Black-necked Stilt

From the U.S. Fish and Wildlife Service:

This black-necked stilt fakes a broken wing in order to trick predators and distract them from the location of their young. Stilts (among many other shorebirds such as killdeer, plovers, and american avocets) will do a "broken wing" display to distract possible predators by flapping their wings on the ground. That way, they resemble a sick or weak or bird, that would be easy to catch.
Photo: Rinus Baak, fws.gov