Climate change is leading to numerous shifts in weather patterns, including an increase in extreme weather events such as drought, hurricanes, and heatwaves. In order to escape these extreme events, animals often need to move to another physical location in a short period of time.
This ability to survive extreme weather events through escape is being made more difficult by increasing habitat fragmentation. Linear infrastructure, such as fencing and roads, can disrupt or even block an individual’s escape route. So far, there are few studies documenting the extent to which a lack of connectivity contributes to animal mobility and mortality when extreme weather occurs.
Aikens, E.O., Merkle, J.A., Xu, W. and Sawyer, H. 2025. Pronghorn movements and mortality during extreme weather highlight the critical importance of connectivity. Current Biology 35(8): 1927-1934.
To better understand the synergy between decreased connectivity and increased extreme weather, a recent study tracked 33 GPS-collared pronghorn during the historically severe 2023 winter in Wyoming’s Red Desert. That winter brought over four times the average cumulative snowfall, burying forage and creating deep snow conditions that pronghorn are poorly equipped to navigate.
In response, 94% of GPS-collared pronghorn undertook long-distance escape movements of up to 399 km to find less severe conditions. These emergency movements forced animals into unfamiliar areas where they encountered roads and fences, some of which were completely impassable. The delays caused by these novel barriers increased both the duration and intensity of snow exposure, increasing the animals’ risk of starvation and death.
Survival outcomes were stark. Over half of the 33 collared pronghorn died during the winter, with mortality 3.7 times higher than in prior years. Early departure from high-snow areas strongly predicted survival: for every week of delay, mortality risk increased by nearly 5%. Almost one-quarter of recorded locations indicated a barrier interaction, of which 93% were with previously unencountered barriers. Movement distance and path straightness had no clear link to survival, emphasizing that timing and barrier encounters, rather than journey characteristics, were most critical to persistence.
The study highlights the essential role of connectivity not just for seasonal migrations, but also for rare and unpredictable escape movements prompted by climate extremes. While much of conservation planning focuses on preserving known migratory routes, this study makes the case for proactively addressing “escape connectivity” – the ability of animals to move rapidly and safely during rare, extreme events. Because escape paths are often unpredictable and cut across unfamiliar terrain, ensuring general landscape permeability, particularly across known impermeable barriers like interstates, may be more effective than narrowly targeting known corridors.
The findings underscore a broader need for dynamic, flexible conservation strategies that account for climate extremes and landscape changes. As extreme weather becomes more frequent and severe, wildlife managers will need to look beyond traditional migration corridors and address a wider range of movement types to safeguard population resilience. This includes retrofitting fences, modifying highways, and integrating connectivity into broader land-use planning before the next mass mortality event occurs.
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