SPECIES STORIES - Wildlife Conservation in China: Preserving the Habitat of China's Wild West - page 147

of a number of mammalian predators, including small Mustelids such as Altai weasels,
steppe polecats, and Eurasian badgers, medium-sized carnivores such as mountain cats,
and even western China's largest-bodied carnivore, the brown bear. One endemic canid,
the Tibetan fox, appears to merit status as a pika specialist, being found only in or near
pika colonies. Similarly, a number of raptors either specialize in capturing pikas or are
at least most common when they are available, including saker falcons, upland buzzards,
and eagle owls. 91
By the early 1990s, evidence had accumulated not only that pikas and zokors had
ecological significance well beyond their own existence, but also that the initial paradigm
had largely gotten it reversed. Experiments in grazing pressure, removal experiments, and
the weight of observational studies (augmented by suggestions from foreign scientists)
strongly supported the concept that pikas and zokors were found in “degraded” areas
not so much because they had unilaterally created such habitats, but rather because they
found ecological advantage there. 92 Grassland conditions conducive to buildups in pika
(and, to a lesser extent, zokor) populations could come about in a number of ways, but
by far, the most likely, logical, and empirically supported agent was excessive livestock
grazing. Thus, rather than pikas and zokors harming grasslands (and, by extension, the
pastoral economy), the consensus was that excessive grazing benefited pikas and zokors,
thus explaining most of the observed association between degraded grasslands and high
“rodent” densities. Once pikas were favored by grassland conditions, they could, of
course, multiply rapidly, remaining at high densities until occasional severe winters set
the population back to a lower density, from which it would recover again within a few
years. But in the absence of overgrazing, this newer paradigm suggested, pikas were
unlikely to compete with livestock or degrade pastures. 93
Unsurprisingly, ecosystems are rarely simple, and the above paradigm, even if more
accurate than that which it replaced, also missed the mark to some degree. To be sure,
pikas and zokors can also be found, at times at very high densities, in areas with little
or no grazing pressure from domestic livestock. 94 More importantly, once established,
pikas in particular act to perpetuate the twin conditions of sparse and short vegetation,
if not by direct consumption, then by clipping of overly dense or tall vegetation to al-
low detection of predators. 95 It is not necessarily a function of cultural or political bias
to conclude that, given a toehold, pikas may act to exacerbate grassland conditions that
make for poor livestock grazing. Attempts to change these habitat conditions while high
pika densities remain may simply be met with frustration.
The issue of pikas and grasslands in western China is strikingly similar to that of
prairie dogs and rangelands in the western United States. Pikas, like prairie dogs, have
been considered “keystone species,” which exert a disproportionate effect on the pres-
ence and abundance of other species. In the “keystone” analogy, these species, although
only one among many, are positioned in such a way that without them many other spe-
cies would find their own ecological niche compromised or eliminated altogether, much
as many stones in a classic arch would come tumbling down if suddenly bereft of the
keystone at the apex. Whether or not they truly deserve such categorization, there is no
doubt that both species play pivotal roles in their respective ecosystems, facilitating the