Photographed from an ultra-light plane last December, these whooping cranes are being taught to fly south for the winter. Almost completely wiped out by 1940, there are now 536 known captive and wild whooping cranes in North America. But those raised in captivity will not migrate to warmer climes automatically — they have to learn the skill.

Lightweight aircraft lead the cranes south. These “trikes” are outfitted with GPS navigation and an MP3 player to broadcast the whooping crane’s distinctive call. The 1,285-mile migration, from Wisconsin to Florida, lasts from 48 to 97 days, depending on the weather. Four pilots fly with the cranes at all times, ready to pick up tired birds. “When I stop and think about it, it’s a pretty amazing thing,” says Joseph Duff, co-founder of the nonprofit Operation Migration, who has flown with the birds since 1993. “It’s an honor to do this.”