Alaska to Hawaii, nonstop. It's among the longest flights any bird has made, and the bristle-thighed curlew does it every year. Monogamous pairs spend the summer nesting and caring for chicks, then flock the Yukon-Kuskokwim Delta to feed and store up energy for the journey ahead. When the birds finally make it to island wintering grounds, their opportunistic diet changes and they employ their unique ability to use rocks and coral as tools to open the shells of albatross eggs. But another unique trait—it's the only shorebird known to become flightless when it molts—lands it in serious danger from an array of introduced predators.