Resident and translocated American black bear movement patterns help identify locations for crossing structures along Interstate 40 in Tennessee and North Carolina

Abstract

Fragmentation caused by roadways can reduce connectivity for terrestrial wildlife species, which can isolate populations and cause reduced gene flow and biodiversity. In the Pigeon River Gorge (PRG) of Tennessee and North Carolina, USA, Interstate 40 separates Great Smoky Mountains National Park from Cherokee and Pisgah national forests, creating a barrier to wildlife movement between largely undeveloped tracts of contiguous forest. Wildlife road mortalities are common on the 51‐km stretch of roadway, with the American black bear ( Ursus americanus ) comprising the greatest proportion of large mammal deaths. Our objective was to use black bear global positioning system (GPS) location data to predict movement and compare road‐crossing behavior of resident and dispersing bears. We used data from conflict bears that were translocated to the PRG as a proxy for dispersers because both would be inexperienced with their new surroundings. We used a combination of hidden Markov models and step selection functions to create a resistance layer for circuit‐theory analysis to predict bear movement (flow) across the landscape. We identified locations along the interstate that had greater‐than‐average flow as key crossing areas. Translocated bears interacted more with the roadway by way of attempted, successful, and unsuccessful crossings, compared with their resident counterparts. Translocated bears had longer step lengths while moving across the landscape. Both translocated and resident bears selected areas with lower percent slope and higher percent canopy, but residents also selected ridgelines and drainages for movement. Flow across the landscape was more generalized for translocated bears, and Interstate 40 was a barrier to movement, particularly for resident bears. Our models predicted several consistent road segments as having greater‐than‐average flow where bears might benefit from crossing structures or other mitigation measures.