>> GENERAL >>>>>
Please note: esp. immature large gulls are notoriously difficult to ID due to very variable plumage features and frequent hybridisation with other Larus sp.
– large gull, about the size of European Herring Gull
– probably mainly diurnal migrant
– migrates singly or in small flocks in formation
– long-range dispersal of juveniles
>> VISUAL ID >>>>>
Caspian Gull Larus cachinnans, 1CY/1W
BIF3218, 16/08/2012, Baltic Sea, Mathias Putze
– classic 1CY bird in August
– minimally marked upper tail coverts and base of rectrices strongly contrasting to broad dark terminal band
– diffuse/crinkled inner primary coverts
– velvety lightened inner primaries
– when moulting into 1W cachinnans features become more obvious
Caspian Gull Larus cachinnans, 1CY/1W
BIF3405, 16/08/2012, Baltic Sea, Mathias Putze
– in 1W plumage body feather markings limited to flanks and neck (hindneck-markings) -> BIF3182
– usually light underwing coverts
– undertail coverts predominantly clean white with dark tips
– flat forehead, high positioned, small looking eye, long parallel-edged bill
– ‘drooping belly’
Caspian Gull Larus cachinnans, 1CY/1W
BIF3409, 03/11/2018, Besh Barmag, Azerbaijan, Michael Heiß
– classic eastern 1st winter bird
– remiges and tail, as well as wing coverts 1st generation
– mantle and some wing coverts renewed, grey, with shaft-streak and ‘diamond pattern’
– brightened inner primaries
– pure white head sharply contrasting to patterned hindneck
Caspian Gull Larus cachinnans, 1CY/1W
Lesser Black-backed Gull Larus fuscus ssp., 2CY/2W
BIF3475, 12/10/2020, North Sea, Patrick Franke
– brightened inner primaries compare with 2CY Lesser Black-backed Gull
– appears rather long-winged
– light underwing
– striking white head
Caspian Gull Larus cachinnans, 2CY/1W
BIF3223, 19/04/2010, Baltic Sea, Mathias Putze
– classic 1st winter bird
– remiges and tail, as well as wing coverts 1st generation
– mantle mostly renewed, unmarked grey, single shaft streaks
– remains of the diffuse pattern of the inner primary coverts
Caspian Gull Larus cachinnans, 2CY/1W
BIF3220, 19/04/2010, Baltic Sea, Mathias Putze
– classic 1st winter bird
– hindneck-markings, pure white head, belly, flanks and rump
– tail with broad black terminal band, contrasting to the rest of the colouration
– comparatively light underwing
– uniform dark, long an fairly pointed bill
– eye appears small, bright white ‘eyelids’
Caspian Gull Larus cachinnans, 2CY/2W
BIF3227, 15/11/2011, North Sea Sea, Mathias Putze
– wing and tail 2nd generation with rounded tips and white terminal band, respectively
– mantle and wing coverts 2nd, partly 3rd generation
– hindneck-markings, pure white head, belly, flanks and rump
– contrasting broad black terminal band in tail
– light inner primaries ‘window’ more pronounced than in 1W with light areas and layered pattern
Caspian Gull Larus cachinnans, 2CY/2W
BIF3221, 15/11/2011, North Sea, Mathias Putze
– 2nd generation plumage, but relatively scuffed (note outer primaries and primary coverts)
– first single 3rd generation lesser coverts and median coverts grey
– long, parallel-edged, pointed bill with noticeable brightening of the base of bill
Caspian Gull Larus cachinnans, 2CY/2W
BIF3225, 15/11/2011, North Sea, Mathias Putze
– almost completely white underwing coverts
– fairly sharp contrasting neck and flank markings
– still rather dark bill
Caspian Gull Larus cachinnans, 2CY/2W
BIF3229, 03/11/2011, Saxony, Germany, Mathias Putze
– wing and tail 2nd generation with rounded tips, note mirror on P10 (left)
– pretty advanced individual
– bill unusually pale with dark band
– still distinctly marked underwing primary coverts
Caspian Gull Larus cachinnans, 2CY/2W
BIF3478, 09/10/2020, North Sea, Patrick Franke
– note subterminal spot on P10 (left)
– almost all-white underwing coverts
– brightening of the base of bill
– striking hindneck-markings
Caspian Gull Larus cachinnans, 2CY/2W
BIF3480, 09/10/2020, North Sea, Patrick Franke
Caspian Gull Larus cachinnans, 3CY/2W
BIF3222, 04/05/2010, North Sea, Mathias Putze
– classic late winter 2W bird
– mainly pure white body with markings restricted to hindneck
– brighting of the bill advanced
Caspian Gull Larus cachinnans, 3CY/2W
BIF3219, 04/05/2010, North Sea, Mathias Putze
– 2nd generation remiges, coverts and tail, worn off
– some 2nd generation primary coverts missing, mantle feathers with delicate shaft streaks
– light areas and layered texture on the inner primaries
