Fire activity during 2020-2021 in California, USA was unprecedented in the modern record. More than 19,000 km2 of forest vegetation burned (10× more than the historical average), potentially affecting the habitat of 508 vertebrate species. Of the >9,000 km2 that burned at high severity, 87% occurred in very large patches that exceeded historical estimates of maximum high-severity patch size. In this two-year period, 100 vertebrate species experienced fire across >10% of their geographic range, 16 of which were species of conservation concern. These 100 species experienced high-severity fire across 5-14% of their ranges, underscoring potentially important changes to habitat structure. Species in this region are not adapted to high-severity megafires. Management actions, such as prescribed fires and mechanical thinning, can curb severe fire behavior and reduce the potential negative impacts of uncharacteristic fires on wildlife.

Jessalyn Ayars (she/her/hers) is a research fellow in the Jones Applied Quantitative Ecology Lab at the Rocky Mountain Research Station/University of New Mexico. She graduated from Carleton College in 2021 with a Bachelor’s degree in Biology and a Math minor, and received a Carleton College Paglia Post-Baccalaureate Research Fellowship to conduct independent research in the Jones Lab from 2021 - 2023.