Saturday, February 03, 2007

More faux-borealis Common Eiders

See Norman van Swelm's delightfully quirky 'Radioactive Robins'

He posted on ID Frontiers to point out these 'borealis' Common Eiders
on the Dutch coast, and to ask if any others had turned up recently.

Norman and I have a long history of good-natured and light-hearted
antagonism, the origins of which are lost in the mists of time but probably
involved a disagreement over gulls.

So I was hoping someone else would take this up and educate me too,
but no one did, so I posted...

If no one else is taking this up, I'll start, cos
it's been bugging me all month. There have been
a few borealis reported around the place in recent
weeks (quite impressive for a bird with only one
accepted british record), so I started checking
our local birds (NE Scotland) more carefully.
Certainly birds with yellow-orange bills are
remarkably common around me and I have seen one or
two with extended scapular sails, and one or two
orange-billed ones that appear to show no sails,
and a reddish female. You can read the semi-literate
'lite' version of what's been going on in George
Bristow's Secret Freezer (
28th and 21st jan entries, with photos).
Have to say, based on my personal prejudices,
which I know you always agree with norman, that
given the known tendency of european Eiders to
shown yellow/mustard tones in the bill, I'm
inclined to think there's a good chance that
they are local breeders. Especially the ones
without good sails like on your site :-) If you
can go back to June entries on the blog there's
a photo of one of the local males with a yellow
bill (but no sails). Blogger seems a bit
screwed up just now, so let me know if you want
any files mailed.

Norman got back with a typically informative reply:

My dear Martin, believe me I am not responsible for Canadian
Eiders breeding in Scotland! May be the same people who were
responsible for the introduction of American Ruddy Ducks in
England are, ask Malcolm Ogilvie. Or 'climate change'? Seen
any icebergs lately? If so, Polar Bears may follow soon!

How do you know your June bird is a local breeder? High Arctic
birds leave Europe from late May onwards and some stay f.i.
because the weather is unfavourable at the time of departure.
I have seen large numbers of seaducks along the Atlantic
coast of Ireland in summer.

The 'sails', if visible, may indicate an arctic origin but are
of no value in determining the bird's subspecies. The
impression is that these 'sails' are being kept down most of
the time so if you maintain Garner's criterion that 'sails'
must be seen than I am not surprised there's only one accepted
British record!
Have a glass of wine with Mrs.Collinson my lad.


Angus Wilson was confused too, but had a good reference:
Can anyone point me to recent literature or good web sites
that summarize the identification criteria for subspecific
ID of Common Eiders?

I'm familiar with some of the classic accounts (e.g. Parkes'
descriptions in Palmer's "Handbook of North American birds"
(1976) and Knapton's 1997 article "Identification of female
Common Eider subspecies in Canada." Birders J. 6: 134–136)
but wondered if there is anything more recent or from a
European perspective.

In light of recent discussions, it seems worth keeping in mind
the following list in the Birds of North America bibliography:

Baker, A. J., A. Grapputo, K. Dickson, S. Wendt, K. Scribner.

Mitochondrial DNA control region sequence variation in Common
Eiders reveals extensive mixing of subspecies. Abstract.
First North American Duck Symposium and Workshop, Baton Rouge,

Cheers, Angus Wilson
New York City, USA

Then Martin Scott provided the killer info on the local provenance of these Eiders.
I didn't know about the ringed bird.

There has been a lot of discussion about this among some of the
Scottish birders of late (as I am sure Martin is aware)

One, of four, "sailed" birds on the Ythan Estuary north of
Aberdeen bears a ring which has been traced to it being ringed
at the same locality as a nestling c.20 years ago. Thereby
either "boreal" Eiders have been breeding in Scotland since at
least then, and have gone undetected or they aint Boreals........

We have also had sailed birds in the Outer Hebrides. Some of thes
have also different in lobe shape (eastern Scottish birds seem
to have pointed lobes, western ones rounded) and in structure.
Perhaps here in the Hebrides we are getting birds of a NW/ Nearctic
origin. Is bill colour so important?

Overall I dont think Boreal Eider is as 'easy' as has been suggested.
Perhaps not every bird with a sail is a Boreal.

Work in progress is the label for this one!

I think I'm happy that borealis is not an easy one to clinch in the field, that
diagnosability is not fully figured out, and that these 'borealis-ish' ones we
see are local breeders.


Alastair said...

That's all rather useful - so thanks Martin. Don't claim and avoid egg on face cos this is tricky stuff.

Now as for disagreements with Norm I seem to recall (from my UKBN days) that to be somewhat easily accomplished. (Tin hat on head as I post.)

Martin said...

Unfortunately, Norman has an unusual memory of the situation, maybe better than mine, but possibly just less accurate. See
btw that is *not* how it happened.