Heather Angel / Giant panda (Ailuropoda melanoleuca) sliding down slope on back after losing footing. Panda Breeding Centre, Wolong, Sichuan, China. January 1987.

John Chan / California least tern chick (Sternula antillarum browni) falling over as it runs towards its parent returning to nest site, Huntington Beach, California, USA, June.

David Perpinan / Blue fronted amazon (Amazona aestiva) chicks, confiscated from illegal wildlife trade, Brazil.

Luke Massey / Close-up of a Wild boar (Sus scrofa) approaching a remote camera and knocking it over, Forest of Dean, Gloucestershire, England, UK, May.

Frederique Olivier / Emperor penguin (Aptenodytes forsteri) walking with chick, Adelie Land, Antarctica, January.

Frederique Olivier / Emperor penguin (Aptenodytes forsteri) chicks calling, with another small chick arriving and falling over, Adelie Land, Antarctica, January.

Frederique Olivier / Southern rockhopper penguin (Eudyptes chrysocome) at nest in breeding colony, stretching and knocking chick over, New Island, Falkland Islands.

Peter Bassett / King penguins (Aptenodytes patagonicus) wading through mud and falling over, Prion Island, South Georgia.

John & Mary-Lou Aitchison / Female European otter (Lutra lutra) grooming her cub on a rock, with the cub falling off and into the water, Scotland, UK, November.

Claudio Contreras / Northern mockingbird (Mimus polyglottos) in courtship display, San Quintin, Baja California Peninsula, Mexico,

Robert Thompson / A cascade of waterfalls falling over a cliff in woodlands. Plitvice National Park, Croatia, May 2010.

Wild Wonders of Europe / Radisics / Water falling over basalt stones, Paul de Serra mountains, Madeira, March 2009