"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

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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.

Another non-juvenile immature skua

Following my last post about a first-summer Pomarine Skua here's another immature skua that's not a juvenile.  This one was seen on a sea watch from Sheringham in Norfolk.

I'm not completely sure if it's first-summer or second-summer.  Whilst it had a dark forehead and forecrown covering pretty much the same area as the dark on an adult pale-phase Arctic Skua it wasn't at all well-defined and didn't really recall the dark cap of an adult.  From what I've read a second-summer would be better defined than this, but do you agree that it must therefore be first-summer?  Are there any other pointers visible in the photos that enable us to age it?

And what about the species.  Having discussed it with Rob I think it's an Arctic, and that's what I thought it was in the field too.  While I was watching it I did wonder if Long-tailed could be ruled out, and I'm still not completely certain I've adequately eliminated that possibility.  What do you think?  Is there anything in the photos that clinches it beyond doubt?

probable first-summer Arctic Skua, Sheringham, 27th September 2012

First-summer Pom

I was hoping to come back from the Scilly birders' pelagic with photos of Wilson's Petrels to share with you but sadly that didn't quite work out (again).

Instead here's something a bit different - a Pomarine Skua in first-summer plumage.  Apparently they don't normally get many Poms down there but this year there have been a few, nearly all first-summers.  Not a plumage we get to see very often here in Norfolk, although if I'm perfectly honest it's quite possible I've overlooked it in the past.

Pomarine Skua, MV Sapphire birders' pelagic trip, 12th August 2012

Oh, and while I'm at it I might as well show off a bit of Great Shear action... something else we don't see in Norfolk very often.

Great Shearwater, MV Sapphire birders' pelagic trip, 12th August 2012