Alex Mustard / A male Yellow-headed jawfish (Opistognathus aurifrons) blowing out a clutch of eggs he has been incubating in his mouth in order to oxygenate them, East End, Grand Cayman, Cayman Islands, British West...

Michael D. Kern / Yellow Headed Day Gecko (Phelsuma klemmeri) between leaves captive from Madagascar

Pete Oxford / Yellow-headed Amazon Parrot (Amazona oratrix) captive, Belize

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male calling and performing courtship / territorial display in cattail marsh, Mono Lake Basin, California, USA

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male perched by clinging between two cattail stems in marsh, Mono Lake Basin, California, USA

Gerrit Vyn / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male in breeding plumage, perched on cattails in wetlands, Alberta, Canada. June.

SINCLAIR STAMMERS / Acellular Slime Mould, 'Many headed slime' (Physarum polycephalum) inhabits shady, cool, moist areas, such as decaying leaves and logs

Wild Wonders of Europe / Nill / Black-headed bunting (Emberiza melanocephala) male perched singing, Bulgaria, May 2008

Mark Moffett / Yellow-banded Poison Dart Frog (Dendrobates leucomelas) portrait, Venezuela

Ben Lascelles / Yellow-headed Caracara (Milvago chimachima) juvenile. Gamboa, Soberania National Park, Panama.

Ben Lascelles / Yellow-headed Caracara (Milvago chimachima) juvenile. Gamboa, Soberania National Park, Panama.

Ben Lascelles / Yellow-headed Caracara (Milvago chimachima). Gamboa, Soberania National Park, Panama.

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male in breeding plumage singing, in a cattail marsh, Mono Lake Basin, California, USA

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male in breeding plumage, preening its wing, Mono Lake Basin, California, USA, June.

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male in breeding plumage displaying with raised wings, Mono Lake Basin, California, USA, June.

Michael D. Kern / Yellow Headed Day Gecko (Phelsuma klemmeri) captive from Madagascar, endangered species

Mike Wilkes / Red headed barbet (Eubucco bourcierii) perched on branch in tree, Mindo, Ecuador

Luiz Claudio Marigo / Green headed tanager (Tangara seledon) perched on branch, mountainous Atlantic Rainforest of Serra Bonita Natural Private Heritage Reserve (RPPN Serra Bonita) municipality of Camacan, Southern Bahia S...

Claudio Contreras / Yellow-headed Parrot (Amazona oratrix tresmariae), portrait. Maria Madre Island, Islas Marias Biosphere Reserve, Sea of Cortez (Gulf of California), Mexico, July. Endangered.

Claudio Contreras / Yellow-headed Parrot (Amazona oratrix tresmariae), feeding on mangoes. Maria Madre Island, Islas Marias Biosphere Reserve, Sea of Cortez (Gulf of California), Mexico, July. Endangered.

Claudio Contreras / Yellow-headed Parrot (Amazona oratrix tresmariae) in foliage. Maria Madre Island, Islas Marias Biosphere Reserve, Sea of Cortez (Gulf of California), Mexico, June. Endangered.

Claudio Contreras / Yellow-headed Parrot (Amazona oratrix tresmariae). Maria Madre Island, Islas Marias Biosphere Reserve, Sea of Cortez (Gulf of California), Mexico, June. Endangered.

Roland Seitre / Violet-headed Hummingbird (Klais guimeti). Rancho Naturalista, Turrialba, Costa Rica.

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) sunbathing surrounded by butterflies sipping salts from the turtle's tears, Yasuni National Park, Amazon, Ecuador

Pete Oxford / Yellow-headed Calico Snake (Oxyrhopus formosus), Yasuni National Park, Amazon, Ecuador

Pete Oxford / Yellow-headed Calico Snake (Oxyrhopus formosus), Yasuni National Park, Amazon, Ecuador

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) eggs for sale -illegally harvested from Yasuni National Park, Pompeya Market, Amazon, Ecuador

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) eggs for sale - illegally harvested from Yasuni National Park, Pompeya Market, Amazon, Ecuador

Hiroya Minakuchi / Yellow-headed Caracara (Milvago chimachima), Costa Rica

Luiz Claudio Marigo / Rufous-headed tanager (Hemithraupis ruficapilla) perched in Atlantic Rainforest, Serrinha do Alambari Environmental Protection Area, Rio de Janeiro State, Southeastern Brazil

Pete Oxford / Yellow-headed Parrot (Amazona oratrix), Belize

Pete Oxford / Yellow-headed Parrot (Amazona oratrix), Belize

Pete Oxford / Yellow-headed Parrot (Amazona oratrix), Belize

Pete Oxford / Yellow-headed Parrot (Amazona oratrix), Belize

Pete Oxford / Yellow-headed Parrot (Amazona oratrix), Belize

Pete Oxford / Yellow-headed Parrot (Amazona oratrix) feeding on fruit, Belize

Pete Oxford / Lesser Yellow-headed Vulture (Cathartes burrovianus) flying, Sian Ka'an Biosphere Reserve, Quintana Roo, Mexico

Bernard Castelein / Yellow-headed Dwarf Gecko (Lygodactylus luteo picturatus) portrait on leaf, Kizimkazi, Zanzibar, Tanzania

David Welling / Black-headed Grosbeak (Pheucticus melanocephalus) male perched on dead snag, Near Yakima, Washington, USA

Luiz Claudio Marigo / Lesser Yellow-headed vulture (Cathartes burrovianus) perched in the Caatinga forest at Serra das Almas Natural Reserve, western Ceara State, Brazil.

