Konrad Wothe / Aggressive Mute swan (Cygnus olor) Upper Bavaria, Germany, Europe

Bence Mate / Keel billed toucan (Ramphastos sulfuratus) in aggressive encounter with Montezuma Oropendola (Psarocolius montezuma) in rain, Laguna del Lagarto, Santa Rita, Costa Rica. Front cover bookplate of the H...

Doug Perrine / Hawaiian monk seals (Monachus schauinslandi) aggressive male attacks a five and a half week pup, mother (right) approaches to intervene; Papaloa Beach, Kalaupapa, Molokai, Hawaii, USA

Anup Shah / Western chimpanzee (Pan troglodytes verus) female 'Fanle' aged 13 years and protecting her infant son 'Flanle' aged 3 years from an aggressive male, Bossou Forest, Mont Nimba, Guinea. January 2011.

Paul D Stewart / 1853 illustration of Gorilla, contemporary coloured copperplate engraving from 'Das Buch der Welt' John Weik, Stuttgart. The lowland Gorilla was first accurately described outside Africa by the missio...

Carol Walker / Wild horses / Mustangs, two stallions play fighting, Pryor Mountains, Montana, USA, July 2010

Sergey Gorshkov / African elephant charging (Loxodonta africana) female with young calf, Okavango Delta, Botswana

Nick Garbutt / Adult male Hippopotamuses (Hippopotamus amphibius) posturing in aggressive 'yawn' behaviour, Luangwa River, South Luangwa National Park, Zambia, November. Digital composite (two frames stitched togeth...

Terry Whittaker / 2020VISION / Stag beetle (Lucanus cervus) two males displaying aggressive behaviour on oak tree branch at woodland edge, Suffolk, UK, Controlled conditions, July

Andrew Parkinson / Whooper swan (Cygnus cygnus) adult aggressively chasing another, UK visitor between November and March. Lancashire, UK, October.

Anup Shah / Adolescent male Lions (Panthera leo) play fighting, Masai Mara National Reserve, Kenya, March

Andy Rouse / Lonnberg's / Subantarctic Skua (Stercoraius antarcticus lonnbergi) displaying aggressive behaviour, South Shetland Islands, Antarctica. (Non-ex)