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?

A Sparrow that looks Italian... but is it?

I've blogged about Italian Sparrows before, but I didn't expect to be blogging about one here in Norfolk!  On Sunday I popped up to see the sparrow at Northrepps that seems to show characteristics of the Italian form italiae, now treated by many authorities as a new species formed by hybrid speciation (i.e. a population of hybrids, in this case Spanish Sparrow x House Sparrow hybrids, that have become sufficiently reproductively isolated from either ancestor species to be treated as a new species).

 Italian-type Sparrow, Northrepps (Norfolk), 18th August 2013

 

It looks good!  But is it really an Italian Sparrow?

Here are the options...

1) Hybrid Tree Sparrow x House Sparrow has been suggested.  They occur occasionally so it wouldn't be all that exceptional - certainly more likely than an Italian Sparrow.  But other than lacking grey in the crown this bird doesn't really resemble Tree Sparrow.  Most (if not all) Tree x House Sparrow hybrids have grey in the crown, most have at least a hint of a dark cheek spot, most show buffier tones on the body, they should probably have a smaller bill than this bird.  I don't see anything to suggest Tree Sparrow involvement in this individual.

 Italian-type Sparrow, Northrepps (Norfolk), 18th August 2013

 

2) An aberrant House Sparrow.  This bird shows reddish-chestnut extending on to the breast band and the white supraloral stripe is virtually absent.  That could be explained by an excess of whatever pigment causes that chestnut colour (is that erythrism?) and if it has that sort of pigment issue then perhaps it could be affecting the crown too, flooding that with chestnut colour?  I think this suggestion deserves some merit, but it doesn't convince me.  It's not extremely unusual for House Sparrows to show very white cheeks, and perhaps the bill bulbous bill is within range for House Sparrow, but what are the odds of a House Sparrow with erythrism generating a completely chestnut crown like an Italian Sparrow also having white cheeks and a big bulbous bill?  I can't rule this option out, but I find it rather unlikely.

  Italian-type Sparrow, Northrepps (Norfolk), 18th August 2013

3) An Italian Sparrow, i.e. a vagrant from Italy or neighbouring regions.  Some features need explaining for this option, namely the chestnut on the breast, the restricted white supraloral and what looks like grey flecking in the crown.  The breast is easy - quite a few photos of Italian Sparrows have this.  It's not typical but it's not exceptional either.  The restricted white supraloral seems to be more unusual, but there are images online that seem to share this feature.  At least some of the grey flecks in the crown are not true plumage features but an effect of moult.  The bird has several loose or missing feathers and this seems to be revealing grey feather bases.  I'm not convinced that there really are any grey feathers in the crown, although this will perhaps become clearer when the bird has completed its moult.  So nothing here rules out Italian Sparrow, but we can't get away from the fact that it's not a completely typical Italian Sparrow.  If the odds of any Italian Sparrow turning up in a Northrepps garden are low then I'd have thought that the odds of one with chestnut on the breast and virtually no supraloral stripe are significantly lower.

 Italian-type Sparrow, Northrepps (Norfolk), 18th August 2013

4) A hybrid between a House Sparrow and a Spanish Sparrow.  There are a few references to hybrids between these species away from Italy.  Spanish Sparrow has occurred in the UK several times and some have been long-stayers oversummering with House Sparrows, so one producing hybrid offspring isn't very unlikely.  Sparrows tend to frequent places that aren't birding hotspots so it's plausible that even a male Spanish Sparrow could have summered and bred locally without being detected - and most birders would be hard-pushed to detect a vagrant female even if it was breeding in their own garden!  It's a pretty subjective call whether a hybrid Spanish x House Sparrow would be more or less likely than an Italian Sparrow to appear in Northrepps, but I am personally inclined to think such a hybrid might be rather more likely than a vagrant Italian.  As yet I haven't been able to track down any photos or descriptions of Spanish x House Sparrow hybrids, so I'm not sure how their appearance fits in with that of the Northrepps bird.  Given the history of Italian Sparrow it seems reasonable to summise that they look a lot like Italian Sparrows, and given that first generation hybrids between any two species (not in every case) tend to be a bit variable we might expect that it will look a lot like an Italian Sparrow but not necessarily exactly like a typical Italian Sparrow.  In other words they might look a bit like the Northrepps bird, perhaps.  But all that is guesswork - I don't actually know what Spanish x House Sparrow hybrids really do look like.  If you can point me to any references that show such a hybrid (proven or not) please leave a comment or get in touch!

 Italian-type Sparrow, Northrepps (Norfolk), 18th August 2013

Whatever it is it's an interesting bird - big thanks to Andy and Carl for finding it, letting us know and allowing me to visit.


Maybe DNA analysis will offer some answers in due course...

