Oreamnos
americanus
(Mountain Goat)
Description:
Mountain goats are striking
with their long, white hair that occasionally
has a yellowish tan tone. In winter their hair appears long and shaggy, in summer
it is shorter. Adults have long hair under their throat forming a “beard” that
may be up to 5 inches long (125 mm). Both sexes have sharp pointed horns
that curve up and slightly
backward, in females they reach 9 inches (230 mm) in males about 12 inches (300
mm). Their hooves are well adapted to their living on cliffs and ledges, they
have a hard, straight outer margin, with soft and flexible inner pads that provide
excellent traction in their precarious habitat. They stand about 3 to 3 ½ feet
(90 to 100 cm) at the shoulder and weigh between 100 and 300 pounds (455-135
kg). Females are about 15% smaller.
Range:
Mountain goats range from southeastern Alaska, south to Washington and the Olympic
Peninsula, to western Montana and southern Idaho. They have been introduced
in Colorado, Oregon, Olympic Peninsula of Washington, Beartooth Mountains of
Montana, and South Dakota. Some Idaho populations were introduced outside historic
range.
Habitat:
Environmental extremes characterize their habitat. They are found in high
mountain alpine and subalpine habitat where extremes of temperature and weather
occur. At various locations in their range they can be found from sea level
to about 8000 feet (2440 m), but they are usually at timberline or above. They
favor steep grassy or talus slopes, grassy ledges of cliffs, or alpine meadows.
During the winter they may seek shelter and food in stands of spruce or hemlock.
They seem comfortable on precarious cliff ledges and extremely steep, talus
slopes.
Diet:
Mountain goats graze on grasses and forbs
in summer, but also browse
on shrubs and conifers.
Their winter diet is often variable; they may feed on mosses and lichens , as well as grasses, shrubs,
and conifers.
Ecology:
They tend to be most active from dawn to mid-morning and late afternoon
to evening. They move to more sheltered habitat in October and November when
snow begins to fall, and back to high alpine habitat in April and May with the
spring thaw. In Idaho, they may move up to 16 km in the winter to appropriate
habitat which typically is the lowest suitable range on south-facing mountainsides.
One Idaho band of 10 animals wintered in only 205 acres (81 ha). Males are solitary
or in small male groups most of the year, but join the female and young groups
in October or November prior to the rut
. There is a strong social
hierarchy in female groups; the dominant are females. Adult females and young
form small groups in summer. Annual home range in different areas of Montana
was reported at 6-24 km2. Because they are so inaccessible they have few predators.
Golden eagles are known to take young, often by forcing them off of cliffs,
and cougars are known predators as well. A major cause of mortality is accidents.
Their habitat is dangerous even though they are so “sure footed”; they do occasionally
fall and are injured or killed.
Reproduction:
Mountain goats mate in November, but the rutting season can last into December
and even January. Males do not butt heads as do Mountain sheep, but most of
their rutting competition consists of threats, with occasional battles in which
the males swipe their sharp horns at each other. Males have scent glands at
the base of their horns, and will scent mark females they will breed with by
wiping the side of their head on the female’s body. Gestation
lasts about 178 days. One
(sometimes 2, occasionally 3) precocial young is born in late May or early June.
Often young are born in a “safe” area consisting of a narrow ledge on a cliff
or very steep slope; while this may seem dangerous for the newly born young,
its location probably provides protection from predators. The young are very
precocial
and can scamper after their
mother with amazing agility. The young stays with their mother for a year until
the next year’s young are born. Young are sexually mature in about 2 years,
although in some areas some yearling females may breed. Young to female ratios
vary between 39:100 and 72:100 were recorded in one Idaho study.
Conservation:
Status: | Game species |
Global Rank: | G5 |
State Rank: | S4 |
Important State References:
Hayden,
J.A. 1989. Status and population dynamics of mountain goats in the Snake River
Range, Idaho. M.S. Thesis, Univ. Montana, Missoula. 147pp.