[Illustration: Young martens show the curiosity typical of their kind.] The MINK is rare in the park, but is occasionally seen on Glacier Creek. This member of the weasel family is an excellent swimmer, and catches fish with ease. Its dense and oily fur keeps it warm in cold water, but it lacks any other apparent adaptations to an aquatic life. So agile an animal has few natural enemies apart from disease; its most important predator is, oddly enough, the great horned owl. The young are born blind and helpless, and only the size of one’s finger, but by summer’s end they become self-sufficient. The WEASEL is a small, sharp-eyed creature with an extremely long body, small triangular head, and furtive ways. Weasels are successful hunters, searching through brush piles and rock heaps and in underground burrows for rodents of all kinds. There are two species in the park—the LONGTAIL WEASEL and the SHORTTAIL WEASEL, or ERMINE. The latter is less than half as large as the former. Like that of certain other mountain dwellers, the fur of weasels becomes white as the snows of winter approach, replacing the brown of summer. Horseback riders crossing Moraine Park and Beaver Meadows are usually wary of the large holes that are the work of the BADGER. Although a creature of the plains rather than of the mountains, the badger lives in some of the lower meadows of the park, and there have been reports of badgers being seen near Fall River Pass. It is a meat eater, and its large front feet have long claws, which enable it speedily to dig out a ground squirrel. [Illustration: Red fox. —Drawing by Walter A. Weber.] Gnawing Mammals The YELLOWBELLY MARMOT, with its reddish underparts, grizzled back, and bushy tail, is seen by nearly all park visitors. Although it is more common in medium altitudes in the mountains, it also may be seen high along Trail Ridge Road, and a pair, reportedly, is living atop Longs Peak! These rodents live in dens, usually rockpiles, into which they pack twigs and grass to make a comfortable nest. They store up a heavy layer of fat in the summer and hibernate during the cold winter. Their natural food consists of grasses, berries, and roots. Their short, sharp whistle can be heard a mile away. During the summer, hikers occasionally see rather humanlike scenes, as marmot families sun themselves on the “front porches” of their rockpile homes.