Changing fire regimes and faunal responses: Habitat use by Flammulated Owls after fire in Colorado

Since European settlement, human activities have resulted in fires that have burned the pine forests of western North America at higher severity and over larger areas than previously. On the basis of global climate models and current fuel loading across the West, larger and more severe fires are predicted to become more common in the future. Despite the potentially severe consequences of such fires on landscape structure and function, the effects of altered fire regimes on the behavior and ecology of birds in western forests have been little studied. We sought to determine how the Hayman Fire, which burned the largest area (560 km2) in Colorado history in 2002, affected habitat selection at multiple spatial scales by Flammulated Owls (Psiloscops flammeolus) that recolonized the burned area from 2003 to 2012. We radiotracked five breeding male owls from 2007 to 2012 and quantified their patterns of habitat use at multiple spatial scales. Breeding males established home ranges in habitats containing less area burned at high severity and more area burned at low severity or remaining unburned than was available within the fire’s entire perimeter. Additionally, the size of a home range was positively correlated with the proportion of area burned at high severity, indicating that such areas represent low-quality habitat for the species. The level of burn severity did not appear to be an important factor in the selection of habitats for foraging or day-roosting, indicating that habitat-selection patterns were altered by fire only at the scale of the home range. Our findings suggest that species with life histories highly adapted to ecosystems dependent on fire of low or mixed severity may not be resilient to human-modified fire regimes in which the proportion and patches of forest burned at high severity are larger. As the area burned at high severity increases, more western forests may become unsuitable for occupancy by species that have otherwise evolved with naturally occurring low-severity fire.