By Gloria Dickie, Mongabay
KEY POINTS:
Long-term research in California shows that many bird populations increase after wildfires and can remain more abundant in burned areas for decades, especially following moderate fires.- Although some bird species are adapted to fire and benefit from low to moderately severe blazes, megafires in California are becoming more frequent.
- Megafires, scientists say, are unlikely to benefit most bird species and harm those that depend on old-growth forests.
- Wildfire smoke poses a serious threat to birds’ health, with evidence linking heavy exposure to particulate matter in smoke to reduced activity, weight loss and, possibly, increased mortality.
In the forests of the Sierra Nevada, the black-backed woodpecker is without parallel. The bird appears almost born of fire, thriving on the flames that flicker through California’s coniferous forests every few years. Swooping in shortly after a blaze subsides, this woodpecker species, Picoides arcticus, nests in the hollowed-out trees the burn has left behind, gorging on an abundance of longhorn and bark beetles. Throughout the forest, a steady whack-whack can be heard from the birds’ bills drilling into charred wood.
The relationship between wildlife and wildfire is a complicated one. Many bird species, like the black-backed woodpecker, need the occasional inferno to create new habitat by opening up the forest canopy and increasing available food by kicking off a boom in insect populations.
“While it’s ephemeral, it’s a native habitat of California that many species rely on and have evolved with over millions of years,” says ornithologist Morgan Tingley, whose research at the University of California, Los Angeles, focuses on the interplay of fire and bird populations.
But historically, this dynamic rested on moderate or mixed-severity fire — not the raging “megafires” that now scorch through the American West and leave little behind.
In California, fires have burned more than 5.3 million hectares (13 million acres) over the past decade. In 2020 alone, blazes ripped through more than 1.6 million hectares (4 million acres), compared to a yearly average of just 110,500 hectares (273,000 acres) between 1989 and 1998.
Scientists who study avian species’ connections to fire say they’re only just beginning to grasp how the state’s birds are being affected during increasingly catastrophic wildfire seasons.
“Until about 10 years ago, the only thing we knew was the opening scene of Bambi,” Tingley says. “We just thought that everything flees, and if it doesn’t flee fast enough, it dies. We’re starting to learn better about how species have adaptive traits to deal with fire.”
He adds that it’s critical to distinguish between what happens to bird populations after a fire and what happens during a fire. In California, researchers have recently found that many bird species fare well in the years — and even decades — after a burn. But that’s only if they survive the initial blaze.
The burn boom
Fires may be ephemeral events, but their impacts on bird populations are anything but. The effects of a fire, it turns out, can persist for decades.
In a recent study published in the journal Fire Ecology, scientists analyzed 35 years’ worth of bird monitoring and wildfire data, collected from 1984 to 2019 in Yosemite National Park and Sequoia and Kings Canyon National Parks. Their goal: to figure out what had happened to 42 species of birds, from the mountain quail (Oreortyx pictus) to the northern flicker (Colaptes auratus), after burns swept through.
“I was really surprised by how many of the species that we studied actually had a positive response to the fire in the very next year,” says study lead author Chris Ray, a research scientist with the nonprofit Institute for Bird Populations, based in Petaluma, California. “And some of those species had more and more positive responses as the years went on.”
Not only did bird population density increase rapidly after a blaze, it also remained higher in burned areas for at least 35 years compared to unburned areas, the study found. Moderate-severity fires led to more immediate and enduring positive effects.
Of the 42 species studied, only 13 didn’t seem to be affected by fire at all, whereas 21 species had a positive response that persisted for more than two decades afterward. Only one species — the black-headed grosbeak (Pheucticus melanocephalus) — responded negatively to fire in every case.
“Fire is, in some senses, devastating. And in other senses, rejuvenating,” Ray says. “As old, big things fall and burn, new, young, high-protein vegetation grows up. Birds can have more to eat, and new places to nest. There are many ways that birds can take advantage of the new landscapes, and apparently, they do. Fire is a tool.”
But Ray cautions their research largely assessed only low- or moderate-impact fires, as there weren’t many “megafires” that hit the parks during the decades studied. But these large, destructive fires are now becoming more frequent in California, owing in part to historical policies that sought to prevent all wildfires. This buildup of fuel, combined with changes in the climate that have fomented hot and dry conditions favorable to fire, has been a deadly recipe.
“We absolutely don’t expect that large, high-severity burns are going to result in positive effects for the majority of species,” Ray says. Only those species that are especially fire-adapted, like the woodpeckers, would likely still thrive after intense wildfires rage through, he says.
“If we want birds to do as well as they can, we need to help them experience landscapes like what they evolved with — not the megafires that we’re starting to see on this landscape.”
Flying through the flames
The other factor, according to Tingley, is what happens to birds during a fire. That, he says, is far less understood. Small mammals shelter in burrows underground, while larger mammals, like black bears (Ursus americanus) and mountain lions (Puma concolor) are often burned trying to flee the flames.
“Birds, presumably, because they have wings, will try to escape,” Tingley says. “But we don’t actually know what percentage of birds escape and what percentage of birds die.” Sometimes, he adds, their responses are even more intriguing.
Tingley recalls visiting the site of last year’s California’s Palisades Fire to set up sound-recording devices. To his surprise, there were plenty of wrentits (Chamaea fasciata), small brownish-gray songbirds, in areas that had been severely burned.
