How will the Wildfires of 2000 Affect Grizzly Bears in the Rocky Mountains?
U.S Fish and Wildlife Service fact sheet-

The wildfires of 2000 were widespread throughout the Rocky Mountains and burned within all grizzly bear recovery zones. Fires burned portions of all grizzly bear recovery areas in Montana (Yellowstone, Northern Continental Divide, and Cabinet/Yaak Ecosystems), Idaho (Yellowstone, Bitterroot, and Selkirk Ecosystems), Wyoming (Yellowstone Ecosystem) and Washington (North Cascades Ecosystem). While the fires of 2000 burned more acreage than any year since the historic fires of 1910, their impact on grizzly bear recovery is viewed as largely beneficial. These widespread fires also provide numerous opportunities for future monitoring and evaluation of the impacts of wildfire on grizzly bears.

 Fire is a natural process integral to maintenance of healthy ecosystems in the Rocky Mountains. Grizzly bears have been living with fire in their habitat for thousands of years, and have evolved to maximize their ability to use burned areas and minimize the negative impacts of fire.

 The 2000 fires that occurred 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.

 Fires that occurred in lower elevation forested areas with greater fuel loads generally burned hotter and resulted in larger patches of stand replacing fires. Many of these fires occurred 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 the 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.

The 1988 Yellowstone National Park Fires: A Case Study   
The fires within the Yellowstone recovery zone in 1988 burned approximately 1.4 million acres. Of the 38 bears wearing radio transmitters, 21 had home ranges that contained one of more of the fires. Thirteen of these bears moved into burned areas after the fire front had passed, three (adult females without young) stayed within active burns as the fire progressed, three remained outside the fires at all times, and two adult females could not be located during the fires. One of the missing bears was relocated in 1990, and the other (a female with cubs of the year) was never relocated and presumed killed in the fires.

Grizzly bears that remained in burned areas were observed feeding on carcasses of ungulates killed in the fires, grazing on newly emerged sedges and bluegrass, digging in logs and anthills for insects, and excavating tubers and corms in non-forest surface burns. As more bears were drawn into burned areas, apparently attracted by carcasses, they were less likely to get into trouble with humans.

Research for 5 years after the fires found the fires had no apparent effects on bears' home range sizes, mean rates of movement, or choice of den sites, five of which were located in burned areas. On average, the bears used burned habitats in proportion to their availability within their ranges.

During spring and summer months, bears grazed more frequently at burned than unburned forested sites. Reduced canopy coverage and increased soil nutrients resulting from the fires increased forb foliage and tuberous roots in burned areas. Ants, an important food source thrived as burned trees fell to the ground and provided ant habitat.

Researchers speculate the most significant effect of the fires could be the loss of about 30% of the park's most productive mature whitebark pine habitats. Whitebark pine seeds are an important bear food. Cone production of this species is highly variable from year to year, and has made it difficult to determine what if any affect the 1988 fires had on the grizzly bear population. However, fire is an important process in whitebark pine ecology because it clears competing trees allowing for establishment of whitebark seedlings and promoting stand regeneration and vigor. Over the long- term, the fires will have a beneficial impact by increasing the age class diversity in whitebark pine stands and insuring the longevity of this important grizzly bear food source.

How Wildfire Impacts Grizzly Bears:   
Wildfires typically create a mosaic pattern of burned and unburned vegetation on the landscape. The immediate impact to grizzly bears is the removal of vegetation in burned areas, which impacts the abundance of grizzly bear foods and cover. 

Grizzly bears are highly mobile with large home ranges often over 100 square miles. They are opportunistic omnivores meaning they forage on a wide variety of foods to include plants, insects, and other animals. Therefore grizzly bears respond to fire by moving to unburned areas to utilize alternate food resources and cover. Bears may return to burned areas in search of carrion from animals killed by the fire. They also forage on lush revegetation of grasses and forbs which occurs quickly, aided by a flush of nutrients recycled to the soil. 

As dead trees fall to the ground, they provide habitat for ants and insects, which are an important component of the grizzly bear's diet.   

Within 3-7 years after the fire, berry-producing shrubs begin producing a berry crop again. Grizzly bears that have moved to unburned portions of their home range to forage on berries in late summer and fall, return to utilize this renewed food source in burned areas.   

If whitebark pine stands are burned, there will be an immediate decrease in the availability of pine nuts. Bears that utilize this food in the fall to increase fat stores for winter hibernation will have to find alternate foods, which may result in increased encounters with humans as they increase their movements in search of food. Bears that do not store enough fat may be forced to leave their winter dens early and females may not produce cubs. The long-term impact of fire on whitebark pine stands is positive in that fire clears overcrowded competing species and stimulates whitebark pine reproduction.   

The overall long-term impact of fire is that it increases the diversity of habitats and maintains the resilience and vigor of ecosystems which is beneficial to grizzly bears. Opportunities to Learn from the Fires of 2000:  

• Monitoring grizzly bear use of burned areas and effectiveness of grizzly bear habitat management strategies in burned areas. Past fires on USDA Forest Service lands occupied by grizzly bears have necessitated the development and implementation of fire salvage guidelines for grizzly bear management. These guidelines were developed by the U.S. Fish and Wildlife Service through Section 7 consultation with the USDA Forest Service. These guidelines have resulted in not harvesting certain areas of burned timber to provide cover for grizzly bears. Monitoring of the effectiveness of these management guidelines has been limited due to the small sample of radio-collared bears and limited application of the guidelines. The fires of 2000 provide an opportunity to expand the monitoring of grizzly bear use of burned areas, and the effectiveness of fire salvage guidelines implemented for grizzly bear management. 
• Monitoring of post-fire response of regeneration of whitebark pine and other bear foods. Whitebark pine seeds are an important grizzly bear food source in areas where whitebark pine occurs. This species has been declining in many areas of its range due to past fire suppression and the introduced fungal disease blister rust. Fire plays an important role in whitebark pine ecology by removing competing tree species and their pests, which allows whitebark seedlings to establish and prosper. The 2000 fires burned in grizzly bear recovery areas where whitebark is still abundant and an important food source. These fires offer an opportunity to observe whitebark regeneration in areas with and without significant blister rust infection to determine if the fires have fostered seedling regeneration and growth. Such information would assist agencies in developing management prescriptions for whitebark pine habitat types to ensure their persistence on the landscape and availability of this important food source for grizzly bears. Also, monitoring of the response of other important bear foods such as berry-producing shrubs and forbs as burned areas revegetate would provide valuable site-specific information on the impacts of fire on the availability and abundance of vegetative bear foods. This information combined with monitoring of grizzly bear use of these burned areas would provide further insight into the impact of wildfire on grizzly bears.