. Distribution of mammals in Colorado. Mammals. 144 MONOGRAPH MUSEUM OF NATURAL HISTORY NO. 3 increasing in a gratifying manner. . ." Young (1908:406) noted that the squirrels also oc- curred at Denver, and Warren (1942:308) reported the presence of a few fox squirrels at Colorado Springs. During the 1920s, the species was introduced at Sterling and at Fort Collins (Lechleitner, 1969:108). Evidently they also have been introduced at Limon. The population in the South Platte Valley is well established. Suitable habitat there is restricted, however, to the river bottom com- munity, dominate
. Distribution of mammals in Colorado. Mammals. 144 MONOGRAPH MUSEUM OF NATURAL HISTORY NO. 3 increasing in a gratifying manner. . ." Young (1908:406) noted that the squirrels also oc- curred at Denver, and Warren (1942:308) reported the presence of a few fox squirrels at Colorado Springs. During the 1920s, the species was introduced at Sterling and at Fort Collins (Lechleitner, 1969:108). Evidently they also have been introduced at Limon. The population in the South Platte Valley is well established. Suitable habitat there is restricted, however, to the river bottom com- munity, dominated by Populus sargentii, and to artificial habitat in towns or in hedgerows along ditch-banks. In recent years, the intro- duced population probably has been rein- forced by natural invasion from the east (Hoover and Yeager, 1953). This has been allowed by the relative stability of the riparian woodland over the past half-century. It is on the strength of the possibility of such a natural invasion that Sciurus niger is included as a member of the native fauna of Colorado. In the distribution map for this species (Fig. 52), only the conterminous range in the South Platte and Republican watersheds is shaded. Extra-limital localities are plotted, however. The status of S. niger in Colorado was detailed by Hoover and Yeager (1953). Yea- ger (1959) discussed the ecology of the spe- cies in Colorado and suggested that the out- look for fox squirrels in the state was un- favorable. The cottonwood stands to which the animals are mostly restricted are being reduced at present. Many of the stands are overmature, and natural reproduction is held back by grazing of livestock in bottomlands and by fire. Cottonwoods frequently are re- moved from irrigated lands because of their high rate of water consumption. As cotton- wood stands are reduced, so also are requisite conditions for a viable population of fox squirrels. The fox squirrel has invaded the foothills to some extent in the deciduous
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectmammals
