Smoke from Canada’s record-breaking wildfires in recent years has done more than degrade air quality in parts of the United States. Wildfires have made it harder for people to see many birds during the breeding season in New York state, a new study suggests.According to researchers at the University at Buffalo, increased wildfire smoke reduced the visibility of many bird species. They say that this does not mean that the number of birds has decreased. Instead, the birds may have changed their behavior, making it more difficult for bird watchers to find them.The findings were published earlier this month in the journal Biodiversity and Conservation, Science X reported. Researchers say the study highlights the often overlooked impact of wildfire smoke and could help improve the way scientists monitor wildlife as climate change increases the frequency and intensity of wildfires.
smoke and bird sightings
The research focused on the breeding season between 2021 and 2023 in New York state. Scientists examined levels of PM2.5, a type of fine particulate matter in the air that is widely used to measure smoke pollution.PM2.5 are extremely small particles that are less than 2.5 micrometers wide. Because of their small size, they can remain suspended in the air and are commonly caused by wildfires.
Birdwatchers recorded the birds they saw and uploaded their observations.
The researchers found that smoke pollution was highest in 2023 – Canada’s worst wildfire season on record. During June and July that year, smoke traveled hundreds of miles and affected air quality throughout New York.Scientists wanted to understand whether the smoke had any effect on birds during one of the most important times of the year, when they breed and raise their young.
Air Quality vs Bird Records
To investigate this, researchers compared air pollution data to bird observations collected through eBird, a citizen science project run by the Cornell Lab of Ornithology.In the case of eBird, birders record the birds they see and upload their observations, creating one of the world’s largest databases of bird sightings.Next, the University at Buffalo team matched PM2.5 levels with nearly 99,000 eBird checklists submitted across New York during the 2021 to 2023 breeding season.Because bird watchers have different levels of experience, the researchers filtered the data and used statistical methods to improve the reliability of the results. In total, they studied 84 bird species.
Half the species were seen less.
The researchers found that 40 of the 84 species were less likely to be observed as PM2.5 levels increased. Many of these migrants were forest songbirds, including warblers, thrushes and vireos.Corresponding author Festus Adegbola, a PhD candidate in the University of Buffalo’s Department of Geography, said the findings show a clear connection between wildfire smoke and observations of birds.
Canada’s 2023 wildfires blanketed much of North America with hazardous smoke for months.
“Our results show an association between wildfire smoke and the likelihood of seeing particular bird species,” Adegbola said, as quoted by Science X.He added, “Wildfire smoke is often overlooked when monitoring biodiversity. Not paying attention to air quality can bias models of species distribution and abundance.”Researchers believe smoky conditions may have changed the behavior of some birds. “It is possible that smoky conditions have changed the birds’ behavior – singing and moving less, spending more time in dense forest canopies, and therefore making them harder to identify,” Adegbola said.
some showed different patterns
Not all bird species responded the same way. The study found that 15 species were actually more likely to be observed as PM2.5 levels increased, while the other 29 species showed no significant change in how often they were observed.Many of these species were aerial insectivores, capturing insects or wetland-associated birds in flight. However, the researchers cautioned that this does not mean that these birds benefited from wildfire smoke.Co-author Adam Wilson, an associate professor of geography at the University at Buffalo, said the difference may be related to whether birdwatchers chose to spend time during the smoke season rather than a change in birds.“These species often live in more open environments than forest songbirds, so it is possible that their enhanced vision is related to where bird watchers chose to observe during smoky conditions, rather than how the birds themselves responded,” Wilson said.