Page:Natural History of the Ground Squirrels of California.djvu/55

Rh small and scattered that it did not attract attention. A typical example is as follows.

Residents of Owens Valley at Lone Pine stated in June, 1917, that the ground squirrels there had only recently invaded the valley and that none were known in that vicinity five years before. But from this same locality specimens now preserved in the Field Museum of Natural History in Chicago were obtained in 1902, fifteen years previously. Although the squirrels are said to be steadily increasing along the west side of Owens Valley, little or no effort appears to have been attempted at controlling the pest.

At the Carl Walters Ranch, two miles north of Independence, on June 26, 1917, Fisher Ground Squirrels were found to be fairly abundant on both this and most of the other ranches in the vicinity. They had been considered a nuisance here for a number of years (A. C. Shelton, MS).

The irrigation and cultivation of extensive areas have resulted in a greatly increased available food supply which has proven acceptable to the ground squirrel and has resulted in greatly increasing its population. It is the authors' belief that the squirrels have been present in Owens Valley from time immemorial and that as long as they were few in numbers and stuck to the rocky, uncultivated ground they remained largely unnoticed, but that when they invaded irrigated fields and became numerous they attracted attention and were then thought to have but just moved into the valley.

It is believed that, on the whole, there are only about half as many Fisher Ground Squirrels to the square mile throughout its range as there are California Ground Squirrels to the same unit of area in the range of that form. Fisher Squirrels nevertheless prove very destructive locally to cultivated crops. Many small isolated orchards and "dry-farmed" grain fields are scattered throughout the western and northern parts of the range of fisheri and these frontier ranches are the ones which suffer. While the money value of the crop destroyed may be small, yet such crops are often the settler's principal means of obtaining a livelihood and, although this may be humble indeed, its loss is felt critically. It is the authors' belief that the Fisher Ground Squirrel ranks third, or next after the Oregon Ground Squirrel, in point of economic importance in California.

Other names.—Island Spermophile; Citellus nesioticus; Spermophilus beecheyi, part.

Field characters.—As for the Beechey Ground Squirrel. Only to be distinguished from it on comparison of series of specimens; coloration averaging darker, general size greater, and tail relatively shorter. Length of body alone, in males, about 11¼ inches; with tail (without hairs) about 7½ inches more.

Description.—Adults in April: Similar to the Beechey Ground Squirrel (San Francisco Bay region) as already described, but general coloration darker; top of head from nose to nape, and broad area down middle of fore back between light