Bharal of the High Plateau

Explanation: Driving the high passes of the Tibetan Pleatau between Yamtrok and Gyantse, we unexpectedly happened upon a heard of ... what are these? Sheep? Goats? Something in between?

These are bharal ... also known as nayaur ... or, most commonly, Himalayan blue sheep. Yet ... although they are Himalayan (of the Himalayan Mountains, more or less, although here they have ranged north onto the Tibetan Plateau), they are really neither blue nor are they (true) sheep.

They are doubtless "goat-like" and go by a litany of other local names in many languages. They may have originated from some proto-goat ancestor in the early Pliocene, and thus may be more goat than sheep in origin, but their evolutionary history is clouded in deep time.

Blue sheep are relatively widely distributed in southern Asia and are not directly imperiled, although IUCN lists one subspecies, the dwarf blue sheep (Pseudois nayaur schaeferi), found in south-central China, as Endangered.

The species inhabits high mountains and passes with grassy slopes, occurring at 10,000 to 18,500 feet (3,000 to 5,550 meters) elevation. They thus overlap their distribution range with snow leopards, and indeed form one of the key prey species of that felid. Occasional outbreaks of mange in herds of blue sheep can greatly suppress their populations, thus causing a food shortage for the snow leopard, as happened in northern Pakistan in 2007.

EPOW - Ecology Picture of the Week