Two weekends ago I was working at the Royal Agricultural Winter Fair, and every morning I walked to our booth I went past the cow ring where there were always lots of adorable cows being shown. So when I had to find a mammal to write about for today, cows immediately came to mind. Of course, this blog is called Our Wild World, so I had to choose a wild relative of the cow. And what bovine is more silly and adorable than the yak?
There are domesticated yaks, but I will mainly be talking about the wild population in this post. Wild yaks live in a very restricted area, on the Tibetan Plateau. This of course includes the Tibet region and parts of China proper. Yaks used to be found in Nepal and Bhutan, but are now extinct in those countries. Wild yaks like cold areas, but need enough vegetation to sustain themselves. They are most commonly found at 3,000 to 5,500 meters, in treeless areas where there are grasses and sedges.
Yaks are large animals, and are the second largest bovid on the planet. They grow to be 1.6 to 2.2 meters at the shoulder, and can weigh as much as 1,000 kg. Female yaks are much smaller than males, and domesticated yaks are smaller than wild ones, with domesticated males only reaching weights of 580 kg. Both sexes have horns, though the horns of males are larger and can reach lengths of almost a meter. Yak fur is long and shaggy, and is usually dark brown or black.
Due to the extremely high altitudes yaks inhabit, these animals have a number of special adaptations. They have a very thick undercoat that is kept matted by a sticky substance secreted in their sweat; this helps with insulation. They also have a very thick layer of fat under their skin, to help protect against the cold.
Yaks have larger hearts and lungs than cattle that live at lower elevations, and higher concentrations of haemoglobin in their blood than other cattle. This allows yaks to breathe and function at the high altitudes in which they live. Yaks also have larger rumens than domestic cattle, which helps extract the most possible nutrition out of yaks’ low quality diet. While domestic cows have to eat 3% of their body weight daily, yaks only need to eat 1% for maintenance. Because of their extensive adaptations to the climate they live in, yaks do not do well at lower elevations, or in warm weather. They can suffer from heat exhaustion above temperatures of 15 degrees celsius.
Yaks are herd animals, though for most of the year males and females live separately. Females live in large herds of up to 200 animals, while males form much smaller bachelor herds of around six animals. Mating season occurs between July and September. At this time the males rut, fighting one another for dominance. Displays during this time include bellowing, scraping their horns along the ground, as well as charging at one another.
Calves are born from May to June after a gestation of between 257 and 270 days. Calves can walk almost immediately after birth, and are weaned at a year of age. Yaks generally give birth every other year, and reach sexual maturity around three or four years of age.
Though wild yaks are not yet endangered, they are a vulnerable species and are threatened by a number of human activities. Hunting is one of the biggest problems facing wild yak, as people hunt them for food. Domestic yaks can also be a problem, because of transmission of diseases and competition for grazing. Hopefully we can protect these silly but majestic animals and keep them around in the wild for a long time to come!