Whooping Cranes nearly went the way of the Dodo. By the 1940s, decimated by hunting and habitat loss, their numbers had plummeted to about two dozen individuals. The bird has made a remarkable comeback since then, with an estimated 450 birds living in the wild today, and another 100 or so in captivity. The whooper’s recovery has been an enormous undertaking. There’s the international effort to protect and boost the only free-living, wild population, which breeds in Canada’s Wood Buffalo National Park and winters in and around Aransas National Wildlife Refuge in Texas. And in the United States, state and federal agencies and non-profits have put considerable resources toward reintroduction programs. One such effort, undertaken by the International Crane Foundation, aims to build a self-sustaining population of around 120 birds that migrates between Horicon Marsh, a national wildlife refuge in eastern Wisconsin, and west central Florida—a goal the group estimates will...