The whitetail deer not only uses its white “flag” to warn others in the herd of danger; it also allows a pursuing predator to use it as a target. When the tail is suddenly dropped—abruptly obliterating the bright white patch—the deer seems to disappear into its dim surroundings. Since overly conspicuous animals are prone to predation, natural selection favors development of appropriate camouflage. [Illustration: For such ground-dwelling birds as the white-tailed ptarmigan, camouflage is an important survival adaptation. The ptarmigan changes its plumage to match its surroundings: it is white in winter, speckled in summer. Moving slowly and refraining from flight, it is less likely than more-active birds to be detected by sharp-eyed, motion-conscious predators.] [Illustration: Birds that when hatched are covered with down and are able to move about freely are called _precocial_. They are less dependent upon their parents than are _altricial_ young, which are naked and helpless when they hatch; but they must rely heavily on a resemblance to their surroundings for survival during their first flightless weeks. This spruce grouse chick, which blends into its sunflecked forest-floor habitat, is an example of a precocial bird.] [Illustration: The bold disruptive pattern of the killdeer chick’s plumage helps this precocial bird avoid detection in its open-prairie environment. This adaptation, coupled with the chick’s instinct to freeze at the approach of danger, ensures that enough young will survive to perpetuate the species.] _Ursus arctos horribilus_: The Vulnerable King At the apex of the food pyramid, this great beast is unquestionably the king of Glacier’s biotic community. Yet the long-range future of the grizzly bear is uncertain. With the grizzly exterminated from most of its former range—which once extended into the midcontinent and south into Mexico—its numbers have dwindled in proportion to its diminished range. Present concentrations in the contiguous United States remain in and around Yellowstone and Glacier National Parks. Probably fewer than 200 of these magnificent creatures live in Glacier National Park. Grizzlies are easily distinguished from the more common black bear. In addition to larger size and heavier build, grizzlies have a characteristic shoulder hump; long, conspicuous claws; and a broad, concave face that gives them a “dished-in” appearance. Fur is usually brown; like the fur of the black bear, however, color may range from black to yellowish. Light tipped hairs make the fur appear frosted, giving rise to the nickname, “silvertip.”