Ovibos moschatus (Zimmermann, 1780)

Horn Characteristics

Both male and female muskoxen (Ovibos moschatus) have long, curved horns.

Shoulder Height

They stand 1.1 to 1.5 meters (3 ft 7 in to 4 ft 11 in) high at the withers.

Body Length

Females measure 135 to 200 cm (4 ft 5 in to 6 ft 7 in) in total length, while larger males reach 200 to 250 cm (6 ft 7 in to 8 ft 2 in).

Tail Length

Their small tail, often hidden under fur, is only 10 cm (3.9 in) long.

Average Weight Range

On average, adult muskoxen weigh 285 kg (628 lb), with a total weight range of 180 to 410 kg (400 to 900 lb).

Weight Relative To Bison

Their thick coat and large head make them appear larger than they actually are; bison, which muskoxen are often compared to, can weigh up to twice as much.

Captive Specimen Weight

Heavily fed specimens kept in zoos have been recorded weighing up to 650 kg (1,430 lb).

Typical Coat Coloration

Their coat is a mix of black, gray, and brown, with long guard hairs that nearly reach the ground.

Rare White Morph

Rare "white muskoxen" have been observed in the Queen Maud Gulf Bird Sanctuary.

Semi-Domestication Purposes

Muskoxen are occasionally semi-domesticated to produce wool, and rarely for meat and milk.

Alaska Wool Farms

The U.S. state of Alaska hosts several muskoxen farms specifically for wool harvesting.

Qiviut Properties

The wool, called qiviut, is highly valued for its softness, length, and insulating properties.

Speed and Lifespan

A muskox can run at speeds of up to 60 km/h (37 mph), and their life expectancy ranges from 12 to 20 years.

Native Modern Range

In modern times, the native range of muskoxen is limited to Arctic regions of Northern Canada, Greenland, and Alaska.

Alaskan Extirpation Cause

The original Alaskan population was extirpated in the late 19th or early 20th century; this decline has been linked to excessive hunting, and may also have been contributed to by climate change.

Alaska Reintroduction

Muskoxen have since been reintroduced to Alaska.

Nunivak Island Introduction

The United States Fish and Wildlife Service introduced muskoxen to Nunivak Island in 1935 to support local subsistence living.

Additional Reintroduced Populations

Additional reintroduced populations are now found in Arctic National Wildlife Refuge, Bering Land Bridge National Preserve, Ivvavik National Park in Yukon, a wildlife conservation center in Anchorage, Aulavik National Park in the Northwest Territories, Kanuti National Wildlife Refuge, Gates of the Arctic National Park, and a wildlife preserve in Whitehorse, Yukon.

Vermont Domestication Effort

At least two separate domestication efforts have taken place. In the 1950s, a U.S. researcher and adventurer successfully captured muskox calves in Northern Canada to relocate them to a prepared property in Vermont.

Capture Permission Terms

One condition set by the Canadian government was that he could not kill adult muskoxen defending their young.

Calf Capture Method

After nets and ropes proved ineffective, he and his crew herded family groups into open water, where calves were successfully separated from adults.

Calf Transport And Acclimation

The young animals were airfreighted to Montreal, then trucked to Vermont, where they acclimated to the temperate conditions.

Vermont Project Outcome

Though the calves survived and grew to adulthood, poor parasite and disease resistance reduced the overall success of the project.

Herd Relocation To Alaska

The remaining herd was eventually moved to a farm in Palmer, Alaska, where it has thrived since the mid-1950s.

Seasonal Habitat Use

During summer, muskoxen occupy wet habitats such as river valleys, and move to higher elevations in winter to avoid deep snow.

General Diet Composition

Their diet includes grasses, arctic willows, woody plants, lichens, and mosses.

Preferred Food Items

When food is plentiful, they prefer succulent, nutritious grasses.

Winter Primary Food Source

Willows are the most commonly consumed plant during winter.

Breeding Fat Requirement

Muskoxen require a high threshold of fat reserves before they can conceive, a trait that reflects their conservative breeding strategy.

