Fire impacts on a forest obligate: western gray squirrel response to burn severity

Abstract

In the southwestern United States, climate change and climate-fire dynamics are affecting the distribution of natural and managed ecosystems. Forest obligate species on sky islands can experience a restriction in range with the increase of destructive forest fires. Using presence/absence data collected by hair tubes, we identified key habitat features that determine the western gray squirrel (Sciurus griseus) distribution on the sky island of the San Bernardino Mountains (California, USA) and determined post-fire differential use of burn severity in a landscape modified by fire. Gray squirrel presence was related to habitat features important for this species' ecology and behavior, especially those associated with mature forests. The species was detected in areas with a high percentage of conifers that provide both an important food resource and good branches and cavities for nest sites. Gray squirrels occurred in all burn severities but occurred more in low and high severity sites than unburned sites. These results suggest that the gray squirrel can persist after a wildfire and can take advantage of the post-fire habitat structure if a mosaic of burn severities is maintained in the forest.