Coping with cold

Continuing on the theme of what animals do to survive winter cold, it can be just as much of a problem being large as being small in intensely cold weather.

deer-in-the-winter woods

When you are big-bodied, there are few places to take refuge from cold temperatures and wind chill, which increases the rate of heat lost to the cold environment.  In addition, large-bodied animals would need a large amount of food per day to maintain a warm temperature, and winter is typically the most difficult season in which to find it.

The twins munched their way across the backyard on a cold morning recently, in search of some nutrition from twigs and stems.

The twins munched their way across the backyard on a cold morning recently, in search of some nutrition from twigs and stems.

Their heavy winter coats insulate their core, but lots of surface area of exposed extremities could be vulnerable to high heat loss.  At sub-zero F air temperatures, even large-bodied deer will have to expend energy to stay warm. Daily food consumption is too meager to support that expense, so deer have to dip into the fat reserves they built up in the fall eating energy-rich foods like acorns.

From Outdoor Life:  What deer eat.  Aug 31, 2012

From Outdoor Life: What deer eat. Aug 31, 2012

The White-tailed Deer strategy for surviving winter cold is a conservative one — reduce energy expenditures to conserve body fat.  They let their extremities chill to the same temperature as their environment, so little heat is lost there.  They eat snow (for moisture), which lowers their core temperature and heart rate, and thus their whole-body metabolism.  They reduce their daily activity, spending less time foraging, which also saves some energy.  In short, deer coast through the winter relying on their fat reserves, hoping for an early spring (don’t we all!).

winter-deer

6 thoughts on “Coping with cold

  1. Hi! Nice post on deer! Here’s a behavioral winter strategy: They tend to yard up under evergreens on south facing slopes. Evergreens catch snow so less accumulates under them, making it easier for deer to move about. South facing means it is sunnier and warmer.

    • Hi Janet, Thanks for the additional information. Behavior is so important in survival; I really only touched on the physiological and anatomical strategies.

  2. Southern slopes are much warmer in the winter, especially when they are out of the wind. If they are rocky the stones absorb sunlight during the day and release it slowly at night. I tend to seek out these places in winter too, because they’re so much warmer.

    • So true — we can even feel the difference through our thick winter coats, and I know what you mean about standing on a south-facing slope with its re-radiating heat.

  3. In the area around here, white tails get a lot, perhaps most, of their winter food from Antelope Brush, AKA Antelope Bitterbrush (Purshia tridentata). When the snow is deep, deer tracks surround the bushes as they browse.

    Mulies choose south-facing open hillsides beneath sharp ridges over which they can find dense cover from cold winds and predators. Through most of the winter the steep hillsides catch enough sun to melt the snow down to expose enough grasses to keep the deer fed.

    I find their various strategies intriguing!

    • Interesting information — thanks for writing. Subtle behavioral techniques can make all the difference between life and death, especially in our (and your) winter environments.

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