Shetland, October 2010 and April 2011
Last October as I co-lead a Shetland Nature tour on Unst (Britain’s northermost island). I noticed a dark Mallard- type, whose dark body contrasted strongly from below with bright white underwings. It was also picked out independently by Brydon Thomason, by members of our tour group and by Unst resident Mike Pennington. From below it looked promising, but from above revealed obvious white borders to its dark specula. We speculated that it might be a Black Duck hybrid but that’s where we left it. See here:
http://birdingfrontiers.com/2010/10/16/black-duck/
About 2 weeks ago Mike P. found the bird again on Unst. This time Robbie Brookes (thank you!) got some on-the-ground shots, revealing more about its appearance and perhaps identity. I do think it’s most likely a Black Duck/ Mallard hybrid (perhaps from the Faeroes).
One thing that struck me was the specula. The pattern of the specula is split between black lower and bluish upper sections with sharp divide between the two, particularly towards the outer part. Seems a tendency at least for Mallard to average more blue and less black. Here’s some wing shots of Black Duck and Mallard to compare: P.S. can I have a half-find ; )
Black Duck: http://www.npwrc.usgs.gov/resource/birds/duckplum/amblack.htm
Mallard: http://www.npwrc.usgs.gov/resource/birds/duckplum/mallard.htm
Hi Martin
Have you seen this on-line reference?
http://www.npwrc.usgs.gov/resource/birds/diplume/index.htm#contents
If I have read it correctly then the dark feathering in the primary coverts of the underwing, which are shown quite clearly in your shots of the initial sighting, seem to be another pointer of its hybrid origin. Checking Nils van D’s book, though, is less encouraging with regards to this feature.
All the best
Geoff