Two varieties of deer inhabit the Park, commonly known as the black-tail and white-tail deer, the former being much the more abundant of the two. Being fleet of foot, they roam over the entire area in passing from one pasturage ground to another. They show a decided preference for gently sloping foot-hills carrying a scattered growth of mingled pine and maple and other deciduous trees, their natural habitat being the border-land between dense forest and open valley. Such favorite spots affording food, shelter, and shade abound, and present one of the most characteristic features of an ideal park country. Deer haunt the valleys of the Gallatin Range and the lava slopes around the head of Black Tail Deer Creek, which flows into the Yellowstone; but more than any other animal they seem to delight in changing their habitat. The ideal country for deer is that paradise for big game, the valleys of the numerous streams forming the sources of the Snake. While by no means as numerous as elk, deer are found in sufficient numbers to allay all anxiety as to their permanence under the new conditions now surrounding the Park.
Antelope, graceful and swift-footed creatures, restrict their range to the open country, with habits nearly identical to those developed on the plain. They are by no means numerous, and were so much shot at before protection was afforded that they nearly became extinct. But in the last few years they have steadily increased in numbers, and experience seems to have taught them that safety lies within the protected region, rather than in seeking in winter the lowlands outside its borders. Swan Valley and the slopes of Mount Everts apparently satisfy their requirements. In summer small bands roam over Hayden Valley, but so far as I know have not increased in size.
The advantages of this region as a game reservation are again shown in its meeting the requirements of the bighorn, or mountain sheep (_Ovis canadensis_), an animal of quite different habits, which lives almost wholly among the crags and cliffs of the steepest mountains. An ideal bighorn country is found in the Absaroka Range, where the bare rocky slopes are interspersed with patches of nutritious grasses. The size of their bands, the frequent well-worn trails over the barren rocks, and the occurrence of sheep "sign" everywhere, indicate conditions suitable to sheep life. The head waters of the Stinking Water and Thoroughfare Creek are among their favorite haunts. In the higher regions of the Gallatin they may occasionally be seen, and, indeed, this may be said of the summits of most of the peaks throughout the Park. They are an agile, wary, keen-scented animal, and apparently never so happy as when on the jump. Next to the elk, they are probably most sought by the horn-hunters and game-butchers; but with a little protection, and only half a show, they are abundantly capable of taking care of themselves.