– long, parallel-edged, pointed bill (‘brush tip’) with noticeable brightening of the base of bill
Caspian Gull Larus cachinnans, 3CY/3W
BIF3231, 18/11/2011, North Sea, Mathias Putze
– classic 3CY/3rd winter bird
– wing and tail 3rd generation with rounded tips
– black comma on P4 outer web
– note mirrors on P9/10
– small terminal spots and white trailing edge to the inner wing
– mantle and wing coverts predominantly 3rd generation, grey, adult like
– hindneck-markings, pure white head, belly, flanks and rump
– tail with vestigial black terminal band
– bill pale greenish yellow with dark subterminal band
Caspian Gull Larus cachinnans, 3CY/3W
BIF3233, 03/11/2011, Saxony, Germany, Mathias Putze
– advanced moult compared to BIF 3231 (appears SUBAD except for the tail)
– remiges and tail 3rd generation, with rounded tips
– black comma on P4 outer web
– note very large, sharply defined mirrors on P9/10
– all mantle and most wing coverts adult-like, single dark primary coverts
Caspian Gull Larus cachinnans, 3CY/3W
BIF3232, 03/11/2011, Saxony, Germany, Mathias Putze
– almost like an adult but note the black tail subterminal band
– underwing coverts usually pure white at this age
Caspian Gull Larus cachinnans, 3CY/3W
BIF3234, 03/11/2011, Saxony, Germany, Mathias Putze
– easily mistaken for an adult but note weak subterminal band in tail
Caspian Gull Larus cachinnans, AD BREED
BIF3236, 08/11/2009, North Sea, Mathias Putze
– P10 with completely white tip not yet fully grown
– continuous black subterminal band on P5
– P4 with black comma on outer web
– pure white head, small dark eye, red orbital ring
– comparatively delicate, parallel-edged, greenish yellow bill with pale red gonys
– flat back
Caspian Gull Larus cachinnans, AD BREED
BIF3239, 02/11/2011, Saxony, Germany, Mathias Putze
– possible hybrid cachinnans_X_argentatus
– appears long-winged with ‘drooping belly’
– fairly little black in ‘hand’
– black comma on P5 outer web only
– grey tongues on inner web of outer primaries
– unusually bulky bill with relatively pronounced gonys
Caspian Gull Larus cachinnans, AD NBREED
BIF3235, 08/11/2009, North Sea, Mathias Putze
– pure white head, in winter plumage with some hindneck-markings
– pale red gonys with dark speckles
Caspian Gull Larus cachinnans, AD NBREED
BIF3238, 02/11/2011, Saxony, Germany, Mathias Putze
– classic bird
– ‘drooping belly’
Caspian Gull Larus cachinnans, AD NBREED
BIF3237, 21/08/2010, Baltic Sea, Mathias Putze
– active moult in remiges
– P10/9 old, worn with grey tongues on inner web
– P8/7 missing, P6 growing, P5-1 fresh
– small dark eye, bright white ‘eyelids’
– pale red gonys with dark speckles
Caspian Gull Larus cachinnans, AD NBREED
BIF3410, 03/11/2018, Besh Barmag, Azerbaijan, Michael Heiß
– eastern bird
– typical primary pattern, P10/9 still growing
Caspian Gull Larus cachinnans, AD NBREED
Black-headed Gull Chroicocephalus ridibundus, AD, 1CY
BIF3232, 31/10/2017, Kühlungsborn, Germany, Roland Neumann
– classic adult bird
Caspian Gull Larus cachinnans, AD
Pallas’s Gull Ichthyaetus ichthyaetus, AD BREED
Black-headed Gull Chroicocephalus ridibundus, AD
BIF3404, 16/03/2012, Besh Barmag, Azerbaijan, Michael Heiß
Caspian Gull X Herring Gull Larus cachinnans-x-argentatus (probably), 1CY/1W
BIF3183, 20/08/2010, Baltic Sea, Mathias Putze
cachinnans-features:
– compact, small-headed
– slightly contrasting light head with rather long bill
– comparatively dark inner primaries, lightened only on inner vains
argentatus-features:
– fairly strong patterned bases of rectrices and uppertail coverts
– rather strong bill
Caspian Gull X Herring Gull Larus cachinnans-x-argentatus (probably), 1CY/JUV (same as BIF3183)
BIF3182, 20/08/2010, Baltic Sea, Mathias Putze
cachinnans-features:
– solid, evenly broad dark terminal band in tail
– flat forehead
argentatus-features:
– dark underwing
– strongly marked undertail coverts
>> ACOUSTIC ID >>>>>
– no particular flight calls
– sometimes some chatting especially during nocturnal flights or near man-made structures
>> COMPARISON SPECIES >>>>>
Pallas’s Gull
Common Gull
Ring-billed Gull
Cape Gull
Lesser Black-backed Gull
Baltic Gull
Heuglin’s Gull
Steppe Gull
European Herring Gull
Armenian Gull
Yellow-legged Gull
Vega Gull
American Herring Gull
Thayer’s Gull
Iceland Gull
Slaty-backed Gull
Glaucous-winged Gull
Glaucous Gull
Great Black-backed Gull
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