Eastern Milksnake Monitoring

The eastern milksnake is listed as a Special Concern species federally due to threats such as habitat loss and road mortality. Eastern milksnakes have historically inhabited the Rouge Valley, which, due to urban sprawl, can exacerbate these threats. Following road mortality surveys conducted in 2010, eastern milksnakes were found dead on the roads surrounding what is now the Rouge National Urban Park (RNUP), which precipitated in the monitoring of this species to this region.

Population surveys began in 2011 when 100 plywood Artificial cover object (ACO) were deployed at three sites to sample the population via mark-recapture methods using head patterns. Head patterns were used as each eastern milksnake has its own unique head markings that can be used to identify individuals. These surveys continued until 2014, but the number of sites was reduced to two. In 2015, the University of Waterloo began monitoring the population using radiotelemetry to track the movements of individual milksnakes and quantify habitat selection and behavioural adaptations. It was found that eastern milksnakes were modifying their behaviors across urban landscapes by increased movement rates and avoiding road crossings. The Adopt-A-Pond Wetland Conservation team resumed mark-recapture surveys using ACOs in 2018. Since then, the survey efforts have expanded with 55 additional plywood ACO added and 11 new sub-sites throughout the Rouge National Urban Park.

Our goal is to continue the long-term monitoring of the eastern milksnake population using minimally invasive techniques to determine the distribution, population size, and location of hibernacula and ensure their population remains stable. Although the eastern milksnake is the target species for our monitoring efforts, an additional benefit is the incidental monitoring of the other snake populations in the area. ACOs are checked weekly from the spring to fall. When a snake is present, the team will take body measurements and check for any abnormalities. This includes looking for signs of snake fungal disease (SFD), caused by the fungus Ophidiomyces ophiodiicola (O.o).

Photo: An eastern milksnake found during artificial cover object surveys.

Eastern milksnakes are an excellent species upon which to model wetland protection initiatives. Eastern milksnakes use a variety of different wetland habitats throughout their life cycle, including prairies, meadows, ponds and connecting travel corridors like ravines and rivers. Protecting eastern milksnakes and their habitat goes a long way to benefit other native snakes, birds, fish, and turtles that use the same wetland homes. Together, we can focus on saving habitat for one species to save an entire ecosystem!

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