Sven Zacek / Black Grouse (Tetrao tetrix) two males facing off on a lekking site, Varumaa county, Southern Estonia. April.

Andres M. Dominguez / Adult male King Eider (Somateria spectabilis).Batsfjord, Norway, March.

Gabriel Rojo / Guanaco (Lama guanicoe) female and newborn baby, nose to nose in grassland. La Pampa Province, Argentina.

Klein & Hubert / Meerkats (Suricata suricatta) standing on the burrow, warming up while facing the sun, Kalahari Desert, South Africa.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two adults brooding chicks. One chick exhibiting aggression towards other. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two adults with chicks aged six to eight weeks. Atka Bay, Antarctica. September.

Will Burrard-Lucas / Black and white image of African elephant (Loxodonta africana) bulls males facing off against each other, Tsavo Conservation Area, Kenya. Editorial use only. Other uses need clearance.

Ashley Cooper / Sun rays reflected onto solar tower at Ivanpah Solar Thermal Power Plant, the largest solar thermal plant in the world. It covers 4,000 acres of desert and produce 392 megawatts (MW) of electricity....

Carol Walker / Two wild pinto Mustang stallions battle for dominance in Sand Wash Basin, Colorado, USA.

Bence Mate / Great egrets (Ardea alba) in breeding colours one with dark beak, facing each other with beaks raised towards the sky, Lake Csaj, Pusztaszer, Hungary, February.

Bence Mate / Black vulture (Coragyps atratus) face to face with King vulture (Sarcoramphus papa) Costa Rica.

Bence Mate / Greater flamingos (Phoenicopterus roseus) with necks intertwined, Pont De Gau Park, Rhone River, France. February.

Bence Mate / Grey heron (Ardea cinerea) face to face in lake, at night with stars, Lake Csaj, Kiskunsagi National Park, Pusztaszer, Hungary. July.

Bence Mate / Orange chinned parakeets (Brotogeris jugularis) two looking at each other, Santa Rita, Costa Rica.

Markus Varesvuo / Two male Black grouse (Tetrao / Lyrurus tetrix) fighting, Kuusamo, Finland, April.

Edwin Giesbers / Barbary macaque (Macaca sylvanus) baring teeth as a sign of submission, Gibraltar Nature Reserve, Gibraltar,

Ben Hall / Galapagos sea lion (Zalophus wollebaeki) mother and young touching noses, Galapagos Islands, May

Pedro Narra / Green turtle (Chelonia mydas) two interacting at surface, Bissagos Islands, Guinea Bissau Endangered species. 3rd Place in the SOS Especes Menacees / SOS Endangered Species Portfolio category of the...

Markus Varesvuo / Dippers (Cinclus cinclus) fighting in snow, Kuusamo, Finland, March. Second Place in the Telephoto Lens Category of the Terre Sauvage Nature Images Awards competitiion 2015.

Bence Mate / Great white egret (Ardea alba) silhouetted at sunset, Lake Csaj, Pusztaszer, Hungary, February. Winner of the Portfolio category of the Terre Sauvage Nature Images Awards competition 2015.

Bence Mate / Grey heron (Ardea cinerea) and Great egret (Ardea alba) fighting over fish, Lake Csaj, Pusztaszer, Hungary, December. Winner of the Portfolio category of the Terre Sauvage Nature Images Awards competi...

Bence Mate / Two Great egrets (Ardea alba) standing opposite each other with Grey heron (Ardea cinerea) in between. Lake Csaj, Pusztaszer, Hungary, January. Winner of the Portfolio category of the Terre Sauvage Na...

Bence Mate / Two Great egrets (Ardea alba) face to face against white sky, Lake Csaj, Pusztaszer, Hungary. Winner of the Portfolio category of the Terre Sauvage Nature Images Awards competition 2015.

Fabrice Cahez / Red fox (Vulpes vulpes) cubs playing, Vosges, France, May.

Fabrice Cahez / Red fox (Vulpes vulpes) cubs playing, Vosges, France, May.

Sven Zacek / Roe deer (capreolus capreolus) buck with velvet antlers and fawn, Tartumaa, Estonia, March.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) rival males fighting during mating season, Cardiff, UK, March.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship dance at dawn, Cardiff, UK, March. Highly Commended in the Animal Behaviour Category of the BWPA Competition 2015.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship dance Cardiff, UK, March.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship dance, Cardiff, UK, March.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship weed dance, Cardiff, UK, March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in courtship display, The Netherlands. March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in courtship display, The Netherlands. March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in courtship display, The Netherlands. March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in 'weed dance' courtship display, The Netherlands. March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) two in territorial fight, The Netherlands, March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) two in territorial fight, The Netherlands, March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in 'weed dance' courtship display, The Netherlands, March.

Angelo Gandolfi / Gannets (Morus bassanus) courtship behavior on nest on abandoned boat, La Spezia Gulf, Italy. Mediterranean Sea. July.

Andy Rouse / Mute Swan (Cygnus olor) courtship behaviour, Wales, UK, April.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship dance, Cardiff, UK, March.

Espen Bergersen / Atlantic puffin (Fratercula arctica) two calling aggresively in snow, Hornøya birdcliff, Finnmark, Norway.

Dong Lei / White eared-pheasant (Crossoptilon crossoptilon) two in front of Buddhist prayer flags, Sichuan Province, China, July.

Ole Jorgen Liodden / Walruses (Odobenus rosmarus) adult and young hauled on ice. Hinlopen, Svalbard, Norway, June.

Chris & Monique Fallows / Wandering albatross (Diomedea exulans), engaged in mating display. South Georgia Island, Southern Ocean.

Andy Sands / German wasp (Vespula germanica) worker carrying rubbish, flying out of nest in air brick, Hertfordshire, England, UK. July

Kristel Richard / Two wild Przewalski / Takhi Horse (Equus ferus przewalskii) stallions play fighting Hustai National Park, Tuv Province, Mongolia. Endangered species. September.

Roy Mangersnes / Polar bears (Ursus maritimus) courting on ocean ice north of Spitsbergen, Svalbard, Norway, July.