Gray wolf (Canis lupus) populations were eliminated from Montana, Idaho, and Wyoming, as well as adjacent southwestern Canada by the 1930s. After human-caused mortality of wolves in southwestern Canada began to be regulated in the 1960s, populations began expanding southward. Dispersing individuals occasionally reached the northern Rocky Mountains of the United States, but lacked legal protection there until 1974, after passage of the Endangered Species Act of 1973. In 1986, wolves from Canada successfully raised a litter of pups in Glacier National Park, Montana, and a small population was soon established. In 1995 and 1996, wolves from western Canada were reintroduced to remote public lands in central Idaho and Yellowstone National Park. ...