Snakes on Roads in Ontario

We are featuring snakes for our 2023 end of year Wildlife on Road update, primarily because snakes are fascinating, but also because they are often misunderstood and left behind in road ecology research.

Lauren Nightingale and a harmless adult Eastern Foxsnake found outside exclusion fencing on the Long Point Causeway, spring 2023.

Over the past three years of our Wildlife on Roads in Ontario project on iNaturalist, we have submitted a total of 1488 snake on road observations made between 2010 and 2023.  For the growth of our project, we are happy to report that 2023 had the most snakes ever recorded with 475 total! We found 11 of Ontario’s 17 remaining snake species, including 25 Eastern Foxsnake observations; a species that is threatened globally with 70% of its range occurring in Ontario. Here are all of our records for 2023 by species:

  • 99 Northern Watersnakes
  • 24 Dekay’s Brownsnakes
  • 25 Eastern Foxsnakes (Endangered)
  • 213 Eastern Gartersnakes
  • 9 Eastern Hog-nosed Snakes (Threatened)
  • 18 Eastern Milksnakes (Special Concern)
  • 2 Gray Ratsnakes (Threatened)
  • 1 Lake Erie Watersnake (Special Concern)
  • 16 Eastern Massasaugas (Threatened)
  • 40 Northern Redbelly Snakes
  • 4 Northern Ribbonsnakes (Special Concern)
  • 15 Smooth Greensnakes

When all years of observations are sorted by month (graph below), you can see our data follows the trend of snake movement in Ontario peaking mid-Fall. In September and October, snakes are travelling across roads to reach their overwintering sites, and they wait for warmer days when temperatures climb towards 20° C to do so.

For example, in 2011 the OREG (Ontario Road Ecology Group) identified a snake migration movement across a road in Rouge National Urban Park when temperatures were between 17 and 19° C. We also found a similar migration occurred across the same road in October 2021 and 2022 when temperatures hovered near 20° C.

These warm days in the Fall may be few and far between, so when they do occur, we wind up with a LOT of snakes on roads over a very short period. For a more recent example, this year there were 18 snakes entered into the database on October 3rd, which is the same day 147 snakes (2 alive, 145 dead) were found on a single biking survey on Erie Boulevard, Long Point. Big thanks to our Wildlife Road Watch volunteers Sheila and Dave Traplin for alerting us about this mass movement of snakes on Long Point that day!

Juvenile Northern Watersnake killed on road, Long Point Park. October 3rd, 2023.

Your submissions to our project have helped us come to better understand when and how to best survey for snakes to identify the locations most in need of roadkill mitigation projects. So thank you for sharing your wildlife on road sightings this year!

Juvenile Eastern Gartersnakes found alive on road. Melanistic, solid black morph (left) and the more common morph (right).
Kari Gunson
Kari Gunson

Kari Gunson, a practitioner in road ecology since 1999, initiated the 'Wildlife on Roads' program recently in response to a need to inspire and harness grassroots efforts for implementation of mitigation solutions.

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