Ask the Naturalist

How Does Smoke Affect Wildlife?

December 11, 2018

What did the poor air quality due to wildfire smoke mean for Northern California animals?

The catastrophic fires in California this past fall had dire and ongoing consequences for everyone and everything in their path.

WildCare is located in San Rafael, in Marin County, so our wildlife hospital and environmental education center were not directly affected by this year’s fires. However, like the rest of California and beyond, our corner of the Bay Area was socked in with heavy smoke for weeks.

What impact did the smoke have on wildlife? It’s a difficult question to answer. WildCare admits and treats as many as 4,000 ill, injured and orphaned wild animals every year, and during the period of heaviest smoke (November 8 – 21, 2018), we admitted 67 animals to the Wildlife Hospital. None of these patients entered our care with smoke exposure as the explicit cause of illness.

However, as is the case with humans, animals will absolutely feel the effects of smoke inhalation in their respiratory systems. With our throats burning and eyes streaming, it’s impossible to imagine that animals aren’t also suffering. Older animals, the very young, and animals that are injured or already ill from other causes would be the most susceptible. In fact, WildCare brought several of our most geriatric educational animals (our nonreleasable Wildlife Ambassadors) inside to “shelter in place” for the duration of the heavy smoke.

Ultimately, this kind of fire season is unprecedented for Northern California and we’re left to speculate about something for which there’s no hard evidence. It makes sense that animals that breathe more rapidly would inhale more smoke and particulates, which could damage the lungs. On the other hand, larger animals bring in more air per inhale, so smaller animals might breathe faster but not breathe as much polluted air with each inhale.

To make it even more complicated, mammals and birds — among our fastest-breathing animals – breathe very differently. Mammals inhale and exhale using a muscular contraction of the diaphragm. Oxygen is absorbed through the alveoli in the lungs during the inhale, and exchanged for carbon dioxide, which is then exhaled. Birds don’t have elastic lungs that can change shape, or a diaphragm, and they’re not inhaling and exhaling the way a mammal does. A bird’s respiratory system consists of air sacs throughout the body (even in the bones!) that are connected to the lungs, which are much smaller in proportion to body size than a mammal’s lungs. The air sacs change shape due to the movement of the bird’s muscles, acting as a bellows to draw air in and push it out. The more active a bird is, the more oxygen it needs, and with the activity, the more air is exchanged in this system. So an inactive bird might not have the same level of risk in a smoky environment than an active one. But we simply don’t know.

A brown pelican comes in for a landing in the smoke at the Sunnyvale Baylands on Nov. 17, 2018. (Photo by Anne Parsons, iNaturalist Creative Commons CC-BY-NC)

Many of the animals that were admitted to the Wildlife Hospital during the smokiest period had flown into windows or were hit by cars. Comparing with intake records for the same period in previous years, there is a slight elevation in intakes for these reasons. It is possible that watering eyes and difficulty breathing made seeing the window or avoiding the car more difficult for these animals. We will never know for sure.

Certainly a dry, scratchy throat was a symptom of smoke exposure for humans, so WildCare’s Living with Wildlife Hotline (415-456-7283) received numerous calls from concerned people wanting to put water out for wildlife. This is a laudable thought, but putting out water can potentially cause more problems than it solves. Stagnant water is a dangerous breeding ground for bacteria and disease, both of which spread easily between animals at a water source. An artificial water source attracts multiple animals, which can lead to aggression, both between animals of the same species and animals of different species. Injuries and infections from aggressive encounters can be deadly to wildlife. The larger-than-normal aggregation of animals can also cause conflicts with humans, which rarely end well for the animals involved.

For these reasons, WildCare does not recommend putting out water for wildlife. However, if you do choose to provide water in an extreme situation, the container MUST be emptied and refilled with fresh water daily, and must be bleached once a week with a 9:1 bleach solution (9 parts water, one part bleach), then rinsed and dried thoroughly before refilling, to prevent the spread of disease. Only putting water out for a short period will also minimize the risks.

WildCare was lucky not to be in the direct path of the fires in 2018, and our hearts go out to all the people, and the animals, dealing with the aftermath of this horrific disaster.

Learn more about WildCare at and call our Living with Wildlife Hotline for help with injured or orphaned wild animals, or for advice on how to live well with wildlife.

About the Author

Alison Hermance is the Director of Communications at WildCare. Each year WildCare treats nearly 4,000 ill, injured and orphaned wild animals in their wildlife hospital, and teaches over 40,000 Bay Area children and adults through their nature education programs. WildCare is located in Marin County. Learn more at