This large western marmot is not too far removed from the ground squirrels in either relationship or habits. It is the largest ground-dwelling rodent native to the Southwest. As mentioned above, marmots occupy a tremendous altitudinal range, reaching from above timberline down into the Transition Life Zone. This distribution from arctic to almost desert conditions is responsible for many variations in their habits. Most important is the practice of estivation by those individuals which live at the lower elevations. This summer sleep is used as a defense against that period of drought between rainy seasons. It usually starts early in June and ends about the latter part of July. In the higher life zones there is no lack of green food throughout the summer, consequently marmots there remain active. Because of large size and ability to make good use of its sharp teeth and claws, the marmot’s life is not so restricted as that of many smaller ground-dwelling rodents. It has enemies, to be sure. Bears, mountain lions, wolves, lynxes, wolverines, and eagles all are alert for a possible catch. Yet it is so well on guard and has so many burrows that it is next to impossible to catch one above ground. Should the marmot be surprised away from a burrow, its bold show of defense often gains enough time to work its way to a place of safety. When cornered its appearance alone is enough to make the average predator pause and consider. With hair standing on end and long claws at the ready, the marmot clatters its sharp teeth and hisses loudly at the enemy. This pose is not all bluff. These big rodents are courageous and able adversaries against any animal up to several times their size. As far as man is concerned, they are timid and secretive. On many an occasion their loud, full-toned whistles will be heard, but the whistler will be nowhere in sight. If cornered, however, they will put up the same courageous defense they display against other enemies, and certainly are not animals with which to trifle. Burrows are usually in open places where a good view of the surroundings is obtained. Too, they are almost always in clefts of rocks, under boulders, or in coarse rocky soil. This lessens the probability of their being dug out by some large predator. Each marmot usually will have several burrows, some being “escape” means and one a permanent home. Well-worn trails lead from one to another, for these are active animals which travel extensively within the limits of their territories. Escape burrows may be deep or shallow, as circumstances dictate, but the home burrow generally is a labyrinth of long passages that terminate in a nest chamber up to 2 feet across. Several auxiliary tunnels are usually reserved for sanitary purposes. None is used for food storage; records indicate that this creature does not lay up stores for later use. The nest is the usual bulky affair, built of coarse materials and lined with the softest grasses and fibers obtainable.