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Snow is Good

February 25, 2011 | by Bruce Auchly

In the middle of this snowy winter, perhaps it’s a good time to ask from a wildlife perspective what good is all this snow and cold.

Most places east of the Continental Divide this winter have lots of snow. Too much snow according to news stories about suffering, dying deer and antelope.

Although it’s tough on individual animals, species that evolved in this northern latitude have the ability to handle winters featuring above average snow and cold.

To us winter is cold, snow, short days and wind.

To animals the ability to survive winter centers on timing, duration, seasonal changes, and repetition, according to “Winter: an ecological handbook,” by James Halfpenny and Roy Ozanne.

Timing is all about when winter hits. An early cold snap without a protective coat of snow will kill those plants and animals not yet ready. A late spring blizzard will kill deer with depleted fat reserves.

Duration, or length, of winter, which we may take as an inconvenience, can hit hard those animals that depend on stored food. If long lasting snow cover doesn’t allow a pika to replenish it food stores, it dies.

Seasonal changes are the ability of an animal to survive large changes between seasons. A good example is the opossum, a native of South America that has spread into North America where seasonal temperature changes are low.

In northern latitudes, like Montana, the swing between summer highs and winter lows is usually too much. Those few opossums that try to hang on through a northern winter may be found with missing parts of tails and ears, the result of freezing.

Repetition of hard winters may lead to a downward population spiral. Deer can deal with a tough winter. Too many tough winters in a row, however, will put a local deer population into a tail spin that may take years to recover from. Or make it more susceptible to other pressures like summer drought and predators.

So where’s the good news?

For predators or scavengers hard winters bring an immediate feast.

For prey species there is good news just not immediately.

Mild winters allow prey species like mice and deer to build populations, perhaps to levels the habitat can’t withstand. Along comes a hard winter and those species start tipping over. Suddenly it’s an all you can eat buffet for eagles, coyotes and weasels. Eventually those predators will find themselves out of food and their populations will fall. But right now, hey, let’s eat.

The prey species that survive will find all that frozen water will eventually melt, nourish the soil and make for lots of lush, nutritional vegetation.

Tough winters also allow only the hardiest to survive and pass along those survivability genes, leading in the long, even evolutionary, term to a hardier species.

That can be a difficult concept to comprehend as we watch deer and antelope succumb to weather. Yet it’s important to keep the species in focus more than the individual animal.

Nature may look tough, even cruel at times, but nature knows best.