blue sheep

blue sheep, (genus Pseudois), either of two species of sheeplike mammals, family Bovidae (order Artiodactyla), that inhabit upland slopes in a wide range throughout China, from Inner Mongolia to the Himalayas. Despite their name, blue sheep (Pseudois nayaur) are neither blue nor sheep. As morphological, behavioral, and molecular analyses have shown, these slate gray to pale brown sheep-looking caprines are actually more closely related to goats (genus Capra) than to sheep (genus Ovis).

Blue sheep are sexually dimorphic, with males larger (60–75 kg [130–165 pounds]) than females (35–45 kg [80–100 pounds]). Adult males have beautiful, rather large, backward-sweeping horns (over 50 cm [20 inches] long and weighing 7–9 kg [15–20 pounds]), whereas females have very small horns. Like sheep, males lack a beard and do not have calluses on their knees or a strong body odour. Like goats, they have a flat, broad tail with a bare ventral surface, conspicuous markings on their forelegs, and large dew claws. Chromosomal analyses have indicated that the ancestral caprine stock led first to the genus Capra (with 60 diploid chromosomes) and blue sheep (with 54 diploid chromosomes) and then to other genera of Caprinae. A more recent molecular analysis has shown that blue sheep are more closely related to goats than to sheep.

The behavioral repertoire of blue sheep shows a mixture of goatlike and sheeplike patterns. Blue sheep live in groups; in treeless slopes, alpine meadows, and shrub zones above the timberline; on relatively gentle hillsides with grasses and sedges; and near cliffs, which serve as useful routes of escape from predators. They seldom move farther than 200 metres (600 feet) from a rocky retreat. This is a sheeplike terrain preference, as goats tend to stay on steep slopes and rocky cliffs. Pseudois probably split early from the ancestral Capra stock and, because of having settled in a habitat usually occupied by sheep, has convergently evolved some Ovis-like anatomical and behavioral traits, thus obscuring its affinity with goats.

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Blue sheep populations are heavily affected by hunting. Although even subsistence hunting by locals can prove destructive because of the use of modern firearms, it is hunting by and for foreigners that is particularly damaging to the survival of the species. From the 1960s to the ’80s, blue sheep were killed commercially in the Chinese province of Tsinghai. About 100,000–200,000 kg (200,000–400,000 pounds) of blue sheep meat from Tsinghai were exported yearly to a luxury market in Europe, principally Germany. Hunts in which foreign tourists kill mature males have greatly affected the age structure of some populations. However, blue sheep are still widespread and are even abundant in some areas.

The dwarf blue sheep (P. schaeferi) inhabits the steep, arid, barren lower slopes of the Yangtze River gorge (2,600–3,200 metres [8,500–10,500 feet] above sea level). Above these slopes, a forest zone extends 1,000 metres (3,300 feet) upward to alpine meadows, where the larger P. nayaur occurs. In blue sheep, horn girth, rather than length, gives an indication of habitat quality, and P. schaeferi has notably thinner horns than P. nayaur. This suggests that the former is only a low-quality population rather than a true species.