Rocky
Mountain Bighorn Sheep:
Crown
Prince of the High Country
by
Mike Roberts, Contributing Columnist
Years ago I asked my good friend and
mentor, Leonard Lee Rue III (America�s most published wildlife photographer), about his favorite animal to
photograph. Knowing he had spent much of his life observing, photographing,
and writing about white-tailed deer, I was somewhat surprised when he ranked
wild sheep at the top of the list. Nevertheless, the reply was
understandable; to witness these animals in the wilderness environs where
they go about their daily routines exemplifies the pinnacle of wildlife
watching.
In North America, there are two recognized species of wild sheep � the bighorn (Ovis
canadensis) and Dall (Ovis dalli). The thin-horned Dall sheep ranges through
the mountains of northwestern
British Columbia, the
Yukon
, the western portion of the
Northwest Territories, and Alaska. In the northern sector of their range, Dall sheep are entirely white, with
the coats of the mature rams sometimes having a yellowish cast. Those in the
southern region are called Stone sheep and vary in color from almost black
to charcoal and light gray. In areas where the two overlap, they are known
as Fannin sheep.
The bighorn sheep�s original
geographical distribution was extensive, spanning throughout the mountains
and intermountain desert regions of western
North America
. When the Spanish first explored the American Southwest, they reported
abundant populations of these sheep, noting in particular their large,
curled horns. In 1805, President Thomas Jefferson�s famed Corps of
Discovery expedition team collected bighorn sheep along the upper
Missouri River. William Clark, who shot the first ram, recorded the animal�s description
in detail. With the historical exploration and exploitation of the American
West, bighorn numbers plummeted. Over-hunting, grazing competition from
domestic livestock and the introduction of various livestock diseases were
the primary factors in the rapid decline.
WHAT REMAINS
Today, three of the four recognized
subspecies of bighorn sheep (the Rocky Mountain, California, and Desert)
inhabit areas least disturbed by humans. The fourth, the Audubon�s
subspecies, which ranged across western
North Dakota, South Dakota,
Nebraska, eastern
Montana
and
Wyoming, is extinct. Sparse populations of the
Rocky
Mountain
bighorn are distributed through the mountainous landscapes of southern
British Columbia, southwestern Alberta, and southward through the Lower 48 in the rugged mountains of
Idaho, Montana, Wyoming, and Colorado. In addition, various western state fish-and-game agencies have
reintroduced, and in some cases introduced, the Rocky
Mountain
bighorn to appropriate habitat. The California
subspecies, though limited in number, ranges from southern British Columbia
southward through
California
and Nevada. The majority of desert bighorns reside in the arid, desolate areas of
Arizona,
California,
Nevada,
New Mexico, Utah, and Mexico
.
As the majestic �King of the Crags,�
the
Rocky
Mountain
bighorn ram averages almost 31⁄2 feet at the shoulder and weighs
between 250 and 300 pounds. Typical of hoofed mammals, the females, called
ewes, are smaller in stature. The chocolate-colored coat, highlighted with
white eye-patches, muzzle, underbelly, leg stripes, and rump patch, is
effective camouflage for an animal that spends much of its time in rocky
habitat. The desert bighorn is somewhat smaller and lighter in color.
Both sexes have true horns that grow as
long as the animal lives, which can be upwards of 14 or 15 years. The rams
have massive, sweeping horns that, at maturity, can exceed 45 inches in
length. Highly visible, annual growth rings are accurate indicators of an
individual sheep�s age. To preserve their precious peripheral vision,
mature rams often broom the tips of the continuous-growing horns, using
rocks to splinter off the keratinous ends. Horn size is a key element in
determining the pecking order within the summertime bachelor groups. Less
imposing, the ewe�s thin, slightly curved horns are usually between 8 and
10 inches in length.
The hooves of bighorn sheep have hard
outer edges and soft, cushioned centers that provide adequate traction for
negotiating travel up and down sheer rock cliffs. This adaptation provides
an effective means of escaping predators such as cougars, wolves, and
grizzly bears. Lambs are occasionally preyed upon by golden eagles. Still,
it is likely that far more bighorns succumb to disease, parasites, and falls
than predation.
