Climate change, wildfires cause bird die-offs


JACKSON — Only time will tell the full effects of severe droughts and large wildfires plaguing 2020 and 2021. But the impact for one species has been immediate.

Last fall an abnormally large number of birds began showing up dead in people’s backyards, on hiking trails and in agricultural fields across Wyoming and the West. Lack of food, habitat and toxic gases released by wildfires led to the high numbers of bird deaths across the Western states and may lead to more this fall, according to University of Wyoming-led research.

That research, published in the April issue of the journal GeoHealth, sought answers to an “unprecedented” migratory bird die-off in Western states during and after the 2020 summer fire season.

Citizens and wildlife officials reported thousands of mysterious bird deaths in backyards, parks and wild spaces across 12 Western states: Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Texas, Utah, Washington and Wyoming.

The bird die-off was devastating, said Andrea Orabona, a nongame bird biologist at the Wyoming Game and Fish Department.

“None of us had seen anything like this ever before,” Orabona said.

The die-off extended into Wyoming, where lead researcher Di Yang, a geospatial data scientist and assistant professor at UW, noticed bird mortalities in Laramie after an unseasonably early winter storm last September.

“Within one week of the snowstorm happening I started to see the dead birds on the street,” Yang said.

Yang quickly found that others had been reporting similar mysterious bird deaths in other Western states on iNaturalist, an online citizen science platform where the public can report sightings and upload pictures and locations of birds and other wildlife species in their area.

“That kind of motivated me to do some geospatial model-level research to try to build the connections and try to find the drivers,” Yang said.

Yang and other research contributors from Colorado State University, the University of Georgia, Oregon State University and the University of Wisconsin-Madison began investigating the effects of environmental and climatic factors on migrating birds. Those factors included wildfires, air quality, drought and winter storms.

Over the summer and fall of 2020 citizen scientists documented their observations with photos and observations. A gallery of photos shows birds from warblers to owls lying dead on porches, in yards and other outdoor spaces. In some of the pictures more than 30 dead birds could be seen in one location, Yang said.

American robins, barn swallows, flycatchers, mountain bluebirds and Wilson’s warblers were the bird species most frequently observed based on the death numbers reported, Yang said.

The sheer volume of observations collected by citizen scientists provided Yang with plenty of data for her study.

“It is impossible for all the ecologists or biologists to collect this data in a short period of time,“ Yang said. “The project was open for, like, three months and collected more than 1,500 observations.”

Citizen scientists also reported another nearly 10,000 dead birds on a similar website, Wildlife Mortality Database.

Yang used the observations recorded under the Southwest Avian Mortality Project on iNaturalist, along with data on air quality, snowfall and other factors, to create her geospatial model and assess which variables might have had the most significant impact on avian mortality.

Yang’s findings suggested that air quality, proximity to wildfires and an early winter storm were major drivers of the bird deaths.

Yang also found that migratory bird species were among the most affected groups, including warblers, American robins, flycatchers, hummingbirds and even some water birds.

In Wyoming in particular, the casualties reported were primarily migratory birds that likely came from the Pacific Northwest, according to Orabona. Both Yang and Orabona agree that severe droughts in Western states and the devastating forest fires that resulted, directly contributed to higher mortality levels in migratory birds by drastically reducing food resources.

“Fires just remove berries and insects and things that these birds need to pack on fat before they migrate,” Orabona said. “Then combined with ... forest fire smoke and then drought conditions elsewhere and climatic issues ... It was overwhelming for so many of them.”

During the summer and early fall of 2020, wildfire smoke was prevalent throughout the western United States, including Wyoming.

Between May and October 2020, wildfire smoke caused Wyoming to exceed national ambient air quality standards 26 times, according to the state Department of Environmental Quality’s annual report.

Yang suggests that the increased levels of particulates and toxic gases in the air from the summer fires may have damaged the respiratory systems of some of the unlucky birds, contributing to the mass casualty event.

“The toxic gasses that are released by the smoke are really important drivers,” Yang said.

A concerning detail the study revealed was the possible long-term effects of climate change: increased droughts and summer fires, and more wildlife deaths.

“We’re seeing more extreme events like this due to climate change,” Yang said. “There might be a large possibility that we’re going to continue seeing this pattern.”

This year, parts of all Western states are considered to be experiencing extreme or exceptional drought, according to the National Interagency Fire Center’s Drought Monitor, and the West is again seeing large numbers of wildfires and intense smoke.

Orabona worries this summer could result in more mass bird die-offs.

“Birds have not started migrating yet, so everybody’s kind of anxious that when migration does start in earnest we’re going to see a similar effect,” Orabona said. “Given the similarities so far ... the intense heat and fires that are ongoing, I wouldn’t be surprised.”

Despite the ominous outlook and rampant climatic disasters experienced in 2021, Orabona remains optimistic that there is still a chance to prevent future climate destruction.

“It’s not too late, so we should try to embrace whatever we can do to help reduce the effects of climate change before it’s too late,” Orabona said. “We have to accept the fact that climate change is real and humans are part of the problem. But we can also be part of the solution.”

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