Investigating Potential Solutions to the Barrier Effect of Interstate 80 on Pronghorn Movements

US Transportation Collection2021PDFTech ReportRobb, Benjamin SRudd, William JKauffman, MatthewHart, ThomasGamo, ScottUniversity of WyomingWyoming. Department of Transportation. Research CenterWyoming. Department of TransportationUnited StatesWyomingDeerLocationMigrationTraffic crashesWildlifeWildlife crossingsConnectivityFencesSimulationUnderpassesUngulatespronghornWyomingmule deerAntilocapra americanaOdocoileus hemionusWY-01/211003849Compton, KeithFinal ReportPronghorn rely on long-distance migrations to access seasonal resources and mitigate the consequences of severe winters and droughts. When barriers sever routes to alternative habitats then pronghorn populations may decline as a result of loss of habitat. Wyoming highways and interstates include woven-wire ROW fencing along the road. Such fencing can be effective deterrents to pronghorn and other ungulates from getting onto roads, which could otherwise pose a threat both to passengers and wildlife. However, this has also exacerbated the barrier effects faced by pronghorn. In our study, we sought to predict the most likely crossing locations for pronghorn across the Wyoming section of Interstate 80 (I80), given seasonal habitats and existing migratory habitat of pronghorn in southern Wyoming. We used a novel approach to develop connectivity models that assign the most likely estimates of movement costs as a function of landscape attributes to predict the probability of corridor use. By combining seasonal habitat predictions with our connectivity models, we simulated the most probable locations of historical corridors used by pronghorn prior to the development of I80. We evaluated the accuracy of our predicted corridors using locations of pronghorn carcasses from attempted crossings, as well as trail camera counts of pronghorn using underpasses, and professional review by wildlife biologists. Our results provide a large-scale assessment of pronghorn seasonal habitat, connectivity, and the identification of crossing structure locations that may best restore migratory behavior across a nearly impermeable barrier.120