Canada lynx occupancy and density in Glacier National Park

Abstract

Protected areas are the cornerstone of conservation strategies for threatened and endangered species. Because protected areas often are insulated from many anthropogenic threats, and contain substantial topographic relief, they may be particularly important as climatic refugia for cold-adapted, at-risk species. Canada lynx (Lynx canadensis) are a cold-adapted, threatened species, and reach the southern limits of their distribution in the contiguous United States, where they exist in several disjunct populations largely on multiple-use lands (e.g., national forests). Glacier National Park (GNP) is one of the few, large, protected areas located within Canada lynx range in the contiguous United States, and therefore a potentially important lynx stronghold within the Northern Rockies lynx recovery unit. Despite its potential importance, knowledge of lynx populations within the park is extremely limited. We completed a park-wide occupancy survey of lynx using an array of motion-sensitive cameras during summers in 2018–2021. Within a smaller area of the park, we also estimated lynx density by identifying individuals from subtle markings on the inside of the front leg and employing spatially explicit capture-recapture analysis. Finally, we linked park-wide predictions of occupancy with local density to estimate lynx population size across GNP. Lynx were distributed across much of the park in summer and occupancy was influenced by a combination of snowshoe hare (Lepus americanus) relative abundance, forest associations, climate, and fire. We were able to successfully identify approximately 75% of lynx captures to individual based on coat markings. Although average park-wide lynx density was low (1.28/100 km2) compared to populations in the core of the range, park-wide abundance was substantial for this threatened predator (52; 95% CI = 30–92). Based on our results, we propose that GNP should be considered as a potentially important area for lynx habitat refugia in a warming climate. Moreover, our ability to rapidly assess distribution and density using camera deployments in summer could be useful for long-term monitoring and recovery assessment.