The Last Best Place for Boise's Mule Deer

September 12, 2005

A unique and special place encompasses the foothills and mountains east of Boise. Fish and Game calls this area Game Management Unit 39, and during the last thirty years, it has provided recreational opportunity for countless wildlife watchers and outdoor enthusiasts. It has also provided between 40,000 and 50,000 days of mule deer hunting opportunity for more than 15,000 hunters. Unit 39 remains one of the top three mule deer hunting units in the state, a position it has held since the 1970s.

Today, it is estimated that more than 25,000 mule deer make up the Unit 39 deer herd. During the spring, summer and fall, mule deer are spread throughout the unit, all 2,300 square miles of it. Normally there is plenty of summer range to support this large deer population, including the new crop of fawns produced each spring.

But when temperatures grow cold, and winter snows begin to fall, much of the unit is no longer hospitable to mule deer. In small bunches and larger groups, mule deer begin their annual migration to winter range - the foothills and lowland areas near Boise - to escape the snow and cold. It is during this time, and in these places, that food, space and thermal cover become limited.

During my twenty-some years in the Boise area, I have witnessed first-hand continued human encroachment on this mule deer winter range. And because it has not happened all at once - a few acres here, another 100 or 200 there - this slow and insidious process has gone relatively unnoticed.

Today, an area of about 700 square miles sustains this deer herd each winter. Almost two-thirds of this winter range remains in private ownership. Fifty square miles of the range are already developed and as Boise's human population continues to grow, so does the pressure to develop and subdivide even more of the remaining deer winter range in the Boise foothills. Each time a piece of this special place is converted from its native shrub steppe vegetation to paved streets and houses, mule deer suffer; reducing mule deer winter range reduces the number of mule deer the remaining range can support - period.

In addition to the direct removal of habitat, human encroachment on this last best place for unit 39's wintering mule deer has other downsides: additional human disturbance during the most difficult seasonal period in a mule deer's life; increased occurrence of human-caused fires which can lead to decades of rehabilitation before the burned area is used by mule deer again; and increased vehicle traffic, which adds directly to deer mortality in unit 39.

The end result of reducing mule deer winter range habitat is a corresponding reduction in the number of deer able to survive there. This incremental reduction of winter range is like gradually exhausting your savings account. After years of slowly spending money without making deposits (which, in the case of winter range is not possible - there simply is no other "vacant" winter range available), you wake up one day and find that your account has vanished.

All outdoor enthusiasts who enjoy watching or pursuing mule deer in this area need to be aware of the ramifications of reduced mule deer winter range and how that reduction will affect the entire Unit 39 mule deer population. If you're like me, you take no pleasure in the prospect of waking up twenty years from now only to find a fraction of today's deer population on the hill.