High temperatures alter core behaviors of mountain goats ( Oreamnos americanus ), a cold-adapted species

Abstract Rapid climate changes are reshaping ecological communities in montane environments. Among those most strongly impacted are cold-adapted organisms that may experience thermal stress at moderate temperatures. The importance of facultative behavioral changes to altered abiotic resources like water, shade, and snow is well documented. However, behavioral patterns of spatial selection may change, particularly for cold-adapted species during summer months. We examine how high summer temperatures affect the behavior of mountain goats (Oreamnos americanus), a cold-adapted species with a Holocene distribution closely associated with periglacial environments in western North America. We hypothesized that habitat use by mountain goats during summer months is modulated by high temperatures, leading to increased selection for habitats that offer thermal refuge, including snow. We evaluated resource selection at 2 spatial scales: within the home range and at 4-h movement steps. During the warmest 15% of summer days, at the home range scale, mountain goats increased use of areas with lower solar radiation, higher elevations, locations further from predator escape terrain, and areas closer to human infrastructure. Contrary to expectations, mountain goats exhibited only modest selection for proximity to snow, and selection further decreased at peak temperatures at the home range scale. At the fine scale (4-h steps), individuals selected for relatively lower elevation and increased solar exposure during the warmest periods. These results suggest that avoidance of thermal radiation may be more effective through changes in behavior at the home range scale. Importantly, we document changes in intrinsic behaviors such as seeking safety from predators in steep terrain during the warmest days. As montane environments continue to warm rapidly, understanding changes in resource use during the warmest periods today offers an invaluable lens for understanding challenges for populations tomorrow.