Re-introduction of the gray wolf into Yellowstone National Park and central Idaho, USA

Summary

Gray wolves (Canis lupus) were deliberately exterminated from the western United States by 1930. After 20 years of political debate and congressional planning from 1988 onward, the US Fish and Wildlife Service and National Park Service re-introduced wolves captured in Canada under a special Endangered Species Act provision allowing flexible management. In January 1995, 15 wolves were hard-released directly into remote central Idaho, and 14 more were soft-released from three one-acre pens in Yellowstone National Park after an eight-week acclimation; the process was repeated in 1996 with 20 wolves in Idaho and 17 in Yellowstone, for a total of 66 founding animals. Every re-introduced wolf was radio-collared, and about 30 percent of the population remained collared through 2007 to track movements and manage conflicts. By 2007 the population had grown 24 percent annually to roughly 1,500 wolves across 160,000 square kilometres of suitable habitat. Wolves killed over 830 cattle, 1,760 sheep, and various other livestock between 1995 and 2007, prompting compensation payments exceeding 900,000 US dollars and the killing of more than 700 problem wolves, but confirmed livestock conflicts stayed below predicted levels. Extensive public outreach, including thousands of media interviews and public presentations, helped sustain political tolerance. In 2007 the northern Rocky Mountain population was proposed for delisting and transfer to state and tribal management. The project rated itself Highly Successful, citing the scale of population recovery and widespread public and agency perception of the program as highly successful.