Although gregarious, bighorn sheep split
into two separate factions during the spring, summer, and early fall. Mature
rams band together to establish rankings in the hierarchy for the
late-autumn breeding season. As the last snow melts from the high country,
these monarchs move up the mountains to alpine pastures where they feed on
highly nutritious plants. Being ruminants, the sheep regularly bed down
during daylight hours to chew their cud. Unlike most members of the bovid
family, which tend to sleep in a different location each night, bighorns are
renowned for using their oval-shaped beds night after night.
Throughout the year, ewes and their
offspring, plus yearlings and the 2-year-old rams, remain together. Led by a
matriarchal ewe, the herd typically resides at lower altitudes. The
exception is when pregnant females leave the flock for a week or so during
May to seek out rock ledges that are inaccessible to most mammalian
predators. There, they give birth to a single lamb. Within hours of being
born, the gray, wooly youngster can traverse the perilous cliffs, though
never straying far from the watchful eyes of its mother. Upon returning to
the herd, the lambs engage in purposeful horseplay � running and climbing
to strengthen developing muscles. Although dependent upon their mother�s
rich milk, the little lambs begin nibbling plants within a few days of
birth. They are weaned at approximately five or six months of age.
Autumn comes early to the high country
and increasing snow depths soon push the rams back down to their traditional
wintering grounds, where they join forces with the ewes and yearlings. With
the seasonal reduction of daylight hours, which triggers an increased level
of testosterone flowing hot through their bodies, the rams begin challenging
each other for the sovereign rights to breed receptive females. Posturing,
lip curling, and rolling their eyes, the contestants rise in slow motion
onto their hind legs and, with a sudden burst of speed, charge head-on
toward each other. The result is one of the most violent collisions in all
of nature. The sharp crack of sheep horns crashing together can be heard for
great distances, especially in the still, brisk mountain air. Although they
are sometimes dazed and pause to shake off the effects of the sudden impact,
the bighorn�s skull and thick, muscular neck are designed to absorb the
majority of such shock. Although often brief, these battles can go on for
hours.
JUST DO IT!
While these magnificent mammals are a
delight to watch in high definition on the Discovery Channel and National
Geo�graph�ic, take a summer hike up Yellowstone�s
Mount
Washburn
or along the Highline Trail in Montana�s Glacier
National Park
for the wildlife experience of your life. As you sit watching or
photographing a bachelor herd of full-curl rams grazing wildflowers along a
grassy slope, remember, you are indeed in God�s Country. Oh, by the way,
because these wild places are usually good grizzly habitat, don�t forget
to carry along a can of bear spray!
Wild Bird Profile:
White Ibis (Eudocimus albus)
The genus name of the white ibis is
derived from the Greek term for �famed.� In ancient times, the sacred
ibis (an
Old World
species) frequently served a significant role in religious ceremonies �
even mummified and buried in tombs with pharaohs. While the white ibis of
North America
�s southern latitudes may not have been legendary among Egyptian kings,
the impressive flocks descending to their nighttime roosts are certainly
admired by today�s birdwatchers.
Averaging about 25 inches in height,
this snow-white wader can be distinguished from species of egrets and herons
by its pink, featherless face, the long, curved, pink beak and pink legs.
Black-tipped primaries and rapid wingbeats, plus alternating periods of
sailing, make the white ibis easy to identify in flight; the bird also flies
with its neck and legs fully extended. Another key identification feature,
especially at close range, is the mysterious-looking, pale-blue eye-color.
Probing the shallows and mud flats, the white curlew, as it is sometimes
called, feeds primarily on crustaceans, but as an opportunistic feeder,
catches frogs, fish, and aquatic insects, too.
The white ibis breeds from the coastal
areas of
North Carolina
southward through Florida
and westward along the Gulf coasts of
Louisiana,
Texas
and
Mexico, to the coasts of Baja, California. Nesting in colonies, each pair of adults constructs a flimsy platform of
sticks in trees and shrubs, usually less than 15 feet above water. The
female lays 3 to 4 green-white eggs, which require 3 weeks of shared
incubation. The young leave the nest to walk about on tree limbs about two
weeks before they learn to fly.