This country provides an extensive summer sheep range in the high
rolling tundra and rugged peaks above timberline, in addition to a large
wintering area in the lower timber and valleys. Strong winds in the
winter sweep snow from the scant tundra vegetation and often make it
possible for sheep to feed at these high altitudes even during the
winter months. Even with these adequate topographic conditions, wild
sheep in the National Park since 1922 have shown a slow, steady decrease
in numbers until 1941, when there were about 300 sheep present. Since
this date there has been a leveling off of sheep numbers, no decided
increases or decreases being evident. All the related factors probably
contributing to the decline of bighorn population or their present
stability at low level are not known. One substantial reason advanced
has been the deficiency of mineral in sheep diet in the higher
mountains, as indicated on previous pages, with a resultant weakening of
sheep stock and a consequent susceptibility to parasitism and diseases
found prevalent among sickened and dead sheep over a period of years.
Another possibility for the decline may be present in the great increase
of elk and subsequent competition for similar grass foods. The Park
Service has placed salt and mineral blocks at known bighorn
concentration places in an attempt to improve the physical condition of
the sheep and thereby increase the sturdiness of their offspring. The
results of this experiment are difficult to measure, but it is believed
to have met with varying success.