Temporary warning signs, posted in spring and fall when mule deer migrate, reduce the number of deer killed in collisions with vehicles. The signs, evaluated in an Institute-sponsored study, represent a simple and cost-effective approach to the problem.
Working with officials in Idaho, Nevada and Utah, researchers at Utah State University developed signs to warn drivers they were entering areas of increased deer activity. Unlike traditional crossing signs that remain in place all year, the signs designed for the study were displayed only during migration and featured attention-getting reflective flags and flashing lights.
Besides the warning signs posted as drivers entered migration zones, there were smaller signs posted at one-mile intervals to remind motorists of the deer migration and indicate the number of miles left in the zone.
Researchers recorded numbers of deer killed in zones where signs were posted versus similar stretches of highway without signs. Records were compiled before and after the signs were posted. Researchers also measured vehicle speeds to see if motorists were exercising caution.
The number of deer killed in signed zones was reduced by half. Vehicle speeds went down.
Temporary signs are simple to erect and maintain. The average cost of treating four miles of road was $1,740. This technique does require coordination between local wildlife biologists and highway officials to track migration seasons. The most applicable areas are western states, where mule deer follow predictable migration patterns. The movements of white-tail deer in eastern states aren't as predictable.