California megafires are causing long-term shifts in wildlife survival strategies: Study

As wildfires across the U.S. West become increasingly severe, scientists are aiming to unravel the ways such large-scale blazes are impacting the survival of species and their habitats — for better and for worse.

About 100 species surveyed in California’s Sierra Nevada, southern Cascades and Klamath regions are experiencing high severity conditions over more than 10 percent of the geographic ranges, a new study has found.

For about 50 species of the more than 600 surveyed, fires spanned 15 percent to 30 percent of the habitat within their range in the Golden State, according to the study published in the journal Proceedings of the National Academy of Sciences.

Of the animals that encounter high fire severity, 16 are considered a species of concern, the researchers determined. Among these are the great gray owl, wolverine, Pacific marten and northern rubber boa.

“Our intent was to take a broad look to gain a better understanding of the impacts of these kinds of fires on wildlife habitat as a whole,” lead author Jessalyn Ayars, of the U.S. Forest Service’s Rocky Mountain Research Center, said in a statement. 

Ayars and her colleagues decided to focus on areas in California ravaged by wildfires in 2020 and 2021 as the state “experienced fire activity unlike anything recorded in the modern record.”

After the smoke cleared, the quantity of forest burned was equivalent to 10 times more than the annual average, dating back to the late 1800s, according to the study.

Nearly half of the forests that burned endured high-severity blazes, which killed 75 percent to 100 percent of vegetation — and often in extensive, continuous areas, the authors noted.

For the 50 species that experienced fire across 15 percent to 30 percent of their habitats, about 5 percent to 14 percent of those ranges burned at high severity, according to the study. 

The long-toed salamander, which endured high-severity fire in more of its range than any other species surveyed, can decline for up to two decades following a fire, the authors noted.

At the same time, however, the researchers expressed some optimism that fires were not disproportionately affecting species of conservation concern — indicating that their habitats could be serving as a sanctuary.

Regarding the 16 at-risk species that were affected by wildfire, the authors noted that certain animals — such as great gray owls — might benefit from fire in terms of foraging habitats.

Nonetheless, they stressed that it is unknown whether that benefit applies to such a significant habitat shift in such a short time.

“Since each species is different, this study provides a good jumping-off point for others to be able to focus on a single species of interest or small group of species that share similar habitats,” Ayars said.