Naturalists are sounding the alarm after a deadly day for at-risk and endangered snakes near a nature preserve in Windsor, Ont.

Wednesday, biologist Jonathan Choquette recorded 91 dead snakes that had been struck by traffic near the Ojibway Park Prairie Complex. At least 30 of those snakes are designated species-at-risk, including the Butler's garter snake and the eastern fox snake. Those two species are endangered.

"I couldn't believe it," Choquette told CBC News. "It just blew me away."

Choquette has been researching road mortality in Ojibway since 2010. He's a co-author of a three-year study on the road mortality of reptiles that was recently published in Canadian Field Naturalist magazine.

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Jonathan Choquette recorded 91 snaked crushed on roads near the Ojibway Prairie Complex in Windsor, Ont. (Meg Roberts/CBC)

Most of the snakes were killed on Malden and Matchette Road, two busy road that connect Windsor and nearby LaSalle, Ont. 

"It's surprising, it's shocking, especially when we're dealing with a site like Ojibway which is a nationally recognized natural site," Choquette said. "I had to stay out until dark because I saw so many of them." 

It appears snakes move toward hibernation spots and cross the roads to get there. With asphalt and pavement warming in the sun, the snakes could also be looking for warmth in the evening.   

This isn't the first time snakes at Ojibway and motorists have come into conflict. In 2014, the Ojibway Nature Centre began a public information campaign to warn drivers from hitting snakes.

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Jonathan Choquette shows one of the snakes crushed by vehicles near the Ojibway Prairie Complex nature preserve. (Meg Roberts/CBC)