野牦牛
- Wild yak blood contains a lot of fetal hemoglobin, allowing it to carry more oxygen. This feature remains throughout the yak's life.
- The wild yak is called "drong" in Tibetan, unlike the domestic one. In winter, it lives at an altitude of 4300–4600 m above sea level, and in summer up to 6100 m.
- Male wild yaks make loud bellows only during the mating season. At other times, they are silent, even during fights, and fatal outcomes are rare.
- Large male wild yaks, especially castrates, carry heavy loads of up to 240 kg easily along steep slopes. Herds trample snow, making it possible to cross passes on horses or yaks with cargo.
- Bones of an unknown “Yak X”, genetically distinct from modern yaks, were found in Denisova Cave.
- Wild yaks have a thick, matted undercoat that protects them from winter cold. In spring and summer, it sheds in large clumps.
- A dense double coat and special haemoglobin allow life in extreme cold and low oxygen.
- Wolves attack yaks only in exceptional cases, in large packs and in deep snow. In such situations, yaks may be weaker, for example, due to deep snow.
- Wild yak horns are long, widely spaced, and curve forward-upward, reaching a length of up to 95 cm. The distance between the ends of the horns is 90 cm.
- Male wild yaks fight fiercely, without rituals, and during fights try to strike opponents with their horns in the side. Their fights are unlike the ritualized battles of most other bovids.
- The domestic yak crosses with cows, producing hybrids called high nak that are very useful as draft animals. High nak are bred in southern Siberia and Mongolia, are larger in size and have a more docile temperament.
- The wild yak has large lungs and heart adapted to high altitude. It has larger lungs and heart compared to cattle from lowland areas.
- The Latin name mutus (“mute”) is misleading—yaks are quite vocal, especially in the rut.
年龄
Wild yaks typically live for 15 to 20 years, with a maximum lifespan of 25 years and a theoretical lifespan ranging from 26 years and 4 months to 26 years and 11 months. The species reaches sexual maturity between 1 year and 6 months and 2 years and 6 months of age, and the young are born with their eyes open and begin walking immediately. During the embryonic stage, the fetus develops inside the mother and receives nutrients via the placenta. The calf, or young yak, quickly stands and feeds on its mother’s milk; this stage lasts from 1 day to 8 months. Following this, the young animal enters a stage of rapid growth, lasting from 8 months to 4 years, where it learns to find food and stay with the herd. The adult stage begins at 4 years and continues until 25 years of age, during which males are larger than females and the animals reproduce within herds.
表型
The young yak has short and soft fur that grows quickly and becomes thicker; after a period of rapid growth, horns begin to develop, appearing small and sharp. Adult yaks possess very long and thick fur that covers their body down to the ground, protecting them from frost and wind. The species has wide hooves that prevent sinking in snow and aid movement on steep slopes. Mature individuals possess powerful horns curved upwards and outwards, which assist in defense against predators and resolving social interactions within the herd.
生理学
Wild yaks stand in height from 1.21 to 1.9 meters and measure in body length from 2.1 to 3.3 meters; their mass ranges from 170.45 kilograms to 0.44 metric tons. The embryonic stage presents with a body mass of from 10 to 25 grams and a body length of from 30 to 60 centimeters. During the newborn stage, the young have a body mass of from 15 to 35 kilograms and a body length of from 80 centimeters to 1.2 meters. The stage of rapid growth results in young yaks with a body mass of from 50 kilograms to 0.25 metric tons and a body length of from 1.2 to 2 meters. Adult yaks possess a body mass of from 0.65 to 1.2 metric tons, and their body length measures from 2.6 to 3.3 meters.
栖息地
Wild yaks inhabit elevations from 3 kilometers to 6 kilometers above sea level and occupy diverse biomes including deserts and dry scrublands, mountainous meadows, and temperate steppes. The species’ landscape preferences encompass terrestrial grasslands and steppes, terrestrial tidal zones, high mountain terrain, and tundra; they are found in cold steppes with sparse trees and abundant grass, areas that are cold and nearly dry year-round, polar tundra characterized by short summers and extensive moss cover, extremely cold regions with snow and ice, and winters with significant snowfall.
庇护所
Wild yaks inhabit areas behind cliffs and in lowlands; the species does not have permanent or long-term shelters. They do not use fixed shelters, and their resting places consist of reeds, grasses, and mosses, providing protection from wind and serving as places for rest.
地理
Wild yaks are found within the biogeographical realms of Palearctica and Indomalaya. The species inhabits thorny scrub forests of the western Aravallis.
食性
The wild yak is an herbivore that feeds on plants; during the summer, it consumes fresh grass on alpine meadows, and in winter, it eats dry grass, mosses, and lichens found under the snow. The species obtains food by biting and tearing plants with its teeth and tongue, consuming grasses, sedges, mosses, lichens, reeds, and rushes. Its feeding strategy is grazing, with a daily food requirement ranging from 8 kilograms to 20 kilograms. Young yaks are fed milk. In some cultures, the animal is eaten, but in Hinduism, cows are sacred, and beef is generally not consumed.
繁殖
The species develops from an embryo that takes 9 months and 1 week to develop. The female gives birth to one offspring, which is born live on land. Male yaks and females form pairs during the mating season in autumn; the female carries a single calf for about 9 months and gives birth in spring or early summer. The mother feeds and protects the young. Yaks reach maturity from 3 to 6 years of age. The interval between reproduction is from 1 to 3 years. The species inhabits and develops on land, outside of bodies of water. Eggs, larvae, or young develop in a nest built on the ground or close to it; the nest is located directly on the surface of the ground on land. Only the mother shows parental care for the offspring. Reproduction always occurs with fertilization, without alternating generations.