A Lesser Whitethroat - from east or west?

Lesser Whitethroat, Burnham Overy (Norfolk, UK), 18th September 2014

 
Back in the 1990s we used to see autumn Lesser Whitethroats that looked a bit different from the typical early-autumn western birds - often they would have quite warm colours on the wings, one I remember being so strongly rufousy that I thought it was a Whitethroat for a second.  I was told they were Siberian Lesser Whitethroats of the race blythi.  Then there was a decree that Siberian Lesser Whitethroats were unidentifiable, even in the hand - in fact if I remember rightly it was even claimed that they were not a valid taxon.  Interest waned a bit but more recently things have taken a turn - they are a valid taxon, and may even by a full species - and some of them might even be identifiable in the field.

I hadn't had time to read the relevant chapter in Martin Garner's new book when I was faced with my first blythi candidate this autumn, and I wasn't prepared.  First day I saw it I just thought it was a western.  Some things looked a bit interesting, but it didn't stand out enough.  Mind you, there was a lot of white in the tail, so I took some photos and resolved to read up that night.  Busy days (easterlies) and busy nights (warm, lots of moths) meant I didn't get round to that before the time I next saw it, but this time I looked harder.

This time I noticed that while sometimes it looked very grey-headed, there was a pretty obvious extension of brown up the nape and on to the back of the head.  The underparts were strongly sullied leaving a clear white throat and the tertials had a good degree of warmth in the colour.  Weren't they pro-blythi features?  Not as brown-headed as one I'd seen photographed recently, but was that enough to force it into the curruca mould?  I wasn't sure, and most other birders on site were only interested in the Red-breasted Flycatcher and Yellow-browed Warbler frequenting the same area.

A quick tweet generated a few responses, generally not very encouraging from a blythi-perspective, but not conclusive.  It's taken me a week to get to sorting the photos out and read up, but in the end I think the naysayers were probably right.  Whatever, it's been a learning experience, and that makes it worthwhile.  I'm still not clear on the validity or practicability of some of the features, but that just means there's still more for me to learn.  Let me know if you think I've missed or misinterpreted anything.

• Head/nape - at times it looked very grey-headed, even wholly grey-headed, but at other times the brown looked pretty extensive.  Never as extensive as it can be on blythi though, and on balance pretty much fine for curruca, I think.  Unsurprisingly the brown was easiest to see from behind.


• Underparts - sullied throughout with a warm buffish wash on the flanks and vent, quite strong on the rear flanks.  Greyer centrally but usually contrasting against the purer white throat.  In some views/angles the contrast was much reduced but generally it was pretty noticeable, and the white never extended down on to the breast, as I think it normally does in curruca.


• Upperparts and wings - at some angles these generally looked pretty brown-grey, not much different from typical curruca.  The tertial edges were a bit warm-toned - certainly warmer than some curruca, but whether it was enough to really suggest blythi I'm not sure.  Again it varied according to light and in some photos it looks very unimpressive.


• Tail - the tail feathers look pretty pointed to me (clearly visible in some of the photos) so I think it's a first calendar-year bird.  The inner web of the outer tail feather was extensively white, or at least whitish.  When the tail was fully fanned it was possible to see a dark wedge on the inside edge of the inside web, but the rest of the inner web was pale.  Not white though, although it looked like it in the field.  In the photos you can see that it's off-white, greyish white and distinctly greyer than the pure white outer web (except at the tip which was pure white).  If I've understood things correctly tail pattern is variable and this is more white than is normal for curruca, but for it to be a good pointer towards blythi the greyish white on the inner web would have had to be pure white.  Am I right about that?


• Wing formula - I thought that with some spread-wing photos I might be able to do something with this, but I can't.  If you're drawing a line to see whether P2 is level with P5/P6 or P6/P7 how do you know what angle to draw the line at?  And is it safe to do so anyway, given that you wouldn't know exactly what plane the wing is in compared to the camera?  Is it possible to interpret wing formula without having the bird in the hand?


