23rd May

It's that time of year when surprises pop up quite out of the blue so on a lovely warm, sunny but otherwise largely migrant-lite day it maybe wasn't too unexpected when a Subalpine Warbler turned up during the morning in a mist-net in the Obs garden; sadly, it proved to be less than obliging after release when it afforded no more than a tantalising series of glimpses as it vacated the Obs Quarry. Earlier, singles of Cuckoo and Corn Bunting had been the pick of the thin scatter of arrivals at the Bill/Southwell that totalled 5 each of Chiffchaff and Spotted Flycatcher, and singles of Wheatear, Redstart, Sedge Warbler and Blackcap.

Cuckoo and Subalpine Warbler - Portland Bill, 23rd May 2105 © Martin Cade

...after all the various taxonomic changes, we've been slightly dreading catching a female Western-type Subalpine Warbler so today's bird was something of an education in seeing how far we could get with it (and, fortunately, one or two feathers were dislodged during handling so we do have those to fall back on!).

Age-wise, although it was moderately worn we weren't entirely sure it was a first-summer (certainly we've handled first-summers that have been far more worn than this individual) - perhaps someone with more experience could comment? - but that didn't have any particular bearing on the ID since the tail pattern didn't indicate it was likely to be anything other than a Western-type. For it to have been a 'classic' Moltoni's Warbler then we'd have liked to have seen a nice fresh wing resulting from a complete pre-breeding moult, but that wasn't the case: the new inner secondaries, some tertials and various other greater and median coverts clearly showed it had only undergone a partial moult. Frustratingly, that in itself evidently doesn't preclude it being a Moltoni's that's only had a partial moult so we were none the wiser on that score. The only other thing we could hope for was that it might call on release: 

Again, there was nothing in those calls to suggest Moltoni's but we're not sure whether that form is actually excluded by what was heard. So, although it seems like Western is very much favoured on the available evidence we were still left short of 100% certain - hopefully the feathers will come up with a definitive answer.