The Wild Yak Brigade, a group of wildlife vigilantes working to protect the chiru, a gazelle-like animal that lives high on the Tibetan plateau, is under fire from poachers and the Chinese government. The chiru — whose fur is turned into shahtoosh wool, which is sought to make fashionable and expensive shawls — is joining the tiger and rhinoceros as one of the world’s most endangered species. Until a few years ago, most people thought the wool was taken from live animals, but it is now believed that poachers are killing up to 20,000 of the animals each year, from a population that is currently estimated at just 78,000. The World Wildlife Fund and Wildlife Conservation Society launched a campaign last week against the buying of shahtoosh wool. Owning shahtoosh is illegal in much of the world, and a U.S. District Court recently issued subpoenas to a number of New Yorkers suspected of possessing shahtoosh shawls, including supermodel Christie Brinkley and socialite Blaine Trump.