Caspian Gull, Steppe Gull, Heuglin's Gull and Baltic Gull

From The UAE Checklist:
Caspian Gull Larus cachinnans
Uncommon to possibly locally fairly common passage migrant and winter visitor.
Confusion with Steppe Gull evident.


Lesser Black-backed Gull complex
- Baltic Gull Larus fuscus fuscus
Rare passage migrant, September to October, return February to April; rarely other months.

 

- Heuglin’s Gull Larus fuscus heuglini
Common or locally common passage migrant and winter visitor; absent or rare June to August.

 

- Steppe Gull Larus fuscus barabensis
Common to very common passage migrant and winter visitor; also recorded in the summer.

Reports of L. f. taimyrensis so far unsubstantiated.

 

Check out this blog by Chris Gibbins

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From the excellent 'Birds of the Middle East' app for iPhone & Android:

Caspian Gull (adult):

The palest of the large gulls in the UAE, as pale as an European Herring Gull.
White mirrors on P10 and P9.

Has the most white in wing-tips, with a large white tongue on the inner web of P10 (outermost primary); often with large all-white tip.
Black wingtip extends strongly to P5.

Grey tongues protrude fairly deep into more restricted black on primaries.

Underside of flight feathers grey against grey coverts.
Flat forehead can be diagnostic, with an angular rear crown.

 

Adult winter with seemingly unstreaked head; very discreet streaking around eye and on crown at very close range. Steppe Gull with streaking to February.

Eyes: 75% of birds with a dark 'bullet-hole' eye. 25% of birds with pale eyes.

Adult winter; bill with red spot restricted to lower mandible, can have small black subterminal band, esp. on upper mandible

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Steppe Gull (adult):

Identification features from Caspian and pale Heuglin's Gulls not fully established.

Darker grey than Caspian, slightly paler than Heuglin's.
White mirrors on P10 and P9.

Grey tongues protrude less deep into the black on primaries compared to Caspian Gull, but deeper than Heuglin's.

Underside of flight feathers grey against white coverts, similar to Heuglin's and Armenian.

Rounded head compared to the flatter forehead of Caspian Gull.

Adult winter with streaking on head and neck to February.

Eyes: Usually dark; birds wintering in the Arabian Gulf often with pale eyes.

Adult winter; bill apparently with red spot on lower mandible, can have thin black band.

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Heuglin's Gull (adult):
Upperwing can range from very dark, almost Baltic-like, to paler grey, approaching Steppe Gull.

White mirror on P10, sometimes also on P9.
 

Adult winter with bold streaking on head and neck to early April.

Eyes: pale.

Adult winter; bill apparently with red spot on lower mandible, can have small black smudge.

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Baltic Gull (adult):

Smallest of the group, slim and long-winged.

Little or no contrast in upperside of wing and primaries, but can wear greyer.

Small white mirror on P10, sometimes also on P9.

Adult winter with sparse streaking on head and neck in winter.

Eyes: pale.

Adult winter; bill ....?

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Armenian Gull (adult)
Not recorded in the UAE. Closest to Yellow-legged Gull, also confusable with Steppe Gull.

Large squared-off black primary area, with little or no grey tongues.

White mirror on P10, sometimes a small mirror on P9.

Adult winter with sparse streaking on hind-neck.

Eyes: iris colour varies from completely pale (14%), to predominantly dark (44%) with all kinds of intermediate stages.

The orbital ring was orange-red in all birds.

Adult winter; bill short and stubby-looking (longer in males), with prominent black subterminal band, band sometimes retained when breeding.

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