Shetland Explorations…

by Martin G.

23rd September 2012 – a year ago yesterday a ‘Desert’ Lesser Whitethroat was trapped at Spurn. Subsequent DNA analysis matched it to birds from a VERY long way away (as suspected based on its plumage and biometrics).

As I head to Shetland, Lesser Whitethroats will again be a subject of close study. Hence this post reblogged from January 2013.

Desert Lesser Whitethroat on Helgoland by Jochen Dierschke

Most recent autumn and winter seasons, the subject of ‘Eastern Lesser Whitethroats’ rises up with the appearance of interesting looking (and sounding) individuals. A long-awaited paper was published here by a host of birding luminaries.

Of interest to West European observers, as expected, blythi (Siberian Lesser Whitethroat) sees a resurgence. The “data suggest that blythi is a valid taxon not closely related to curruca”. Meanwhile minula (Desert Lesser Whitethroat) was found to have a more restricted range than previously understood being limited to within China. It’s impressive research with interesting conclusions and much as yet unresolved.

Consequently, the extralimital Lesser Whitethroats to be on the look out for are halimodendri and blythi…

halimodendri

halimodendri (Desert) Lesser Whitethroat. This bird was trapped at Spurn on 23rd Sept. 2012 (more here). It was tentatively identified at the time as halimodendri based on plumage (esp. tail pattern) and biometrics (with thanks to Paul Leader). It was similar to other birds in W Europe which are usually claimed as minula. Subsequent DNA analysis from a feather sample matched halimodendri from the eastern part of the range. Martin Collinson (once again) doing a great job said: “That Spurn Lesser Whitethroat you sent us looks most likely to be halimodendri. It’s genetically most similar to a bird in the database from Xinjiang, the grid coordinates putting it just the Chinese side of the Kazakhstan border, which should be halimodendri”.

blythi?

While evidence so far suggest halimodendri types are likely to (continue) to prove rather rare, the harder to distinguish blythi types are probably annual. With breeding and wintering range at least in part similar to Siberian Chiffchaff, perhaps that species give an idea of the number of blythi that might be occurring in Western Europe?

As with good numbers of Siberian Chiffchaffs annually Shetland is also known to host browner, ‘Eastern’ type Lesser Whitethroats annually. With thanks (and apologies for lingering) to group members from the 2012 Shetland Nature Tours, here is a bird we spent a fair bit of time with last autumn. With some plumage and wing formula characters visible in some photos (not these) I think this is probably a blythi (thanks again to Paul Leader). Proving it may be another thing…