Outside in[box]: Does smoke from forest fires have an impact on bird migration?


Every other Friday, the Outside / In podcast team responds to a listener’s question about the natural world.

This week’s question is from Rebecca from the California Bay Area.

“I’m sitting here and watching the geese fly above me and it made me wonder: is the thick smoke from all these forest fires in Oregon and California having an impact on migrating birds ? Just curious! I hope that’s not the case. “

You have to admire Rebecca’s optimism here, but going into this question I didn’t feel too optimistic myself.

And yet, it’s worth noting that wildfires aren’t always a bad thing for birds. Some species of birds (as well as other types of animals and plants) have adapted to live in areas where fire is a normal and regular part of the ecosystem.

For example, the black-backed woodpecker has adapted to nest in burnt tree trunks. This is their niche – and without fire they would have a harder time surviving.

In other words, the right combination of forest fires in a given area can actually increase biodiversity overtime.

But the increasingly common “mega-fires” we see today are hotter and more destructive than typical forest fires. This means that the benefits to wildlife are less clear and the costs are much, much higher.

And while some birds to do enjoy forest fires in the landscape, all birds are vulnerable to smoke inhalation.

Bird’s breath

Olivia Sanderfoot is a doctoral candidate in the School of Environmental and Forestry Sciences at the University of Washington. Her work focuses on how smoke from forest fires and urban air pollution affect birds.

Birds, she says, don’t breathe like humans.
“They have rigid lungs that don’t expand or contract, instead their breathing is supported by an airbag system which constantly pushes fresh air into their lungs.

It’s hard to explain, but if you’re into the musical genre, this analogy might help: These airbags work much like the bag on a bagpipe set.

Photo by Roy W. Lowe / USFWS

California brown pelicans winter at the Oregon Coast National Wildlife Refuge.

Or, alternatively, like the cheeks of didgeridoo players who use a technique called “circular breathing” in order to expel air from the instrument even when breathing through your nose.

The bottom line here is that – breath for breath – these air sacs allow birds to absorb more air and more oxygen than humans.

This is ideal for maintaining intense physical activity, such as flying.

Unfortunately, this also means that they are more vulnerable to toxic gases and fine materials, like carbon monoxide, dust and pollution.

Never heard the phrase, “Canary in the coal mine?” “ Birds have been used as early warning systems for air quality for a reason: if something in the air is bad for us humans, chances are it is worse for birds.

And to be clear: the smoke from forest fires is definitely bad for human health.

Outside in[box]  Header 2

Yellow sky

We have therefore established that smoke is bad for the health of birds. But the hardest question to answer is: are we able to see these detrimental effects at the population and / or migration level?

I am sorry to say that yes we can.

Anni Yang is an Assistant Professor in the Departments of Geography and Environmental Sustainability at the University of Oklahoma.

She was in Fort Collins, Colorado in 2020. In September of the same year, the August complex became the biggest forest fire never recorded in California history.

“Those yellow skies… smoke was everywhere during this time,” Yang said.

Around the same time, there were reports in the southwestern United States of people suddenly finding lots of dead birds – what scientists are calling a “mass mortality event.”

Many of them were tropical songbirds on a fall migration process.

Anni and her colleagues started collecting data from the citizen science educational app called iNaturalist.

They looked at the number of reports, the number of dead birds found per report, as well as where and when they were found. They compared this with geographic data on where wildfires and smoke from wildfires occurred during those times.

The researchers found a strong correlation between toxic air and mass death event: evidence that smoke from forest fires was partly responsible for the increase in bird deaths, although they also indicated a snowstorm in start of the season which probably contributed to the problem.

“I really think the wildfire will have an impact on the health of the birds,” says Annie. “It will cause direct death, as well as loss of habitat.”

A hazy future

In a recent study by the US Geological Survey, researchers were able to get a real-time view of the impact of smoke from forest fires on the migration of four White-fronted Tule Geese (a species of special concern).

Geese were actively migrating south during the intense wildfire season of 2020. On average, the migration took them twice as long and covered 470 miles more than usual.

Birds were not only forced to suspend migration sometimes; they also had to rest outside their usual habitats and stopover sites, and change course or gain altitude in an attempt to fly over the thickest smoke.

Because migration is so energy intensive, this type of disturbance can kill a bird or reduce reproduction rates (birds that do not have enough calories for the trip might not) although the four geese followed in the The USGS study all reached their eventual destination.

But smoke doesn’t just impact bird health – it also obscures our own ability to witness – and potentially research – bird activity.

One of Olivia Sanderfoot’s latest studies used another app – eBird – to track how smoke from forest fires affects birding.

Unsurprisingly, reported bird sightings for many species declined when the air was smokiest – but they also increased for some species. Olivia thinks this may be because some birds are forced to land more often or feed closer to home during forest fires.

Ultimately, the study is further evidence that the behavior of humans and birds is altered by the thick smoke from forest fires.

With larger, hotter fires occurring more often as a result of climate change, these effects are likely to worsen.

One way to help is to contribute to the data pool, as these studies have relied heavily on participatory citizen science.

Sharing your observations of nature on an app may seem like a little potato in the face of climate change, but you are not alone: ​​citizen science is an example of collective action.

“It will really help advance research,” Anni Yang said. “And by attracting more people to science, which will help improve our planet.” “

If you would like to submit a question to the Outside / In team, you can save it as a voice memo on your smartphone and send it to [email protected], OR call the hotline, 1-844-GO-OTTER .

Outside / In is a podcast! Subscribe wherever you get yours.

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