But although these little creatures were such chatterers, they appeared very industrious, for many hillocks of sand indicated where their homes were burrowed. Each little hole was occupied by a pair of dogs, one of which was often seen perched on the apex like a sentinel. But like many other sentinels, they appeared on the watch for danger, not to combat, but to avoid it, for they darted like a flash into their holes whenever a lean, prowling wolf stalked near them, or even a prairie hen flew by.