Joseph Grinnell

“ The Antelope Ground Squirrels constitute a group distinct in many ways from all our other species. They are hardly less inhabitants of the ground, as compared with the tree squirrels and true chipmunks, but in manner they are more vivacious than any of the other ground squirrels; they run at a much faster clip and hence can forage at greater distances from safety refuges. Their coloration is distinctive, too, gray, with one white stripe along each side of the back, and with the under side of the tail brilliantly white. ”

“ The sure test, on the basis of behavior, of a ground squirrel as compared with any true tree squirrel, such as the California Gray, is that the former, no matter how high in a tree when discovered, will, upon alarm, take to the ground as quickly as possible, and seek safety in a burrow below ground, rather than make off through the branches from tree to tree, or ascend into the uppermost foliage of a treetop. ”

“ Males and females are present in a general population in about equal numbers. Even though but one litter is reared by each female squirrel each year, this would mean that for each pair of squirrels at the beginning of the breeding season there will be ten individuals at the close of the breeding season. The evidence we have examined goes to show that all the squirrels breed the first year of their lives—that is, when each is not quite one year old—as well as subsequently, and that the life-time of a squirrel, if it dies of old age, is five years. ”

“ There is nothing to show that there has been any extension of the general range of the species, or any retraction in it either. As already set forth, the arrival of the white man and the institution of agriculture has undoubtedly had the effect locally of increasing the ground squirrel population. On the other hand, where man has been aroused by the seriousness of their depredations to the point of adopting and putting into force effective means of control the numbers of the squirrels have been conspicuously reduced. ”

“ The Golden-mantled Ground Squirrel is a spermophile in the truest sense of the word; it is preëminently a gatherer and eater of seeds, and most of its time aboveground seems to be occupied in diligent search for this sort of food. The cheek-pouches in this squirrel are developed to a maximum degree, and it is no uncommon thing to see an individual returning to its burrow from a foraging expedition with its two pouches so distended with seeds that the head seems double its ordinary width. We have counted 636 seeds from the two pouches of one squirrel. ”

“ At various points within the range of fisheri we have been told by old residents that digger squirrels have only recently invaded the locality and that a few years ago there were none where many squirrels are now present. In many such cases the sudden increase in the number of ground squirrels is evidently due not to invasion from without, but to the breeding up, under favorable conditions, of the local stock of squirrels which have been present all the time, but which was formerly so small and scattered that it did not attract attention. ”

“ Twenty-five minutes elapsed after this before any of the young squirrels reappeared above ground.
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 within but a few feet of the mouth of its burrow and first taking alarm, a squirrel will rise quickly on its haunches and assume the rigid, upright, "picket-pin" posture (see fig. 20c) . This usually brings the animal's head well above the grass tops, so that it can get a good view all about. Also it can then be seen a long way, looking in the distance like a tent-stake or picket-pin out on the meadow. During this pose the fore limbs are pressed closely against the body. ”

“ We have heard the argument advanced against the poisoning of ground squirrels on wild mountain land in the northwest coast district that reducing the squirrel population will deprive the coyote of one of his chief sources of subsistence and that he will thereupon be forced to seek food elsewhere and so be more prone to raid the poultry of the valley ranches and the flocks of sheep in the mountains. ”

“ This latter feature is in itself unique, for it is accompanied by a most striking mannerism, that of the almost constant carriage of the stubby, flat-haired tail in an upright position, held against the back, so that the white under surface shows as a white "flag" when the animal is scurrying away, much as with the similarly advertising marks of the cottontail rabbit and antelope; only with the ground squirrel the effect in catching the eye of the observer is still further heightened by the way in which it is spasmodically twitched whether the animal be at rest or running. ”

“ Man either purposefully or incidentally begins at once to modify the original complement of animal and plant life both through destruction of native species and by bringing in with him alien kinds. Some native species become more and more restricted in range, even disappearing altogether; others tend to increase and spread, finding conditions for their existence to be improved through man's activities.
In the case of the ground squirrels of California, we have a group of mammals which seems to have in many places benefited by human invasion. ”

“ At any rate, the squirrels are seen crossing open spaces but momentarily, and thenceforth they remain in the shade of bushes until they take final alarm and descend into their burrows.
The long, slender, ratlike tail is exclusively characteristic of this species of ground squirrel. The body, too, is rather slender, though after a full meal of green stuff individuals have been seen which showed a rather pot-bellied outline. The mere rims of ears give the animal a round-headed look. The movements are rather more agile than in most of its relatives. ”

“ I caught sight of one standing upright at the mouth of its burrow, squeaking, and of two others running over the sand beneath the trailing green mesquite branches. The lines of footprints in the sand centering at the mouths of their burrows are diagnostic. The animals are extremely shy, going below ground at the slightest alarm. ”

“ 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. ”

