On the Grand Mesa, which is more elevated than, and some 110 miles north of, the Mesa Verde (see Figure 1), 55 per cent of the species of mammals have boreal affinities and the other 45 per cent are wide-spread species (Anderson, 1959:414). Boreal species from the Mesa Verde are _Sorex vagrans_, _Sylvilagus nuttallii_, _Spermophilus lateralis_, _Marmota flaviventris_, _Tamiasciurus hudsonicus_, _Microtus montanus_, and _Microtus longicaudus_. These seven species comprise only thirteen per cent of the mammalian fauna of the Mesa Verde. Other boreal species that occur in the mountains of Colorado on the Grand Mesa or elsewhere (Findley and Anderson, 1956:80) and that do not occur on the Mesa Verde are _Sorex cinereus_, _Sorex palustris_, _Ochotona princeps_, _Lepus americana_, _Clethrionomys gapperi_, _Phenacomys intermedius_, _Zapus princeps_, _Martes americana_, _Mustela erminea_, and _Lynx canadensis_. The 47 species from the Mesa Verde that are not exclusively boreal make up 87 per cent of the mammalian fauna. Most of these are wide-spread species and are more abundant in the deserts or other lowlands than in the coniferous forests of the highlands, for example the eight species of bats, and _Sylvilagus audubonii_, _Thomomys bottae_, _Taxidea taxus_, _Bassariscus astutus_, _Canis latrans_, _Cynomys gunnisoni_, _Reithrodontomys megalotis_, and _Lepus californicus_. A few of the wide-spread species are more common in the highlands than in the lowlands, for example _Ursus americanus_, _Felis concolor_, _Castor canadensis_, _Erethizon dorsatum_, and _Cervus canadensis_, and the ranges of three of these, the bear, mountain lion and wapiti, are more restricted today than formerly. A few species find their favorite habitat and reach their greatest abundance in altitudinally and vegetationally intermediate areas such as upon the Mesa Verde, or in special habitats, such as the rock ledges, and crevices that are so abundant on the Mesa. Examples of this group of species are _Spermophilus variegatus_, _Peromyscus crinitus_, _Peromyscus truei_, _Neotoma cinerea_, and _Neotoma mexicana_. One species, _Dipodomys ordii_, is restricted to the desert. Species that are restricted to the desert and that occur in Montezuma County, Colorado, but that are not known from the Mesa Verde are _Ammospermophilus leucurus_, _Perognathus flavus_, and _Onychomys leucogaster_. Species known to have changed in numbers in the past 50 years are the mule deer that has increased, and the prairie dog that has decreased. Possibly beaver have increased along the Mancos River. The muskrat, mink, beaver, and raccoon usually occur only along the Mancos River, as there is no other permanent surface water in the Park.