Tui De Roy / Salvin's Albatross (Thalassarche salvini) returning en masse to crowded nesting colony at sunset, Proclamation Island, Bounty Islands, New Zealand

Floris van Breugel / Hibernating Ladybirds (Hippodamia convergens) assembled en masse to overwinter, King's Canyon National Park, California, USA, May 2009

Andy Sands / Water avens (Geum rivale) growing en-masse on roadside verge, Upper Teesdale, Co. Durham, England, UK, June

Pete Oxford / Communal caterpillars travelling en masse for protection to make predators think they are larger. Amazonia, Peru

Michael Quinton / Pink Salmon (Oncorhynchus gorbuscha) spawning en masse, Alaska

Michael Quinton / Pink Salmon (Oncorhynchus gorbuscha) spawning en masse, Alaska

Michael Quinton / Pink Salmon (Oncorhynchus gorbuscha) spawning en masse, Alaska

Peter Blackwell / Wildebeest crossing river en masse {Connochaetes taurinus} Masai Mara, Kenya, Africa

Peter Blackwell / Wildebeest (Connochaetes taurinus) crossing river en masse. Masai Mara, Kenya, East Africa