Study finds wildfire caused massive bird die-off

Research using crowdsourced data found a correlation with the birds’ deaths, nearby fires and toxic air.

 

Thousands of migratory birds were found dead across the Southwest in September 2020.

This story originally appeared in Eos and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.

After an abnormally large number of migratory birds turned up dead in people’s backyards in Colorado and other parts of western and central U.S. states, locals began to document their observations on a crowdsourced science platform called iNaturalist. Within the app, a special project was set up specifically for this die-off, which occurred in August and September 2020, so that records of the dead birds could be compiled together.

Around the same period as the birds’ deaths, more than 7.8 million acres of land burned, which resulted in habitat loss and the emission of toxic compounds that threaten the health of both avian species and humans. In addition, snowstorms struck parts of the Northwest in early September while these birds were in the midst of their annual migration. Some areas experienced temperature drops of as much as 72°F in just a few hours.

Researchers heard of this die-off event and wanted to see whether there was a link between the birds’ deaths and the other major events (wildfires and snowstorms) occurring in the United States at the time. In a new study published in GeoHealth, Yang et al. used the iNaturalist data, which included recordings of a number of migratory species such as warblers, geese, hummingbirds, swallows, flycatchers and sparrows. The scientists also studied map readings that showed where observations were taken on iNaturalist to compare the locations of the birds’ deaths with the locations of the wildfires and storms.

Their findings were starkly clear. “The wildfire and also the toxic air were the two factors that influenced the birds’ mortality,” said Anni Yang, a postdoctoral fellow in spatial ecology at Colorado State University and one of the study’s authors. There was a strong correlation between the observations of dead birds and wildfires and the toxic gases they produced, but not with the early winter storms.

“The birds are sensitive to the environment,” Yang said. The respiratory system of avian species in particular easily can be damaged by air pollution. Although wildfires have always occurred and birds have evolved to cope with them in some measure, the combination of climate change and decades of fire suppression in parts of the United States has led to fires that burn far hotter and larger than fires that burned in centuries past. The larger fires could cause problems that birds nowadays aren’t capable of dealing with.

“The wildfire and also the toxic air were the two factors that influenced the birds’ mortality.”

The researchers also discovered that there were some differences in local areas. In parts of California, for example, more bird deaths occurred farther from the wildfires. The reason could be secondary impacts of the fires affecting humidity levels, which could lead to the deaths of birds in hot, humid air over the ocean.

The researchers also noticed other trends. Land cover had an impact on bird deaths; the data showed that more birds died in urban areas. According to the authors, the reason could be known issues that affect birds, such as building strikes. But Yang noted that this correlation may be slightly biased because of quarantining due to the pandemic. In other words, people were spending more time in urban areas and perhaps paying more attention to dead birds around their homes, which inadvertently may have boosted the numbers in cities compared with rural areas.

Yang also suggested that the lack of correlation between bird deaths and the snowstorms could be explained by shortcomings in the crowdsourced science application. In that case, fewer people may have been going outside during the bad weather, which could translate to fewer observations of dead birds.

Yang said other local factors might have played roles in the deaths of some species. The researchers looked at all bird deaths equally, but different species could be affected in different ways by climate events like wildfire smoke or a snowstorm.

Rongting Xu, an ecosystem modeler at Oregon State University and another of the paper’s authors, said that it would be great to run the same study over multiple years, comparing the summer of 2020 with previous summers, for example, to see whether wildfires or early snowstorms in other years caused similar die-offs. Such long-term examinations could also reveal whether factors like climate change are playing a role in bird deaths, she said.

Joshua Rapp Learn writes about the environment, archaeology, wildlife and space. He has contributed to publications like National Geographic, Inside Science, Smithsonian Magazine, Discover, Scientific American and others. Email High Country News at [email protected] or submit a letter to the editor. 

