Muskox, Ovibos moschatus

The muskox (Ovibos moschatus), also known as the musk ox, is native to the Arctic areas of Canada, United Sates, and Greenland. Populations have been introduced into Norway, Sweden, and Siberia, but these are small. There was a population in Antarctica, but it was wiped out due to hunting and climate change, which caused its habitat to decline. Despite this, the United States Fish and Wildlife Service introduced a new population onto Nunivak Island in Antarctica, as a means of supported living for people there in 1935.The muskox prefers a habitat in wetland areas like river valleys in the summer, but in the winter it will move to higher ground to avoid deep snows.

The muskox is more closely related to goats and sheep than to actual oxen, and it has been placed in its own genus, Ovibos. It reaches an average height between four and five feet, but the body length varies between sexes. Males are longer reaching an average length of up to 8.2 feet, while females reach a length of up to 6.6 feet. The average weight of both sexes is 600 pounds, but this can range between 400 to 900 pounds, while some captive individuals weigh as much as 1,400 pounds. The tail is small, reaching only 3.9 inches and is typically covered by the musk oxen’s long fur. Both males and females grow curved horns. The fur of this species is typically brown, grey, and black in color, and the outer coat can almost touch the ground. In Queen Maud Gulf Bird Sanctuary, some white musk oxen have been reported.

The muskox will live in herds that vary in size depending on the season. During the winter, it gathers in herds between 8 and 20 individuals, but during the summer, these groups are typically lager ranging between 12 and 24 individuals. Instead of marking and holding specific territories, this species will mark paths using preorbital glands. There is a distinct age based hierarchy within herds that both males and females adhere to, with older oxen taking precedence over younger oxen.  The oxen that hold a higher position typically have better access to resources like food and water. Bulls, or adult males of this species, will display a few dominance behaviors towards both cows, or females, and younger musk oxen. These behaviors include kicking with a fore foot, and roaring while shaking its head. The most common dominance behavior occurs when bull rushes at a lower ranking individual, but it will not butt the ox in the side without giving it a warning first. This is known as a “rush and butt.”

The mating season for the musk ox begins in the summer time, in late June or early July. This is known as the rutting season as well. During the rutting season, bulls will expel all other males from a herd and form a harem group containing between six and seven cows and the young produced during this time. In order to claim a harem group, bulls must fight to see which individual is stronger. First, the oxen reverse for up to 65.6 feet, and then they charge, repeating the process until one bull gives up. Any bulls that are either too young or too old to breed will leave the herd on their own, but they can return to the herd if danger is present. The bull that leads a harem group does not allow any females to leave, and he will kick the female with his fore foot in order to make her more receptive to his breeding advances.

Although bulls are dominant during the breeding season, once the cows become pregnant, the group falls under their control. The cows become aggressive towards the bull, and will choose how far to travel and when to stop. After eight to nine months, cows give birth to a calf. The baby calf will nurse for up to two months, and the herd travels over longer distances in this time in order to find more food. Cows do not always give birth every year, and will not go into estrous if winter is harsh. After two years of age, calves will begin to lose the bond with their mothers.

When a herd of muskoxen feels threatened, males and females will line up in a semicircle to protect the younger members of the herd. During the mating season, males choose the order of individuals in this formation, but females decide this for the rest of the year. Common predators include the grizzly bears, Arctic wolves, and polar bears. The diet of the muskox consists of woody vegetation, grasses, mosses, arctic willows, and lichens. During the summer, grasses are eaten more frequently than any other vegetation, while arctic willows are eaten more frequently in the winter. This species can have a lifespan between 12 and 20 years.

In the past, the man threat to the muskox throughout its range was hunting, but hunting laws have proven to be an effective means of controlling over hunting. Populations in Greenland are small and fragmented, and this makes them vulnerable to climate changes. However, most of the Greenland populations occur in protected areas, with one occurring naturally in Northeast Greenland National Park. The muskox appears on the IUCN Red List with a conservation status of “Least Concern.”

Image Caption: Muskox (Ovibos moschatus) in the Lüneburg Heath wildlife park, Germany. Credit: Quartl/Wikipedia (CC BY-SA 3.0)