Long-term benefits of burns for large mammal habitat undermined by large, severe fires in the American West

Escalating wildfire frequency and severity are altering wildland habitats
worldwide. Yet investigations into fire impacts on wildlife habitat rarely
extend to the macroecological scales relevant to species conservation and
global change processes. We evaluate the effects of wildfire on habitat
quality and selection by large mammals spanning three trophic levels in
the Western United States. We analyze 12 years of GPS telemetry data for
2,966 mule deer (Odocoileus hemionus), 52 black bears (Ursus americanus),
and 74 cougars (Puma concolor) across Utah and Nevada, USA. Over 800 areas
burned between 1990-2022 overlapped with the home ranges of 1,892 animals,
resulting in almost 23,000 km2 of burned habitat and representing 12.8% of
the total home range area for animals in our sample. Habitat suitability
models for 664 mule deer, 14 black bears, and 11 cougars indicated that
burns improved summer home range quality for mule deer and black bears by
7% and 14%, respectively, highlighting the benefits of fires for nutrient
cycling, understory herbaceous growth, and resultant caloric value for
animal nutrition. When making fine-scale movement decisions, however, mule
deer avoided burned habitats, and all three species generally avoided
high-severity burns for up to 30 years post-fire. Thus, the effects of
burns on wildlife habitat selection appear to be dependent on spatial
scale. Given projected increases in large, severe fires, our results
suggest potential reductions in beneficial habitat for wildlife in the
long term. However, our results also suggest that prescribed burns,
because of their smaller spatial footprints and lower severity relative to
wildfires, can benefit wildlife habitat quality through improvements in
forage, cover, and other vegetation characteristics. Therefore, managing
for low-severity burns and limiting large, severe wildfires, e.g., via
prescribed burns or fire control policies, could positively impact the
habitat quality of these three common species and, therefore, the economic
and ecosystem services they provide.