Wildlife Crossing

Mule deer walkingCABNR - in collaboration with Nevada Department of Transportation (NDOT), Nevada Department of Wildlife (NDOW) and the Nevada Wildlife Record Book - has turned out some big numbers for the state's mule deer population.

Professor Kelley Stewart and graduate student Nova Simpson have been tracking the migrating mule deer across some of the state's busiest-and most dangerous-highways.

The project is a statewide effort to keep deer and other animals off the highways in order to preserve wildlife populations and reduce vehicle collisions, Stewart said.

"Already, 12,000 mule deer have used the pass in the first three migrations," she said. "That means 12,000 deer that never touched the highway."

Within the mule deer's 120-mile migration pattern, the ungulates cross two points of U.S.- 93 and Interstate 80, Stewart said.

The two crossing areas-designed as combination overpasses and underpass tunnels  were chosen originally by NDOT and NDOW because they were identified as places with frequent animal-vehicle collisions. The deer move in small groups during migration with about 4,000 animals using the structure during each migratory period in spring and autumn.

Mule deer walkingThe animal crossings were monitored using a network of infrared, motion-sensing cameras. Simpson reviewed each of the 117,000 photos taken during autumn 2011 migration alone. Along with the 12,000 mule deer, she spotted American pronghorn, elk, coyotes, bobcats, red fox, domestic livestock and a variety of birds.

She also noted that the mule deer favored the overpass design to the underpass tunnels.

"During the first migration, 96 percent of the deer who approached the overpass crossed it successfully where as only 30 percent that approached the underpasses crossed successfully," Simpson said.

"It makes sense actually," Stewart said. "Most deer would rather climb a mountain than enter a cave, although they do get used to the underpasses and more deer have crossed them successfully with each subsequent migration."

Coyotes walkingSimpson and Stewart estimate that vehicle mortality rates of mule deer have decreased 50 percent with the addition of the crossing structures. They'll get a better sense of those figures when the project runs through a fourth migration season.

Looking ahead, NDOT and NDOW envision another crossing over Interstate 80 but have yet to finalize these plans. Zong Tian at UNR's College of Engineering is working on a cost-benefit analysis which will be finished in the coming months.

"Hopefully we'll get to continue with this," Stewart said. "It's a fantastic multidisciplinary project for the school, and it's great for conservationists, hunting enthusiasts and anyone driving on those highways who will now be less likely to encounter mule deer on the road."