This is the nest of the Killdeer, the long-legged common bird of parks and grassy areas. Killdeer lay their eggs right on the ground, trusting to camouflage to keep them safe. The birds have a back-up behavior. When their nests are threatened, they drag a wing and act injured to lure predators away. When dog, cats or people chase the “injured” bird, being drawn away from the hidden nest, the Killdeer miraculously recovers and flies away.