High Country News Classifieds
  • FRIENDS OF CEDAR MESA DEVELOPMENT DIRECTOR
    Friends of Cedar Mesa is hiring a Development Director who will have the overall responsibilities of leading our fundraising programs and reports directly to our...
  • WATER RIGHTS/ADJUDICATION BUREAU CHIEF
    Job Overview: Working to support and implement the Department's mission to help ensure that Montana's land and water resources provide benefits for present and future...
  • CLIMATE CHANGE COORDINATOR
    The Greater Yellowstone Coalition is seeking a Climate Change Coordinator to play a lead role in shaping our programs to make the Greater Yellowstone Ecosystem...
  • EXECUTIVE DIRECTOR
    Executive Director Position Announcement POSITION TITLE: Executive Director ORGANIZATION: Friends of Cascade-Siskiyou National Monument REPORTING TO: Board of Directors EMPLOYMENT TYPE: Part-time - Full-time, based...
  • HEALTHY CITIES PROGRAM DIRECTOR
    The Healthy Cities Program Director leads and manages the Healthy Cities Program for the Arizona Chapter and is responsible for developing and implementing innovative, high...
  • CONSERVATION PROGRAM MANAGER
    Grand Staircase Escalante Partners (GSEP) Conservation Programs Manager Job Opening Our Mission: Honoring the past and safeguarding the future of Grand Staircase-Escalante National Monument through...
  • ASSOCIATE DIRECTOR
    Grand Staircase Escalante Partners (GSEP) Associate Director Job Posting Our Mission: Honoring the past and safeguarding the future of Grand Staircase-Escalante National Monument through science,...
  • UNIQUE, ENERGY-EFFICIENT HOME ON ACREAGE NEAR MOSCOW, IDAHO
    Custom-built energy-efficient 3000 sqft two-story 3BR home, 900 sqft 1 BR accessory cottage above 2-car garage and large shop. Large horse barn. $1,200,000. See online...
  • OUTDOOR ADVENTURE BUSINESS FOR SALE
    Missoula Outdoor Learning Adventures (MOLA) - established and profitable outdoor adventure & education business in Missoula, Montana. Summer camp, raft & climb guide, teen travel,...
  • OJO SARCO FARM/HOME
    A wonderful country setting for a farm/work 1350s.f. frame home plus 1000 studio/workshop. 5 acres w fruit trees, an irrigation well, pasture and a small...
  • STEWARDSHIP COORDINATOR
    Join Skagit Land Trust (the Trust), a not-for-profit conservation organization based in Mount Vernon, Washington, and help protect land for people and wildlife. Skagit Land...
  • 2022 SEASONAL SCIENCE EDUCATOR
    The Mount St. Helens Institute Science Educator supports our science education and rental programs including day and overnight programs for youth ages 6-18, their families...
  • POLICY DIRECTOR
    Heart of the Rockies Initiative is seeking a Policy Director to lead and define policy efforts to advance our mission to keep working lands and...
  • CHIEF FINANCIAL OFFICER
    Self-Help Enterprises seeks an experienced and strategic CFO
  • CONSERVATION SPECIALIST - LAND PROTECTION FOCUS
    View full job description and how to apply at
  • RIVER EDUCATOR & GUIDE
    River Educator & Guide River Educator & Guide (Trip Leader) Non-exempt, Seasonal Position: Full-time OR part-time (early April through October; may be flexible with start/end...
  • LAND AND WATER CONSERVATION DIRECTOR
    The Land and Water Conservation Director is a full-time salaried position with the Mountain Area Land Trust in Evergreen, CO. The successful candidate will have...
  • FOOD SYSTEMS ENVIRONMENTAL FELLOWSHIP
    If you were to design a sustainable society from the ground up, it would look nothing like the contemporary United States. But what would it...
  • EXECUTIVE DIRECTOR
    The Rio Grande Headwaters Land Trust (RiGHT) is seeking an Executive Director who will lead RiGHT toward a future of continued high conservation impact, organizational...
  • COMMUNITY ORGANIZER
    Help protect Montana's water quality, family farms and ranches, & unique quality of life. Work hard, meet good people, make the world a better place!...