Eastern Subalpine Warbler


Today we recieved news that the Subalpine Warbler trapped and ringed at Kew on 31st May 2020, has mtDNA of an Eastern! Specifically nominate Curruca cantillans cantillans

At the time we thought this was going to either be a Western or Moltoni's due to the lack of a white wedge in T5. So to get results back as an Eastern shows that there is much more to learn on female Subalpine Warbler ID. Unfourtunatly it wasn't seen in the field after release and wasn't heard to call (which makes identifying them in the field much easier!)

This is of course of particular interest following the IOC's decision to split Western and Eastern Subalpine Warbler earlier this year. This is the first genetically confirmed Eastern Subalpine Warbler for Spurn, (following on from our only genetically confirmed Western in 2017), however we already have 3 non-genetically confirmed records of Eastern;

1968 - The first record of Subalpine Warbler at Spurn was a first-year male which was trapped at the Warren on 9th May. The detailed description in the log and sketches of its tail pattern reveal the bird to be an Eastern Subalpine. This becomes the first Eastern Subalpine on mainland Britain. (Accepted by BBRC).

1998 - A male was present along the Canal on 12th and 13th May.

2009 - A first-year male was found at the Point on 18th April. It was not seen after mid-morning but then showed well in a favoured area behind the VTS tower on 19th and 20th April. (Accepted by BBRC)

It remains to be seen if BBRC will keep these records, as they tend to be quite harsh and only accept genetically confirmed birds on a tricky species split like this. However spring male Subalpine Warblers should be identifiable to species, much more so than females as shown here!

Big thanks once again to Thom Shannon and Martin Collison at Aberdeen University for carrying out the mtDNA test on this bird. We need to dig out some of the new literature on Subalpines!

Right side of the tail showing the pattern, we would have expected more white forming a wedge in T5 for an Eastern, but apparently not! Pic © Bethan Clyne

Left side of the tail showing the same pattern as the right side. Pic © Ian Smith

Pic © Bethan Clyne

Pic © Ian Smith

Phylogram showing where the Spurn bird sits, firmly in the Eastern Camp! Thanks to Thom Shannon for this.

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Posted: 04 August 2020

Eastern Subalpine Warbler