SPECIES STORIES - Wildlife Conservation in China: Preserving the Habitat of China's Wild West - page 150

realize that the well-known domestic yak is simply a highly modified (and considerably
smaller) wild yak, 105 that wild yaks still roam certain portions of the Tibetan Plateau, but
their populations are small, somewhat isolated, and their future far from secure. Their
domestic cousins have made yaks famous, but wild yaks remain essentially unstudied,
noteworthy more as symbols of the remaining wildness on the plateau than for their
identity as a valid wild species.
Yaks have presented something of an enigma for taxonomists and paleontologists.
Even restricting oneself to the recent literature, one readily comes across three different
Latin names referring to the same beast— Bos grunniens , Bos mutus , and Poephagus
grunniens —and some earlier taxonomists considered it congeneric with Bison . 106 Although
clearly a member of the subfamily Bovinae (cows and their relatives), it remains unclear
how close, and through what pathways, its familial relationship is to other large cows.
And a large cow it is, weighing generally more than any wild bovid, heavier even than
American bison or African buffalo. At a reputed weight of up to a ton in adult males 107
the wild yak is larger than all other animals in Eurasia except for Asian elephants and
Indian rhinoceroses.
But wild yaks are not simply hairy cows. They are high-elevation specialists, thriving
in oxygen concentrations that domestic cattle cannot tolerate, frequenting steep hillsides,
marching over talus slope and navigating glaciers like overgrown goats. Particularly in
summer, they prefer mesic sedge meadows tucked under snowfields or glaciers, normally
at the upper limit of vegetation, close to 5,000 meters high. Here, mixed-sex herds of
up to several hundred animals will graze together, young calves always located toward
the center for protection from predators, otherwise invulnerable adult animals forming a
loosely knit protective shield around them. In autumn, when these sedge meadows become
dry and nutritive quality drops, yaks descend to slightly lower-elevation grasslands, where
cured grasses still provide sufficient calories for them to survive the long, frigid winters.
Unlike many other bovids, numerous adult males generally accompany these maternal
groups. There also exist separate, bachelor groups of males, moving independently and
often quite distantly from the maternal groups, yet these males are not, as one might as-
sume, youngsters awaiting sexual maturity, but rather elderly bulls, seemingly unable to
successfully contest for breeding. 108
Because wild yaks have become relatively rare, researchers do not have much experi-
ence with them. But Yeniugou, which I have already discussed in relation to grassland
conditions and nature reserves, is probably the single most important area for wild yak
conservation in the world. Nowhere else can wild yaks be seen in such numbers and with
such regularity. 109 Exploring the reasons why will be helpful in understanding why they
are rare elsewhere.
First, Yeniugou is positioned squarely under some of the most frequent storm tracks on
the Tibetan Plateau; although situated in the relatively arid Kunlun Shan, small glaciers
and permanent snowfields are particularly concentrated on the north-facing slopes of all
the major peaks in this area. This moisture, together with conducive soils, produces large
bands of mesic sedge meadows (primarily consisting of species of the sedge Kobresia ) that
produce abundant summer forage. These sedge meadows appear tolerant to heavy graz-