The pine tree is a high-elevation grocery store for grizzlies and other wildlife. It produces high-protein nuts that fatten pre-hibernation grizzlies. As long as the up-country food is available, grizzlies stay in the high country, away from the fatal attractions of foothills civilization. But the pine has been decimated by beetles and forest fires--both intensified by global warming, say some scientists--and lately bears have been roaming in search of food. Those forays often result in encounters with humans' cars, cattle, cat food and cow calls, and the encounters rarely turn out well for the bears.