"Green" Pheasants

For several years I noticed increasing numbers of reports of Japanese Green Pheasants in Norfolk, but when I eventually started seeing these birds, something didn't seem quite right.  I've never been to Japan, and have never seen a real Green Pheasant, but in the photos I've seen they've had pale blue wing-coverts and a pale blue rump.  The birds I was seeing were superficially similar, but they weren't quite right.  Sometimes they looked green, but in some lights they looked blue or purple - or even black.  Notably the wing-coverts and rump always seemed to be more-or-less the same colour as the rest of the wings and body - or at least not significantly paler as they should be on Green Pheasants.

A bit of research first turned up information about "melanistic" Pheasants, and these reports clearly related to the birds I was seeing.  A bit more research uncovered talk of Pheasants of a mutant variant known as 'tenebrosus'.  These were the same birds, and apparently it wasn't strictly correct to call them melanistic.

Pheasant (var. 'tenebrosus'), Ringstead, 25th March 2013

I've not managed to determine the origins of this variant.  Some reports hint at the possibility that there are some Green Pheasant genes present, but so far as I can tell this idea is based only on speculation from its appearance rather than any firm evidence (but please correct me if you know otherwise).  Green Pheasants and Common (or Ring-necked) Pheasants are of course closely related - variably treated as either a subspecies or full species - so they doubtless have similarities in their genetic make-up.  A mutation in one species could easily result in the bird throwing up features normally associated with the other species.  I suspect that's the explanation, rather than them being hybrids.  And as with domestic duck breeds, when a mutant has characteristics that are desired by keepers birds are selectively bred to establish these characteristics.  That seems to be what's happened, and the result is Phasianus colchicus var. 'tenebrosus', or Tenebrosus Pheasant.

However they came to be they're stunningly beautiful birds.  I've noticed that they seem to become quite common in an area for a while and then disappear, presumably because the local gamekeeper has favoured them for a bit and then they've either died out or they've lost favour with the gamekeeper for some reason.  Outside of these localised patches of abundancy they seem to be fairly widespread and not desperately uncommon - I see odd birds at widely scattered locations from time to time.

Here are a few males:

  

Pheasant (var. 'tenebrosus'), Coxford, 26th March 2013

Pheasant (var. 'tenebrosus'), North Creake, 26th March 2012 

Pheasant (var. 'tenebrosus'), Great Hockham, 12th March 2006 - one of the first birds I saw well.  At around this time Tenebrosus Pheasants seemed to outnumber ordinary Pheasants in this area but in recent visits to the area I've not seen any

Pheasant (var. 'tenebrosus'), Hockham, 14th February 2009

Pheasants (var. 'tenebrosus'), south of Wells, 13th April 2011 - there were loads here in spring 2011 but I've not seen any on subsequent visits

Some birds have a few paler brown markings along some of the feather shafts.  Not sure if a breeder would regard such birds as 'pure' Tenebrosus or not.  This one's pretty close if not:

 

Pheasant (var. 'tenebrosus'), south of Wells, 13th April 2011 

The brown internal markings on some of the feathers of this bird are a bit more obvious.  Still a Tenebrosus?

Pheasant (var. 'tenebrosus'?), Saham, 17th March 2012

I've been able to find remarkably little information about what females are supposed to look like.  But I have seen a lot of dark female Pheasants, often in the same places as I've seen male Tenebrosus Pheasants, so I presume that's what they are.

Supporting the argument that the often-used term "melanistic" isn't technically correct for these Pheasants, many of these dark females show obvious pale fringing on the feathers, despite the brown base colour being much darker than on normal Pheasants.  Here are a few:

Pheasant (var. 'tenebrosus'), Anmer, 6th September 2011

Pheasant (var. 'tenebrosus'), between Flitcham and West Newton, 20th February 2009 - not sure what the significance of the bluey patch around the eye is - this isn't a typical feature of any form of Phasianus colchicus so far as I know

Pheasant (var. 'tenebrosus'), North Creake, 8th April 2011

Pheasant (var. 'tenebrosus'), Wolferton, 21st March 2011 

Notice how the females seem to often show an irridescent purply patch on the side of the neck, a feature absent from normal female Pheasants.

Variation in Wigeons

Every now and then I hear discussions about Eurasian Wigeon that have turned up in North America showing some green behind the eye.  Most books don't illustrate this and the sceptics cry, "Hybrid!".  Of course most of us who are lucky enough to look at lots of Wigeon this side of the Atlantic know well that Wigeon often show a little green behind the eye - it's not a sign of hybrid origin.