Winter Range Snow Condition

Winter ranges typically have shallow snow, which reduces the energy cost of digging through snow to reach food.

Primary Predator

The primary predator of muskoxen is the arctic wolf, which may be responsible for up to half of all mortality for the species.

Other Predators

Other occasional predators, which mostly target calves or weak adult muskoxen, include grizzly bears, polar bears, and wolverines.

Seasonal Herd Size

Muskoxen live in herds of 12 to 24 individuals in winter, and 8 to 20 in summer, when dominant bulls force other males out of the herd.

Trail Marking Behavior

They do not defend fixed territories, but they mark their travel trails using preorbital glands.

Social Hierarchy Structure

Male and female muskoxen each have separate age-based social hierarchies, with mature muskoxen being dominant over juveniles.

Hierarchy Resource Access

Dominant muskoxen tend to access the best resources, and will displace subordinate muskoxen from grass patches during winter.

Bull Dominance Behaviors

Muskox bulls use several different behaviors to assert dominance. One common behavior is the "rush and butt", where a dominant bull rushes a subordinate from the side with its horns, and gives the subordinate a warning to allow it a chance to retreat.

Additional Dominance Displays

Bulls also roar, swing their heads, and paw the ground to signal dominance.

Dominant Bull Subordinate Interactions

Dominant bulls sometimes interact with subordinate bulls in the same way they interact with cows: a dominant bull will tap a subordinate with its foreleg, a motion they also use with cows during mating.

Sexual Dominance Displays

Dominant bulls will also perform mock copulation with subordinates and sniff their genitals.

Dominance Challenge Behavior

A subordinate bull can challenge a dominant bull's status by charging it.

Rutting Season Timing

The mating (rutting) season for muskoxen begins in late June or early July.

Rut Harem Structure

During this period, dominant bulls fight other bulls out of the herd and establish harems usually containing six or seven cows and their offspring.

Pre-Fight Rituals

Before fighting, bulls will rub their preorbital glands against their legs while bellowing loudly, then display their horns.

Bull Fighting Process

The bulls then back up around 20 meters (66 ft), lower their heads, and charge into one another, repeating this until one bull concedes.

Subordinate Bull Grouping

Subordinate and elderly bulls leave the main herd to form all-male bachelor groups or live alone.

Threat Response Of Outside Bulls

However, when threatened, these outside bulls can return to the main herd for protection.

Harem Guarding Behavior

Dominant bulls prevent cows from leaving their harems.

Mating Foreleg Tapping Behavior

During mating, a bull will tap an estrous cow with his foreleg to calm her and make her more receptive to mating.

Post-Summer Herd Reassembly

The full herds reassemble once summer ends.

Seasonal Herd Leadership

While bulls are more aggressive during the rutting season and lead their groups during this time, females lead the herd during gestation.

Pregnant Female Herd Control

Pregnant females are aggressive and decide how far the herd travels each day and where the herd will bed for the night.

Lactation Herd Movement

Herds move more frequently when cows are lactating, to let cows access enough food to nurse their offspring.

Gestation And Calving Period

Cows have an eight- to nine-month gestation period, and calves are born between April and June.

Breeding Frequency Dependence

Cows do not give birth every year; if a winter is particularly severe, cows will not enter estrus and will not calve the following year.

Birth Herd Protection

When giving birth, cows remain in the herd for protection.

Calf Development

Muskox calves are precocial, and can keep up with the herd within a few hours of birth.

Early Calf Care

Calves are accepted into the herd and nursed for the first two months.

Weaning Process

After two months, calves begin eating vegetation and only nurse occasionally.

Cow-Calf Communication

Cows communicate with their calves through braying.

Maternal Bond Duration

The bond between a calf and its mother weakens after two years.

Threat Defensive Formation

Muskoxen have a distinctive defensive behavior: when the herd is threatened, adult muskoxen face outward to form a stationary ring or semicircle around the calves.

Defensive Line Structure

Bulls usually form the front line of defense against predators, with cows and juveniles gathered close behind them.

Defensive Formation Decision-Making

Bulls determine the defensive formation during rutting, while cows make this decision during the rest of the year.