The Tibetan yak is a massive wild bovine native to the Tibetan Plateau and the Himalayas. It is the largest native mammal of the Tibetan Plateau: wild males can reach 2 m at the shoulder and weigh up to 1,000–1,200 kg. The body is covered in dense, long dark-brown fur with a thick woolly undercoat that protects the animal from temperatures below −40 °C. Characteristic features include powerful curved horns up to 1 m long, and a thick “skirt” of long flank hair that hangs almost to the ground, insulating the animal from snow and cold when resting. The word “yak” comes from the Tibetan word “yag”. The wild yak (Bos mutus) and the domestic yak (Bos grunniens) are now considered separate species. Domestication took place at least 4,000–7,000 years ago.

Key facts

• Scientific name: Bos mutus (wild) / Bos grunniens (domestic)
• Lifespan: up to 25 years in the wild; up to 28 in captivity
• Shoulder height: 160–205 cm; body length: 240–380 cm
• Weight: males 500–1,200 kg; females about 300 kg
• Habitat type: alpine meadows, steppes and cold deserts above 3,000–4,500 m
• Conservation status: Vulnerable (IUCN)

Lifestyle
The Tibetan yak feeds on grasses, mosses, lichens and sedges — plants that withstand the harsh climate of the plateau. During the dry season, the animals undertake long seasonal migrations. Females with young gather in herds of 10 to several hundred individuals; males are mostly solitary or form small bachelor groups. The rut takes place between July and September. Thanks to large lungs, a high red blood cell count and elevated haemoglobin concentration, yaks are superbly adapted to the thin air of high altitude. Unlike most large bovids, yaks and their dung have virtually no detectable odour, and their wool is naturally odour-resistant.

Conservation status
Wild yaks survive only on the Tibetan Plateau, where they have declined greatly in range and numbers during the past century due to excessive hunting. Whereas only 50 years ago as many as one million wild yaks roamed the plateau, only around 10,000–15,000 remain today. Poaching is considered the most serious threat to the yak population. Additional threats include hybridisation with domestic yaks, displacement by livestock, and disease. The species is regionally extinct in Nepal and Bhutan.

Distribution
Wild yaks persist in several small populations and in one large tract of alpine steppe and alpine desert, mostly above 4,500 m in elevation, covering about 400,000 km² primarily in the Tibet Autonomous Region. Small remnant populations also occur in Ladakh (India) and Pakistan. The Chang Tang Reserve, 284,000 km² in size, covers a substantial part of this area.