India, Oct. 27 -- For a species once thought lost, the road back began with a very small population. The black-footed ferret, a nocturnal predator of North America's grasslands, disappeared from much of its historic range as prairie habitat was lost. By the 1970s, it was widely believed to be extinct in the wild.

According to the Smithsonian's National Zoo and Conservation Biology Institute, the last 18 known wild black-footed ferrets were brought into human care between 1985 and 1987 after disease devastated the remaining population in Wyoming. They became the foundation of a conservation breeding program.

Since reintroductions began, more than 10,500 ferret kits have been born in human care, while the U.S. Fish and Wildlife Service es...