How animals react when forests burn
By Tom Bansak
As Forest Service division boss Rick Floch monitored a purposefully set backfire, he observed 50 head of elk walk straight into the advancing flames.
The animals had been on another hillside when the fire began, but then they began moving toward the blazing hill. The crews had stopped road traffic, hoping the animals would venture across the road to safer ground. In vain, Floch thought, for he assumed all the animals had just died.
The nation has heard how the dramatic fire seasons of the past two years have impacted humans, but what about the wildlife that inhabit these forests? What becomes of them? During a fire, most animals react like humans: They run. Early Montanans knew this, as both Native Americans and early settlers occasionally set fires to drive game from forest cover. The likelihood of an animal’s escape from fire is most directly linked to its mobility.
As a general rule, bigger is better. Larger animals, such as deer, bear and elk are better able to flee from a fire’s path than smaller ones. According to John Ormiston, wildlife biologist with the Bitterroot National Forest and a peer of Floch, such was the case with the elk Floch observed. Floch traveled over the same hillside a week later and found nothing of the elk. Normally if the animals had died in the fire, scavengers would have been on the site, stripping the bones. He realized once atop the hill, the animals had skirted the flames, stepped into an already burned area and on up to the safety of an adjoining hillside.
The Roaring Lion fire outside Hamilton, Mont., Aug. 1 2016
Ormiston says this kind of escape behavior is typical of elk, adding that of the thousands of elk that inhabit Yellowstone National Park, officials found only 60 that died as a result of the historic 1988 fires there.
Smaller animals, like mice, voles and chipmunks may escape less intense fires by burrowing, but usually populations of small mammals decline dramatically during a fire. Many are killed by the heat and smoke inhalation.
Wings also facilitate escape and survival. Some birds, however, such as the black-capped chickadee and the American kestrel, do not fly away. Instead, they are attracted to fire, which equates to a dinner buffet, as large concentrations of their respective prey, insects and small mammals, are driven in front of the fire. Some birds, like grouse, apparently get confused by the smoke and have been seen flying directly into fires. For others, their dedication to parenting is their downfall, and many birds have perished refusing to leave their nests of eggs or young.
FIRE AND WATER
Aquatic animals have the advantage of being able to hide and travel underwater. In most cases, streams do not heat to lethal temperatures, so the aquatic animals, such as fish, beaver and amphibians may escape either up or downstream away from the fire. Very intense fires, however, can raise water temperatures enough to kill fish and frogs, or to de-water sections of streams. In fact, officials reported heavy fish kills in some streams during Yellowstone’s 1988 fires. Toxic levels of chemicals leaching from burned wood and soils sometimes kill fish as well.
For the bulk of the critters that do survive, the effects of fire on habitat far outweigh the events of the fire itself. Fire does not often mean the total destruction of a forest. Instead, fire usually creates a mosaic of habitats of different types and ages, which in turn support a diversity of animal species.
The blazes clear undergrowth and can create meadows, allowing grasses and shrubs the space and light they need to flourish. Fire also fertilizes soils, so these grasses and bushes are high in nutrients. This high quality forage attracts large browsers and grazers, such as deer, elk, moose and bighorn sheep. Population increases for these species have been recorded for up to 20 years following a fire. Subsequently, these larger populations can cause an increase in the presence of their main predator, the wolf.
Many rodents also feed on the nutritious grasses, and despite suffering high losses during the fire, their numbers frequently rebound quickly. This is good news for their major predator, the coyote, which has often been seen hunting in recently burned areas. Both black and grizzly bears can also benefit from the habitat changes wrought by fire. Many berries, including huckleberries, a favorite bear food, increase in abundance following fires. Another food that is abundant following fire is the wood of dead or damaged trees. Numerous insect species, such as wood-boring beetles, arrive in the wake of fires to lay eggs and feed upon the decaying wood. The dramatic increase in insect numbers in turn benefits the many bird species that depend upon insects for food. Insectivores, such as woodpeckers, swallows, turkeys and grouse, have all shown population increases in the years following fires. Even Montana’s state bird, the Western meadowlark, relies heavily on post-fire habitats. Bird diversity often maximizes two to three years following a fire, as they take advantage of the bountiful insect food.
Not all animals, however, profit from fire’s habitat alterations. Weasels, martens and fishers are small predators that rely on dense forests and understory for cover. When fires remove this cover, their hunting success and numbers may decrease. In addition, they frequently rest and breed in cavities of large downed trees and stumps. When fire destroys this habitat, they lose their homes—just as many people in the Bitterroot Valley did in the summer of 2000. In addition, when fires are severe and burn into the forest canopy, the critters that use that habitat for either feeding or roosting are adversely affected. These animals include porcupines, bats and a number of bird species, such as sparrows, flycatchers and warblers.
The good news is that wildfires are part of nature’s balance, so in time a species generally rebounds, as does its habitat. A report, “Yellowstone in the Afterglow: Lessons from the Fires,” written in 2000 by Mary Ann Franke for the Yellowstone Center for Resources, recognizes that not all of the species of the park have been studied to determine the impact the 1988 fires had on them, but pragmatically observes that the continuity of the area’s wildlife has not changed significantly during the past 2,000 years, although a number of fires equal in intensity to those of 1988 have burned through. Franke reports that conditions may favor one species during one year, but then change the next.
Despite the initial loss, natural wildfires have a positive impact on wildlife. Humans sometimes benefit as well, because the changes in habitat and food availability enhance a birder’s or hunter’s chance for success. The wildfire clears a forest’s understory, allowing for greater visibility. Burned areas, too, offer an interesting and at times surreal environment in which to explore first-hand the dynamic processes of renewal in forest ecology.