Unusual 'yellow-browed warbler' at Quendale, Shetland
On 1st October 2011, David Fairhurst (who was leading a group for Shetland Wildlife) and I found an unusual ‘yellow-browed warbler’ in bracken at the lower end of the valley at Quendale. Having seen several Yellow-broweds already that day, and indeed 100s abroad previously, this bird was noteworthy in several aspects of its plumage – enough for us to think of Hume’s at one stage (or several stages actually).
In the field it had very grey upperparts, slightly darker grey on the head and a subtly pale rear median crown stripe; in prolonged views there was a hint of olive in the mantle and scapulars, but this was weak. The contrast of the upperparts colour with the yellow wing edges was particularly marked and, as we discussed at the time, rather like that of an autumn ‘bonelli’s warbler’; the dark ‘shadow’ at the base of the secondaries was weak, and the pale fringes to the tertials narrow. The supercilium was creamy white (lacking yellow); the underparts had a hint of smudgy marks at the breast sides, but not greatly and dependent upon angle; the bill was notably dark, but the legs, and especially feet, were pale.
Sadly, it did not call, but luckily Heather Gerrard managed to get some good photos that show the plumage well. On the images it is interesting that the olive on the mantle seems to be more obvious than it was in the field.
Having shown these images about, it has been speculated that this may well be a Hume’s (or something else), but do others have experience of birds like this? Any opinions?