John Chan / Male California Least Tern (Sternula antillarum browni) courting a female, presenting a fish before chasing off another male, Huntington Beach, California, USA, May.

Frederique Olivier / Pair of Blue footed boobies (Sula nebouxii) courting, with the male picking up and offering grass, Isla Lobos de Terra, Peru.

John Cancalosi / Group of gravid female Timber rattlesnakes (Crotalus horridus) basking before giving birth, Pennsylvania, USA, July.

Christophe Courteau / Male BurchellÕs zebra (Equus quagga burchellii) pulling the head of a dead pregnant female that died due to complications whilst giving birth, trying to wake her up, Etosha National Park, Namibia. Par...

Ingo Arndt / Pea aphid (Acyrthosiphon pisum) giving birth (viviparous during the summer month), Germany. Winner of Fritz Polking portfolio prize, GDT 2012 competition.

Danny Green / Atlantic Puffin (Fratercula arctica) coming out of its burrow with a gift, Skomer Island, Wales, UK, May

Tony Heald / Asian elephant (Elephas maximus) domesticated elephant working, picking reeds, Kaziranga National Park, Assam, India, March 2009.

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

Ole Jorgen Liodden / Waved albatross (Phoebastria irrorata) pair in courtship display, Espanola, Galapagos Islands. Critically endangered species.

David Pattyn / Great crested grebe (Podiceps cristatus) pair performing their 'weed dance' in which they take a vertical position in front of each other and offer plant material to each other. The Netherlands. March...

Staffan Widstrand,Staffan Widstrand / Mangrove planting team from CRINEO planting Rhzophora mangrove trees, Pulicat Lake, Tamil Nadu, India, February 2013.

Paul D Stewart / Aerial view of Grand Prismatic thermal spring in Yellowstone National Park, USA. The bright colours are natural, coming from thermophile bacteria in the water. People can be seen walking on the raised...