“A wrentit really does not move more than like 200 meters [660 feet] in its entire life. And they can fly, but they’re bad flyers,” Tingley says. “A wrentit could not have outflown the Palisades Fire when it was expanding. And I don’t think they would have recolonized that quickly. So they must have done something else. They must have found a stony creek bed and hid.”
Meanwhile, scientists working in the Sierra Nevada have come across spotted owl (Strix occidentalis) carcasses in the aftermath of big blazes. A 2016 study in the journal Frontiers in Ecology and the Environment assessed the impact of California’s 2014 King Fire on spotted owl populations in El Dorado county.
It found that the likelihood of spotted owls being extirpated from a patch of affected forest was seven times higher than before the fire at severely burned sites. This, the authors concluded, contributed to the greatest annual population decline across 23 years of observation.
“The fire also rendered large areas of forest unsuitable for owl foraging one-year post-fire,” the study reads. While wildfires can create new habitats, they can also destroy existing ones — particularly the old-growth trees and dense canopy vital to the spotted owl’s survival.
Smoky skies
Tingley’s own thinking about the impacts of fire on bird populations, he says, has evolved rapidly over the past seven years. Whereas he once saw wildfire as largely a force for good when it came to California’s birds, back then he was considering only the long-term effects. But many blazes are far from benign. Earlier this year, he received a grant from the California Department of Forestry and Fire Protection to begin studying how birds respond to extreme fires.
“Presumably, fire does decrease bird population in the very short term, through direct mortality during the fire, and probably a fair amount of it is due to asphyxiation, particularly close to the fire from carbon monoxide. And there could also be long-term chronic effects,” he says.
Because of their physiology, birds particularly suffer from exposure to thick plumes of smoke and fine particulate matter — 2.5 micrometers or smaller, known as PM2.5 — emitted by wildfires.
“Birds are really sensitive to the PM2.5 particles in the smoke because their lungs are adapted to flying and have to work really efficiently,” says Joanna Wu, an ecologist at UCLA. “There is evidence that, physiologically, smoke can be bad for birds, and maybe worse for birds than it is for humans.”
Scientists recently took stock of how wildfire smoke may be impacting California’s birds. They found for the first time that “smoke exposure has quantifiable, adverse effects on the health of wild birds across a range of species,” says study co-author Olivia Sanderfoot, who now leads Project FeederWatch with the Cornell Lab of Ornithology.
Sanderfoot and her colleagues assessed how frequently birds were captured in mist nets as well, as their body condition, using two decades of banding data collected from 2000 to 2021 at the San Francisco Bay Bird Observatory’s Coyote Creek Field Station in Milpitas.
They found that following acute exposure to particulate matter, birds adjusted their day-to-day behavior, with capture rates near the field station dropping during or immediately following periods of unhealthy air.
That change, Sanderfoot theorized, may be due to birds reducing their activity during smoky periods, or leaving the area around the station for less polluted environs.
Birds also appeared to lose weight following chronic smoke exposure. As the number of days with poor air quality increased, body mass declined across 18 species. That may have been, the study said, because birds were expending more energy to cope with the health effects from prolonged smoke exposure.
“There is much we still have left to discover about the impacts of wildfire smoke on the health and behavior of birds,” Sanderfoot says. “One of the best opportunities to learn more is through participatory science and long-term monitoring … This data is incredibly powerful in helping us build studies to understand the effects of wildfire smoke and what we need to do to limit risks to birds.”
Citations:
Calhoun, K. L., Steel, Z. L., Parker-Shames, P., Oyler, H., & Brashares, J. S. (2025). Severity outweighs pyrodiversity in shaping avian and bat species distributions following an oak woodland megafire. Ecosphere, 16, e70263. doi:10.1002/ecs2.70263
Jones, G. M., Gutiérrez, R. J., Kramer, H. A., Tempel, D. J., Berigan, W. J., Whitmore, S. A., & Peery, M. Z. (2019). Megafire effects on spotted owls: Elucidation of a growing threat and a response to Hanson et al. (2018). Nature Conservation, 37, 31-51. doi:10.3897/natureconservation.37.32741
Jones, G. M., Gutiérrez, R. J., Tempel, D. J., Whitmore, S. A., Berigan, W. J., & Peery, M. Z. (2016). Megafires: An emerging threat to old-forest species. Frontiers in Ecology and the Environment, 14(6), 300-306. doi:10.1002/fee.1298
Nihei, A., Sanderfoot, O. V., LaBarbera, K., & Tingley, M. W. (2024). Wildfire smoke impacts the body condition and capture rates of birds in California. Ornithology, 141(4), ukae023. doi:10.1093/ornithology/ukae023
Ray, C., Siegel, R. B., Wilkerson, R. L., Schofield, L., Tingley, M. W., Aronson, S., … van Wagtendonk, K. (2025). Fire gives avian populations a rapid and enduring boost in protected forests of California. Fire Ecology, 21, 56. doi:10.1186/s42408-025-00402-2
Tingley, M. W., Stillman, A. N., Wilkerson, R. L., Sawyer, S. C., & Siegel, R. B. (2020). Black-backed woodpecker occupancy in burned and beetle-killed forests: Disturbance agent matters. Forest Ecology and Management, 455, 117694. doi:10.1016/j.foreco.2019.117694
