Two-barred Greenish Warbler' on Scilly: new to Britain and Ireland Colin Bradshaw he fact that October 1987 was a Blyth's Reed Warbler Acrocephalus dume- 'classic Scilly October' was scant torum near my home inTynemouth.Tyne & Tcomfort to me, since I had arrived on Wear, on the day that I arrived on the islands. the Isles of Scilly just too late to see both a On 22nd October, a drab Yellow-browed Philadelphia Vireo Vireo philadelphicus and Warbler Phylloscopus inornatus was a Hermit Thrush Catharus guttatus. To add reported on Gugh (the small island to the insult to injury, my friends had trapped a east of St Agnes, accessible by a causeway at low tide), and, on the fol­ lowing day, my father,Tom, and I went there to look for migrants. We had covered most of the moor on the south side of the island, and were coming back to the central fields when we saw a small Phylloscopus warbler, flicking through the brambles Rubus along the southern edge of the fields. We watched it for several minutes, and were Cottridge completely perplexed. It looked superficially like a David Yellow-browed Warbler, with 167 & 168. Greenish Warbler Phylloscopus trocbiloides of the race an obvious supercilium and plumbeitarsus ('Two-barred Greenish Warbler'), Gugh, Scilly, two wing-bars, including a October 1987. broad greater-covert bar. It showed no sign of any pale tertial edges, however, and it had dark legs, and a pale bill which we thought may have been slightly larger than that of a Yellow-browed Warbler. We discussed whether it could be an adult Yellow-browed, perhaps with the pale tertial fringes worn away, since neither of us was aware of the moult strategy of that species, but we were still at a loss to explain the bare-part col­ Cottridge oration. In addition, it seemed to have a longer tail than we David 284 British Birds 94:284-288, June 2001 Bradshaw: Two-barred Greenish Warbler on Scilly expected. We took full notes and retreated Upperparts The mantle and rump were olive- back to St Agnes. green, slightly greyer than the crown. The wings While we were away, pandemonium had were generally of a similar colour, but without the broken out on St Agnes, with a Booted grey cast. There were bright green edges to the secondaries and tertials, while the primaries were Warbler Hippolais caligata, a Red-rumped dark, with bright edges on the proximal two- Swallow Hirundo daurica, and a strange thirds. The median coverts were tipped white, Rufous Nightingale Luscinia megarhynchos forming an indistinct wing-bar that was more near the Post Office (Bradshaw 1996). Never­ obvious on the left wing.The greater coverts were theless, I collared Alan Dean, John Ridley and dark-centred, with broad green fringes, and with Pete Lansdown to talk through the warbler broad, square, creamy tips forming an obvious, which we had just seen on Gugh. We were wide wing-bar that reached right across the whole soon able to eliminate aberrant Yellow- width of the greater coverts. There were bright browed Warbler, since the freshness of the green edges to the tail, most obvious near the base rest of the plumage ruled out the possibility of the feathers. that the tertial edges might be missing through wear. While none of us was particu- Underparts The underparts were sullied white, larly familiar with Greenish Warbler P. with grey smudging on the sides of the breast. There was some yellow present on the sides of the trochiloides of the race plumbeitarsus breast, near the wing-bend. ('Two-barred Greenish Warbler', and referred to as such hereafter), there was enough in Bare parts The bill was predominantly pale, with my description to convince everyone that just the culmen and tip of the upper mandible we needed another look, even though the dark. It was perhaps slightly longer than that of tide was on its way in. Pete,Tom and I set off, Yellow-browed Warbler, but this was not a notice­ and spent the high-tide period over on able feature. (Some observers thought that the bill Gugh, during which time we managed looked long, but this is not supported by the pho­ superb, prolonged views of the bird, and tographs, which suggest that the bill was relatively obtained a series of photographs sufficient small). The legs were dark grey-brown, with the to confirm its identification as Two-barred feet less grey and more brown. Greenish Warbler. Call I did not hear the warbler call, but others The next day, the bird showed well to all reported hearing it give a slurred, sparrow-like those who were able to visit Gugh, and it 'chirrup'. remained on the island until 27th October. Discussion Description The identification of this bird was, at the General A small, bright, active Phylloscopus time, quite challenging, since most