Thousand Islands National Park of Canada

Promising new habitat creation program for black rat snakes

You can get involved!

A female black rat snake exits a nesting box after checking out its interior.  Local landowners have been able to  attract this endangered snake to artificial nesting sites and have witnessed successful hatching.
A female black rat snake exits a nesting box after checking out its interior. Local landowners have been able to attract this endangered snake to artificial nesting sites and have witnessed successful hatching.
© Josh Van Wieren

Black rat snakes are vanishing from the 1000 Islands Ecosystem. This is an alarming fact that has encouraged regional residents, researchers and organizations to develop a promising black rat snake (Elaphe obsoleta obsoleta) habitat creation program.

The Ontario Ministry of Natural Resources, residents of the 1000 Islands region, Queen’s University Biological Station, the Leeds County Stewardship Council and Thousand Islands National Park are participating in this project, which began in 2003. Its aim is to create safe egg-laying locations for female black rat snakes.

“Females normally nest in compost piles, brush and leaf piles, dead trees and decomposing logs,” explains Melissa Francis who leads the Artificial Nesting Site program at Thousand Islands National Park.

“Racoons, a parasitic beetle and unknowing humans all pose a threat to the mother snake and her eggs. Since our black rat snake populations are declining, the mothers, eggs and young need all the protection we can give them.”

Black rat snakes are nationally and provincially designated as ‘threatened,’ which means that they will face extinction if help isn’t provided to them.

One major threat to the population is a lack of suitable places for females to lay their eggs. Female black rat snakes do not reach sexual maturity until 9 or 10 years of age so when they lay their eggs, these eggs are ten years in the making and a huge contribution to the diminishing population. Females often share nesting sites and return during every reproductive year, which makes a single nesting site crucial to species survival.

The artificial nesting site program is a very low cost, low maintenance and potentially effective way to provide a safe haven to mother snakes and their eggs. Two site designs are being experimented with, both with their own advantages and disadvantages. The ultimate goal of the boxes is to keep raccoons and other predators out while allowing the females to enter the box, lay their eggs and enabling the eggs to hatch in a safe environment. The nesting sites blend well into their surroundings and are filled with leaves, hay, wood chips, manure and other organic debris.

Artificial snake nesting boxes are designed to blend into their surroundings.  Boxes are filled with organic debris and closed to prevent predators from finding and eating the snake eggs.
Artificial snake nesting boxes are designed to blend into their surroundings. Boxes are filled with organic debris and closed to prevent predators from finding and eating the snake eggs.
© Parks Canada

Staff at Thousand Islands National Park have had numerous inquiries into the program and are pleased with the interest people are showing.

“Species monitoring and recovery programs can become much more effective when local citizens are involved. Species such as the threatened black rat snake do not know to stay within a protected area such as Thousand Islands National Park. This is why individuals from beyond protected area boundaries are needed to assist this species in strengthening its population,” explains Chris Bellemore, Park Interpreter-Species at Risk at Thousand Islands National Park.

The nest box program, only in its third year, has already been successful.

“A regional resident involved in this nesting site program near Landon Bay reported that 14 eggs were laid in his nesting site with 9 successful hatches,” said Francis. “This was a very positive result of the project and it is predicted that the success will continue to spread.”

What you can do to help the snakes

Create spots on or around your property for female black rat snakes to lay their eggs. Compost piles, manure heaps and leaf/brush piles are ideal. Remember that black rat snakes can keep your mice populations down while remaining a quiet and shy member of your backyard environment.

Spread the word about the declining black rat snake population and what people can do to help.

Did you know?

The harmless black rat snake is Canada’s largest snake. Most adults reach lengths of 1.5 to 1.8 metres (5-6 feet).