While most snakes in Ontario can be found slithering about on the ground, you're more likely to spot the province's largest snake by looking at the trees overhead, as they climb up in preparation to shed their skin or hunt for prey. 

The gray ratsnake (Pantherophis spiloides), also known as the black ratsnake or the eastern ratsnake, is a non-venomous species that has the potential to reach up to two metres in length. 

The snakes are excellent climbers and constrictors, meaning they spend most of their time hunting for small mammals and birds. Similar to other larger and more famous constrictors, the species squeeze their prey to death and swallow their food whole. 

Gray ratsnakes can be distinguished by their shiny black bodies with white chins and throats. Their bellies are commonly white or yellow with dark spots that often produce a checkerboard-like pattern. 

Photo: dkHDvideo/Shutterstock. 

Throughout Ontario, two populations of gray ratsnakes can be found in different habitats. 

The Frontenac Axis population is usually found in deciduous forests, wetlands, lakes, rocky outcrops, and agricultural fields, while the Carolinian population is found in a mix of agricultural land and deciduous forest, preferring habitat where forest meets more open environments.

Currently, the Carolinian population is listed as endangered, meaning that the species still exists in the wild in Ontario but is facing imminent extinction or extirpation. 

On the other hand, the Frontenac Axis population is listed as threatened, meaning that while it is not endangered, it is likely to become endangered if steps are not taken to address factors threatening it. 

Photo: Jay Ondreicka/Shutterstock.

According to the provincial government, the most significant threats faced by the species are the loss and fragmenting of habitat, persecution by people, motor vehicles, and the destruction of suitable hibernation sites. 

Ratsnakes typically hibernate in groups at the same site year after year, meaning destroying these sites can have a devastating impact on the local population. The snakes are also slow to mature and reproduce, which may inhibit their recovery even further. 

To protect the species, there are several steps you can take, including reporting sightings to the Natural Heritage Information Centre, with specific locations or mapping coordinates. 

Make sure to also pay close attention when driving, as all types of snakes are known to cross busy roads throughout Ontario, particularly between May and October.