Andrew Walmsley / Grey-headed honeyeater (Lichenostomus keartlandi) Uluru National Park, Australia, October

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male calling and performing courtship / territorial display in cattail marsh, Mono Lake Basin, California, USA.

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male calling and [performing courtship/territorial display in cattail marsh, Mono Lake Basin, California, USA

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus), female carrying damselfly prey young in her bill, Mono Lake Basin, California, USA

Marie Read / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) female perched in willow, Mono Lake Basin, California, USA

Guy Edwardes / Black-headed / Village Weaver (Ploceus cucullatus) male perched on branch, Ndutu, Ngorongoro Conservation Area, Serengeti, Tanzania, Africa, February

Steve Gettle / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) female, J. Clark Salyer National Wildlife Refuge, North Dakota

Steve Gettle / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male, J. Clark Salyer National Wildlife Refuge, North Dakota

Steve Gettle / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male, J. Clark Salyer National Wildlife Refuge, North Dakota

Steve Gettle / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) female, J. Clark Salyer National Wildlife Refuge, North Dakota

Andy Sands / Yellow Wagtail (Motacilla flava flavissima) male wading in shallow water, with reflections Lincolnshire, UK, May

Pete Oxford / South American River Turtle (Podocnemis expansa) and Yellow-spotted Amazon River Turtle (Podocnemis unifilis) yearlings in rearing program, Orinoco River, Apure, Venezuela

Pete Oxford / South American River Turtle (Podocnemis expansa) and Yellow-spotted Amazon River Turtle (Podocnemis unifilis) yearlings in rearing program, Orinoco River, Apure, Venezuela

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) tracks from female that came to shore to lay eggs, Orinoco River, Apure, Venezuela

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) tracks from female that came to shore to lay eggs, Orinoco River, Apure, Venezuela

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) yearlings, part of reintroduction to the wild program, Orinoco River, Apure, Venezuela

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) nests being dug up to be relocated, Orinoco River, Apure, Venezuela

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) yearlings, part of reintroduction to the wild program, Orinoco River, Apure, Venezuela

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) in water, Iwokrama Rainforest Reserve, Guyana

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) in water, Iwokrama Rainforest Reserve, Guyana

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis), Iwokrama Rainforest Reserve, Guyana

Pete Oxford / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) in shallow water, Iwokrama Rainforest Reserve, Guyana

Pete Oxford / Yellow-banded Poison Dart Frog (Dendrobates leucomelas), Surama, Guyana

Pete Oxford / Greater Yellow-headed Vulture (Cathartes melambrotus), Rupununi, Guyana

Pete Oxford / Greater Yellow-headed Vulture (Cathartes melambrotus), Rupununi, Guyana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male perched on cattail, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male calling from blooming Yellow Iris (Iris pseudacorus), western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male calling from cattail, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male calling from cattail, western Montana

Murray Cooper / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) group basking on logs, Tiputini River, Amazon, Ecuador

Pete Oxford / Yellow headed caracara {Milvago chimachima} perched, Cerrado habitat, Brazil

Gerrit Vyn / Adult Lesser Yellow-headed Vulture (Cathartes burrovianus). Veracruz, Mexico

Gerrit Vyn / Portrait of an adult Lesser Yellow-headed Vulture (Cathartes burrovianus) Autumn, Veracruz, Mexico

Gerrit Vyn / Adult Lesser Yellow-headed Vulture (Cathartes burrovianus) perched on a fence post. Veracruz, Mexico.

Konrad Wothe / Yellow-spotted Amazon River Turtle (Podocnemis unifilis) group basking on log, Tambopata National Reserve, Peru

George Sanker / Male Yellow-headed blackbird (Xanthocephalus xanthocephalus) perched on reed, Grand Teton National Park, Wyoming, USA, May

Steven Kazlowski / Yellow-headed blackbird (Xanthocephalus xanthocephalus) on a wire fence, National Bison Range Wildlife Refuge, Montana, USA.

Claudio Contreras / Yellow headed amazon parrot (Amazona oratrix) juvenile, Tamaulipas, northeast Mexico, June

Chien Lee / Yellow-banded Poison Dart Frog (Dendrobates leucomelas), Las Claritas, Venezuela

Chien Lee / Yellow-banded Poison Dart Frog (Dendrobates leucomelas), Las Claritas, Venezuela

Chien Lee / Yellow-banded Poison Dart Frog (Dendrobates leucomelas), Las Claritas, Venezuela

Chien Lee / Yellow-banded Poison Dart Frog (Dendrobates leucomelas), Las Claritas, Venezuela

Chien Lee / Yellow-banded Poison Dart Frog (Dendrobates leucomelas), Las Claritas, Venezuela

Chien Lee / Yellow-banded Poison Dart Frog (Dendrobates leucomelas) on leaf litter, Las Claritas, Venezuela

Chien Lee / Yellow-banded Poison Dart Frog (Dendrobates leucomelas) on leaf litter, Las Claritas, Venezuela

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) chick on cattail, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male on cattail, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) female on cattails, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male with insect prey, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) female with insect prey, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) chick begging for food from female, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) chick calling, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male on cattails, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) chick, western Montana

Donald M. Jones / Yellow-headed Blackbird (Xanthocephalus xanthocephalus) male, western Montana