This story was originally published by cabling and appears here as part of the climatic table collaboration.
California wildfire season has begun in earnest, with the Oak Fire chomping extraordinarily fast through the parched landscape around Yosemite National Park. The fire has burned nearly 17,000 acres so far, forcing thousands from their homes and blanketing the surrounding area with smoke.
For millions of years, creatures on Earth have dealt with wildfire smoke, a noxious mix of toxic gases and particles. They really have had to: lightning ignites wildfires, and the occasional small fire actually results in a net benefit by resetting the ecosystem for new growth.
No more. A variety of factors, including climate changea history of firefighting and growing human populations, have conspired to turn what were once light flames into monsters like oak fire. And that means more smoke and longer exposure to gases like carbon monoxide and dioxide, benzene, formaldehyde and ozone. It also increases exposure to the soot carried in the cloudwhich may contain solids such as lead, cadmium and polyaromatic hydrocarbons.
Scientists know how this smoke affects human health, exacerbating asthma and other respiratory problems, but know next to nothing about other species. As wildfires grow larger and more intense, researchers are racing to find out how birds, non-human primates and livestock might be suffering, and early results are concerning.
In 2020, Amy Skibiel, an animal scientist at the University of Idaho, supervised a group of 13 cows between the state fire season of July through October. She and her team examined the concentrations of carbon dioxide and minerals in the cows’ blood, their respiration rates and temperatures, and the amount of milk they produced. “The big question was: What effects does wildfire smoke exposure have on dairy cattle production, immune status and metabolism?” Skibiel says. “Most humans can retreat from poor air quality conditions, while livestock are housed in open-air barns, or are out on pasture or dirt lots. They are exposed 24 hours a day, 7 days a week, to the prevailing environmental conditions.”
Skibiel found that a particularly smoky day could cause a loss of nine pounds of milk per cow. (A cow typically produces 70 to 80 pounds a day, so this is a significant drop.) “Another interesting thing we found was that milk production was reduced for seven days. after their last day of exposure,” says Skibiel. “So even when the smoke clears, there are still lingering effects. And we really don’t know how long that lasts.”
what people are reading
More frequent smoky days in the western US may already be affecting milk production, and Skibiel’s team is working with dairy farmers to see if that’s happening. The team will have to carefully isolate other factors that complicate the situation: high temperatures and humidity also reduce milk production, for example. But wildfire smoke may actually be conspiring with the heat to reduce yields: The fires are more likely to flare up on hotter days when the vegetation is dry. Smoke plus heat can even equal less milk. Skibiel also found changes in immune cell populations in the cows’ blood, suggesting that their bodies were responding to respiratory pollution.
Other animals on the farm may also be vulnerable to wildfire smoke. Horses have huge lungs – animals are born to run and suck in a lot of air in the process. “We don’t know for sure, but horses may be one of the most smoke-sensitive species of all mammals,” says Kent E. Pinkerton, director of the Center for Health and the Environment at the University of California, Davis. “The volume of air that they’re taking in, which is basically loaded with airborne particles that they’re breathing, could really be quite devastating to the horse.”
the Infamous Camp Fire of 2018, which destroyed the city of Paradise, bathed the UC Davis campus in smoke, giving Pinkerton and his colleagues a unique opportunity to determine the effects on another species: the rhesus macaque. At the California National Primate Research Center on campus, the macaques live in open-air enclosures. So, like Skibiel did with the dairy cows, Pinkerton was able to monitor them as the fog approached.
Wildfire smoke is terrible for you. But what does it do to the #cows and birds? #Forest fires #Forest fire smoke #Air pollution #Livestock
Found a increased miscarriage during the breeding season, which coincided with the smoke event: 82 percent of smoke-exposed animals gave birth when in a normal year, the average live birth rate is between 86 and 93 percent. “In fact, we had a small but statistically significant reduction in birth outcomes,” says Pinkerton. “We don’t know all the details, or what the precise cause would be, other than the fact that it was associated with wildfire smoke.”
