Monday, January 27, 2014

How do wild animals deal with severe cold?

Chickadees spend the cold nights in woodpecker holes

Deer might be at risk this winter with both bitter cold and deep snow

Red foxes and other furbearers should be unaffected
We have now experienced nearly two months of severe winter cold here in Northwestern Ontario and I'm beginning to wonder if this long stretch of continuous bitterness will have an effect on wild animals.
We would normally say that the cold has little impact on native creatures, that they are adapted to it, but this is not a normal winter, not even a normal cold one. December was the coldest on record and when January is over, it's going to either set another record or be right there in the running. And already the long-term forecast for February is more of the same.
And those low-temperature records are only part of the story. The wind chill is far worse this year than any time I can remember. It seems four days out of every week have a wind chill warning attached to them. That means human skin can freeze in just a minute or two. It must also have a chilling effect on animals.
The one native animal that is known to suffer from a cold winter is the black bear. If the cold gets down to them in their dens they can freeze to death. These dens are typically just barely below the surface of the ground. They are just about always in the cavity left from a tree tipping over and uprooting. The bears can line this tiny little tent with leaves and branches and once they crawl inside, turn their backs to the hole. You can see their fur sticking right out.
Bears would certainly be in serious trouble this winter if it wasn't for all the snow. We have about two feet of the stuff and that should provide enough insulation to the bears down there in their dens.
Furbearing animals such as wolves, foxes, marten, fisher, etc. should also be OK. They are really built for staying warm and if it gets too bad, they too can dig down through the snow and get out of the wind.
It's the deer and moose that I think could take a hit. From the time the last leaves fall off the trees in the autumn to emerging new growth in the spring, deer and moose are in a negative nutrition state. That is, the calories they get from browsing woody twigs aren't enough to sustain them. They lose weight every day. If spring comes too late, even in a normal year, they are at risk of starvation. This year, however, they will need to be expending even more of their fat reserves just to keep warm.
For the deer, snow is usually the limiting factor. If there's too much for them to plow through, it uses up more of their fat and they are at risk. We already have two feet of the white stuff. That's enough to make life a little difficult for deer, and we usually get most of our snow in March. So the worst is still to come on that front. Between the snow and the bitter cold, I think deer could be in trouble.
Moose are less affected by snow because they are so much taller, but even these huge animals prefer winters with less snow depth. You can tell this just by where they go in the depth of winter -- often on the tops of the tallest, most-exposed hills. These would be the coldest places around because of the wind but they frequently have little or no snow. It just blows away. So the moose would seem to trade less snow for more cold.  I wonder if that's the case this year with so much bone-chilling windy weather.

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1 comment:

patricia morris said...

We spend summers on Lunny Island in the Lake of the Woods. I greatly miss the Whitetails this year - we only have one or two on the island when we would usually see families of around 5. I know that deer are in great danger in a lengthy winter of severe temperatures and deep snow drifts but learned more from your
article. Thank you very much, Pat Morris