Marie Read / Eastern bluebird (Sialia sialis) male fluttering wings while perched on cherry (Prunus sp.) branch in spring, New York, USA, April.

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

Gavin Hellier / Timelapse from day to night of an American flag fluttering on the Iwo Jima Memorial, Washington DC, USA, June 2016. Hellier

Dave Bevan / Slow motion clip of a Great tit (Parus major) fledgling begging for food by fluttering wings, chased off by adult, Carmarthenshire, Wales, UK, June.

Hanne & Jens Eriksen / Wilson's storm petrel (Oceanites oceanicus) fluttering over the sea, yellow foot web visible, Oman, November

Marie Read / Blue jays (Cyanocitta cristata) two fledglings beg by fluttering wings at adult (center bird), New York, USA.

Brent Stephenson / Fluttering shearwater (Puffinus gavia) sitting on the surface of the sea, undergoing post-breeding moult. Hauraki Gulf, Auckland, New Zealand, February.

Brent Stephenson / Fluttering shearwater (Puffinus gavia) taking off from the surface of the sea, showing the underwing and worn feathers at the end of the breeding season. Hauraki Gulf, Auckland, New Zealand, February.

Brent Stephenson / Fluttering shearwater (Puffinus gavia) on the ground near its nest site. Mokohinau Islands, Hauraki Gulf, New Zealand, October.

Mike Potts / View of Vardo harbour entrance, Vardo, Varangerfjord, Norway, March 2013.

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.