Oscar Dewhurst / Red deer (Cervus elaphus) stag roaring, silhouetted under trees at sunrise. Bushy Park, London, UK. September

Jack Dykinga / Bighorm sheep (Ovis canadensis) males grouped together before the rutting season. Valley of Fire State Park, Nevada, USA, February.

Paul Hobson / Red deer (Cervus elaphus) herd during rut in morning light. Derbyshire, England, UK. October.

Jeff Vanuga / Shiras moose (Alces alces shirasi) bull in rut. Grand Teton National Park, Wyoming, USA, October.

Cyril Ruoso / Red deer (Cervus elaphus) male calling during rut, Denmark. Non-ex

Andy Rouse / Red deer (Cervus elaphus) stag during rut, Wales, UK. September. Captive in deer park.

Andy Rouse / Red deer (Cervus elaphus) stag silhouetted at dusk, Wales, UK. Captive in deer park.

David Tipling / Red deer (Cervus elaphus) stag during rut on a misty dawn in Richmond Park National Nature Reserve, London, UK, October.

Eric Medard / Ibex (Capra ibex) males fighting, Jura, Switzerland, captive

Laurent Geslin / Red deer stag (Cervus elaphus) bellowing in rutting season in morning with steam rising from its body, New Forest, Hampshire, UK.

Laurent Geslin / Roe deer {Capreolus capreolus} male leaping during the rutting season, France

Cyril Ruoso / Red Deer (Cervus elaphus) stag bugling during autumn rutting season, Denmark