Tony Wu / Bowhead whale (Balaena mysticetus), group socialising in shallow water, aerial view. Part of larger group of more than 50 whales congregating, Sea of Okhotsk sub-population, Russia.

Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) crossing road in huge numbers during annual migration, Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) shortly before sunrise sitting on rock ready for spawning, Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Flock of Bramblings (Fringilla montifringilla) perched together in branches. It's estimated that four million individiuals return to roost during winter in Black Forest, Germany. February.

Ingo Arndt / Shoal of Pacific / South african sardines (Sardinops sagax) Monterey Bay Aquarium, USA

Ingo Arndt / Bed of Blue mussels (Mytilus sp.) densely packed together on rock, Lamberts Bay, South Africa

Ingo Arndt / King penguin (Aptenodytes patagonicus) colony with adults and chicks. St Andrews Bay, South Georgia Island, Southern Ocean, Antarctic Convergence

Ingo Arndt / Ladybirds (Hippodamia convergens) gathering to mate, California, USA.

Ingo Arndt / Aerial view of crowd of people at the Rheinkultur Festival, Bochum, Germany.

Gerrit Vyn / Snowy Owl (Bubo scandiacus) fluffing feathers, this image was taken during a massive increase in the range and population of snowy owls. Boundary Bay, Canada. March.

Cyril Ruoso / African elephant (Loxodonta africana) hanging upside down, during translocation by Kenya Wildlife Service, due to over population, Mwaluganje Reserve, Kenya. October 2006.

Erlend Haarberg / Norway lemming (Lemmus lemmus) jumping aggressively, during the lemming population explosion, Vauldalen, Norway, May, 2011.