• Call - I didn't personally hear it call.  Let me know if you did.

Lesser Whitethroat, Burnham Overy (Norfolk, UK), 18th September 2014

Although most of the upperparts are obscured by blackberries, this picture shows the warmth that was often apparent on the tertial better than most.  You can also see the brown extending up the nape, but looking pretty indistinct here.

Lesser Whitethroat, Burnham Overy (Norfolk, UK), 18th September 2014

In these two images it looks pretty much like a bog-standard curruca!  No hint of brown in the head from this angle and the contrast between the white throat and dirty underparts isn't even apparent here.  From this angle there's no sign of the warmth in the wings.

Lesser Whitethroat, Burnham Overy (Norfolk, UK), 18th September 2014

The brown on the head and nape was easiest to see from this angle, but it never looked as extensive as I would have expected to see on a stronger blythi candidate.  Not sure how much variation there is in either taxon in respect of this fieldmark.

Lesser Whitethroat, Burnham Overy (Norfolk, UK), 18th September 2014

The tail feathers are pointy, making this a bird of the year I think.  Note the outer tail feather pattern - extensively pale on the inner web but not pure white.  I can't do anything with the wing formula - can you?

Lesser Whitethroat, Burnham Overy (Norfolk, UK), 18th September 2014

Looks pretty cold in these shots and the upperparts don't really give much reason for blythi-thinking, except perhaps in how pale it looks.  It didn't really look this pale in the field, but nor did it look so cold - shows how misleading photos can be.  Notice how the brown on the head appears and disappears with just a slight change of angle.  The underpart colour also varies - in the field I thought it more obvious and this was one of the things that got me wondering about blythi the most.



Didn't manage to get any decent photos over the next couple of days, but for what they're worth (if anything), here's what I did get.

Lesser Whitethroat, Burnham Overy (Norfolk, UK), 20th September 2014

In conclusion I think this is very probably a western curruca, and at the very least not identifiable as a Siberian blythi based on what information I can glean.  There was enough about it to make me think though, and I'm glad I asked the question.  It's made me learn a bit, and that's given me some pointers as to what to look for with future Lesser Whitethroat encounters.



*** Update 2nd October ***

I'm interested to see photos of the Lesser Whitethroat currently present at Portland.  This bird was trapped and is considered by some to be possibly a blythi and by others to be definitely a blythi.  I've not seen it, but from the photos it looks strikingly similar to the Burnham Overy bird in a lot of ways.  It looks different in different photos, as does the Burnham one, with some looking more brown headed and others looking very grey-headed.  It looks to be a colder greyer looking bird than the Burnham one, consequently with less contrast between the back and the head, but it will be interesting to see how it pans out with the DNA analysis.  Maybe the bird looked more distinctive in the field, but if the Dorset bird is blythi and mine was curruca then I've got a lot more learning to do before I can tell them apart!
 

Wigeons with white on the head (and Brent Geese)

Just curious about this - does anyone know the answer?

Wigeon, Salthouse (Norfolk, UK), 22nd February 2014

I know leucism and other pigment-deficiency conditions can affect birds in different ways, for example making the whole bird very pale, or just making parts of the bird white, but the situation with Wigeon strikes me as being different from most other instances.

Thinking of the birds I've seen that have had patches of pure white in their plumage, this white can appear in different places on different individuals.  I've seen lots of Pink-footed Geese showing white patches but the position varies by bird (though typically it includes primaries and bands across the neck or belly).  I've seen lots of Blackbirds with white plumage, but haven't noticed any pattern as to which bits will be white.  But Wigeon seem different.  I've seen half a dozen Wigeon with obvious white patches and each one has had this white patch on the head.  The exact size and shape has varied (usually diffuse and sometimes more or less tending towards speckling) but always just behind the eye.

