Identifying impediments to long-distance mammal migrations

Area of Science:

• Wildlife ecology
• Conservation biology
• Movement ecology

Background:

• Long-distance mammal migrations are increasingly threatened by human development, including roads, fencing, and energy infrastructure.
• Identifying and mitigating barriers to animal movement is crucial for conserving migratory species.
• Anthropogenic developments can impede animal movement and alter habitat utilization patterns.

Purpose of the Study:

• To identify anthropogenic impediments to pronghorn (Antilocapra americana) migration in the Greater Yellowstone Ecosystem.
• To assess the impact of fences and highways on pronghorn migratory behavior and habitat use.
• To inform conservation strategies for migratory mammals facing development pressures.

Main Methods:

• Applied Brownian bridge movement models to high-frequency GPS location data of pronghorn.
• Utilized resource utilization functions to evaluate threats posed by fences and highways.
• Compared pronghorn habitat use at highway crossings with known migration bottlenecks versus those without.

Main Results:

• Migrating pronghorn avoided areas with dense natural gas development.
• High-traffic highways and woven-wire sheep fences acted as complete barriers to pronghorn movement.
• At bottleneck crossings, pronghorn showed reduced use of high-quality forage and shrub habitat near highways, unlike at non-bottleneck crossings.

Conclusions:

• Minimizing future development in crucial migration corridors is essential.
• Mitigation strategies such as removing barriers, reducing development footprints, or installing crossing structures are needed to support migratory animals.
• Conservation efforts must address existing human-caused impediments to ensure the persistence of long-distance migrations.