Shattil & Rozinski,Shattil & Rozinski / Black bear (Ursus americanus) cub climbing a fence, Minnesota, USA, May.

Luiz Claudio Marigo / Gregarious caterpillars of Morpho butterfly {Morpho hercules} Brazil

Remi Masson / Common barbel (Barbus barbus) gregarious behavior, River Rhone, France, March.

Michael Pitts / Gregarious lobster krill (Munida gregaria) adult sea floor, Falkland Islands. February.

Michael Pitts / Gregarious lobster krill (Munida gregaria) in defensive position. Beagle Channel. Argentina.

Michael Pitts / Gregarious lobster krill (Munida gregaria) juvenile. Beagle Channel. Argentina.

Heidi & Hans-Juergen Koch / Desert Locust (Schistocerca gregaria) hatching from ground, native to Afria and Asia. Sequence 3 of 4

Ingo Arndt / Desert Locust (Schistocerca gregaria) life stages from larva through stages L1 to L5, Africa

Ingo Arndt / Desert Locust (Schistocerca gregaria) life stages from larva through stages L1 to L5, Africa

Piotr Naskrecki / Desert Locust (Schistocerca gregaria), Tankwa Karoo National Park, Northern Cape, South Africa

Edwin Giesbers / Profiles of a Rook (Corvus frugilegus), right, and a Hooded Crow (Corvus cornix), left, standing on snow. These species are gregarious and sometimes flock together but do not interbreed. The Netherlan...

Marie Read / Black-tailed Prairie Dogs (Cynomys ludovicianus), two pups (right) seem to be kissing their parent. The behaviour is a gesture of recognition and identification among members of a social group of thes...