Tui De Roy / Greater Flamingo (Phoenicopterus ruber) pair in territorial display while two other feed, Galapagos Islands, Ecuador

Michael & Patricia Fogden / Southern Grasshopper Mouse (Onychomys torridus) male singing on its territory, Chihuahua Desert, Mexico

Sumio Harada / Red Squirrel (Tamiasciurus hudsonicus) mother protecting territory near her nest from other squirrels, Rocky Mountains, North America

Flip Nicklin / Narwhal (Monodon monoceros) males sparring over carcass of dead female, Baffin Island, Canada

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) silverback beating chest, Parc National des Volcans, Rwanda

Donald M. Jones / Black Bear (Ursus americanus) rubbing back on pine, Jasper National Park, Alberta, Canada

Mark Raycroft / White-tailed Deer (Odocoileus virginianus) buck rubbing antlers, North America

Sergey Gorshkov / Brown Bear (Ursus arctos), at dock with Domestic Dogs (Canis familiaris) Kamchatka, Russia

Mark Moffett / Green Tree Ant (Oecophylla smaragdina) trio from two different colonies fighting over territory, Daintree, Queensland, Australia

Mark Moffett / Green Tree Ant (Oecophylla smaragdina) pair from two different colonies fighting over territory, Daintree, Queensland, Australia

Gerrit Vyn / Snowy owls (Bubo scandiacus) roosting on coastal driftwood. The immature female in the centre is giving the 'mewing whistle' call as a territorial signal to other owls. Grays Harbor County, Washington...

Donald M. Jones / Caribou (Rangifer tarandus) bull rubbing tree on fall colored tundra, Denali National Park, Alaska