Road carcass study documents many wildlife collisions on US-20

By Mary Van Fleet | Guest columnist | Jun 4, 2020 | Post Register

I’m an Island Park resident and have witnessed many wildlife-collisions and heard many stories. One hit a deer on Ashton Hill, causing $8,000 damage to his truck; another hit a moose and it resulted in a lifetime in a wheelchair. Many such incidents could be avoided with better road design.

Besides risks to people when they hit a big animal, vehicles and roads are potential barriers to wildlife movement. Wildlife-vehicle collisions are an increasing cause of death to wildlife. These impacts and effects are being looked at more closely around the country, especially in areas rich in wildlife, such as Fremont County and Island Park.

Mary Van Fleet
Mary Van Fleet

In 2017 the Idaho Department of Fish and Game initiated a two-year study of wildlife mortality on US-20 from Ashton north to the state line. The study shows there is far more roadkill there than has previously been reported. Five times higher. While there is some historical data on this, reported by local law enforcement and IDFG staff and private citizens, no formal study has been done until the work just completed by IDFG.

The data was collected by IDFG staff and trained volunteers (master naturalists). Some funding was provided by a USFS grant. For all observations, a specific protocol for data collection was adhered to and duplicate reporting was removed. It required driving US-20 from Chester and US-87 to Montana (63 miles) every two to three days for 24 months and recording each roadkill observing species, sex, age, location and condition.

In terms of big-game, 246 roadkills were counted for the period of December 2017 to December 2019. There were 126 mule deer, 52 elk, 24 moose, 19 white-tailed deer, six pronghorn and 19 unidentified. The highest season for wildlife-vehicle collisions was May and October, during spring and fall migrations. However, elk and moose were hit throughout the summer months and the entire US-20 Island Park area.

This study provides the first scientific baseline of wildlife-vehicle collisions on US-20. And the five-times higher numbers emphasize the need to take a closer look than had been taken in the past. Every wildlife-vehicle collision carries the risk of human injury or death. In the summer of 2018, five people were rushed to the hospital after a crash on US-20 when drivers encountered a herd of elk on the road. In 2017 several people were injured when their vehicle hit a bison near Targhee Pass.

The moose, elk, deer and pronghorn are all important species to Island Park and Idaho’s hunters. More care should be taken when driving US-20 during the May through October time. Although this data gives us a baseline for big-game killed on US-20, it does not tell us to what extent the road and its traffic may be impacting wildlife movements and migration.

Such information should be incorporated into decision making related to traffic and highway management. This is as important to the lives of people driving US-20 as it will to wildlife trying to cross the highway.

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