“ In such cases the squirrel population from the wild land immediately adjacent seemed to have moved in en masse, as harvest time approached, to take advantage of the special food supply thus made available. Nevertheless, the Douglas Ground Squirrel, by reason of its relatively sparse population over most of its range, and the ease with which it can be reduced in numbers with reasonable effort, does not rank as of so much economic importance as some other species. We would place it fourth among our ground squirrels, giving precedence to the California, Oregon and Fisher. ”

“ The burrows of the Belding Ground Squirrel are generally located in the meadows which form their forage grounds. Sometimes, near timber line, one finds them in the scant gravelly soil between granite boulders, but always in or near patches of the kind of bunch grass occurring at such altitudes. The mounds are rarely conspicuous, and the holes open up to the surface steeply. Often there is no surplus earth at all around the mouths of the burrows, but this condition might be accounted for by the effects of washing from heavy rain or melting snow. ”

“ The convulsive movements of the body were synchronous with the notes as uttered. The picket-pin attitude is really not so frequent as a crouching one, though when it is assumed it renders the squirrel visible a long way, especially where the grass is short. ”

“ A few days later a squirrel of this species was seen gathering dry seeds of the alfilaria. It is difficult in the field to be sure just what kind of seeds the squirrels are seeking out, since the seeds are too small to be seen at any great distance even with the aid of binoculars, and the stomach contents are so finely chewed that it is impracticable to identify the food constituents. ”

“ Human interest in the California Ground Squirrel naturally concerns itself most especially with the questions of total population, rate of increase, and rate of re-invasion of territory previously cleaned of squirrels. As to the first question, we have found it difficult to find an accurate basis for determining the squirrel population living on any given unit of area, such as an acre or a square mile. Counts may be taken of living squirrels that happen to be aboveground at any one time, or of burrows which give evidence of current use. ”

“ 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. ”

“ Upper surfaces of feet dull white; palms naked; soles of hind feet clothed with dull whitish hairs to about halfway forward from heel; claws blackish, with horn-colored tips. Tail flat-haired, but narrowly so, and tapering from base to tip; upper surface buffy drab; beneath dull white at base, becoming dusky pinkish buff toward end. Lower surface of body silvery white, faintly buff tinged, particularly as forming a band along each side, and with much of the leaden-hued bases of the hairs showing through.
We have at hand but two specimens of this ground squirrel, and these are both immature. ”

“ During the past spring and summer our work of excavating squirrel burrows after the occupants had been gassed, has shown that one frequent cause of failure in the ordinary waste-ball method of applying carbon bisulphid is due to the fact that sudden elevation in the course of the burrow, of as much as two feet in some cases, prevents the heavy gas from reaching the animal. ”

“ Level sandy ground is, as a rule, but sparsely inhabited; and we know of some stretches of desert, such as the floor of the Coachella Valley northwest of Salton Sea, where none at all seem to exist, although the species is abundant in the foothills adjacent. The kind of ground most generally preferred seems to be hard-surfaced, gravelly wash-fans or hill slopes. Kinds of vegetation present seem to be immaterial, though clumps of squaw tea, creasote bush, cactus, or tree yucca characterize much of the territory where the Antelope Squirrels are most abundant. ”

“ Not infrequently, when surprised in a tree, a ground squirrel will for the time being "freeze" and attempt to escape being seen by remaining motionless. But after being further disturbed and once starting, he makes for the ground by the shortest route. ”

“ We have weighed and examined the stomach contents of a series of squirrels, with results already given. These, summarized, show that one ounce of dry grain or seeds, or four ounces of green vegetation, is consumed each day by an average California Ground Squirrel. If we take fifty pounds of green stuff as representing the amount of forage consumed daily by one steer on open range, then 200 squirrels would appropriate the forage which would keep one steer. ”

“ It would seem that, if absolute extermination prove not possible over any large area, eternal vigilance must be exercised to prevent the quick return of the squirrel population to the danger point. The squirrels must be looked after like weeds, which have to be dealt with year after year. ”

“ Ground squirrels reproduce rapidly. In the California the average number of young in a litter is 7.2, with 4 and 11 as extremes. There is but one litter reared each year, and the young begin to appear aboveground about the first of May. The sexes are equally divided in a given population, and it is believed that each female breeds the first season of her life, that is, when she is slightly less than a year old, and that she has an "expectation" of rearing four more litters in case she lives to die of old age. ”

“ When feeding, the squirrel hunches over on its haunches, and uses both front feet and the fingers of these for holding and manipulating the food. When foraging the squirrels do much slinking along, with body horizontal and seemingly touching the ground. When a general alarm is sounded one sees them running in every direction, with a rather clumsy and not rapid, hopping gait. When so running the tail, short and never conspicuous, is held either out straight behind or raised at an angle of 30 degrees. ”