But what about Wigeon with complete green headbands?  Is this just normal variation?  Or are these birds hybrids?  Like these:

Eurasian Wigeon, Pentney Lakes, 31st March 2009

Eurasian Wigeon, Burnham Norton, 13th March 2010

Most people I've discussed this with consider that it's just the extreme of variation within pure Wigeons.  These birds don't show any other sign of hybridisation so they can't be first-generation hybrids, and many first-generation Eurasian x American Wigeon hybrids don't show a green headband like this anyway.  The theory is that Wigeons have inherited the mix of genes required to produce a green headband from a common ancestor but that these genes are not usually expressed in Eurasian Wigeon.  Always present, normally suppressed, but expressed in just a few individuals.  A recent discussion on ID-Frontiers seemed to reach the same conclusion but thanks to Joern, Carl Gunnar, Lars and Henry with whom I had already discussed these birds.

Whilst this theory has much merit, two observations haven't sat comfortably with it for me:

1. My experience was that Wigeon with a little green behind the eye are common and Wigeon with an extensive green band are occasional, but I'd never noticed any Wigeon with anything in between.  If it were simply variation I'd expect a continuum, with the greater extents being increasingly rare. 
2. I've heard one or two people with experience of Wigeons in Europe and in the Far East claiming that birds in the Far East have a much higher tendency to show green head bands.  American Wigeons turn up in the Far East more often than in Europe and so backcrossed hybrids might be expected more commonly there than here.  Moreover someone recently claimed that Wigeon in India (where so far as I know American Wigeon has never been recorded) never show any green behind the eye.  Thus anecdotal evidence seems to suggest that the occurrence of green on the head correlates with the frequency of vagrant American Wigeons in the population.

Well this is one mystery I made some progress with recently.  I had the opportunity to study a few hundred Wigeon at close range and in excellent light the other day.  The main thing I learned is that there is in fact much more variation than I had appreciated, and it's more common than I'd realised.  My initial observations described as point 1 above proved not to be valid - there is indeed a continuum, with many birds showing green extending further behind the eye than most, but not as far as the few.

Eurasian Wigeon, Snettisham, 8th December 2012

It still doesn't explain the geographic variation but there may be other explanations for that.  Moreover it's only anecdotal so far as I know and like my first point, maybe it won't stand up to more careful observation.  Sadly I've got no trips to the Far East or India planned so I won't be able to test that one myself - but if you travel more widely let me know if it stacks up with your experience!

I noticed a couple of other things on some of the earlier green-banded Wigeons I saw, which I wondered if they might be linked.  A couple showed a small dark (green?) wedge at the upper point of the cream forecrown, absent from most Wigeon.  However I've since found this on other Wigeon that don't have green behind the eye, so it seems not to be linked.  One also showed pale at the base of the bill extending further into the cheek area than normal, but again this seems to be a variable feature and not linked to the extent of green behind the eye.

Eurasian Wigeon, Pentney, 31st March 2009 

(the same bird as the one at the top of this post, now showing the dark wedge at the apex of the cream forecrown)

Nothing to do with the above, but worth a mention while I'm talking about variation in Wigeon, I also had the opportunity to photograph a few first-winter drake Wigeon in flight.  It's well-known that young male Wigeon lack the white forewing of adults but perhaps not quite so well-known that they continue to lack this after they've moulted their head and body feathers.  Actually it's quite well documented, so this is nothing new, but I thought it was interesting to show a couple of shots that illustrate it nicely.

first-winter male Eurasian Wigeon, Snettisham, 8th December 2012

 

Lots more photos of Wigeon on my website of course.

And while we're talking about green on duck heads where we perhaps don't expect it, here's a nice first-winter drake Pintail with a green sheen.  Not the same issue as the Wigeon here of course - in this instance I think it's just a case of how the light catches it, a bit like Tufted Duck I suppose only less obvious.

first-winter male Pintail, Snettisham, 8th December 2012

_____________________________

Follow up, Feb 2013

A quick postscript following more study of Wigeon over the course of the winter.  I knew that the green on a duck's head is irridescent, i.e. the intensity of colour and the colour itself is variable according to the intensity of the sunlight and the bird's angle to the light compared to the observer.  I had even noticed that some of my observations of Wigeon with the most green on the head had been in strong sunshine (including the photos above).  But I hadn't quite realised the extent to which the light impacts the colour when the normal ground colour is chestnut-brown as on a Wigeon's head.

A few days after I posted this I studied a flock of several hundred Wigeon a bit further round the Norfolk coast in dull and cloudy conditions - not one of them showed the slightest hint of green in their head.  

Many of the questions about variability remain.  Most Wigeons don't seem to show green behind the eye even when it's sunny.  A few do even when it's not sunny.  What causes that variation is still an unanswered question, but the impact of sunlight does mean it will be difficult to assess how much it varies geographically.  As the extent of green varies according to the brightness and direction of sunlight it will be nigh-on impossible to make meaningful comparative assessments between different populations.

Thanks to everyone who has commented privately about this subject, and especially for the offers to get involved in further study in different countries, were we to find a meaningful way of doing that.