Heuglin's Gull (L. heuglini / antelius)

(last update: 6-3-2011)

3cy heuglini: May

General description of 3cy heuglini in April-May in Finland

Under-parts & Head: By April, most birds are immaculate white on the under-parts (HERE), but some delicate black pencil-streaks can be visible in the hind-neck (HERE). Birds with obvious brown on under-parts and in wing-coverts may appear surprisingly white on the under-wing (HERE).

Bare parts: Legs yellow to pale yellow, only flesh-coloured pink in a small minority of birds. Bill normally 4-coloured: yellow bill-base, black band, red gonydeal spot and whitish tip of bill. Iris speckling very variable, including birds with completely dark irides.

Scapulars and wing-coverts: In standing, resting birds, the upper-parts appear adult-like in many birds, with most of the scapulars and a large number of wing-coverts replaced for grey feathers (HERE). Feathers with brown patterns can normally be found in the outer greater coverts and the lesser coverts in the carpal edge (HERE).

Rectrices: Vestiges of black in some tail-feathers (HERE), but tail completely white in several birds.

Secondaries: Variable number of 3rd gen, adult-like secondaries. Normal pattern on 2nd gen secondaries is a broad blackish centre with a white tip (HERE & HERE). Third gen secondaries are normally very adult-like, the centre grey with a white tip (HERE). Some early acquired 3rd gen secondaries may show some vermiculation.

Primaries: No primary moult in April. Due to the variable number of primaries replaced in first winter, birds are very hard to score on exact primary generations. To do such scoring accurately, we should follow ringed birds individually, and even when this is possible, the distance between breeding grounds and winter quarters very much prevent adequate data collection. Nominate fuscus probably is a taxon with many birds colour-ringed and they demonstrate the difficulties for following individual birds and subsequent problems to build up a solid concept of the variation in primary moult stages we see in 3cy birds in spring.
Birds with a graellsii-like moult strategy (type 1 birds; see 2cy May & 2cy June) normally have all primaries typical 2nd generation, as illustrated by THIS & THIS bird. Again, as stated earlier for heuglini, the variation in loci involved in 3rd gen primaries seems endless (HERE, HERE & HERE).