It’s September 8th, 2020 when I step out my front door in Eastern Washington into a landscape that looks like the aftermath of a Martian dust storm. The video I am recording captures my bizarre, sepia-colored surroundings as I try to put words to the experience of having your world an entirely different color than it was the day before. Like any inconsequential casualty in a disaster movie, my usual sense of self-preservation has been abandoned in favor of standing in harm’s way, mouth agape with my phone outstretched to the sky. After a minute, I realize my error and head back inside where I, and millions of other people on the West Coast spent the next several weeks hiding from air that can kill you.
That year, wildfires would go on to burn a total of 10.2 million acres on the west coast, cause $19.8 billion dollars in damage and directly kill at least 37 people. Over the last 30 years, fire severity and duration have increased and it’s impossible not to notice. Decades of wrongheaded fire management coupled with increasingly hotter, drier summers have meant that the 2-3% of wildfire starts we fail to suppress burn under the very worst conditions, pumping the air full of the kind of fine particulates that are irritating at best and deadly at worst. Unsurprisingly, the public health community has been swift to respond, with hundreds of studies examining the outcomes of smoke inhalation on humans. But while I and many other people were able to escape indoors during the worst of it, crows were unanimously stuck in a sepia haze…breathing. One has to ask; how do they cope? How does any wild animal cope?
Among those wondering was Olivia Sanderfoot, an imminent PhD graduate from the University of Washington. While there, she spent the majority of her time asking different questions about how smoke impacts wildlife, especially birds. In pursing her own research, Dr. Sanderfoot made a striking realization: despite the fact that nearly every birder, biologist and person were all wondering about how animals deals with smoke, there were only a few research studies. So with the help of her graduate lab, including myself, she resolved to collect and synthesize what papers were available into a comprehensive review. Published just this week, I am eager to share what we found.
As of the time our article was accepted, there have been only 41 English language studies examining the impacts of smoke on wildlife. Of those, less than half (44%) examined in situ (free ranging) animals dealing with real smoke events. Most were controlled studies where animals were intentionally exposed to smoke to learn about its impacts on their health or behavior. We found that from insects to sugar gliders a variety of different animals had been studied, but only 7 papers focused on birds (and sadly none on crows). Birds are of particular interest not only because, crows, but also because birds have a more efficient respiratory system than any other vertebrate. While this usually offers many advantages, it also quite literally makes them the canary in the coal mine—their high sensitivity to air quality acting as an important bioindicator in addition to the obvious consequences to welfare and conservation.
Although we had hoped to find clear answers to exactly how wildfire smoke impacts animal health, we only found 10 papers that addressed health outcomes specifically, and only 4 that ultimately looked at survival. Still, there are many more papers examining this question either in domestic animals, or animals models that are used as proxies for humans. When taken together with those findings, it’s clear that smoke isn’t good for animals, resulting in anything from carbon monoxide poisoning, to respiratory tissue damage, higher blood acid levels, stunted growth, compromised immune systems, and even death. Beyond direct health effects, exposure to smoke can may also reduce reproductive success. For example, researchers monitored the red-knobbed hornbill, a sort of toucan-like bird native to Indonesia, suggested that smoke might have contributed to a decline in the bird’s nesting success.
Smoke can induce behavioral responses among animals as well. Animals may become confused, agitated, vocal, lethargic, or quiet. For example, Bornean orangutans rest more during and after smoke events, Bornean white-bearded gibbons sing less, and sugar gliders extend the duration of torpor. Meanwhile pinecone lizards flick their tongues more, Psammodromus lizards start running, and many species of bats rouse from their torpor. Some birds are harder to detect like bald eagles, bushtits, killdeer, osprey and marsh wrens, while cedar waxwings, western tanagers, red breasted nuthatches, and yellow warblers actually become easier to detect as particulate matter (smoke) increases.
When taken together, it’s clear that wild animals are sensitive to smoke, and that smoke can have dramatic impacts on their health and behavior. But perhaps the most important finding of our review is that the predictability of these consequences for any future wildfire event remains almost completely out of reach. Because the thing about smoke is that it’s not all created equal. Smoke can have vastly different consequences to health depending on what’s burning (just think of the carcinogenic difference between cannabis and cigarette smoke), not to mention the impact that concentration and duration of exposure can have. And unfortunately, most existing studies haven’t undertaken the kinds of robust studies of air quality that are needed for this kind of future predictive power. Still, knowing this, and having a framework of existing knowledge and methodology, means that future studies are poised to finally start building the foundation we need for sophisticated, predictive modeling.
Until then, we can expect that smoke events like the kind we experienced in 2020 will continue to haunt our changing planet, and while some humans can safely nest alongside their air purifiers, many more, and all our wildlife, are at the mercy of an airscape they cannot retreat from. For now, this is our reality but it need not get inhospitably worse. Just has humans are capable of bullheaded, catastrophic damage, we are also capable of a profound capacity to change, improve and heal. It’s time to take bold, industry/system level steps towards changing our climate future, if only we can find the will to do so.
Read the whole paper here: https://iopscience.iop.org/article/10.1088/1748-9326/ac30f6/pdf
corvidresearch.blog 
Smoke in recent wind fires must have significantly affected wildlife. Thank you!
Huh. We used to have a bunch of crows that hung out in a nearby maple tree, with only an occasional raven dropping by. Can’t remember when I noticed the change – late last year, I think – but now it’s reversed: I see ravens more often than crows. I wonder if the change was brought on by the smoke..?
I really love both – crows and ravens – but there was a particular trio of crows who were regular visitors, and I rarely see them any more. I miss them.