The TASSEL-EARED, or ABERT, SQUIRREL is an excellent example of the zonal specialization of mammals. It is almost entirely restricted to the ponderosa pine forest belt. Its showy ear tufts, although often absent during the summer, set it apart from other local squirrels. It feeds mostly on ponderosa pine seeds, the bark of twigs and young trees of this species, and such wild fruits and succulent vegetation as are available. The Abert squirrel builds nests in the trees and is a familiar sight to hikers in the ponderosa pine forests. It is usually gray-colored, but may be brown or even completely black. Another small arboreal rodent, the SPRUCE SQUIRREL, chatters and scolds when a stranger enters its patch of forest. It roams both the lodgepole pine and higher spruce-fir forests with their bitter winters, yet it does not hibernate. Even after the most severe storms it will emerge to travel through the treetop world it occupies. Some bird enthusiasts have little regard for it, because of its habit of eating eggs and young birds whenever the opportunity presents itself. However, in a National Park the squirrel’s desire to live is considered to be as important as is the bird’s. A certain “balance” of population is the result, which is, after all, one of the desirable features in an area dedicated to preserving natural conditions. CHIPMUNKS are particularly familiar at Trail Ridge Road parking areas. These small squirrels are reddish-brown above, with white underparts and with four white stripes running along the back. A definite stripe across the face distinguishes them from the golden-mantled ground squirrels, with which they are often found. The GOLDEN-MANTLED GROUND SQUIRREL is often confused with the smaller chipmunks which it joins in begging for visitor handouts at parking areas below treeline on Trail Ridge Road. Its natural food is succulent plant material and seeds, but many of the gregarious little animals are becoming more or less dependent upon food offered them by humans. You can see them most conveniently at Many Parks Curve. Another little rodent, common in the lower meadows, is the RICHARDSON GROUND SQUIRREL (“picket pin”). It lives in colonies, after the fashion of the prairie dog of the plains. It is abundant in Moraine Park. Relatively few park visitors see the BEAVER; but all can see examples of its work. It works at night as a rule, and usually remains out of sight when humans are abroad. These industrious rodents are much larger than the related chipmunks and marmots, and weigh as much as 90 pounds. Beaver pelts were part of the lure that led to the early exploration of the West. Almost exterminated about 50 years ago, they are now relatively abundant in Rocky Mountain National Park. [Illustration: Yellowbelly marmot—seen by most visitors.]