Animals Co-Exist With Wildfires
Aug. 26, 2000 — -- The wildfires out West have burned hundreds of buildings, rousted thousands of people from their homes and caused millions of dollars in property damage. But people are not the only ones being burned out.
Many animals are also being forced to flee the flames. But for those concerned about the critters, fire and wildlife ecologists have a reassuring message:
“Don’t worry about the animals,” says Bill Leenhouts, a fire ecologist with the U.S. Fish and Wildlife Service. “Most animals actually escape the fires.”
The real test for the animals comes later, when the landscape is transformed and their homes look nothing like they used to, say fire and wildlife ecologists. But even so, woodland and grassland animals have been living with a cycle of fire and regrowth for ages.
“In the long term, these wildfires will benefit all animals,” says Leon Neuenschwander, a fire ecologist with the University of Idaho. “In the short term, some animals will be displaced.”
Many burned-out animals simply find a new place to live. But at the same time, the scorched area often blooms as a perfect new home for more animals. A cycle begins, perhaps lasting decades or centuries, until the forest grows back and the departed animals return.
“What happens after the fire is more important than the actual fire” in determining animal survival, says Jim Peek, a retired wildlife biologist in Idaho.
Logically enough, plants and animals that prefer open fields, nutrient-rich soils and sunlight benefit soon after the biggest forest fires, scientists say, while animals that like deep, dark, damp forests must move on.
Short-term winners can include wildflowers, bees, pollinating insects and insect-feeding birds. Herbivores such as deer, elk and mice often are drawn to fresh vegetation, and that draws back predators such as coyotes, mountain lions, bobcats, wolves and bears.
Short-term losers include mosses, lichens, shallow-rooted deep-forest plants, pine martins, woodland caribou and spotted owls, although they may return years or decades later.
Flames themselves can be fleeting emergencies because healthy, mature animals’ natural defenses usually cause them to run or fly away, or take cover, experts say.
“There is some [animal death], there’s no doubt about it,” Leenhouts says. “Surprisingly, there’s not that much.”
Birds and large animals rarely die because they can flee quickly, experts say. And returning predators and scavengers can eat the relatively few smaller animals that die from smoke inhalation or, less frequently, flames. The smaller species usually can sustain the losses because many tend to reproduce rapidly, Neuenschwander says.
Even when the fire is burning, there can be winners. For example, one study revealed wild turkeys feasting on insects flushed out as a forest fire burned, Leenhouts says.
Out West, there even is a species of beetles that waits for fires, and has heat sensors to draw them in from miles away to feast on injured trees, according to Jane Kapler Smith, an ecologist with the U.S. Forest Service who has edited a paper on wildlife in wildfires.
Wide differences in the locations, types and intensity of wildfires cause nature’s winners and losers to vary from scenario to scenario, scientists say. But it is possible to generalize for broad types of wildfires — those that burn underbrush, and those that burn entire forests.
The most frequent forest fires burn through underbrush, postponing larger fires that leap from overgrown underbrush to the tops of the tallest trees. The understory fires occur naturally every five to 30 years in ponderosa pine forests, Smith says.
Birds and animals that prefer large, old-growth trees, such as pileated woodpeckers, benefit from the brush fires because they allow tall trees to grow and prosper, Smith adds.
In extreme cases — perhaps once a century, or even less frequently in many cases — entire forests burn from the ground to the treetops. Such fires also have a role in nature.
The regeneration process begins amid dead and dying trees, smoke and ash.
“Sick trees may or may not die, but they become homes for insects … [and] forage sites for many woodpeckers,” Neuenschwander says.
The woodpeckers peck away, and create holes in the trees.
“They become nesting houses, bird condos if you will, for almost 200 different species of birds,” he adds. “Eventually, small mammals use those — chipmunks, squirrels, mice.”
The nutrient-rich ash remains of the old forest, sometimes ankle deep, plays a key role, too.
“That becomes the fertilizer for the new plants to grow,” Neuenschwander says. “The new plants often are more tasty because of the nutrients. Because of that, the plants absorb more water and become more juicy. That attracts a lot of the animals, the herbivores, back into the [fire-affected areas]. … Of course, that will draw the predators.”
At the same time, dead and dying trees fall, and the decay breeds ants and fungus that other animals can eat.
“Even the fish eat the ants when they fall into the stream,” Neuenschwander says.
The fallen trees become hollowed-out homes to medium-sized animals such as raccoons and foxes.
“The next forest fire may come 50, 100 or 300 years later and begin the cycle again,” Neuenschwander says.
But things can and do go wrong.
For example, if violent rainstorms follow big fires, the water can erode too much ash into streams — heating water, choking fish and robbing nutrients from the soil, Neuenschwander says.
In addition, some ecosystems do not regenerate themselves well. Such is the case with current sagebrush wildfires in southern Idaho, Peek fears. Cheatgrass, an introduced species from Europe, tends to replace the original sagebrush after burns, he says.
“Those fires are really hurting pronghorn antelope, mule deer, sage grouse, sage thrashers and sage sparrows,” Peek says. “But on the other hand, we’ve just completed some work that says elk would actually prefer to feed on the post-burn vegetation.”
Another problem is that putting out brush fires can accelerate the onset of the larger fires and disrupt natural cycles. Experts blame the intensity of some current wildfires on such a phenomenon, which, along with excessive logging, can deplete old-growth forests.
“There’s potential to truly lose a resource,” Smith says. “There is the potential for the loss of old-growth ponderosa pine that will be really hard to replace. I don’t think it will threaten any species, but I still think it’s a [potentially] substantial resource loss.”
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