Page:Natural History of the Ground Squirrels of California.djvu/35

Rh As far as is to be observed, the male takes no active interest in the welfare of the young. Indeed, he dwells altogether separately from the family and does not see his offspring until they begin foraging out of doors. His only function at all, as regards the upbringing of the young, is that of sounding general alarm throughout the colony when danger threatens. As for the mother, even she is notably indifferent to her young after they appear above ground. When suddenly alarmed, she flees to safety on her own account, leaving the youngsters to shift each for himself as best he may.

The rate of growth of the young is such that they reach mature size by September, when they are from four to six months old (McCoy, 1912, p. 1069). But before this time, by the first of August, the young of the year begin to emigrate locally, so as to establish each for himself a new home. It is likely that this process of emigration is hastened by the development on the part of the parents of an attitude of incompatibility. According to this idea the initial solicitude of the mother for her young at the helpless age is later reversed, so that she becomes antagonistic to them and finally speeds their departure. The young, at the same time, begin to give evidence of an instinct to wander. At any rate, the month of August sees the important phenomenon of emigration or dispersion well under way. Young of the year then put in their appearance in unexpected places; new ground is invaded, and the total territory occupied by the squirrels increased in extent insofar as the increase in population makes necessary and the favorable nature of the country permits. Undue congestion of population tends thereby to be prevented.

The natural enemies of the California Ground Squirrel are of many kinds, and under original conditions so many as regards individuals as to provide a regular automatic check to any abnormal increase of the squirrel. The most important are golden eagles, red-tailed hawks, coyotes, badgers, wildcats, weasels, rattlesnakes and gopher snakes. Each of these various animals pursues the squirrels in its own particular way. Hawks and eagles swoop down on them from their vantage points in the air. Wildcats and coyotes lie in wait near the burrows until the squirrels venture forth in search of food, when they pounce upon them. Badgers, weasels and snakes capture the squirrels in their burrows. Some specific cases will be cited here. It must be remembered that, while casualties to squirrels may be inflicted by their customary enemies almost hourly in any general neighborhood where man has not exterminated these predators, the chances of a person's being in a position at the critical moment to witness a tragedy of this sort are rare. At the San Emigdio Ranch in Kern County on April 25, 1918, the junior author watched a Golden Eagle (Aquila chrysaetos) capture and devour an adult ground squirrel. The eagle was first observed flying quietly down a canyon. By weaving in and out in its course the bird was able to skirt the irregular hillside so as to keep within fifteen or twenty feet of the ground. At length the eagle skimmed abruptly around the shoulder of a hill, just clearing the tops of the wild oats, and dropped quickly down upon a luckless ground squirrel. The latter had evidently been on a foraging expedition and did not have time to reach his burrow, so complete was the surprise. The eagle seized the squirrel with both sets of talons, and the piercing grip by these effective