actions and the success of the annual crop. During good years, bears stay in high-elevation, 

 whitebark pine habitats. But in poor years, they are found foraging near roads and settlements 

 where they are more likely to encounter humans and become objects of control actions. Many 

 whitebark pine stands in the northwest have been infected and killed by whitebark pine blister 

 rust. Whitebark in the GYE has been infected by this disease, and the IGBST monitors the 

 extent of infection. 



A second, high-fat food source for grizzlies during the hyperphagic period is the army cutworm 

 moth. Moths collect under rocks in alpine areas in late summer and fall. The importance of 

 moth aggregation sites to grizzly nutrition has only gained appreciation in the last decade. This 

 relationship is an area of current interest as new seasonal gathering sites are being discovered. 



Anthropogenic foods (i.e. garbage, livestock feed, pet food, bird seed, human foods, garden 

 crops, honey) are used by brown bears wherever humans and bears coexist. Open garbage 

 dumps can be a source of highly nutritious foods when available. Use of dumps can lead to food 

 conditioning, habituation, and increases in property damage and human-caused bear mortality. 

 In the GYE, considerable effort has gone into eliminating availability of anthropogenic foods. 

 These efforts have been largely successful in reducing incidents of bear-human conflicts. Here, 

 and in other regions where bears and people live in close proximity to one another, most 

 conflicts occur during years when important natural foods fail. 



Due to reliance on sporadic food sources, grizzly home ranges may be seasonally dependent. 

 Ranges vary to include seasonal food aggregations, which may cause many individual ranges to 

 overlap. Yet, not all bears rely on all food sources, and individual variation is the norm. 



In summary, grizzlies are opportunistic and omnivorous foragers able to take advantage of a 

 wide variety of locally important foods. Home range size seems determined by food abundance, 

 and many individuals are able to abandon, or overlap, their ranges to exploit concentrated food 

 aggregations such as pine seeds, moths, fishes, carrion or garbage. Much of this behavior seems 

 influenced by experience and habit. This adaptability has obvious survival advantages, but also 

 results in large spatial requirements that complicate grizzly management. Currently, designated 

 Wilderness areas as well as roadless areas which may be given Wilderness status at some future 

 point are important to meeting these spatial needs in major parts of this area. Monitoring of key 

 foods is performed systematically by state and federal agencies both within and outside the PCA. 



Habitat for Denning 



Yellowstone grizzlies spend up to seven months a year in dens. In general, bears den by mid- 

 November, although pregnant females den somewhat earlier. Their emergence from wintering 

 dens occurs from mid-February to late March for males, followed by single females and lastly by 

 females with new cubs, as late as mid- April. The exact timing for this event may be climate 

 dependent. 



Site selection for dens occurs on steep slopes and at high elevation (>6500 feet) and in all cover 

 types in the GYE. Dens are usually excavated, although natural shelters such as caves and 



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