Can a country with cold winters actually have ectothermic, or cold-blooded, reptiles? Surprisingly, the answer is yes. Canada is home to 24 snake species, 5 lizards, 9 land turtles plus 4 sea turtles that occasionally inhabit our Pacific or Atlantic coastal waters. While most are found in the southern part of the country, there is one snake – the common or red-sided garter snake – found as far north as the Northwest Territories.
Famous for our harsh and variable climate, it may seem astonishing that these animals survive here. But survive they do, and with some amazing adaptations.
Many reptiles retain their eggs inside their bodies and give birth to live young. If the female keeps her eggs inside until they hatch, she is better able to regulate their temperature – a survival advantage in cooler regions. The trade-off is fewer broods, as females who give birth to live young are only able to do so once every year or two.
All turtles come on land to lay their eggs in a nest chamber dug deep in soft soil. Young turtles break out of their shell and dig their way to the surface. If the temperature on the surface is not warm enough when they hatch, they spend the winter deep in the protective nest chamber, emerging in the spring.
Lizards and snakes may also make use of communal nesting sites. Multiple femals lay their eggs in a particularly choice site, rather than use a less desireable one on their own. This improves the chance of a successful hatching, and is common in areas where good nesting sites are scarce.
During the winter reptiles rely on warm, dry den sites that provide protection from the elements. The temperature in the den site never drops below freezing. Snakes are often found in dens, or hibernaculums, numbering several hundred animals. Even enemies during the summer months will spend the winter huddled together.
Aquatic reptiles like turtles snuggle deep down into the mud on the bottom of ponds, or over winter in muskrat or beaver lodges, below the water line. Many species of turtle also hibernate in groups, and may sometimes be seen basking on the shore on warmer days.
If they don’t hibernate together, many species rely on holes in the ground to protect them from freezing. A few species dig their own burrow, but most use one that has been abandoned by a small animal. The temperature of the ground below the frost level is warm enough for them to survive the winter.
Our reptiles are not brightly coloured. Dark colours absorb heat from the sun more readily than lighter ones. Reptiles living this far from the equator need to receive as much heat as they can from the weaker sun rays.