Long-Term Population Monitoring Reveals Changes in Mesocarnivore Occupancy in Response to Severe Drought.

Rapid shifts in climate conditions can disrupt disturbance regimes and generate novel spatial conditions that have consequences for wildlife. In the montane Sierra Nevada range of California, USA, many species occur in sympatry, with local variation in elevation, climate conditions, and forest structure allowing species that may compete with each other to persist. However, shifting climate conditions in this region have potential impacts for species persistence and coexistence. From 2012 to 2015, a historic drought in California resulted in < 5% of expected snowpack and atypically warm winter conditions. These climatic conditions were thought to impact mesocarnivores, with particularly negative effects for species occurring at their range limits. Understanding how rapidly shifting conditions may affect species occurrence and persistence provides an opportunity to guide contemporary conservation efforts and better understand how continued change may imperil sensitive species. We examined the effects of this historic drought and contemporary forest structure on the occurrence of four sympatric mesocarnivores: Pacific martens (