Milestone reached in saving Florida grasshopper sparrow, North America’s most endangered bird

On a recent morning, 10 Florida grasshopper sparrows, tiny brown-speckled birds that are the most endangered on the continent, took their first scampers and flaps on the state’s central prairie.

It happened so fast it was hard to distinguish which of the captive-raised sparrows was the 1,000th released on this expanse of grasslands not far from Walt Disney World, the only place on Earth where the birds are found in their natural habitat.

Dozens of conservationists, gathered some distance away to avoid spooking the skittish sparrows, celebrated the milestone in an unprecedented recovery program that in only a few years has doubled...