Mammals
Muskox
Ovibos moschatus · also called muskox, musk ox, umingmak
The muskox is a shaggy relic of the Ice Age, still standing on the Arctic tundra where mammoths and woolly rhinos once grazed beside it. It wears the warmest wool in nature, and it meets a wolf pack by forming a wall of horns — a tactic that kept the species alive for tens of thousands of years and then nearly finished it when the threat became a rifle.
Overview
Muskoxen live on Arctic tundra in northern Canada and Greenland, with reintroduced herds in Alaska and introduced ones in Arctic Russia and Scandinavia. They are herbivores, grazing tundra plants in summer and digging through snow with their hooves in winter for grasses, sedges, and willow. They live in herds of a dozen to a few dozen, larger in winter, and move relatively little to save energy in the cold.
The warmest coat in nature
The muskox has a double coat: long, ground-sweeping guard hair over a dense layer of ultra-fine underwool called qiviut. Qiviut is finer than cashmere, does not shrink, and is about eight times warmer than sheep’s wool by weight. It is shed in spring and collected for spinning into one of the world’s most valuable yarns.
The circle
Faced with wolves, a muskox herd bunches into a circle or line, calves protected, horns outward, with bulls breaking ranks to charge and hook before backing in. It defeats wolves reliably. Against hunters with guns it was a disaster — a group that stands its ground is an easy target — and combined with commercial hide and meat hunting it drove the muskox extinct across most of its range by around 1900.
Not an ox
The muskox is closer to sheep and goats than to cattle — its own genus, Ovibos (“sheep-ox”). The “musk” is the strong smell bulls produce in the autumn rut.
Status
The muskox is Least Concern, recovered to about 170,000 through legal protection from 1917 and decades of translocation. Some Arctic herds are now declining again with rain-on-snow icing, heat stress, insect harassment, and northward-spreading disease.
Muskox: common questions
How does the muskox stay warm in the Arctic?
With an exceptional two-layer coat. The outer layer is long, coarse guard hair that hangs almost to the ground and sheds wind and snow. Underneath is a dense layer of extremely fine underwool called qiviut, which traps a thick blanket of still air against the skin. Qiviut is finer than cashmere, does not felt or shrink, and is roughly eight times warmer than sheep's wool by weight — one of the warmest natural fibres known. The muskox also has a compact, low-surface-area body, short legs and ears to limit heat loss, and it minimises movement in winter to conserve energy. It sheds the qiviut in spring, when Arctic peoples and, now, cooperatives collect it for spinning into a very valuable yarn.
Why do muskoxen form a circle?
It is a defence evolved against their main natural predator, the wolf (and, historically, other pack hunters). When threatened, the adults of a herd bunch together with the calves in the centre or behind them, presenting an outward-facing wall of horns and heavy heads. Wolves cannot get past the horns to reach the vulnerable calves, and individual bulls periodically break formation to charge and hook at an attacker before backing into line. Against wolves this works extremely well. Against humans with firearms it is catastrophic — a stationary group of large animals that does not flee is the easiest possible target, and it was this behaviour, combined with commercial hunting for hides and meat, that drove the muskox to extinction across most of its range by the early 1900s.
Is a muskox actually an ox?
No. Despite the name and the cattle-like bulk, the muskox is not closely related to cattle. Genetically it sits within the goat-antelope group of the bovid family, closer to sheep, goats, and the takin than to true oxen. It is the only living species in its genus, Ovibos, a name that literally means "sheep-ox" and captures the confusion. The "musk" part of the name refers to the strong odour bulls produce during the autumn rut, from glands near the eyes, which they also rub onto their legs.
How did the muskox recover?
By the 1920s the muskox was gone from Alaska and Eurasia and reduced to small remnants in Arctic Canada and Greenland, with perhaps a few thousand left. Canada gave it full legal protection in 1917, and populations in the safe core of its range slowly rebuilt. From the 1930s onward, animals were captured and translocated to re-establish herds — muskoxen from Greenland were used to restock Alaska in 1930, and later reintroductions and introductions were made in the Canadian Arctic, Russia (Wrangel Island and the Taymyr Peninsula), and Scandinavia. The total is now around 170,000. Some herds are again declining, however, linked to warming (rain-on-snow icing that seals off food), heat stress, insect harassment, and outbreaks of a lungworm and a bacterial disease that appear to be spreading north with the climate.