What wildfire smoke means for birds

The Maui wildfires are an ongoing human tragedy. At least 111 people have died, more than 1,000 people are unaccounted for, and many have been displaced from their homes.

But such fires also put animals at risk. Wildlife, livestock and pets often perish in fires. Flames can destroy critical habitats for endangered species and set back conservation efforts. (The Hawaii fires threatened the Maui Bird Conservation Center, which is home to some of the world’s most endangered birds.) And all creatures that breathe air are susceptible to smoke.

“Birds are especially vulnerable, because they have an incredibly efficient respiratory system, which is designed to deliver enough oxygen to power flight,” said Olivia Sanderfoot, an ecologist at the University of California, Los Angeles, who studies how smoke affects birds and other wildlife. The avian respiratory system is especially adept at drawing oxygen out of the air, but if there are pollutants wafting around, birds take those up readily, too.

Precisely how smoke affects birds is still a nascent field of research, with many unanswered questions. But studies have shown that smoke can damage birds’ lungs and make them more vulnerable to respiratory infections. And the fine particulate matter that is present in smoke — and causes well-documented health problems in humans — can also accumulate in birds’ airways. “We know that air pollution, and smoke specifically, causes respiratory distress and makes it more difficult for birds to breathe,” Dr. Sanderfoot said.

Plumes of smoke may also disrupt the journeys of migrating birds, many of which are under threat. In 2020, tule geese, which summer in Alaska, began their fall migrations in the middle of a record wildfire season on the West Coast. The geese needed more than double the usual time to arrive at their traditional Oregon stopover site, and their flight paths were nearly 500 miles longer, scientists found.

“We’re beginning to see that birds have to make hard choices when they come across thick smoke,” said Andrew Stillman, an ecologist at the Cornell Lab of Ornithology who studies how major fires affect birds.

Birds can sit and wait for the smoke to clear, which can leave them stranded for days in unfamiliar territory and delay their migration. They can fly around the smoke, making detours that extend their journeys and use up precious energy reserves. Or they can continue to fly through, gulping down smoke as they go. “Either way, the migrating birds are worse off when they finally arrive,” Dr. Stillman said. “And not everybody survives that perilous journey.”

Dr. Sanderfoot is exploring how smoke alters bird behavior and how those responses vary according to species and circumstance. (Some birds of prey seem to be attracted to fires, perhaps because fleeing or injured small animals make for an easy dinner.) Which species are most vulnerable to wildfires? Do birds with larger home ranges find escape easier than do those with smaller territories? Do birds that live in fire-prone areas respond differently than those inhabiting places where wildfires are a newer threat? Do responses vary at different times of year?

“And all of this work is geared toward answering questions that I hear over and over from birders in our community,” Dr. Sanderfoot said. “Folks want to know what’s happening to birds when it’s smoky.”

She is also enlisting amateur bird watchers to help her answer these questions. One new effort, called Project Phoenix, is now seeking California residents who are willing to spend 10 minutes a week observing their local birds through the fire season. Dr. Sanderfoot hopes to learn how birds alter their habitat use in response to smoke, and whether providing bird feeders and baths “could help them thrive as smoke persists on the landscape,” she said. “I’m hoping to put that all together and really help us learn, from a policy standpoint, what we can do to help birds as we see more and more smoke.”