American Bullfrog

Lake Erie Watersnake Joe Crowley

Lake Erie Watersnake
(Nerodia sipedon insularum)

Other names: Natrix sipedon insularum

The watersnakes, and other harmless snakes that bear live young, were included in the family Colubridae but recently have been placed in the family Natricidae.

Characteristics

The Lake Erie watersnake, a subspecies of the northern watersnake (N. s. sipedon), varies in colour, but many individuals are brown or dark brown with faint alternating dark (sometimes reddish) horizontal banding on the back and sides (exactly the same as in the northern watersnake). Some, however, are more of a slate grey colour and the banding can range from very faint to pronounced. The belly is normally light yellow to grey. The scales of this species are keeled (ridged down the centre), which gives the snake a rough, rather than a shiny, appearance.

Similar Species

Many of the species that can be confused with the northern watersnake are not present on the Lake Erie Islands where this species is found. It may be mistaken for the eastern foxsnake, blue racer or melanistic gartersnake. The eastern foxsnake has a yellow to light brown body with brown blotches down its back and two alternating rows of smaller blotches along the sides. The blue racer is blue or blueish green and has smooth scales. The melanistic gartersnake is much smaller than the Lake Erie watersnake and has a black back with no patterning. Lake Erie watersnakes are found along the shorelines of the western Lake Erie islands they inhabit, whereas the blue racer occurs in interior savannah habitat. Juveniles of these and other species look very similar and can be very difficult to differentiate.

Habitat

The Lake Erie watersnake is found along the shorelines of Pelee and other western Lake Erie islands. These snakes use the dolomite and limestone rocks, ledges and crevices along the shoreline for basking and hiding, and are rarely found far from these rocky shoreline habitats. They can also be found in sandy areas, where logs, debris and vegetation provide cover. The Lake Erie watersnake hibernates inland in underground dens, crevices and burrows, hollow logs or rock piles.

Biology

Male Lake Erie watersnakes reach sexual maturity at two years of age, females at three. This species can live up to 12 years in the wild. It breeds from late May to late June after emerging from hibernation. Females develop the eggs within their bodies and give birth to live young in late summer or early autumn. On average, females have 27 young, but the litter size can range from 9 to 50!

The Lake Erie watersnake eats fish, which it catches along the shoreline ofthe Lake Erie islands. The round goby was introduced into Lake Erie and has become the primary prey of this species. It is an excellent swimmer and can be found up to three metres below the surface of the water, but it rarely swims more than 50 metres from shore. Although the Lake Erie watersnake usually swallows small prey head first upon capture, it may carry large fish to shore before consuming them.

Like the northern watersnake, the Lake Erie watersnake is curious and not as wary of humans as many other snakes are. It may even approach swimmers as it investigates the source of ripples in the water (which could be from a fish or other prey) or if it mistakes them for a floating log or other debris it can hide in or bask on. Lake Erie watersnakes are harmless but will bite in self-defence if they are captured. Although often their bite is not even felt, it can cause mild bleeding because the snake’s saliva contains an anticoagulant.

Threats & Trends

The Lake Erie watersnake continues to decline in Ontario. It is severely threatened by habitat destruction resulting from the development of cottages and homes along the shoreline. Shoreline alteration, such as the construction of barrier walls or conversion of rocky shorelines to lawns and beaches, also destroys the natural habitat on which this species relies. Despite significant local education efforts and the knowledge that this species is not venomous, human persecution is still a serious threat to it on Pelee Island. Road mortality and predation also threaten the Lake Erie watersnake, especially on Pelee Island.

Current Status & Protection

The Lake Erie Watersnake is currently listed as Endangered under the Ontario Endangered Species Act, 2007 and Endangered under the federal Species at Risk Act. The species has also been designated as a Specially Protected Reptile under the Ontario Fish and Wildlife Conservation Act. These acts offer protection to individuals and their habitat. The habitat of this species is further protected in Ontario by the Provincial Policy Statement under the Planning Act. The International Union for Conservation of Nature has not assessed the global status of the Lake Erie watersnake. The species’ status was last confirmed in January 2010. Additional detail about legal protection for species at risk in Ontario is available on our Legal Protection page.

Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Reptile and Amphibian Stewardship page.

 

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Range

Lake Erie Watersnake Range Map

Ontario range (click to enlarge)

In Ontario, the Lake Erie watersnake is found on Pelee, Hen, East Sister and Middle islands in Lake Erie. Globally, this subspecies is limited to the southern shoreline of Lake Erie in Ohio and the western Lake Erie islands.

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