Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"

Time for me to venture out of Africa again! Today we look at a beautiful animal from North America, the Rocky Mountain Goat, Oreamnos americanus. The scientific name means 'American mountain lamb'. This is not a true goat, of the genus Capra, but a close relative. It is very close to the Takin and the Chamois, a goat-like mountain dweller from Eurasia. As you might gather, the Rocky Mountain goat inhabits the Rockies and other mountain ranges in western north America, as far north as Alaska and the Yukon of Canada. About half of them live in British Columbia. They've been introduced to a few areas outside their natural distribution, though not very far away – including in South Dakota, Nevada, Utah and Idaho.

Immigrants from Asia

Followers of this column will likely remember that I've covered a large number of extinct goat-like animals. Goats and their kin, the subfamily Caprinae of the horned-and-hooved-mammal family, the Bovidae, mainly diversified in the late Miocene, and mainly in Asia. The ancestors of the Rocky Mountain Goat, also, likely arose from this burst of diversification, probably somewhere in east-central Asia. From there, they used the land bridge over the Bering Strait (this bridge having passed into and out of existence several times as sea levels rose and fell during the Ice Ages) to cross over into America. There the new goats colonized their new lands, finding the great, rugged mountain ranges much to their liking. At least one other species of mountain goat, Oreamnos harringtoni, is known to have lived, in the southern Rockies, during the Pleistocene.

Today these lovely goats thrive in the American mountains. They are extremely hardy mammals, living most of their lives above the tree-line, and are the largest animals that live at such heights. Here they feed on the sparse vegetation able to exist close to the permanent snow and glaciers, including mosses and lichens, the leaves of low shrubs, herbs, ferns and grasses. They get most of the moisture they need from their food, or from snow banks. They depend much on salt licks, to ingest vital minerals, and to get these they will if necessary descend to lower levels and enter forests. This also brought them into conflict with humans when some were introduced to the Olympic Peninsula in Washington: because there were no natural salt licks in the area, they sought out areas frequented by humans, being attracted to the minerals in human sweat and urine. One goat killed a hiker in 2010. Subsequently, the goats were removed from the area, most being translocated to the Cascade Mountains.

Like other goats, Rocky Mountain goats are expert climbers. Their hooves can spread apart, with rough, rubbery pads in between that help them 'cling' to the rocks, so that they can ascend slopes as steep as sixty degrees. Between the hooves are scent glands, and so they mark their territories wherever they go. Their stocky bodies have powerful muscles. They range from 45 kg/100 lbs to 140 kg/308 lbs in bodyweight (but rarely over 82 kg/180 lbs), and can stand around a metre at the shoulders. Males (billies) are generally bigger than females (nannies). Both billies and nannies have horns and beards. The horns are more curved in the billies, and have growth rings, as each year they grow a little more. Their lovely white coats are composed of two layers: a soft, very dense undercoat, through which grow the long guard hairs that make up the outer coat. This protects them against the frequently freezing mountain winds. They go through a yearly moult, shedding the long coat on the onset of warmer weather in the spring. The billies shed first, and the pregnant nannies last. They rub against rocks and trees to rid themselves of the sloughed wool. In the past, Native Americans of these regions went out to gather the moulted wool left by the goats to use in their weaving.

Although protected against extreme low temperatures, the goats do have limits to their tolerance. They prefer the sunnier southern slopes to the dreary northern ones, and in winter they migrate down to lower elevations where it's slightly warmer. On the move, they may pass through areas of forest on their way to more suitable open terrain.

Rocky Mountain goats are somewhat sociable. They may be solitary in the summer, or live in small herds, but come together in bigger groups in the winter. The nannies come intro oestrus in mid-winter in October to early December. Billies will stare at the nannies, dig rutting pits, and fight each other for dominance. Unlike other goats which fight by charging at each other head-to-head, these goats fight side-to-side. A billy will present itself side-on to a challenger, curving his back and neck to make himself look bigger. If the confrontation escalates, the two billies will stand beside each other and swipe at each other sideways, aiming for the flanks. Their sides are well-protected by thick skin, but even so, there are sometimes serious or even fatal injuries. Both billies and nannies mate with multiple partners. The kids, usually just one per mother, but rarely two or three, are born in May to June, usually on a ledge above a very steep cliff where no mammalian predator can reach it. It is born at a high level of development and within an hour or few starts walking and climbing. It is weaned at the age of three or four months but stays close to its mother until she gives birth again the next season. She leads her kid away from danger, shielding it from possible predators or from steep falls using her own body.

It has been found that older, higher-ranking females have more kids than younger, lower-ranking ones. Those who had the most kids were 8 to 9 years of age.

In the wild, adult goats are vulnerable only to large predators such as cougars/pumas, bears and wolves. The kids are in danger of golden eagles, coyotes, wolverines and bobcats as well. Adults defend themselves using their sharp horns, and one has been recorded killing a bear. They can live to the age of fifteen years, eventually dying as their teeth become completely worn down.

At present, Rocky Mountain goats are not in danger of extinction. They're actually multiplying in some areas where they've been introduced, such as Yellowstone and Olympic National Parks, and causing ecological problems by destroying the natural vegetation that hasn't evolved to withstand them. They also threaten other ungulate species by the parasites they carry. They're allowed to be hunted in such places. But in other places, where they are native, such as the Cascade Mountains, they may not legally be hunted. In the Cascades they seem to be decreasing in numbers; we don't quite know why and need to research this.

Willem

25.09.23 Front Page

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