Guy Edwardes / Northern gannets {Morus bassanus} pair in courtship display, Great Saltee, Co. Wexford, Republic of Ireland, June

Tim Laman / Goldie's Bird of Paradise (Paradisaea decora) displaying to female, Fergusson Island, Milne Bay Province, Papua New Guinea.

Konrad Wothe / Feral pigeons (Columba livia domesica) mating on roof, Germany, September

Roger Powell / Northern gannets (Morus bassanus) flying past their breeding colony, Great Saltee Island, Wexford, Republic of Ireland, June

Roger Powell / Northern gannets (Morus bassanus) hovering in flight, looking to land in colony, Great Saltee Island, Wexford, Republic of Ireland, June

Roger Powell / Northern gannet (Morus bassanus) adding nesting material to its nest, Great Saltee island, Wexford, Republic of Ireland, June

Bernard Castelein / Northern Gannet (Morus bassanus) courtship display, Helgoland, Germany May

Juan Carlos Munoz / Pair of Rockhopper penguins (Eudyptes chrysocome) with egg, with a group of penguins in the background. Penguin Island, Puerto Deseado, Patagonia, Argentina, Nov 2008

David Tipling / Brown Jay {Psilorhinus morio} collecting nest material, Tikal, Guatemala

Tim Laman / Male Carola's Parotia (Parotia carolae) (mostly black bird) displaying to females plumage birds (mostly brown birds) at his display court, which is an area of ground cleared of leaves with a horizonta...

Tim Laman / Magnificent Bird of Paradise (Cicinnurus magnificus) male at calling perch near his display court. Huon Peninsula, YUS Conservation Area, Morobe Province, Papua New Guinea.

Tim Laman / Blue-footed booby (Sula nebouxii excisa) male performs sky-pointing display for female. Espanola / Hood Island, Galapagos, June

Tim Laman / Medium ground finch (Geospiza fortis) with nest material. Floreana / Charles Island, Galapagos, June

John Cancalosi / Griffon Vulture soaring (Gysp fulvus) carrying feather in beak for nest, Spain

Steve Knell / Horned / Slavonian grebes {Podiceps auritus} Pair mating on future nest site. Norway, May 2006

Steve Knell / Horned / Slavonian grebe {Podiceps auritus} mating pair, Sweden, 2006

Steve Knell / Horned / Slavonian grebe {Podiceps auritus} pair in courtship display, Sweden, 2006

John Cancalosi / Red-winged Blackbird {Agelaius phoeniceus} male courtship display, NY, USA

John Cancalosi / Cactus Wren (Campylorhnchus brunneicapillus) gathering nest material, Arizona, USA

John Cancalosi / Cactus Wren (Campylorhnchus brunneicapillus) gathering nest material, Arizona, USA

John Cancalosi / Cactus Wren (Campylorhnchus brunneicapillus) gathering nest material, Arizona, USA

John Cancalosi / Red-winged Blackbird {Agelaius phoeniceus} male courtship display, NY, USA

John Cancalosi / American Coot {Fulica americana} carrying nest material, NY, USA

John Cancalosi / American Coot {Fulica americana} carrying nest material, NY, USA

Shattil & Rozinski / Longbilled marsh wren {Cistothorus palustris} nest material from Cattail reed, USA

Shattil & Rozinski / Great blue heron {Ardea herodias} flying with nesting material in beak, USA

Bernard Castelein / Pair of Nazca / Masked booby (Sula dactylatra granti) courtship behaviour, Galapagos, Ecuador

Tom Vezo / Semi-palmated plover {Charadrius semipalmatus} sitting on nest, Long Island, New York, USA

Shattil & Rozinski / Greater sage grouse {Centrocercus urophasianus} male displaying at lek, Colorado, USA

Shattil & Rozinski / Greater sage grouse {Centrocercus urophasianus} males displaying at lek, Colorado, USA

Shattil & Rozinski / Greater sage grouse {Centrocercus urophasianus} males displaying at lek, Colorado, USA

Shattil & Rozinski / Greater sage grouse {Centrocercus urophasianus} male displaying at lek, Colorado, USA

Shattil & Rozinski / Gunnison sage grouse {Centrocercus minimus} male display at lek, Colorado, USA

John Cancalosi / Killdeer {Charadrius vociferus} on nest with eggs, USA.

Bernard Castelein / Lesser kestrel {Falco naumanni} pair mating on roof, Lake Bafa, Turkey

Tom Vezo / American golden plover (Pluvialis dominica) on nest, Churchill, Manitoba, Canada

Tom Vezo / Lapland bunting (Calcarius lapponicus) female. Nome, Alaska, USA

Thomas Lazar / Snowy egrets mating (Egretta thula) Florida, USA

Tom Vezo / Arctic terns mating {Sterna paradisaea} Long Island, NY, USA New York

Tom Vezo / Harris hawk pair flying with nesting material {Parabuteo unicinctus} Arizona USA Tucson