Surviving the cold — part I

Even though I’ve just read that 2015 was the hottest year in historical weather record-keeping (2 degrees F above average world annual temperature), the backyard here is buried in the deep freeze.  Several of my fellow bloggers have been posting queries about how animals survive conditions like this in the wild — or how humans who live and work outdoors all winter survive these extremes.  So, being somewhat of an expert on this topic once upon a time, I’m going to try to explain how they do it.

goldfinch-winter chill

Yikes — it’s chilly out there. for this young American Goldfinch

First — the challenges of winter at far northern latitudes:

  • low temperatures mean warm-blooded animals need to turn their heat producing furnaces to high to offset heat lost to the environment
  • wind, sleet, and any precipitation carry body heat away even faster than just being surrounded by cold air
slate-colored-junco

Who ordered this sleety, icy rain?  But Slate-colored Juncos are tough, and they outlast this kind of inclement weather.

  • the sun is low in the sky and it’s often cloudy and overcast, so radiant heat input is hard to come by
  • where’s the food?  Summer production is long past, food is buried under snow, other animals got to it first — so how does a warm-blooded animal get enough energy daily to fuel the heat-producing furnace?
white-tailed-deer-in-snow-

Really, there isn’t much here to fuel the needs of a large-bodied animal like these White-tailed Deer.

Solutions:

1. Prepare for it:  Those chilly fall mornings and waning daylength are signals that challenging days are ahead.  Animals prepare for the challenges of winter by hoarding or stashing food in places where they can find it later. Usually, there is a flurry of activity at bird feeders as birds and squirrels take seeds to their winter roosting sites.

chipmunk

Packing those cheek pouches full, a chipmunk carries his prize underground to eat later.

And — a new set of freshly molted feathers in the fall not only disguises once brightly colored birds, but provides a nice, new downy coat of insulation.  An under coat of dense fur beneath longer guard hairs helps keep mammals warm in the winter.

2. Eat like crazy — in order to put on a nice layer of fat reserves.  This strategy works better if you’re a fleet-footed mammal, because when birds put on too much fat, they can’t fly.  In addition to the insulative value of a layer of fat, it does provide an energy reserve for overnight energy expenses and the days when foraging for food was inadequate.

house-finches

Dining with friends (House Finches) is always a good idea, so that many eyes can spot the skulking predators.

common-redpolls-

Pine Siskins are so good at searching out and consuming high volumes of seed per day that they can maintain their body temperatures, even at very low extremes.  Like Common Redpolls, these little birds are champions at cranking up the metabolic furnace to generate heat.

And — since there aren’t many insects active in the winter, avian insectivores like chickadees switch their diet to take advantage of the high-energy content in seeds.

black-capped-chickadee

Do you wonder how a bird that weighs less than a McDonald’s ketchup packet stays warm in sub-zero cold weather?

3. Hide from the worst extremes:  Chickadees, nuthatches, and woodpeckers find a refuge from extreme temperature and wind in a roost hole.  Some sparrows and larger birds like Robins and Blue Jays huddle in the thickest part of evergreen vegetation which protects them from the effects of wind and precipitation.  Many mammals retreat to underground burrows, tree cavities, or leafy nests to hide from extremes.

bear-in-den-illustration (nps.gov)

Below ground, temperatures are above freezing, and mammals are protected from wind and precipitation. (Illustration from http://www.nps.gov/katm/blogs/Bear-Hibernation.htm)

To be continued tomorrow with more solutions….

white-tailed-buck-in-snow

7 thoughts on “Surviving the cold — part I

  1. Pingback: Surviving the cold – part II | Back Yard Biology

  2. I feel bad for all those puffed up birds, but I know they are equipped to handle the cold. I’m not so sure how humans do it though. I need those HotHands and feet heat packs to go out birding in this weather.

    • I think you acclimate to the cold more than you realize. Remember how warm 20-30 degrees F feels in February, compared to how it felt in November? We may use our big brains to warm up the environment around us, but we do have some ability to cope with a cold temperature challenge, naked skin notwithstanding. 😃

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