We’ve had such an interesting spring season in 2020, with the COVID-19 pandemic and shifting to working from home, it’s been nice to have the opportunity to continue to keep up with fieldwork in a solo capacity to maintain social distancing measures. One of our projects has involved conducting surveys for snake emergence this spring which has meant trying to find days with nice weather, clear skies and warm temperatures! Considering the weather we’ve had in Muskoka this spring, these days have been tough to find!
Snake emergence surveys are conducted to identify if there is active reptile hibernaculum on a property. For snakes, hibernation takes place in sites located below the frost line in burrows, rock crevices and other natural or naturalized locations. The existence of features that go below the frost line, such as rock piles or slopes, old stone fences, and abandoned crumbling foundations are often good indicators that there is potential for hibernation. Wetlands can also be important for overwintering in conifer or shrub swamps and swales, poor fens, or depressions in bedrock terrain with sparse trees.
Snakes typically hibernate in large groups. As reptiles, they are ecothermic, which means they can’t produce their own body heat, and must rely on their outside environment to warm their bodies. They hibernate in large groups to share their little remaining warmth during the cold winter seasons. Their hibernation sites are carefully selected – reptiles are particularly sensitive to changes in microhabitat structure. The site they choose must remain within a correct temperature and humidity range for the entire winter season. The amount of sunlight (solar orientation), depth, distance from the water table, distance from the frost line, ground material and structure all contribute to the site’s suitability. Small changes to the arrangement of woody debris or the addition of stones to the ground surface can destroy snake hibernacula.
All of these limitations mean that there are few sites suitable for reptiles, like snakes, to choose from, and local populations often rely on returning to the same locations year after year. Other critical life processes, such as mating, often take place in close proximity to hibernacula. It’s important to be able to identify these areas and do what we can to mitigate the risk to the population as much as possible when considering development projects. Spring emergence surveys are conducted on sunny days when the air temperatures are first starting to reach above 10 degrees Celsius (or in overcast conditions when temperatures are above 15 degrees Celsius). These surveys involve visual encounter surveys to identify groups of snakes that might be emerging from their hibernation sites and basking to gain energy. In the early spring, when snakes are just emerging from their hibernation sites, they are slow moving and a bit lethargic until they gain back enough fat reserves to become more active hunters and resume their summer activities. This is the best time to observe them and make note of their hibernacula.
Typically, once an area of hibernation is confirmed, it is recommended to place protection on the habitat and include a 30 m radius of protection around the habitat as well. Many reptile hibernaculum are well known sites and reports from local field naturalist groups, herptologists, MNRF staff, NHIC records and conservation authorities can be helpful as a starting point in determining the suitability of a site.
If you’re lucky enough to come across a group of snakes in the early spring who may be basking in the sunshine, it’s very likely you are close to an area that is actively used during hibernation!