How did the California megafires impact wildlife habitats?

The 2020-2021 California megafires marked a significant event in the state’s history. These wildfires were unprecedented in the modern record. 

The fires burned ten times more forest area than the annual average since the late 1800s, raising concerns about the fate of the affected wildlife and their habitats.

Survival prospects 

Experts at the Rocky Mountain Research Station set out to gain a better understanding of how such extreme fire severity alters the habitat and survival prospects of various species.

Wildlife in western forests have coevolved with habitat changes and disturbances like wildfires. However, the scale and intensity of recent fires are beyond what many species are adapted to, and little is known about their ability to cope with these “megafires.” 

How the research was conducted 

To address this knowledge gap, the researchers utilized California’s Department of Fish and Wildlife’s extensive wildlife database, which maps the habitat suitability of hundreds of species. 

The team combined the wildlife data with Forest Service wildfire records and advanced computational analysis. This approach allowed for a broad examination of how megafires are reshaping wildlife habitats across California.

Focus of the study 

“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,” said study lead author Jessalyn Ayars.

“And 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.”

The study was predominantly focused on areas in the Sierra Nevada, southern Cascades, and Klamath mountain regions. The team analyzed the habitats of over 600 wildlife species. 

Key insights

The results revealed that 100 species experienced high-severity fire in over 10 percent of their geographic range across the state. Notably, 16 of these species are of management concern, including the great gray owl, wolverine, Pacific marten, and northern rubber boa.

While previous studies suggest that some species like the great gray owl may benefit from fire-induced habitat changes for foraging, the current study underscores the uncertainty of such benefits given the magnitude and speed of these changes. 

Habitats of conservation concern 

The experts found that the fires did not disproportionately impact habitats of conservation concern compared to other wildlife species. This suggests that the habitats of threatened species might provide a refuge in the face of such catastrophic events.

“Special-status species were not disproportionately affected by the 2020 and 2021 California megafires, and birds and reptiles of greatest conservation need had less of their range burn than expected, even at high severity,” wrote the study authors. 

“While this is encouraging, the overall area burned and at high severity was large for all species, and the effects of fire on special-status species should be addressed on a case-by-case basis.”

Highly variable responses

“The long-toed salamander (Ambystoma macrodactylum), which experienced high-severity fire across a greater portion of its range than any other species examined (14%), has been shown to decline one to two decades postfire, particularly in the most severely burned areas,” noted the researchers.

“The most fire-affected bird, the great gray owl (Strix nebulosa), has been shown to persist immediately after severe fires and is thus thought to be fire-resilient.”

“But, for this and other species examined here, there is simply no frame of reference for understanding population responses to the scale and severity of the fires seen in 2020 to 2021 in California, and it is unlikely that many species have adaptations to survive these fire events.” 

“While our goal was to examine broad-scale fire impacts on habitat, species’ responses to wildfire are highly variable and will depend on life-history and other traits that should be a focus of future research.”

Forest management strategies 

Study senior author Gavin Jones had previously investigated the role of proactive forest management in mitigating habitat loss for species like the California spotted owl due to increasing wildfire size and severity. 

This new paper contributes significantly to Jones’ research, highlighting the urgent need to accelerate and expand proactive forest management strategies, especially considering the expected rise in extreme fire events in the future. 

The study is published in the journal Proceedings of the National Academy of Sciences.

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