NOTES A useful field-character of the Icterine Warbler. — Icterine Warblers ( icterina) were watched at Fair Isle, and identification confirmed by trapping- and examination of the wing- formula, on 30th May and 9th September 1954. The purpose of this note is to draw attention to a useful distinguishing characteristic which is not mentioned under the heading "Field- characters" in The Handbook (vol. II, pp. 61-62) or other recent -identification guides. The spring specimen was bright greenish-olive above and exceedingly yellow beneath, and perhaps likely to be confused with a Wood Warbler (Phylloscopus sibilatrix) on a poor view. The autumn example trapped on 9th September, and an apparently identical bird watched for some time at close quarters on 7th and 8th, were much duller above and only very pale yellowish beneath: in indifferent light they could easily have been confused with a (Sylvia borin). The best field-mark at both seasons was afforded by a light patch in the closed wing, pale golden-yellow in the spring bird and off-white in the autumn examples, which made a sharp contrast with the dark brown flight-feathers. This patch is caused by the overlapping pale fringes of the secondaries, and creates a wing-pattern which at once precludes confusion with any Sylvia or Phylloscopus species. Although this character does not appear to have been recorded, I may point out that the pale wing-patch is clearly visible in the excellent photographs of the Icterine Warbler taken by Eric Hosking and Ian M. Thomson and published antea, vol. xlvii, plates 21 and 25. An important point is whether or not this pale area in mid-wing will serve to separate the Icterine from the (Hippolais polyglotta), since The Handbook and other authorities regard the two as virtually indistinguishable. The coloured plates by G. J. Keulemans in H. E. Dresser's of (vol. II, plates 80 and 81) depict this feature quite clearly in the Icterine, but show a uniformly brown wing in the Melodious. Skins I have examined suggest that the fringes of the secondary feathers are at best somewhat obscure in the Melodious, and in fact one with a prominent wing-patch labelled H. polyglotta proved to be icterina when I checked the wing-formula. The only Melodious Warbler I have examined in life was trapped at Fair Isle on 16th September 1955 (see pp. 94-96), and all who saw it in the field agreed that there was no suggestion of a wing-patch in this bird. I have had correspondence with other bird observatory personnel on this problem, and their experience supports my own in so far as the Melodious Warbler is concerned, though some of the observa­ tions on the Icterine are indefinite. Roy Thearle (Bardsey Island)

119 120 BRITISH BIRDS [VOL. XLIX says no light wing-patch was seen in Melodious Warblers trapped in autumn 1954 and 1955, though field-observation of these birds was not possible; and R. F. Ruttledge (Great Saltee) informs me that no relevant observation is to be found in the laboratory records for a Melodious trapped in 1954 and two Icterines captured on 24th August 1955. He himself watched the Melodious Warbler closely in the field, but has no note or recollection of a pale wing-patch. John Ash (Portland Bill) writes: "The last Icterine I saw was a migrant in September in Sweden several years ago. In my notes on this bird there is one passage which may be relevant: . . . a fairly conspicuous pale patch on each closed wing is apparently formed by the pale margins to the primaries and secondaries: is this a good field-character? So far as the Melodious is concerned, I examined a bird trapped at Portland on 4th September 1954, but did not see it in the field. In the laboratory description there is no mention of any pale edgings to primaries or secondaries. A Hippolais warbler watched at the same place in the field on 19th September 1954 by myself and many others was probably polyglotta too. In the somewhat detailed description of this bird there is no mention of pale edgings to wing-feathers". Thus, on the evidence at present available, it would appear that the pale wing-patch in the Icterine Warbler may well be diagnostic, and a safe field distinction between this and the closely-allied Melodious Warbler. It would be of great value if final proof of this could be obtained, and it is hoped that other observers—and particularly those who are engaged in bird observatory work— will follow up this note by giving the matter their close attention. KENNETH WILLIAMSON