The mule-deer differs widely from the whitetail in its habits, and especially in its gait, and in the kind of country which it frequents. Although in many parts of its range it is found side by side with its whitetail cousin, the two do not actually associate together, and their propinquity is due simply to the fact, that the river bottoms being a favorite haunt of the whitetail, long tongues of the distribution area of this species are thrust into the domain of its bolder, less stealthy and less crafty kinsman. Throughout the plains country the whitetail is the deer of the river bottoms, where the rank growth gives it secure hiding-places, as well as ample food. The mule-deer, on the contrary, never comes down into the dense growths of the river bottoms. Throughout the plains country it is the deer of the broken Bad Lands which fringe these river bottoms on either side, and of the rough ravines which wind their way through the Bad Lands to the edge of the prairie country which lies back of them. The broken hills, their gorges filled with patches of ash, buck brush, cedar, and dwarf pine, form a country in which the mule-deer revels. The whitetail will, at times, wander far out on the prairies where the grass is tall and rank; but it is not nearly so bold or fond of the open as the mule-deer. The latter is frequently found in hilly country where the covering is so scanty that the animal must be perpetually on the watch, as if it were a bighorn or prongbuck, in order to spy its foes at a distance and escape before they can come near; whereas the whitetail usually seeks to elude observation by hiding—by its crouching, stealthy habits.