The musk ox. Photo: GETTY
Appearance
Externally, the musk ox (or muscular bull) resembles a bison: a hunchbacked back and long dark brown fur emphasize short legs. Both females and males have sharp rounded horns of impressive size. The bases of each horn in bulls run across the forehead and form a solid massive “boss” of horn and bone up to 10 cm thick.
The musk ox owes its ability to survive temperatures up to -70 °C in strong winds and snowstorms, to a large extent, to its amazing coat. The fur coat has both a wool and a hair layer. The thermal insulation wool layer adheres to the skin. Wool is stronger than sheep’s wool, eight times warmer and thinner than cashmere.
The musk ox has a very long hairline among all mammals. The outer part of the coat can reach 100 cm in length, it reaches almost to the ground, but is shorter around the muzzle and legs. The nose, lips, horns, and hooves are the only hairless parts.
In the middle of summer, musk oxen lose their fluffy undercoat in order not to overheat under the scorching sun rays. At the same time, long hair does not fall out. For several weeks, the animals become shaggy and mangy. Many adult bulls have clumps of old wool stuck to their “skirts”.
The musk ox has several other physical adaptations to a harsh environment.:
· Chunky body reduces the ratio of body surface area to volume. This reduces heat loss and the animal is less exposed to the cold. Short legs and small ears also help in this.;
Rounded hooves with two toes on each foot provide better grip and stability on uneven surfaces. They do not allow the animal to be immersed in soft snow.;
· The front hooves are larger than the hind hooves and allow the musk ox to dig through the snow in search of food;
· High levels of body fat act in the same way as fat does on marine mammals, providing internal organs with additional insulation from the cold.
Usually slow and unhurried, the musk ox can run and climb mountains with great agility if necessary. Their hooves are not designed for frequent running, but in case of danger they can reach speeds of up to 40 km/h!
The musk ox is a formidable beast. Although the animal is not very tall, the musk ox is relatively heavy due to its stocky and compact build. The tail is short, with a maximum of 10 cm. Males are larger than females with a body length of 2.1-2.6 meters, in females 1.9-2.4 m. Average body weight: 350-650 kg in males (bulls), 260-300 kg in females (cows). Newborn’s weight: 8-10 kg.
Lifestyle
The musk ox. Photo: Yuri Smityuk
Musk oxen are usually found on low-lying coastal and inland plains or in river valleys of the Arctic tundra, where shrubs are most abundant. During the long summer days, the plants adjacent to the ground grow rapidly, bringing colorful flowers and rich food for musk oxen.
In the high Arctic, the sun does not appear above the horizon from November to February. The Arctic winter is very long; temperatures below -20 °C last up to eight months. Despite the cold, wind and darkness, the musk ox breaks its usual diet and rest only during severe storms, which it endures lying down with its back to the wind.
The musk ox is a herd animal. In winter, musk oxen form large mixed herds of up to 60 individuals. During calving, winter herds break up into smaller ones consisting of several animals. Throughout the summer, these herds alternate between feeding and resting periods.
During the rest period, musk oxen lie down, stretched out and stretching their legs. Calves, instead of resting, usually gather together and jump around adults or engage in energetic playful fights. Adults also play sometimes, especially when crossing rivers. Jumping and circling in shallow water are typical of the playful behavior of adult musk oxen.
Although bulls engage in vigorous fights for most of the year, the frequency and intensity of these conflicts increase in late summer as bulls seek to establish dominance in the herd. A typical clash consists, first of all, of a demonstration of threat, and then slowly and “pompously” the bulls walk with their horns tilted towards the opponent.
Then both slowly retreat, shaking their heads, after which they rush forward from a 50-meter distance, colliding head-on with a loud crash. A powerful blow is absorbed by large thick horns and a strong skull. Such blows can be inflicted dozens of times during a fight.
Late winter and early spring are critical times for musk oxen to survive. Fat reserves can be very low, and any combination of causes – old age, worn teeth, severe parasite infestation, poor walking, impassable snow crusts and unusually strong storms – can lead to death from starvation.
The musk ox is a herbivore. On the mainland, the musk ox plentifully feeds on shrubby willows that float along the river. Here they find some protection from mosquitoes and biting flies that attack their unprotected eyes. On Arctic islands, they are less bothered by biting insects, as they feed in wet meadows.
By September, snow covers the ground, and musk oxen are forced to dig holes in the snow to find willows, grasses, and sedges, which make up the bulk of their diet. They can also feed on lichens, mosses, and roots.
In most areas of the tundra, the snow cover is relatively shallow and usually does not interfere with feeding and free movement. Musk oxen often feed in valleys or lowlands where the snow depth is less than 20 cm. Here, the wind constantly blows away the snow and forms a crust on the ground.
When the soil freezes hard, the musk ox breaks through the crust, hitting it with its head. The animal pushes away the torn pieces of hardened snow with its hooves and exposes the vegetation. The dominant musk ox often displaces low-ranking individuals from these vegetation craters.
The musk ox’s keen eyesight is useful during the long polar night, and its sensitive sense of smell allows it to find food under the snow that covers the ground from September to June. The musk ox, being a ruminant, has a four-chambered stomach that helps break down tough fibers. This helps the musk ox extract maximum nutrients from the food.
Reproduction
The spread of musk oxen. Photo: Wikipedia
Today, natural populations of the musk ox are found only in Greenland (20,000 individuals) and northern Canada (85,000 individuals). Moreover, 75% of the musk oxen live in Canada. Smaller populations are found in Svalbard, Western Greenland, Norway, and Russia. Musk oxen have a small migration range: in winter they move to more elevated areas. This helps them avoid deep snow.
In late spring and summer, the herds are of different sexes and of different ages. As the breeding season approaches, the composition of some herds changes, usually one adult bull forms a group with several cows, calves and juvenile bulls. Thus, during the mating season, musk oxen live in harems, where the dominant male mates with the females of his herd.
The competition between males for a dominant position is fierce. During the breeding season, bulls often emit a deep rumbling roar, challenging other males. Bulls attack each other and violently butt heads, but fights rarely end fatally.
Breeding interval: once a year or every two years, depending on the quality of the food supply, the breeding season lasts from the end of August to September. Cows under favorable conditions, from about the age of three, bring one calf each. The duration of pregnancy is from 7.5 to 8.5 months, and the cubs are carried for about 8 months. Females remain reproductive until they are 11-14 years old.
On the northern islands, musk ox pups are born between April and June; at this time of the year, the snow cover is deepest, temperatures reach -34 °C, and snowstorms are frequent. Like most ungulates, musk oxen are born with thick woolly fur and can stand on their feet in less than an hour after birth. This is important if they want to have a good chance of protecting themselves from predator attacks.
Pregnant females stay in the herd, and a cow-calf pair can move with the herd for several hours after giving birth. The cry of young calves helps to maintain contact between mother and calf. Playful young calves soon begin to feed on vegetation. The average age of sexual or reproductive maturity is 2-3 years for females and 3-4 years for males.
Few predators attack an adult musk ox, and even then with caution: Arctic wolf, grizzly, wolverine and polar bear. Musk oxen are most often attacked by small packs of wolves that prey on weakened individuals and calves.
Musk oxen exhibit a unique defense mechanism when attacked. If musk oxen are attacked by predators, they line up facing the attackers. They squeeze the croup together, forming a tight ring from which they rush at the enemy. During the attack, the calves cling tightly to the mother’s side. Only a very brave predator can try to overcome such a powerful barrier.
By Olga Ivanova
