<p>An adult Grus americana makes a splashing run-up to flight through a marsh in Canada's Wood Buffalo National Park.</p>

An adult Grus americana makes a splashing run-up to flight through a marsh in Canada's Wood Buffalo National Park.

Counting Cranes

How many wild whooping cranes are there? Not enough.

Nearly grazing the treetops, a tiny red plane swoops in dizzying circles over the bogs and forests of Canada's Wood Buffalo National Park. As pilot Jim Bredy banks hard for another pass, he and his two passengers press their faces against the glass, squinting to spot familiar white smudges on the ground—adult whooping cranes—with russet-feathered young in tow. This wil­der­ness is the summer home of the last wild mi­gra­tory flock of Earth's most endan­gered crane.

The aerial census takers are Bredy, Tom Stehn of the U.S. Fish and Wildlife Service, and Lea Craig-Moore of the Canadian Wildlife Service (CWS), and they're worried. The flock's population had reached 266 in the spring of 2008. But by the following spring, 57 had died, 23 of them on the birds' wintering grounds in south Texas, where drought had decimated their main food—blue crabs and a plant called wolfberry. Others probably perished during migration, often after striking power lines, the biggest known killer along the flyway. The higher-than-average death count has added urgency to a new effort that tracks some migrating birds with GPS anklets.

Still, whoopers, as they're called, aren't nearly as bad off as they once were. A key event in their revival took place 42 years ago, when CWS biol­ogist Ernie Kuyt went on a spring treasure hunt. A helicopter let him off on the soggy boreal land­scape, a vast expanse of sedge meadow and ponds broken up by islands of black spruce and willow. Using a jack pine pole as a staff, he trudged through muck that might have stolen his resolve—and his boots. At the heart of a shallow pool, he spied a massive nest cradling a pair of blotchy eggs, each the size of an Idaho potato. Kuyt had left his container in the copter, so he tucked a sole egg into a wool sock, sensitive to the weight of the future life—and the pos­sible salvation of a species—he'd carry home.

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