Study: Mass bird deaths in Colorado due to toxic gases from wildfires

Mass bird die-off in Salida from wildfires_iNaturalist
Posted at 6:00 AM, Apr 22, 2021
and last updated 2021-04-22 08:44:27-04

DENVER — A new study suggests a mass death of birds last summer was likely due to toxic gases produced from wildfires.

The study, published in the journal "GeoHealth," reviewed pictures of dead birds that were uploaded to a crowdsourced science platform called iNaturalist. Various users across the western United States, including Colorado, took the pictures after noticing the birds in their backyards and even on hikes.

The study highlights the birds that died were all in the middle of migrating. Geese, hummingbirds, sparrows, swallows and warblers were among the recorded dead.

Anni Yang, a postdoc fellow at Colorado State University and one of the study's authors, said it's hard to give an estimated number for the bird deaths because of the varying ways they were documented by the citizen scientists.

"Most of the species that died are the warblers and also hummingbirds, fly catchers, and we just looked at one of the events out there," she said. "There's one photograph showing seven or eight of them, and that's what happened. That's kind of like example for what's happening in Colorado."

Anni Yang thinks fewer people may have gone outside during the snow and wildfires, so there could have been more dead birds that haven't been observed.

Anni Yang and Di Yang, an assistant professor at the University of Wyoming's Geographic Information Science Center, unrelated to Anni Yang, also looked at weather data recorded around the same time as the bird's deaths.

They concluded the wildfires, which burnt 7.8 million acres of land across the country in 2020 prior to Oct. 5, emitted toxic compounds, like nitrogen dioxide. They found a strong correlation between those toxic gases and the dead birds that were observed.

"The smoke and toxic gases that are produced by the fire will significantly impact the respiratory systems for the avian species, especially like those avian species are known to be sensitive to the air pollution," Anni Yang said.

Additionally, the smoke can make it harder for the birds to see and disrupt their migrations. It also makes it harder for them to find food.

Anni Yang also suggested the snowstorm that followed the wildfires in early September may have played a role in the deaths.

"That can impact the migratory bird's behaviors," Anni Yang said. "It may trigger their migration, say before they are physically ready to migrate from one place to another."

The authors also point to how wildfires are getting worse because of climate change.

All 20 of the largest wildfires in state history have occurred since 2001, and nine of them have occurred over the past three years," Anni Yang. "The number of fires and acreage burned has steadily increased since the 1960s when Colorado averaged under 500 fires per year that burned about 8,000 acres annually. In 2020, there were more than 6,700 fires reported in Colorado that burned 744,120 acres.

The state expects more intense wildfires throughout 2021.

While climate change is exacerbating and intensifying the wildfires, there are other ways to save bird populations aside from climate activism.

Anni Yang said ordinary people can play a big role in helping scientists by playing the part themselves, emphasizing the scientific community can gain invaluable information from regular citizens.

"People here living in Colorado are really like outdoor experts," she said. "They like to go out, they like to go hiking, they like to go onto the trails — they can try to record the live or even the dead animals they've seen. Then, they are really trying to help the scientists to observe and visualize the ecosystem."

The authors also suggested implementing methods to change or alter the birds' migration patterns by turning off house lights while they're migrating.

"So, we are going to form a pattern. For example, if it's on the peak of the migration, we are going to turn down the lights so they can continue. That is a great idea for a continental scale," Anni Yang said.

The authors plan to conduct future studies on the issue and focus on how different bird species respond to environmental changes and natural hazards. Those studies could also cover multiple years in order to get a more detailed understanding of the effects of climate change.