Jussi Murtosaari / Black tern (Chlidonias niger), in flight, Finland, July.

Andy Trowbridge / Black-fronted tern (Chlidonias albostriatus) in flight. Ashley River, Canterbury, New Zealand. August.

Andy Trowbridge / Black-fronted tern (Chlidonias albostriatus) stretching wings. Ashley River, Canterbury, New Zealand. July.

Andy Trowbridge / Black-fronted tern (Chlidonias albostriatus) perched on beach, ruffling feathers. Ashley River, Canterbury, New Zealand. July.

Loic Poidevin / Common tern (Sterna hirundo) offering fish to mate, Vendeen Marsh, Vendee, France, May

Tony Wu / Eden's whale (Balaenoptera edeni edeni) named Mae Gunya and her calf Jao Khamsamut feeding on anchovies in the shallow waters of the upper Gulf of Thailand. Around them are whiskered terns (Chlidonias...

Ingo Arndt / Whiskered Tern (Chlidonias hybrida) male passing pike (Esox lucius) to female during courtship on newly built nest, Danube Delta, Romania. June.

Hanne & Jens Eriksen / White winged tern (Chlidonias leucopterus) moulting, stretching wings, Oman, April

Hanne & Jens Eriksen / White winged tern (Chlidonias leucopterus) on the water, Oman, April

Hanne & Jens Eriksen / Whiskered tern (Chlidonias hybrida) on beach, Oman, April

Hanne & Jens Eriksen / Whiskered tern (Chlidonias hybrida) in flight, Oman, January

Bruno D'Amicis / White-winged tern (Chlidonias leucopterus) taking off, Lake Tana Biosphere Reserve, Ethiopia.