New research links Canadian wildfire smoke to fewer bird sightings in New York State. Despite burning hundreds of miles away, Canadian wildfires have become a familiar source of disruption in New York State. Air quality advisories and a spike in emergency room visits for asthma are common consequences. Now, the new study has identified another consequence: fewer sightings of dozens of bird species across the Empire State.
The study, published in Biodiversity and Conservation, found that 40 different bird species were less likely to be observed in New York as levels of fine particulate matter (PM2.5) in the air increased during recent breeding seasons.
Researchers analyzed PM2.5 levels during New York’s 2021–2023 breeding seasons. The highest concentrations occurred in 2023, when smoke from Canada’s historic wildfires degraded air quality across New York throughout June and July. PM2.5 levels exceeded World Health Organization guidelines on multiple occasions, at times reaching eight times the recommended limit.
They then matched the PM2.5 data with nearly 99,000 birdwatching checklists submitted to Cornell University’s eBird database. The citizen science project allows birdwatchers to record the birds they observe, creating one of the world’s largest collections of bird observations.
Nearly half of the 84 different bird species studied were less likely to be observed when PM2.5 rose. These included many migratory forest songbirds, such as warblers, thrushes, and vireos. However, 15 species were actually more likely to be observed as PM2.5 levels rose, while another 29 showed no significant change in how likely they were to be observed.
Smoky conditions may have changed the birds’ behavior—singing and moving less, spending more time in dense forest canopy—and therefore made them harder to detect. The findings suggest that fewer bird sightings during smoky periods don’t necessarily mean there are fewer birds—they may simply be harder to detect.
It is essential to recognize this distinction for accurate biodiversity monitoring. Temporary declines in detectability must not be mistaken for true population declines. As climate change continues to intensify wildfires, understanding how birds will be affected by increased smoke pollution is vital.
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The study is a first step to better understanding how species respond to wildfire smoke exposure. The researchers hope it will lead to further investigation. Other coauthors are from the University at Buffalo and the Cornell Lab of Ornithology.
Climate change plays a role.
The researchers used rigorous data filtering and statistical methods to ensure reliable results, as the observations come from birdwatchers with varying levels of experience. This approach allowed them to account for potential biases in the data and increase the accuracy of their findings.
The analysis of 84 different bird species across nearly 99,000 eBird checklists collected across all of New York during the three recent breeding seasons provided a full understanding of the impact of wildfire smoke on bird sightings. The diversity of species studied, including migratory forest songbirds, aerial insectivores, and wetland-associated birds, highlighted the complexity of the relationships between wildfire smoke, air quality, and bird behavior.
The fact that 15 species were more likely to be observed as PM2.5 levels rose, while another 29 showed no significant change, suggests that the impact of wildfire smoke on bird sightings is not uniform across all species. This variability shows the need for further research to understand the specific mechanisms by which wildfire smoke affects different bird species and their behaviors.
Understanding how birds respond to wildfire smoke exposure is key for developing effective conservation strategies. As climate change continues to intensify wildfires, it is essential to recognize the potential impacts on bird populations and to develop monitoring programs that can accurately detect changes in population sizes and distributions.
The use of citizen science projects, such as the eBird database, can provide valuable insights into the impacts of environmental changes on bird populations. By leveraging the contributions of thousands of birdwatchers, researchers can gather large datasets that can be used to inform conservation efforts and develop more effective management strategies.