The Effect of Forest Fires on Grizzly Bears

Fires that occur within remote wilderness portions of the grizzly bear recovery ecosystems, generally created a natural mosaic pattern of burned and unburned vegetation.

Grizzly bears will benefit from increased diversity in the landscape and increased abundance of grizzly bear foods over time.

Survival of mammals in forest fire areas is in the upper 90% range. By creating many different food sources, these fires are beneficial to the grizzly bears. First of all, by burning away dense timber and smaller plants, it creates nutrients for future successional plants. In Montana , grizzly bear diets include huckleberries, which are successional plants. The fires also open up the canopy of trees in wilderness areas, allowing sunlight to filter in for smaller plants to be established. Some of these plants are also food sources for grizzly bears.

Forest Fires

Fires that occur in lower elevation forested areas with greater fuel loads generally burn hotter and result in large patches of stand replacing fires. Many of these fires occur adjacent to valley bottoms with human interface areas. Such fires on the periphery of the recovery zones will impact grizzly bears by removing cover, which is critical to their use of these more developed areas. As a result, grizzly bears may avoid these areas because of lack of cover.

Bears that use or move through these areas may have a higher potential for encounters with humans and a greater risk of human-induced mortality.

Grizzly bears often stay only a few hundred yards from a burning fire line. It has been observed that in these situations, they have appeared calm and unafraid of the fires. By staying close to the fire lines, bears are able to capture small prey running out of the burning forests. When the fires have subsided, grizzly bears re-enter the burn area, and obtain food sources from uncovered caches of pine nuts, homeless, small rodents, and those "barbecued" animals that were trapped by the fires. The overall long-term impact of fire is that it increases the diversity of habitats and maintains the resililience and vigor of ecosystems which is beneficial to grizzly bears