Steppe Gull versus Caspian Gull, and a look at Heuglin's 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 June to August.
- Steppe Gull Larus fuscus barabensis
Common to very common passage migrant and winter visitor.
Reports of L. f. taimyrensis unsubstantiated.
Check out this blog by Chris Gibbins