Wildlife and Wildfire: What Happens to the Animals?
Each summer we can expect wildfires in the Intermountain West. This region has adapted to periodic wildfires, which are natural for sagebrush habitats and ponderosa pine forests, as well as other habitats. As fires burn through large acreages of habitat, many of us wonder how this affects wildlife. The good news is that most wildlife native to these habitats have evolved with the ability to respond to the periodic fires that are expected.
During the Fire
Most wildlife make it out alive. Smoke, heat and noises associated with fire are cues to take cover. With the onset of a fire, invertebrates start to move out of its range, either flying or burrowing down into the soil. As the soil heats up, they respond by burrowing down farther. Reptiles and amphibians will do the same, also taking cover under rocks and logs. Birds and mammals will fly and run away in advance of the fire. Larger mammals may even take refuge in streams and lakes.
Of course, there is still risk. Small animals cannot respond quick enough to fast-moving fires. For those that burrow or take shelter on the surface, their chosen site may not be adequate for high-intensity fires, that can heat the soil to a burning temperature as deep as 2 inches, or they may suffocate in the smoke. Young animals may not be able to fly yet or to fun fast enough, or their mechanisms for safety (e.g. hiding in grass and staying still, climbing a tree) will leave them vulnerable to the fire. Finally, those that do make it away from the fire may be displaced, and unable to find adequate shelter in their new environment; or unsure how to stay safe away from the herd or flock. Even as there are those that are victims of fire, there are winners, too. To predators and scavengers, fires are an opportunity to find food.
Short Term
Each fire is different in its pattern of burning the landscape and the intensity of the fire. Many wildfires are of light intensity (burning quick and low) and are patchy, leaving a mosaic of unburned and burned habitat. Prescribed fire, also called “controlled fire”, is a way to purposefully create this mosaic habitat by managing a light intensity fire to benefit wildlife. Unfortunately, each year there are also “mega” fires, that burn with high intensity across thousands of acres. In 2017, the Brian Head Fire in southern Utah (>70,000 acres), and the Power Line Fire (>50,000 acres), near Pocatello Idaho are good examples of “mega” fires that had both high intensity burns and large acreages burned.
Once the fire has passed, those animals that survived now have to adjust to a potential loss of food and shelter. When the wildfires create a mosaic of burned areas, the negative impacts to many animals may be very minimal. Animals can return to their home range, but may have to find a new shelter. Herbivores may find a decrease in the availability of forage (grass, berries, leaves), having to expand their home range temporarily, but can stay in the same general area. During this time, people that live at the intersection of natural habitat and urban areas can experience an increase in wildlife related issues - herbivores may take advantage of orchards, landscaping, etc. until their native vegetation returns. The risk of harassment from us is worth having food to eat!
Many animals benefit right away or nearly so. For example, woodpeckers will come and gorge on dead and dying invertebrates that lived in the now-dead trees. Greater sage-grouse have been recorded foraging in burned areas looking for insects and grubs. Even deer and elk may stay close to a burned area to take advantage of the growth of grasses and flowers that occur soon after a fire. Research has shown that the number of small mammals increase after a fire, compared to before the fire, especially in areas that experienced a patchy fire that created a mosaic of burned and unburned areas. In the southwestern US, fires appear to benefit bird species within 2-3 years after a fire - especially those that nest in cavities or eat flying insects.
As the total acreage of the fire increases, the opportunities for wildlife to return to the area right after the fire diminishes, because the available shelter (leafy trees, downed logs, tall grass) and food (grass, berries, leaves, insects) is less. Animals may have reduced health because they are searching for a new home range that has the food and shelter the species needs to survive. The first year after a fire, the area may experience a lower number of young animals surviving - they may have died in the nest or burrow, they may not have enough energy to find new food and shelter, or they are unable to put on enough fat to survive the winter.
