Sunday, July 1, 2012

It has been suggested that we may have dropped a bit of a bollock. More precisely, a few very experienced birders have suggested that yesterday's Greenish Warbler bares more than a passing resemblance to a Green Warbler. This may be partly due to the two photographs we posted yesterday; the last day of June was glaringly sunny so the photos were either in full sun (the two posted), or in the deep shade of the ringing hut (see below). But the heavy appearance of the bill, coupled with yellow tones to the supercilium, have rightly raised a few questions. The bird clearly doesn't show the Wood Warbler-like tones to the mantle and throat which are perhaps the first thing that comes to mind for this recently split species, but perhaps a summer bird wouldn't be as obvious as when in fresh autumn plumage? Yoav Perlman's fantastic blog shows what a classic Green Warbler looks like in June here:
but what about a more worn individual?

Our bird was tape lured. As soon as the tape was played the bird responded emphatically with several flybys before soon hitting the net. But it would seem that this means very little. Prior to the split of trochiloides and nitidus, it was suggested by some authorities that the propensity of Green Warbler to respond to Greenish Warbler song was a good reason not to split them! So what about the song itself? Our bird sang frequently. Here it must be pointed out that our experience of singing Greenish Warbler is limited to two previous singing males on Bardsey and an oft played recording said to be of viridanus Greenish. However to our inexperienced ear the song seemed identical, when singing to the tape the phrases matched perfectly. It wasn't the longer song, including buzzy bits, which is meant to be classic Green Warbler. But then apparently the song can sometimes be very close to Greenish. It didn't call so no help there.

In the hand the wing formula was almost identical to the Greenish Warbler trapped earlier in June. That is to say that there were emarginations to the third to sixth primaries (although not as strong on P6) and the longest primary was the fourth. The second primary fell between P7 and P8 on the bird in early June, this bird had P2 closer to P8 (which is possibly more Green Warbler although such a slight difference must fall in the realms of individual variation). The wing was 63mm, which doesn't help much.

So we are left with plumage and structure. The pro-Green Warbler argument would point to the very striking supercilium which has yellow tones, the yellowish cheek and the heavy looking bill (bill measurements overlap considerably between the two species but Green averages heavier). But the (worn) mantle is grey green rather than moss, the (worn) wingbar lacks any yellow tones and the underparts and throat are whitish, although with some very pale yellow. The supercilium reaches the bill as in Greenish but it could be argued that it gets a bit more vague above the bill, as in Green Warbler. The legs were surprisingly pale, but we can't find much reference to leg colour other than that Greenish Warblers sometimes have paler legs than normal.

The top photo is of the same bird in the shade. To us it still seems to fit Greenish, albeit a bright individual, and the song must clinch it. But this is the perfect opportunity for everyone with lots more experience than us to tell us we're wrong! We'd love to hear any comments. The lower two photos are of our other two recent Greenish Warblers for a direct comparison (but beware very different lighting conditions). (c) Richard Brown 

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