Second-year Southern Atlantic Yellow-legged Gulls - Southern atlantis
In late July and August, when the birds are about one year old, their appearance is very variable.
Compared to juveniles the body is generally a much cleaner white with much reduced breast and belly streaking. However, some retain quite extensive streaking on the sides of the breast and the belly. The heads retain a conspicuous eye-spot but the head as a whole is usually whiter. Some show extensive streaking on the lower neck and around the back of the neck and spots on the nape and sides of the head. The outer primaries are a conspicuous dark brown-black, showing a much greater contrast with the scapulars and back that are beginning to show the adult grey colour.
The inner wing shows a pronounced secondary bar but the greater coverts bar is rarely obvious. The pale window on the inner primaries is obvious and the tail and upper rump are a bright white, virtually devoid of mottling, with a neat dark subterminal tail band. At rest the mantle looks a rather uniform mixture of brown and grey with few obvious spots on the greater coverts. The underwing also shows a tendency to a greater uniformity with the underwing coverts rarely being obvious. The bill varies from still being almost completely black to having a pale pink-yellow base extending one-quarter of the bill length. The legs are rarely bright pink, often being a darkish straw colour or a creamy colour.
In late September the bills nearly always show a pale base extending 1/3 to 1/4 of the length of the bill; the legs are also mostly a straw colour now with few remaining flesh coloured.
By late March and April they are more advanced particularly in the bare parts. Most by now have a pale area on the bill extending to 2/3 of its total length and most have some yellow in the legs. The general appearance in flight is of contrast with the dark brown-black outer primaries, secondary bar and narrow carpal bar looking very dark compared to the grey scapulars, back, lesser and median coverts and inner primaries. The greater coverts are often weakly mottled, the underwing coverts are much faded and the head is paler.
The more retarded individuals still show extensive mottling on the lesser and median coverts, a solid subterminal tail band, a small pink-yellow base to the bill, pink-yellow legs and some residual streaks on the head and neck.
The more advanced individuals have white heads, necks and bodies. Their bills are almost adult, except for a black mark on the upper mandible above the red gonydeal spot and their legs are a clear ochre that in some individuals can look quite pale and in others quite dark. Their subterminal tail bands are beginning to break up, looking sparsely mottled rather than solid. At rest though the advanced birds still show some mottling on the coverts and a prominent secondary bar. Such birds can look almost adult when perched but in flight their immature status is very obvious with the striking brown-black areas on the wing.
In May advanced individuals show pale yellow bills with no black near tip, bright pale ochre legs, a diffuse tail band and a deep blue-grey mantle. The coverts remain mottled and the most obvious dark areas are the outer primaries and the secondary and carpal bars. Retarded individuals still show black on the terminal quarter of the bill, a less obviously clear mantle, more mottling throughout the wings and a solid tail band.
Primary moult has not yet started in April or May indicating that the timing is similar to that for adults.
Ageing of large gulls is not a precise subject particularly for immatures that are in their third- and fourth-years. It is possible that some of the putative advanced second-year birds are in reality retarded third-years.
The identification of second-years is likely to remain problematical with size, structure and mantle shade perhaps being the best indicators.
Second-years of other forms
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© Copyright Nick Rossiter 2001.
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