Update, July 30, 2018: This story was originally published on September 14, 2015. It has been updated with information about the recent California wildfires.
Right now, dozens of wildfires are raging across the world. Earlier this month, blazes broke out in Greece, and consistent heat and drought conditions this summer have set the table for fires in Sweden, Norway, Finland, Spain, and England. In North America, states like California, Oregon, and Alaska have reported persistent, deadly blazes that have already charred millions of acres of land this year alone.
Currently, wildfires in Northern California are leaving a trail of destruction. The Carr Fire in Redding, which is about 160 miles north of Sacramento, has claimed several lives and destroyed hundreds of buildings. But for some wildlife species that have evolved to live with fire, the scenario is not so dire.
In these regions, "wildlife have a long-standing relationship with fire," ecosystem ecologist Mazeika Sullivan of the Ohio State University said in a previous interview. "Fire is a natural part of these landscapes."
Many animals have some ability to escape the heat. Birds may fly away, mammals can run, and amphibians and other small creatures burrow into the ground, hide out in logs, or take cover under rocks. And other animals, including large ones like elk, will take refuge in streams and lakes.
Gabriel d'Eustachio, a bush firefighter in Australia, said in 2014 that he has witnessed a mass-movement of small invertebrates fleeing from blazes. "You get overrun by this wave of creepy crawlies walking ahead of the fire," he says. (See video: "Fighting Wildfires.")
Fires can benefit predators who prey on these fleeing animals. Bears, raccoons, and raptors, for instance, have been seen hunting creatures trying to escape the flames. Several species of birds may even help spread fires in Australia, some research suggests, as doing so may help flush out small animals for them to eat. (Read "Under Fire" in National Geographic magazine.)
"In those short-term situations," such as when creatures flee from flames, says Sullivan, "there's always winners and losers."
A moderate level of fire in areas where it naturally occurs may also increase the “patchiness” of forests and create a wider variety of micro-habitats, from open meadows to re-growing forest, research shows. Having a diversity of biomes supports multiple species of animals and the ecosystem as a whole.
Scientists don't have any good estimates on the number of animals that die in wildfires each year. But there are no documented cases of fires—even the really severe ones—wiping out entire populations or species. (Watch: “Fish Skin Bandages Help Burned Bears and Cougar Heal”)
Of course, some animals do die in the smoke and fire—those that can't run fast enough or find shelter. Young and small animals are particularly at risk. And some of their strategies for escape might not work—a koala's natural instinct to crawl up into a tree, for example, may leave it trapped. (See "Koala Rescued From Australia Fires.")
Heat can kill too—even organisms buried deep in the ground, such as fungi. Jane Smith, a mycologist with the U.S. Forest Service in Corvallis, Oregon, has measured temperatures as high as 1,292 degrees Fahrenheit beneath logs burning in a wildfire, and 212 degrees Fahrenheit a full two inches below the surface.
The California wildfires are affecting more than just organic life. Particularly high temperatures are forming new clouds, called pyrocumulus clouds. Usually created out of volcanic eruptions, pyrocumulus clouds are quickly formed when heat burns moisture out of vegetation, which latches on to smoke particles and condenses as they rise. These dark gray giants are filled with smoke and ash, and can be nearly five miles high.
In some cases, pyrocumulus clouds hold enough moisture to trigger heavy rainfall to extinguish fires. But in California, the clouds are making firefighting efforts more difficult. Pyrocumulus clouds can lead to sudden, dramatic temperature swings, which can create unpredictable and severe winds that fan the wildfire flames.
Wild areas like forests and prairies naturally grow and change in composition over time. A year-old forest will have a different set of plants and animals living in it than a forest that's 40 years old. A disturbance like a wildfire can serve as a sort of reset button, letting an old forest be born again, says Patricia Kennedy, a wildlife biologist at Oregon State University in Union. And "a lot of species require that reset." (See National Geographic's wildfire pictures.)
Exactly what happens after a fire occurs depends on the landscape, the severity of the fire, and the species involved. But the event always sparks a succession of changes as plants, microbes, fungi, and other organisms recolonize the burned land. As trees and plants age, light and other features change—and the composition of creatures in the area changes in response.
Streams and other water bodies that flow through a burned area can also change. Water flow, turbidity, chemistry, and structure can be altered. Fish may temporarily move away. And there can be short-term die-offs among aquatic invertebrates, which can affect animals on land.
"The water and the land," says Sullivan, "are highly connected."
Let It Burn?
Many species actually require fire as a part of their life history. Heat from the flames can stimulate some fungi, like morel mushrooms, to release spores. Certain plants will seed only after a blaze. Without fire, those organisms can't reproduce—and anything that depends on them will be affected. (Related: “Why These Birds Carry Flames In Their Beaks”)
So, although fire can have unexpectedly positive outcomes for some species, too many blazes are bad for most. Since the early 1970s, the wildfire season in the western U.S. has grown from about five to more than seven months. Climate change drives up temperatures, causing the snow atop mountains to melt, and making forests deprived of that moisture more susceptible to burning.
As Kennedy says, fire is a bad thing when it happens in your backyard. But to an extent, it can be a healthy event for a forest—and for at least some of the animals that live there.