Winter On The Boise Front (January 25, 2010)

By Ed Bottum, Wildlife Biologist, Idaho Department of Fish and Game (IDFG)

Winter is the time of year the Boise River Wildlife Management Area was created for.

During winter, the WMA functions at its “highest and best use,” providing a place for one of Idaho’s migratory mule deer herds to spend the winter in relative comfort. Relatively more comfortable say, than at higher elevations where snow depths are greater, temperatures lower and winter conditions last longer.

Winter is a time of stress for most animals when how well they fared during the summer months may determine whether or not they will see another summer. Mule deer and elk will spend the next few months using up their stored reserves of body fat while they wait until abundant food becomes available again next spring when plants begin to grow. In the meantime, they conserve their energy as much as possible while looking for things to eat to make their fat reserves last. If their fat reserves run out before food becomes available, they face starvation.

As so often happens, situations we think are straight forward sometimes turn out to be more complex than expected. Take winter recreation for example. Many people know how important it is for our physical and mental well being that we stay active. We might assume the same holds for mule deer and elk, too. Well, in fact, just the opposite is true for them. They spend their winters not moving around anymore than is necessary while finding food and favorable places to “hang.” One day it might be out in the open on a sunny south-facing slope while on another it might be sheltering behind shrubs out of the wind on a darker, north-facing slope.

People whose winter recreation plans include a visit to Boise’s foothills should remember that their presence in an area where big game spend the winter adds another stressor to a long list that wintering wildlife contend with every day.

Deer can become accustomed to vehicles going by, and eventually they pretty much ignore them. But deer often view people on foot as more of a threat, and they will likely stop what they are doing (eating or resting or moving from one favorable spot to another) and flee to a place out of sight of hikers or skiers.

Responding to human intruders costs deer extra energy. The more energy they have to use moving around unnecessarily, the less energy they have to get them through the winter. And if people bring dogs, the impacts are far more severe because deer view them as predators – even the lovable, well-behaved, leashed best friend.

Migrating big game herds bring more than their graceful beauty to the foothills around Boise. They also “bring” their predators. Mountain lions and now wolves follow prey to their wintering grounds just as they have done for thousands of years. People who recreate around wintering big game should be aware of the potential for encounters with their predators.

Mountain lions can be a danger to smaller people. While wolves present little danger to humans, they are a very real danger to dogs. Use good judgment when recreating around wintering wildlife. The life you save might be theirs.

Mule Deer in Winter
Photo by Scott Rudel

Ed Bottum is a wildlife biologist and manager of the Boise River WMA.