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The Effects of An Icy Crust on Wildlife

1-19-15  ruffed grouse snow cave IMG_8590This winter has brought us several storms that have ended in rain and were followed by plummeting temperatures. Just a few inches down into the powdery snow on top of the ground there is a ¼”-thick crust, and if you dig down several more inches, there is a second layer of ice, roughly 1/8”-thick. When a thick, icy layer of crust forms, it can have a dramatic effect on the lives of wildlife both above and below it.

Some animals are relatively unaffected by the presence of a crust but many predators and prey are significantly helped or hindered by it. Ruffed grouse cannot seek overnight shelter from the bitter cold and/or predators by diving into a foot of soft snow and creating a snow cave (see photo). On the other hand, small rodents have a distinct advantage — mice and voles have several layers of ice between themselves and hungry coyotes, foxes and owls. Snowshoe hares lose the advantage they usually have on deep, soft snow — “snowshoes” that keep them on top of the snow when the bobcat or fisher chasing them has to flounder through it. Turkeys don’t have the strength to dig down through one thick crust, much less two or more, in order to reach hidden acorns. If a deer is being chased, its pointed hooves will break through the crust, slowing the deer down, whereas the crust may well support a lighter predator, allowing it to outrun the deer. Red squirrels have to work much harder to reach their cached winter cones and to create tunnels.

What is a mere inconvenience to us humans literally is costing as well as saving the lives of wildlife this winter.

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3 responses

  1. Great post! Seemingly simple events in nature are so complex, with so many ramifications for so many species, if we take the time to look beneath the surface (pun intended!).

    January 19, 2015 at 9:10 am

  2. Elizabeth

    Agree. Great post. Gives one something to think about when out in the woods.

    January 19, 2015 at 9:40 am

  3. I’ve been thinking about this lately as well. After last year’s vole damage, I’m not so happy about them having an advantage again this winter. I’d rather see more owls, turkeys, grouse and fox!

    January 20, 2015 at 7:21 pm

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