Fires can also alter the way water flows through the landscape, changing the invertebrates and fish that can exist in a stream. For example, fire will decrease the amount of cover a stream has, increasing its temperature. More water running off the land, without vegetation to stop it, can increase the amount of sediment in a stream. This changes the species of invertebrates in the stream, and consequently, the species of amphibians and fish that live off those invertebrates.
Long Term
Because fire is a natural part of most of the ecosystems in the Intermountain West, its occurrence is usually a good thing. Fire sets back succession, returning stands of trees or shrubs into grasslands. This is a natural event that is necessary to put nutrients back into the soil. After fire, grasses and flowers (forbs) used the new nutrients to increase their growth, filling the barren area with a carpet of green. Also, trees like aspen and ponderosa pines need fire — aspen respond by sending out root shoots, and ponderosa pine cones open to release seeds after they are burned. Even large fires have patches that didn’t experience high heat intensities, and these patches will recover quickly.
The increased grasses and flowers provide food for herbivores, and these birds, mammals, reptiles, and invertebrates return to the area to feed. Grasses can have more nutrition in them after a fire, benefitting those species that eat them. Very soon after, the carnivores and scavengers come back too, and the ecosystem is rebuilt. Standing dead trees become shelter for cavity nesting birds and mammals, and daily shelter for reptiles and amphibians. Shrubs begin to grow, and create more shelter and food opportunities.
When small fires burn, the ecosystem can rebuild within a few years - and perhaps is never even negatively affected. When large fires burn, the ecosystem will take longer to recover, it all depends on how long it takes for vegetation to return. If the fire was large in size, a new ecosystem is created, and the community of wildlife species changes. For example, a large, high intensity fire in a wooded habitat will create a large grassland. For those animals that depended on the wooded habitat, they have a loss, and will need to find a new place to live or they will perish. However, the grassland a new opportunity for those animals that require this habitat. Thus, we see a change in wildlife species for a time.
What you Can Do
• Leave animals that you find after a fire alone. Mothers will often hide their young to keep them safe while the mothers feed. They will come back to them. But, if you “rescue” the young animals, wildlife biologists cannot find the mother to reunite them. The young animals often die as a result.
• If you find an injured animal after a fire, leave it alone. Take note of the location and contact your local wildlife biologist. The local biologist will know what the best course of action is, and will retrieve the injured animal in a way that is safe for the animal, if necessary.
• Do not feed animals displaced by fire. Allow them to find new habitat and food sources in their own time. This will be better for them in the long term.
• Be tolerant of wildlife that use your land for food — not provided by you! — or shelter immediately after a fire. While you may receive temporary damage to your landscape, it could be a matter of life or death for those animals.
Conclusion
Wildfires are a natural part of the ecosystem in the western US, creating new habitats and restoring nutrients into the soil. While they are dangerous to wildlife, most wildlife can survive a fire by hiding or leaving. In the short term, wildlife can be stressed by the loss of shelter and food. However, fires create food opportunities for those animals that eat invertebrates, or scavenge those animals that didn’t survive the fire. As vegetation begins to grow, wildlife actually benefit from fires. In the long term, wildfires create a mosaic of healthy habitats, and support healthy ecosystems. As fires get larger and more intense (hotter), the benefits of fire can be reduced or take longer to emerge. As large fires become more common in the West, research is being conducted to determine their short and long term effects on all species.
References
Janssen, H. June 10, 2016. 5 unexpected ways that wildfires affect wildlife, ecosystems of forests. Accuweather. com. Accessed at: https://www.accuweather.com/en/weather-news/five-effects-wildfire-west-forests-wildlife-ecology-animals-plants/53289791
Logan, B., Singleton, P. Thompson, C., Saab, V., and Block. W. 2016. Wildfire!
Toward Understanding Its Effects on Wildlife — from The Wildlife Professional. The Wildlife Society. Accessed at: http://wildlife.org/wildfire-toward-understanding-its-effects-on-wildlife-from-the-wildlife-professional/
The Nature Conservancy. 2017. Wildlife and Fire: What’s an animal to do? Accessed at: https://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/arizona/wildlife-and-fire.xml