Each photograph is also credited where it appears. The comparison plates and diagrams are drawn for this site and carry no third-party credit; the landscape and habitat photographs come from Wikimedia Commons and are credited in the list below like every other picture.

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  Aegypius monachus Photograph by egorbirder · CC BY · original observation Used on Cinereous Vulture
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  Aix sponsa Photograph by Adrienne van den Beemt · CC BY · original observation Used on Wood Duck
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  Anas platyrhynchos Photograph by Blake Ross · CC BY · original observation Used on Mallard
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  Anas platyrhynchos Photograph by Gavin Slater · CC BY · original observation
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  Anas platyrhynchos Photograph by euqirneto · CC BY · original observation
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  Anas platyrhynchos Photograph by Jan Ebr & Ivana Ebrová · CC BY · original observation
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  Anas platyrhynchos No rights reserved · CC0 · public domain · original observation
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  Anas platyrhynchos Photograph by Andrew Skotnicki · CC BY · original observation
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  Anas platyrhynchos Photograph by Philip Schaffer · CC BY · original observation
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  Anas platyrhynchos Photograph by Bobo-X · CC BY · original observation
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  Anas platyrhynchos Photograph by Joss Carr · CC BY · original observation
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  Anas platyrhynchos Photograph by Patrick Hacker · CC BY · original observation
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  Anas platyrhynchos Photograph by Liva Erkul · CC BY · original observation
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  Anas platyrhynchos Photograph by Sabarni Sarker · CC BY · original observation
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  Anas platyrhynchos Photograph by David Kleuker · CC BY · original observation
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  Anas platyrhynchos Photograph by Philip Schaffer · CC BY · original observation
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  Anas platyrhynchos × acuta Photograph by Diego González Dopico · CC BY · original observation
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  Anas platyrhynchos × Mareca strepera Photograph by Nodnarb Nedloh · CC BY-SA · original observation
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  Anas platyrhynchos conboschas Photograph by Nathan Earley · CC BY · original observation
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  Anas platyrhynchos domesticus Photograph by Codrin Bucur · CC BY · original observation
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  Anas platyrhynchos domesticus No rights reserved · CC0 · public domain · original observation
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  Anas rubripes Photograph by Mark Apgar · CC BY · original observation Used on American Black Duck
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  Aquila adalberti Photograph by Jan Ebr & Ivana Ebrová · CC BY · original observation Used on Spanish Imperial Eagle
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  Balaenoptera acutorostrata Photograph by Nils · CC BY · original observation Used on Minke Whale
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  Sunrise over farmland, Lüdinghausen Photograph by Dietmar Rabich · CC BY-SA · file page
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  Bradornis microrhynchus Photograph by Caroline Quinn · CC BY · original observation Used on African Grey Flycatcher
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  Buteo buteo buteo Photograph by Codrin Bucur · CC BY · original observation Used on Common Buzzard
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  Buteo buteo vulpinus Photograph by Mark Liptrot · CC BY-SA · original observation Used on Steppe Buzzard
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  Buteo jamaicensis Photograph by Brooke J. · CC BY · original observation Used on Red-tailed Hawk
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  Calidris pygmaea Photograph by Jason Alexander · CC BY · original observation Used on Spoon-billed Sandpiper
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  Calidris ruficollis Photograph by Andrew Bazdyrev · CC BY · original observation Used on Red-necked Stint
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  Calidris tenuirostris Photograph by white_cheeked_barbet · CC BY · original observation
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  Calidris tenuirostris Photograph by pimelea · CC BY · original observation
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  Camarhynchus heliobates Photograph by Michael Dvorak · CC BY 2.5 · file page Used on Mangrove Finch
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  Chroicocephalus genei Photograph by Christoph Moning · CC BY · original observation Used on Slender-billed Gull
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  Chroicocephalus ridibundus Photograph by Christoph Moning · CC BY · original observation Used on Black-headed Gull
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  Ciconia boyciana Photograph by Jason Alexander · CC BY · original observation Used on Oriental Stork
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  Ciconia nigra Photograph by Zinogre · CC BY-SA · original observation Used on Black Stork
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  Circus cyaneus Photograph by Griha Hasanov · CC BY · original observation Used on Hen Harrier
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  Corvus splendens Photograph by Miguel · CC BY-SA · original observation Used on House Crow
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  Coturnix coturnix No rights reserved · CC0 · public domain · original observation Used on Common Quail
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  Cuculus solitarius Photograph by Brian du Preez · CC BY-SA · original observation Used on Red-chested Cuckoo
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  Ectopistes migratorius Photograph by John G. Hubbard · public domain · file page Used on Passenger Pigeon
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  Elanus caeruleus Photograph by 雲一百香果 · CC BY · original observation Used on Black-winged Kite
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  Emberiza calandra Photograph by Людмила Алимова · CC BY · original observation Used on Corn Bunting
