Movement and Distribution Patterns of Pronghorn Antelope in Relation to Roads in Southwestern, WY: FHWA-WY-06/02F
Pronghorn antelope (Antilocapra americana) evolved in response to variable food sources and weather conditions on the open, western high plains. Survival of the species is dependent on their ability to move in response to fluctuations in food supplies and weather conditions. Using global positioning system (GPS) collars and geographic information systems (GIS), the movement and distribution of adult female pronghorn (n=72) within a population in southwestern Wyoming was studied.
While unfenced roads did not appear to be a barrier to pronghorn movement in my study area, the combination of heavy traffic volume (Buechner 1950) and fences along roads can be barriers to movement and fragment habitat. Fences in southwestern Wyoming influenced distribution and movement patterns of pronghorn. Fence density was found to be lower in seasonal home ranges than in the study area. Fence density influenced location of seasonal range with pronghorn choosing those areas within the study area with lowest densities.
Fence density was greater within the periphery of home ranges than the remainder of the home range, suggesting home range conformation could be influenced by fences within the outer portion of home ranges. Most (64%, n=28) monitored pronghorn were migratory and their migration routes tended to encounter fewer fences than had they traveled randomly in the study area. The presence of fences and, in turn, the type of highway right-of-way fence determined whether roads were included in seasonal ranges and where pronghorn crossed roads within season and during migrations. Seasonal crossings of primary roads within the study area consistently occurred along unfenced sections.
These results support limiting fences on pronghorn range and maintaining unfenced sections of highways as movement corridors to reduce the potential for habitat fragmentation through loss of connectivity and allow access to crucial winter range within the study area.