warbler, reminiscent of both Yellow-browed and observers' experience of the taxon, if they Greenish Warblers. Compared with Yellow-browed had any at all, was limited to a few individ­ Warbler, it seemed slightly larger and longer-tailed, uals in spring, in Siberia. The perception of it had a more obvious neck, and it also lacked the those Siberian birds was quite at odds with constant motion of that species. Compared with the warbler on Gugh, particularly in relation Greenish Warbler, it appeared to have a larger head and to be slightly more pot-bellied. to the grey cast. In addition, most of the ones which I had seen had been singing, relatively Head and neck Crown olive-green with a grey high up in tall trees, and had therefore cast, darkening slightly towards the lateral edges. offered little opportunity for close study. There was a prominent yellow supercilium, flaring Two-barred Greenish Warbler was also some­ behind the eye, where it was broad and very what outside the mind-set of most British striking, before narrowing again with a suggestion birders, and even Ian Wallace (1980) had of an upward kink onto the nape; in front of the failed to predict it as a likely vagrant (though eye, the upper border was somewhat less distinct, less than a year later, in 1981, he would have and with a slight indentation, making it slightly done: Brit. Birds 74: 100). This latter point less obvious there. There was a thin, very dark eye- was amply demonstrated when I telephoned stripe in front of the eye, which became broader the news through to the Porthcressa that and paler behind the eye, and there was a distinct yellow crescent below the eye. The cheeks were evening: 'Two-barred Greenish? - never smudged grey, and the throat was white. heard of it, mate! Are you sure you know British Birds 94:284-288, June 2001 285 Radsbaw: Two-Barred Greenish Warbler on Scilly what you're talking about?' Once everyone confused with Yellow-browed Warbler, had seen the photographs, of course, the although most European field guides high­ identification became straightforward. By the light Greenish Warbler (i.e. viridanus) as the next day, everyone knew that it could not be main confusion species. The presence of an adult Yellow-browed Warbler, since that square tips on all the greater coverts species has a complete post-breeding moult (forming a broad whitish wing-bar), and a and therefore adults in autumn appear short median-covert bar are the key differ­ similar to young birds (including tertial ences from Greenish Warbler. These two fea­ edges). This situation was in marked contrast tures, however, together with an obvious to that on the day of discovery, when Alan supercilium that broadens behind the eye, Dean was the only person who seemed sure give Two-barred Greenish Warbler more than of the species' moult strategy. a passing resemblance to Yellow-browed In terms of field characters, Two-barred Warbler. Of course, the size, the lack of white Greenish Warbler occupies the overlap zone tertial edges, the call, and the bare-part col­ between Yellow-browed Warbler, Greenish oration can all be used to separate the two. Warbler of the race viridanus and Arctic In addition, Two-barred Greenish lacks Warbler P. borealis. In fact, while taxonomi- Yellow-browed's dark base to the secon­ cally most closely related to the second of daries that contrasts with the pale greater- those three, it is perhaps just as likely to be covert wing-bar. Two-barred Greenish Warbler is, perhaps, even more likely to be confused with Arctic Warbler, and in Hong Kong, where both species occur regularly, the identifica­ tion criteria have only recently been clarified, and the true status of both taxa determined (Leader 1993). In China, the situation is complicated some­ what by the presence of Arctic Warblers with dark legs, which, to my knowledge, is Cottridge not a problem likely to be encountered in western David Europe. The head pattern of 169 & 170. Greenish Warbler Phylloscopus trochiloides of the race the two can be similar, with plumbeitarsus ('Two-barred Greenish Warbler'), Gugh, Scilly, the supercilium not reaching October 1987. the base of the bill, a strong loral line, and sullied cheeks with an obvious pale crescent below the eye. In addition, Arctic Warbler in autumn can often show a double wing-bar, although the greater-covert bar is rarely, if ever, as broad or as long as that of Two-barred Greenish. Furthermore, the supercilium of Arctic Warbler does not usually widen behind the eye, while the legs are usually strikingly pale, and the call is different (although see Cottridge Bradshaw & Riddington David 286 British Birds 94:284-288, June 2001 Radsbaw: Two-Barred Greenish Warbler on Scilly 1997).