Male black grouse (Lyrurus tetrix) fighting on snow covered field, Finland

Male black grouse (Lyrurus tetrix) fighting on snow covered field, Finland

Southern elephant seal (Mirounga leonina) bulls fighting for territory for mating, Gold Harbour, South Georgia, UK Overseas Protectorate, Polar Regions

Antarctic fur seal bulls (Arctocephalus gazella) fighting for mating territory on South Georgia, Southern Ocean, Polar Regions

Southern elephant seal (Mirounga leonina) mating behavior on South Georgia Island, Southern Ocean

Adult bull southern elephant seals (Mirounga leonina) fighting for breeding grounds on South Georgia Island, Southern Ocean

Adult bull southern elephant seals (Mirounga leonina) fighting for breeding grounds on South Georgia Island, Southern Ocean

Adult black-legged kittiwake (Rissa tridactyla) in aerial combat against another kittiwake near Alexander Island, Russia, Eurasia

Adult black-legged kittiwake (Rissa tridactyla) in combat with a second kittiwake near Alexander Island, Franz Josef Land, Russia, Arctic Ocean, Eurasia

Hamerkop (Scopus umbretta) carrying nesting material, Zimanga Game Reserve, South Africa, Africa

Lava lizard (Microlophus spp) courtship behavior in the Galapagos Islands Archipelago, UNESCO World Heritage Site, Ecuador, South America