Blog # 442 Canaries & Coal Mines: Canada’s Wildfire Smoke

June 15, 2023

Osprey in haze, courtesy of Charles Bush.

The pungent air jolted many last week as they witnessed what looked like an advancing Saharan dust storm. A lemony-orange haze gave a two-dimensional perspective to the rolling Finger Lakes landscape, jarring those not familiar with the commonplace smog in California. Acerbic, biting smoke from the Canadian wildfires choked those in the northeast—wildlife and humans alike. The haze is still heavy nearly a week later, making it difficult to sense the time of day.

Warnings flashed to stay inside with pets. The bottom line is smoke isn’t healthy to inhale and, depending on its components, can cause carbon monoxide poisoning, respiratory tissue damage, high blood acid levels, stunted growth, compromised immune systems, cancer, or death.

The influence of smoke on birds is very different than on mammals. Avian respiratory systems exchange oxygen more efficiently than other vertebrate systems. Birds have relatively small lungs and uniquely have nine air sacs that aide in respiration but not

2003 Alberta wildfires, courtesy of CNN.

gas exchange. The air sacs permit a unidirectional flow of air through the lungs allowing the lungs to completely expel deoxygenated air. The path into the lungs is different than the path out. In contrast, air flow in mammals is bi-directional with air moving into and out of the lungs by a mere reversal of the flow. Consequently, air in a mammal's lungs has a lower percentage of oxygen content as it is diluted by the residual air. While avian respiration typically offers many advantages, their high sensitivity to air quality is an important bioindicator. They are “canaries in a coal mine.”

Tidal breathing in vertebrates vs unidirectional breathing in birds, courtesy of Frontiers for Young Minds.

Avian respiratory systems are said to be twice as sensitive as other vertebrates. The wildfire smoke, which is harmful for humans, is even worse for the birds, especially

The larger the fine particulate matter (PM2.5), the less detectable Ospreys,

bald eagles, and great blue heron become, courtesy of O.V. Sanderfoot.

Female osprey hunting, courtesy of Cindy Sedlacek.

Ospreys since they are always out in the open. Ospreys tending nests in open settings are more exposed to smoke particles and pollutants than other birds hiding in bushes. These particles settle in the lungs and irritate them, leading to difficulty breathing and impacting their overall health.

A 2020 University of Washington research team reviewed the scientific literature and found only 7 studies that addressed the harmful effects of wildfire smoke on birds in the wild. The investigators characterized how wildfire smoke affected birds using PM2.5, a marker of particulate matter in wildfire smoke that affects the probability of observing birds. PM2.5 is used to assess the effects of wildfire smoke.

Thick smoke can significantly reduce visibility, making it difficult for birds to navigate, to locate food, to find their nests or roosting sites, and avoid collisions. Degraded hunting success of birds of prey can prompt them to relocate. The 2020 University of Washington study highlighted reduced sightings of Ospreys, Bald Eagles, Red-tailed Hawks, Turkey Vultures, and Northern Harriers at elevated PM2.5 readings. Prey species become more active and more prevalent during these high readings owing to the reduction of predators. Future studies should investigate how home-range size, territoriality, vigilance, predator-prey dynamics, and daily activity patterns influence behavioral responses to wildfire smoke.

As I write, concerns for Canadian birds are high. Wildfires are destroying large forests, disrupting ecosystems, and reducing available food sources such as insects, seeds, and fruits. Depending on the severity and extent of the wildfires, some bird species may be forced to migrate or disperse to other areas in search of suitable habitat and better air quality. There they will have to compete with the local species for limited resources. These fires are predicted to last all summer. This could dramatically change bird populations and distributions in the affected regions.

If the PM2.5 continues to rise, decreasing the nestling birds’ lung capacity and stunting their development, this year’s young Ospreys may not survive. Those that do survive may lack the lung power to migrate. Adult lungs may also be severely compromised.

In the long-term, nature always heals itself and wildfires are an opportunity to regenerate. Fires add nutrients to the soil, remove invasive insects or disease, and create new habitats that plant and animal species need to thrive. However, large wildfires may become more common in the future as our climate changes. Understanding how birds are affected by wildfire smoke is critical to furthering avian conservation.

Eyes to the sky!

Candace

Candace E. Cornell

Friends of Salt Point, Lansing, NY

Cayuga Lake Osprey Network

cec222@gmail.com