Mystery photographs JQ A medium-sized or largish • O wader is wading at the edge of a pool. Knowing that almost any species could occur, the first thoughts are aimed at identifying the genus or group of species. The size and relatively long straightish bill instantly indicates the larger Tringa species—Greenshank T. nebularia, Spotted Redshank T. erythropus or Greater Yellowlegs T. melanoleuca—or the godwits Limosa. The Tringa species have a distinctive feeding action which has its basis in the detection of food by sight. The bill is therefore fine or tapered to a point. This bird's bill has a fairly broad terminal third, and even its tip is slightly rounded, leading one towards the godwits, which probe into mud. The distinctive leg colours of Tringa species are a useful further distinction from godwits, but this cannot be used here. It is often important to attempt to determine the age of waders in the field, because diagnosis of the age of an individual wader can greatly aid the identification process for some difficult pairs or groups of species. In this case, the general freshness and neat uniform patterning of the coverts and scapulars clearly indicate juvenile plumage. On this bird, there is very little stongly contrasting white or grey on its underparts, and the coverts and scapulars have broad, pale notches and edges (rather than a neat pattern of pale spots): these are clear features of a juvenile godwit rather than a juvenile Tringa. The most useful points for distinguishing between standing Bar-tailed L. lapponica and Black-tailed Godwits L. limosa (when the totally diagnostic 281. Adult winter Bar-tailed Godwit Limosa lapponica, Cork, winter 1974 (Richard T. Mills) 579 580 Mystery photographs wing- and tail-patterns cannot be seen) are bill shape, the proportionately longer legs of Black-tailed (especially the distance between the 'knee' and the body), the upper breast and neck pattern, and (on juveniles only) the covert and scapular markings. Here, the bill is long, but not disproportionately so, and is slightly but clearly upturned. Fine dark streaks abound on the pale background of the upper breast and neck; and the broad pale notches and edges on the coverts and scapulars (giving a pattern recalling that of a Curlew Numenius arquata) lead one straight to the Bar-tailed Godwit. The barred outer tail feather showing beneath the wing-tip also confirms the identification. The bill of Black-tailed Godwit is straight and longer, the breast and neck virtually unstreaked (cinnamon on juveniles or grey in winter), and on juveniles the more uniformly fringed coverts and scapulars give a neat scaly pattern recalling that of a juvenile Ruff Philomachus pugnax. The original photograph (plate 273, repeated here at reduced size), taken by Dr K. J. Carlson in Suffolk in September 1979, shows a juvenile Bar-tailed Godwit. Juveniles have the striking covert and scapular pattern, while in the adult non-breeding plumage (plate 281) these feathers grade relatively evenly from a dark centre to pale edges. Like other waders, juvenile head and body feathers are replaced by first-winter plumage in a moult during the first autumn: first-winter birds are ageable until at least January by the retained scaly juvenile wing-coverts. A. J. PRATER 282. Mystery photograph 49. Name the species. Answer next month .