Diane McAllister / Male Anna's hummingbird (Calypte anna) hovers in mid-air looking at the camera in a backyard in Reno. Nevada, USA, August

Marie Read / American Cliff Swallow (Petrochelidon pyrrhonota) fluttering its wings while it gathers mud in its bill to use as nesting material. Mono Lake Basin, California, USA, June.

Marie Read / American Cliff Swallow (Petrochelidon pyrrhonota) fluttering its wings while it gathers mud in its bill to use as nesting material. Mono Lake Basin, California, USA, June.

Marie Read / American Cliff Swallow (Petrochelidon pyrrhonota) fluttering its wings while it gathers mud in its bill to use as nesting material. Mono Lake Basin, California, USA, June.

Christian Ziegler / Greater Bulldog Bat (Noctilio leporinus) uses its feet to collect insects fluttering on lake surface, Barro Colorado Island, Panama

Piotr Naskrecki / Althoff's Acraea (Acraea althoffi) fluttering while drinking seeping water rich in sodium, Guinea, West Africa