Laura Erickson's For the Birds

This softly-colored curlew, with coloring much warmer than that of the Whimbrel, winters on atolls and islands in Oceana (including Hawaii) and breeds only in two very remote areas of Alaska, on the Seward Peninsula and the lower Yukon River. It is the only migratory shorebird that winters exclusively on oceanic islands. It’s also the only shorebird known to become flightless during molt. As if those two unique qualities weren’t enough, this is also the only shorebird known to use tools when foraging. And to add to its unique features, it’s named for the unique bare shafts of some of its thigh feathers. No one knows why it has this feature.

All Bristle-thighed Curlews fly at least 2,500 miles nonstop each way between Alaska and the northern end of the winter range in the Northwestern Hawaiian Islands, and some make nonstop flights of more than 3,700 miles each way. To accomplish this, they put on huge fat deposits to fuel the flights over open ocean, and reduce some internal organs to reduce the load. Along with the Bar-tailed Godwit, they make one of the longest nonstop flights known for any bird. (Arctic Terns have a longer migration, but eat all along the way.) Adult Bristle-thighed Curlews arrive on their breeding grounds in early to mid-May.