In November 2011, Mexican officials found the carcass of a Mexican gray wolf near a ranch in Sonora, poisoned and left to die.A few weeks later, in December, officials found three more dead wolves, all poisoned, their skin showing similar lesions. The wolves belonged to the first Mexican gray wolf pack released from captivity onto the Mexican landscape since private and government eradication campaigns nearly drove the species extinct in the middle of the last century.

Source: Ranchers, advocates square off on Mexican gray wolf