In Indonesia, which is plagued by peat firesPrimatologist and ecologist Wendy Erb of the Cornell Laboratory of Ornithology has studied the effect of smoke on another primate, the orangutan. Peat fires have created a serious public health crisis in Indonesia, where developers drain peatlands and set them on fire to create farmland. This is a particularly unpleasant type of conflagration, as it burns through carbon-rich fuel to months in a rowbathing cities and surrounding forests in smoke for far longer than, say, a California wildfire ravaging vegetation.
Erb monitors individual orangutans in the wild by collecting urine and fecal samples (yes, that means standing under trees to catch things) and following them throughout the day to see how much they eat and how much energy they expend. From urine samples, you can determine ketosis, or if the animal is metabolizing fat for energy.
After smoke events, she found, ketosis among orangutans increased significantly. “In fact, we saw that they were eating more calories, but despite eating more calories, they were also resting more and traveling shorter distances,” says Erb. “So they’re displaying this energy conservation strategy: They’re moving less, they’re slowing down, and they’re eating more calories, but they’re still going into ketosis.”
One hypothesis, not yet tested by the team, is that the orangutans’ bodies are mounting an immune response to the rush of smoke and that they need more calories to fuel that defense. But this could deplete calories that animals need for other necessities of life, like growing, reproducing, and feeding their young. (Of all the primates, orangutan mothers spend the most time raising their children.) Saving energy by moving less also means fewer opportunities to socialize, which is a concern for a primate that is already critically endangered because it is losing their habitat due to deforestation.
Erb has a related concern: These unnatural fires occur year after year, so orangutans in the wild are exposed to chronic smoke inhalation. Erb found that the vocalizations of orangutans exposed to smoke change, just as the voice of a human smoker changes over time. Could that affect the way animals communicate in the wild? If the animals’ voices become hoarse, for example, they may not be able to communicate as far away.
“For a long time, people didn’t think about how widespread and how massive the effects of smoke itself could be, even for animals lucky enough to be in a forest that doesn’t burn,” says Erb. “You could still be hundreds of miles from the nearest fire and experience really poor air quality.”
Orangutans don’t have the means to flee from the mist, but surely birds do. Not anymore. When the fires are small, birds can detect those flames and fly a few miles away with no problem. But the wildfires have gotten so big that the animals can’t even escape the calls fast enough, much less the smoke: the 2019-20 Australian bushfires moved so fast they consumed anything with wings.
Part of the problem is smoke inhalation: stale air can confuse birds and potentially drive them away within the flames instead of safety. “Carbon monoxide poisoning, if not fatal, can also cause confusion. It can be disorienting,” says Olivia V. Sanderfoot, an ecologist at the University of California, Los Angeles, who studies the effect of wildfire smoke on animals. “So there’s also the concern that maybe even if they have the ability to escape from a fire, maybe No because they don’t know how to escape because they don’t feel well.”
Consider the royal canary in the coal mine: the birds are so sensitive to carbon monoxide that miners would take them underground as an early warning system. If the animal got sick, soon they would. But wildfire smoke is more complex than underground air: It’s burning plants, soil and even towns, where it consumes plastics and other building materials. “Wildfire smoke is all this sticky soup of evil,” says Sanderfoot. “It contains a lot of different toxins, and depending on what is being burned and in what concentrations and then what the weather looks like, the smoke is going to be very different.”
That makes it extremely difficult to determine what in the smoke is causing a particular effect in a particular species, be it a cow, a horse, a bird or a primate. And the problem will only get worse, as the world heats up and the flames become more catastrophic, bathing more of the planet in smoke.
“These fires that we are seeing now are much more intense and faster and causing more serious damage,” says Sanderfoot. “And that kind of event is not something that animals can necessarily detect, avoid and successfully escape.”