Saturday, 23 April 2011

Black Ratsnakes

Chris Robinson, Park Naturalist and Education Coordinator at Charleston Provincial Park, treated us to his talk at the April General Meeting entitled "The Constricted Constrictor:  The Life of the Black Ratsnake". Chris told us many things about the black ratsnakes, and gave us a few pointers on their identification, and how to distinguish it from similar species such as the northern watersnake.  Black ratsnakes are the longest snakes in Ontario, and are generally slim in comparison with their overall length.  They can grow to be 4 to 5  feet long, some earlier records have shown even larger specimens, but black ratsnakes over 6 feet long would be very rare.  These snakes can live to be 20 or 30 years old, and do not reach maturity until about age 9.  Black ratsnakes have a body shape on the cross-section  that can be described as being like a bread basket, flat on the bottom then coming up to a dome on top.  Northern watersnakes, the snake most commonly confused with black ratsnakes, grow to about 3  or 4 feet long, are thicker in the middle, and have a cross-section shape of  being oval.  One feature that Chris told us to look for in comparison is on the head, the watersnakes generally have a groove underneath the eye.

The colour of snakes cannot always be relied upon, there are some very dark watersnakes, and the skin colour can vary depending on whether a snake has recently shed its skin.  Young snakes can also be difficult to differentiate. 

Black ratsnakes are currently listed under threatened status in Ontario.  Habitat loss, traffic danger, and human persecution have diminished their numbers. The range of these snakes is now limited in Ontario to the Frontenac Axis and to a few fragmented areas along the north shore of Lake Erie.  It is unfortunate that these snakes don't receive more respect, they are harmless and beneficial, as they eat rodents such as mice.    Chris handed out some copies of the booklet "The Black Rat Snake/A Landowner's Guide to Helping It Recover".  This information can be downloaded online at
Hibernacula can be difficult to find, and due the nature of places where these snakes overwinter (rock piles, under snaggly tree roots) these places are  even more difficult to examine.  Several snakes can gather together in these hibernation shelters, and in the company of other species of snakes as well.  These are places especially important for preservation. 

This is only a short account about black ratsnakes, we would encourage people to find out more about this interesting species.  A google search will provide many more details on nesting, habitats, etc., and there are many field guides and reptile books available containing good information about Ontario snakes.
                                                                                          Posting and Photos:  R. Burke

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