada, the species is found only in Ontario, where there are five remaining populations isolated from one another:

  • Four populations are found near Lake Erie in the Carolinian Life Zone
  • A fifth population occurs on either side of the St. Lawrence River, in the Frontenac Axis, which includes St. Lawrence Islands National Park of Canada

What is the status of the Eastern Ratsnake?

The Eastern Ratsnake is not venomous and its teeth are only 1–2 mm long (shorter than a rose or raspberry thorn).

In 1998, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated the Eastern Ratsnake as a threatened species in Canada. This means that it is protected under the Species at Risk Act.

In addition, under Ontario law, killing, trapping or harassing the Eastern Ratsnake is illegal.

The species is also listed as threatened in several U.S. states.

What's so special about the Eastern Ratsnake?

The Eastern Ratsnake has lived in Canada for roughly 7,000 years. It plays an important ecological role, helping to control rodent and bird populations among other things.

Eastern Ratsnake recovery efforts not only benefit the species but can also help us learn a great deal about natural habitats in eastern Ontario, particularly their state of health and potential threats.

Many other species will benefit if we succeed in protecting and improving the health of these habitats. The Carolinian Life Zone, for example, contains not only the Eastern Ratsnake but also over 40% of species designated as threatened or endangered in Canada!

The longest known Eastern Ratsnake was 2.5 metres long but despite their size and appearance, this species is not aggressive.

Why is the Eastern Ratsnake in danger?

Eastern Ratsnake populations in Canada are threatened because:

  • In the past 200 years, human activities such as urbanization and intensive agriculture have destroyed and fragmented ratsnake habitat.
  • Ratsnakes reproduce at a slow rate and, in small populations, the death of a few individuals may have major consequences.
  • Ratsnakes gather in large numbers (30–60 individuals) to spend the winter in winter shelters, or hibernacula. Destroying a hibernaculum can wipe out an entire population.
  • In fall and spring, ratsnakes seek warm, sunny spots to bask such as roads, where they can be run over by cars.
  • They are persecuted because people are afraid of snakes or hunt or trap them.

What is Parks Canada doing to save the Eastern Ratsnake?

Two Parks Canada employees with an Eastern Ratsnake; the one on the right is putting a device on the snake’s tail while the one of the left holds the snake.
Parks Canada uses techniques such as telemetry, microchips and genetic analyses to study the snakes’ natural history and monitor populations.

Parks Canada is a member of the Eastern Ratsnake Recovery Team.

The recovery team’s objectives are to:

  • Maintain the Eastern Ratsnake’s current range.
  • Prevent further extinctions of local populations.
  • Restore connectivity among isolated populations.

The main ways identified to achieve this include:

  • Studying the natural habitats, biology and habits of the Eastern Ratsnake to better understand its requirements.
  • Increasing awareness of the species’ situation, to encourage individuals and organizations to get involved in recovery efforts.
Close-up of a young Eastern Ratsnake being held by a Parks Canada employee.
Juvenile Eastern Ratsnakes have a different colouring than adults.

How can I help?

If you live in or visit an area where the Eastern Ratsnake lives:

  • Learn more about it and how to identify it.
  • If you see a ratsnake, report it to Parks Canada or Ontario Parks staff.
  • Let other people know that it is harmless and needs our help to survive.
  • Do not harass it.
  • Leave areas where it can live and breed (dead or hollow trees, rotten logs, compost, brush piles, etc.).
  • Drive slowly and keep an eye on the road to avoid running over snakes, particularly in spring and fall, when they are likely to be basking on roads.
  • Discuss possible conservation activities with the staff of Parks Canada, provincial parks or wildlife conservation organizations

To find out more about the Eastern Ratsnake and what you can do to help protect and restore it, see the brochure "The Black Rat Snake. Live & Let Slither".

As little as 5% of the Eastern Ratsnake’s range is on protected land. Support from the community is crucial in saving it! If you come across a hibernaculum or nesting site, inform your local resource conservation official so the site can be recorded and monitored.