Rare black-footed ferrets chattered angrily before dashing out of pet carriers and ducking into burrows Monday at the Rocky Mountain Arsenal National Wildlife Refuge—a milestone for the highly endangered animals and for the former toxic waste site on the industrial edge of Denver. The US Fish and Wildlife Service released 30 ferrets at the site as part of a program to reintroduce them in 12 states where they once thrived, from Montana to Texas. "They're a native species. They belong here," says an outreach specialist with the reintroduction program. Their new home is a 25-square-mile preserve of short-grass prairie. Chemical weapons and pesticides were once manufactured there, but it became a wildlife refuge in 2010 after a $2.1 billion cleanup.
Black-footed ferrets, slender creatures that dine on prairie dogs, were once thought to be extinct, but a small colony was discovered in 1981 in Wyoming. Researchers have been trying to restore the population since then, reintroducing them at 24 sites, and officials estimate about 300 ferrets now live in the wild from Canada to Mexico. "This remarkable place shows that nature will recover and will thrive if given a chance," says Fish and Wildlife Service Director Dan Ashe, who watched the releases. At the Rocky Mountain Arsenal refuge, the ferrets join a bison herd that was reintroduced in 2007. The refuge is also home to prairie dogs, deer, rabbits, coyotes, eagles, hawks, meadowlarks, and other native prairie wildlife. (Wild bison have returned to Illinois after almost 200 years.)