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Roads and Rattlesnakes Don’t Mix

August 24, 2010

No one has been bitten by a rattlesnake in Vermont in over 50 years. But a few weeks ago this streak ended when a man in Fair Haven was struck between the thumb and index finger by a snake when he was supposedly trying to move it off the road with a stick.

Game warden Don Isabelle told the Rutland Herald, “I think it’s important to get the message out that snakes aren’t necessarily lying in wait to ambush people. It’s actually the opposite — they’re very timid and docile. This individual was just too close. Doing what he did, that’s not a wise move.”

If the man was trying to help the snake off the road, he had one thing right. Rattlesnakes and roads don’t mix. Recent research in nearby New York shows that rattlesnake populations are severely limited by roadways.

Northern populations of Timber Rattlesnakes are concentrated around traditional winter dens, called hibernacula. Males and females often return to their natal hibernacula as adults. When they emerge in the spring, the adults disperse into the surrounding forests to forage and mate. Males often move twice as far as females, up to 7 km.

Behavioral studies show that rattlesnakes appear to avoid both paved and unpaved roads. When they do cross them, it is often deadly. They cross very slowly and when they sense traffic they often pause for long periods.

Biologists from Cornell University and Skidmore College teamed up to examine the impacts of roads on genetic variation within and between populations of Timber Rattlesnakes in New York State. Snakes from hibernacula isolated by roads had lower genetic diversity and higher genetic divergence than those in contiguous forest. The roads have only been in place for 7 to 10 generations of rattlesnakes, indicating just how negative roads are to spring dispersal.

Even seemingly intact forests might be fragmented and cause deleterious effects on gene flow for some species like rattlesnakes. Hopefully, roadways near hibernacula can be identified and mitigation measures such as underpasses can be constructed.

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3 Comments leave one →
  1. Pete permalink
    August 24, 2010 8:30 am

    “supposedly” trying to move it eh?

  2. Rosemary Allen permalink
    August 24, 2010 1:45 pm

    Have successful underpasses been built in the past for this type of situation?

    • Kent permalink
      August 26, 2010 7:10 pm

      Not that I know of, but I think this study suggests that it would be a really good idea. There are overpasses and underpasses for everything from migrating ungulates to spotted salamanders. I think we are going to see more and more of this kind of engineering in the future. However, it is expensive.

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