Here are some of them:

Wigeon, Salthouse (Norfolk, UK), 22nd February 2014

Wigeon, Salthouse (Norfolk, UK), 1st December 2012

female Wigeon, Buckenham (Norfolk, UK), 25th January 2004

male Wigeon, Buckenham (Norfolk, UK), 25th January 2004

female Wigeon, Caerlaverock (Dumfries & Galloway, UK), 29th December 2005

Why is it always the side of the head that is affected - I've never seen a Wigeon with patches of white anywhere else (I have seen generally washed out birds, but that's a different condition affecting all or most of the plumage making it paler than normal, not white).

Brent Geese are the same.  Again I've seen birds that are generally washed out, paler than normal all over, but the birds I've seen with abnormal pure white plumage affecting only a small part of the bird have all been similar - they've all had white speckling on the head, albeit varying in extent.  Here are a few, but I've far more in addition to these, all similar.

Dark-bellied Brent Goose, Cley (Norfolk, UK), 28th February 2004

Dark-bellied Brent Goose, Salthouse (Norfolk, UK), 18th January 2004

Dark-bellied Brent Goose, Cley (Norfolk, UK), 5th January 2008

Dark-bellied Brent Goose, Cley (Norfolk, UK), 5th January 2008 (second bird)

Dark-bellied Brent Goose, Salthouse (Norfolk, UK), 20th November 2004 (a bird with just a few white flecks)

Dark-bellied Brent Goose, Stiffkey (Norfolk, UK), 31st January 2009

Is this the same with the other forms of Brent Goose?  I've only seen it in Dark-bellied but that's probably just because it's the only form I see thousands of every year.



Update January 2015

Yet another Wigeon with white on the head here...

female Wigeon, Welney (Norfolk, UK), 10th January 2015

Update December 2015

Seems that the first two birds from Salthouse in February 2014 and December 2012 were in fact both the same bird, as it is back in December 2015, still looking the same.  Can't be a first-winter then and I assume it's an intersex female.  More on that in this post.

Pied Flycatcher in Iberia

Well I didn't get much response on my last post about a Pied Flycatcher so let me try another...

Pied Flycatcher, Ebro Delta, 20th May 2013

This one was in Spain, by the visitor centre in the Ebro Delta, in May 2013 (I've only just got round to sorting the photos out).  It wasn't in suitable breeding habitat so can be assumed to be a migrant.  As such I imagine (but don't know for certain) that the nominate hypoleuca is more likely than the Spanish iberiae.

One feature caught my attention: the pattern at the base of the primaries.  I was looking to check the size of the white patch at the base of the primaries.  In itself the white patch was not especially remarkable but what was more interesting (to me) was that around it, covering an area more comparable to the more extensive white patch of a Collared Flycatcher, was a diffuse pale patch - contrastingly browner than the smaller clear-cut white patch but also contrastingly paler than, though diffusely separated from, the dark brown colour of the more distal section of these feathers.

I don't remember seeing that before.  That doesn't mean it's unusual - just that I've not noticed it.  Maybe I haven't looked hard enough - quite possible.  I checked quite a few images, of my own and on the internet, and at first couldn't find others like it.  Eventually I did find some, including breeding females photographed in England and in Russia.  So probably not unusual and clearly not an indicator that it might be anything other than nominate hypoleuca.

In the meantime though I tried to research how to identify female iberiae, just in case it hadn't turned out to be ok for hypoleuca.  I found very little info on ID of female iberiae.  In fact the only reference I could find on separating female iberiae from nominate hypoleuca was BWP which states that in female iberiae the tertial margins are much broader than in female nominate hypoleuca, forming small white wing-patch.  Well the white tertial edges on this bird are pretty broad and they form a white patch, but are they too broad for hypoleuca?  I'm not convinced, though there are certainly lots of photos of spring female nominate Pied Flycatchers on the internet where the white fringes are narrower.  Here are some more views - what do you think?

Pied Flycatcher, Ebro Delta, 20th May 2013

Are there any other differences between the two forms to look out for?