Heuglin's Gull (L. heuglini / antelius)

(last update: 6-3-2011)

4cy / sub-adult heuglini: February

General description of sub-adult heuglini in February-March in Bahrain

Upper-parts in 4cy heuglini: the scapulars and mantle feathers are adult-like grey. Some brown wash on the greater coverts (especially in the outer greater coverts) or lesser coverts (in the carpal edge) may be present.

Primaries: primary moult completed or last primaries to be moulted. Fresh black, with small white tips and with only a small mirror on P10 in 4cy winter heuglini. In birds that show immature features, the primaries may appear very much adult-like.

Secondaries: if different generation of secondaries are easily recognised, birds are probably in second winter plumage, not in third winter.

Tail: white. If there are still black markings in the tail, it is hard to fully exclude second winter birds in February-March; moreover as heuglini can have very advanced moult already in first winter. We did not come across enough birds in Bahrein to get in-depth insight in the variation of the tail pattern in sub-adult heuglini.

Legs: yellow to pale yellow. Occasionally also flesh-coloured or pink.

Head shape is not rounded and pigeon-like as in many (female) barabensis, rather square or blocky, with a sloped forehead which smoothly continues onto the bill, reminiscent of cachinnans. The thumbprint in front of the eye (common in barabensis) is not obvious in heuglini, the facial expression is dominated by the strong eyebrown, creating a rather vicious look, not unlike West-European Herring Gulls.

Most 4cy birds have a white head with only limited delicate neat streaking, concentrated in the lower neck, on some running down to the sides of the breast and over most the area behind and above the eye. The bill is yellow or pink-based with an obvious black bill-band. Often there is some red at the gonydeal angle, but this can be largely obscured by the black markings. Iris is brown-yellow to green or amber.

Sub-adult heuglini in third winter normally show a plumage very much similar to adult birds. A variable number of immature features may still be possible, but best clue to age this group probably is the presence of broad dark centres of the greater primary coverts. Small, sharply defined centres on slate grey feathers probably is possible in full adults as well, but when the centres are broad brownish-black and the tips of these greater primary coverts are pale whitish, this may be good indication for 3cy birds. Furthermore, black may still be apparent in the rectrices, some brown wash may be vsible on some wing-coverts and the bill-band may be obviously broad in third winter birds.