Safe Passage for People and Wildlife (June 16, 2010)

by Ed Bottum, Wildlife Biologist, Idaho Department of Fish and Game

From Idaho’s capital city to Mores Creek summit and beyond, State Highway 21 snakes its way across the Boise Mountains. Also known as the Ponderosa Pine Scenic Route, the highway has long been a preferred route for Treasure Valley residents to access their favorite high country recreational haunts.

Just outside Boise, the Scenic Route intersects another favorite travel route. For millennia, mule deer and elk have travelled to and from low elevation ranges, where they spend the winter, to mountain meadows where they grow fat each summer feasting on the rich vegetation found at higher elevations. In doing so, they must cross State Highway 21. For many of these animals, those few steps on the pavement are their last.

Each year, scores of deer and elk are killed as they attempt to cross Highway 21. With more development along the highway, commuter traffic to and from Boise has increased also, bringing with it a dramatic increase in vehicle/big game collisions. In recent years, from 75 to 200+ mule deer and elk attempting to cross the highway between Boise and Robie Creek have been killed by vehicles.

For the past several years, a group of local people have come together with the common goal of finding ways to reduce wildlife/vehicle collisions on our roads and highways. Dubbed the Boise River Wildlife Linkage Partnership, the group includes private citizens, business people, non-profits and city, county, state and federal representatives. One place in particular where the group has focused attention is the Ponderosa Pine Scenic Route.

In an effort to raise awareness among motorists traveling the route, the partnership worked with the Idaho Transportation Department and Fish and Game last winter to install deer and elk “tally” signs along the highway. The signs regularly update the number of deer and elk killed along the route in motor vehicle collisions during the calendar year.

This educational effort will undoubtedly help reduce the number of wildlife/vehicle collisions along the route. But they do not address the issue of big game animals having to cross the highway. An exciting development directly related to this effort will.

This summer, a wildlife underpass will be built on Highway 21 near milepost 18.2, a well-documented big game migration “funnel” and subsequent collision “hotspot.” A bridge will be constructed where fill now supports the roadway. Following bridge construction, the fill beneath will be excavated, opening this migratory corridor to deer and elk. By physically separating wildlife and motorists, the wildlife underpass will provide protection for both.

The second phase of this project involves building a wildlife fence designed to direct deer and elk away from the highway and towards the underpass. Federal stimulus funding is being used to construct the bridge and a portion of the fencing. But additional funding is still needed to complete the fencing project.

For more information regarding the Boise River Wildlife Linkage Partnership, or to donate to the wildlife underpass project, visit the Partnership website at And watch for additional information regarding the Linkage Partnership and its ongoing efforts to reduce wildlife/vehicle collisions on the Ponderosa Pine Scenic Route.