Most of the sheep spend the winter north of the road. This is favorable winter range because the snowfall is relatively light and strong winds keep the exposed ridges free of snow.
Many sheep remain on the winter range all year, but more of them migrate toward the heads of the rivers in May and June. In making the migration, the sheep must in places cross 2 or 3 miles of low country. They are fully aware of their vulnerability to grizzlies and wolves in these crossings. Before venturing away from a safe take-off ridge, they may scrutinize the low country for a day or two, until they feel that no danger lurks along the way. A band of 60 or 70 sheep may move across slowly in a rather compact group; at other times urgency replaces caution and they frequently break into a hurried gallop. Having reached the safety of rough country again, the sheep may gambol about as though the weight of tension has suddenly been lifted. The return migration is made in August and September.
The large amber-colored horns of the rams with transverse ridges and sweeping outward curl have a rugged, graceful beauty. They may spread widely at the tips or curl rather close to the head. The ewes are less imposing. Their horns are slender spikes that extend upward in a slight curve, resembling those of the mountain goat but they lack the shiny jet black color and are not as sharp. The horns are never shed and continue to grow throughout the sheep’s life span of 11 to 14 years. The growth is slight during the later years. Growth takes place during the summer when food is highly nutritious. In winter only a groove or ridge encircling the horn is formed. By counting these annual rings the age of a sheep can be determined.
For detecting danger the sheep depend on their sharp eyes. They appear to disregard scent which for many animals is the final decisive word on any situation. But this seems quite logical, because the sheep generally have a strategic view, and in the varying air currents no dependence can be placed on getting scent messages. Noises are considered rather unimportant unless the sheep have already caught a glimpse of movement nearby.
To approach sheep for photography it is usually best to move slowly toward them from below with no attempt to hide. They at once become suspicious if they glimpse someone stalking. However, I have at times stalked sheep where the opportunity for undetected close observation was obvious. On one occasion, from a ragged rocky ridge top, I spent most of an afternoon watching a band of rams some 50 yards away without being discovered. Some bands are wilder than others and the same band does not always behave uniformly. A band that has rested and is ready to move may take your approach as an excuse for a romp.
The food of sheep consists of grasses, herbaceous species and browse, chiefly willow. Scattered over the range are a number of salt licks which the sheep seek for minerals.
The most active mating period extends from about the middle of November to the middle of December. The rams who have been fraternizing on friendly terms for many months, now and then showing mating behavior such as gentle joustings, begin to take greater notice of the ewes. The old rams continue to associate, but now serious battling takes place. The fighting follows rather uniform conventional rules. The two matched battlers move apart several yards, then, as though by a signal, they turn and face each other and at the same time rise up on their hind legs, then charge full speed at each other, their horns crashing together with a loud thud. If the joust is even, they may repeat the performance until the superiority of one of the combatants is evident. But there is some tolerance among the rams, for two or more may breed with ewes in a band indiscriminately.
The numbers of sheep on a range under natural conditions may vary considerably. In the park, a very high population, possibly as high as 5,000 or more, suffered severe losses during 1929 and again in 1932, due to extremely deep snow conditions, and an icy crust in the latter year. In 1945 the population was down to about 500. Since 1945 there has been a steady increase. The numbers in 1959 were up to about 2,000.
Dall sheep; rams on the Alaska Range in summer.