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  Emberiza jankowskii Photograph by Mikael Bauer · CC BY · original observation Used on Jankowski's Bunting
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  Falco punctatus Photograph by Josh Noseworthy · CC BY · original observation Used on Mauritius Kestrel
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  Hasankeyf on the Tigris, before the dam Photograph by Hamdigumus · CC0 · public domain · file page
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  Heteromirafra archeri Photograph by Forest Botial-Jarvis · CC BY · original observation Used on Liben Lark
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  Hirundo rustica rustica Photograph by Donald Davesne · CC BY · original observation Used on Barn Swallow
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  Starlings over the north pier Photograph by Tony Hisgett · CC BY 2.0 · file page
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  Ichthyaetus melanocephalus No rights reserved · CC0 · public domain · original observation Used on Mediterranean Gull
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  Moorland in the Aberdare range, Kenya Photograph by Nina R · CC BY 2.0 · file page
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  Larus canus No rights reserved · CC0 · public domain · original observation Used on Common Gull
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  Larus canus kamtschatschensis Photograph by Ryan F. Mandelbaum · CC BY · original observation Used on Kamchatka Gull
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  Lasioglossum calceatum Photograph by Brenda Black · CC BY · original observation Used on Furrow Bee
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  Lybius leucocephalus Photograph by William Stephens · CC BY · original observation Used on White-headed Barbet
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  Macronyx sharpei Photograph by Adrien Jailloux · CC BY · original observation Used on Sharpe's Longclaw
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  Melanocorypha calandra Photograph by SIA · CC BY · original observation Used on Calandra Lark
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  Meles meles Photograph by Ewan Shilland · CC BY · original observation Used on European Badger
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  Mergus squamatus No rights reserved · CC0 · public domain · original observation Used on Scaly-sided Merganser
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  Merops pusillus meridionalis Photograph by Sunčana Bradley · CC BY · original observation Used on Little Bee-eater
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  Motacilla alba Photograph by Ani Sarkisyan · CC BY · original observation
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  Neophron percnopterus No rights reserved · CC0 · public domain · original observation Used on Egyptian Vulture
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  Nesoenas mayeri Photograph by alanbedfordshaw · CC BY-SA · original observation Used on Pink Pigeon
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  Otis tarda Photograph by Shane Austin · CC BY · original observation Used on Great Bustard
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  Otus scops Photograph by Diego González Dopico · CC BY · original observation Used on Scops Owl
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  Oxyura leucocephala Photograph by Andrew Bazdyrev · CC BY · original observation Used on White-headed Duck
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  Panthera leo melanochaita Photograph by David Knox · CC BY-SA · original observation Used on Lion
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  Pelecanus crispus Photograph by David F. Belmonte · CC BY · original observation Used on Dalmatian Pelican
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  Perdix perdix Photograph by Julia Moning · CC BY · original observation Used on Grey Partridge
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  Platalea minor Photograph by 高山田鼠 · CC BY · original observation Used on Black-faced Spoonbill
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  Prunella montanella Photograph by Nigel Voaden · CC BY · original observation Used on Siberian Accentor
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  Psittacula eques Photograph by Matthew Morgan · CC BY · original observation Used on Echo Parakeet
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  Psittacus erithacus Photograph by Daniel Onneweer · CC BY · original observation Used on Grey Parrot
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  Pterodroma cahow No rights reserved · CC0 · public domain · original observation Used on Bermuda Petrel
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  Rallus aquaticus Photograph by egorbirder · CC BY · original observation
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  Saundersilarus saundersi Photograph by 林孫鋒(Lin Sun Fong) · CC BY-SA · original observation
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  Intertidal flats at Juist Photograph by Dietmar Rabich · CC BY-SA · file page
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  Reedbed at dawn, De Kleine Wielen Photograph by Dominicus Johannes Bergsma · CC BY-SA · file page
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  Birdwatchers with telescopes Photograph by King of Hearts · CC BY-SA · file page
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  A track past Heathery Howes Photograph by Bill Boaden · CC BY-SA 2.0 · file page
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  Books in a stack No rights reserved · CC0 · public domain · file page
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  Redwood forest interior, Muir Woods Photograph by Dale Cruse · CC BY · file page
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  Streptopelia turtur Photograph by Mourad Harzallah · CC BY · original observation Used on Turtle Dove
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  Tauraco hartlaubi Photograph by desertnaturalist · CC BY · original observation Used on Hartlaub's Turaco
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  Tetrax tetrax Photograph by Антон Лабачоў · CC BY · original observation Used on Little Bustard
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  Thalasseus bengalensis Photograph by Afsar Nayakkan · CC BY · original observation Used on Lesser Crested Tern
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  Todus mexicanus Photograph by Thibaud Aronson · CC BY-SA · original observation Used on Puerto Rican Tody
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  Uria lomvia Photograph by Christoph Moning · CC BY · original observation Used on Brünnich's Guillemot