A collection of their burrows has been termed by travellers a 'dog town,' which comprises from a dozen or so, to some thousands in the same vicinity; often covering an area of several square miles. They generally locate upon firm dry plains, coated with fine short grass, upon which they feed; for they are no doubt exclusively herbivorous. But even when tall coarse grass surrounds, they seem commonly to destroy this within their 'streets,' {230} which are nearly always found 'paved' with a fine species suited to their palates. They must need but little water, if any at all, as their 'towns' are often, indeed generally, found in the midst of the most arid plains--unless we suppose they dig down to subterranean fountains. At least they evidently burrow remarkably deep. Attempts either to dig or drown them out of their holes have generally proved unsuccessful. [Illustration: "Dog Town," or Settlement of Prairie Dogs] Approaching a 'village,' the little dogs may be observed frisking about the 'streets'--passing from dwelling to dwelling apparently on visits--sometimes a few clustered together as though in council--here feeding upon the tender herbage--there cleansing their 'houses,' or brushing the little hillock about the door--yet all quiet. Upon [Pg281] seeing a stranger, however, each streaks it to its home, but is apt to stop at the entrance, and spread the general alarm by a succession of shrill yelps, usually sitting erect. Yet at the report of a gun or the too near approach of the visitor, they dart down and are seen no more till the cause of alarm seems to have disappeared. Two other animals appear to live in communion with the prairie dogs--the _rattle-snake_ and a small _owl_;[171] but both are no doubt intruders, resorting to these burrows for shelter, and to feed, it is presumed, upon the 'pups' of the inmates. {231} Rattle-snakes are exceedingly abundant upon these plains: scores of them are sometimes killed in the course of a day's travel; yet they seem remarkably harmless, for I have never witnessed an instance of a man's being bitten, though they have been known to crawl even into the beds of travellers.[172] Mules are sometimes bitten by them, yet very rarely, though they must daily walk over considerable numbers.