Heuglini 2cy, March 03 2001, Bahrain: Ashkar landfill. 

Advanced moult in the coverts and tertials, much streaking on the head and under parts favour heuglini. A gentle gull with a slender bill, resembling cachinnans.

In Bahrain, such birds with almost parallel bills are either cachinnans or heuglini. Cachinnans, being a southern breeder from the steppe belt, normally doesn't show such fresh looking, dark brown centred juvenile feathers (note the central greater coverts) and cachinnans normally doesn't show active post-juvenile moult in February. Moreover, most cachinnans have finished their post-juvenile moult by early November as 1cy birds. Hence, active post-juvenile moult in February in 2cy birds is a strong indicator for nortern breeders from the tundra region, i.e. heuglini and fuscus in Bahrain.

By July, when some of these birds return to N Europe, the wing-coverts will appear worn and they show just a simple arrow-pattern.