Monday 28 March 2016

Northern Shoveler x Garganey

Northern Shoveler x Garganey hybrid, Mai Po (Hong Kong), 16th March 2016 - copyright John Allcock
(photo ID: 2750)


This interesting bird was consorting with Northern Shovelers and a female Garganey.  Note how the vermiculated rear flanks seem to extend to beneath the tail, which may not be expected.  A quite similar pattern is shown on the Shoveler x Garganey hybrid illustrated on plate 35 of Sébastien Reeber's new Wildfowl book (Helm, 2015).  But the long hanging black-and-white scapulars are a sure sign of Garganey influence.  A faint hint of Garganey's pale supercilium also seems to be just visible in front of the eye.


Northern Shoveler x Garganey hybrid (same bird as in photo ID 2750 above), Mai Po (Hong Kong), 16th March 2016
- copyright John Allcock
(photo IDs: 2751-2752)



Northern Shoveler Anas clypeata
Garganey Anas querquedula

Monday 14 March 2016

Sedge Warbler x Eurasian Reed-Warbler

Sedge Warbler x Eurasian Reed-Warbler hybrid, Lac de Grand-Lieu (Loire-Atlantique, France), 6th September 2015 - copyright Sébastien Reeber
(photo ID: 2745)


Here is a rare but not unprecedented Old World Warbler hybrid.  This individual is clearly intermediate between Sedge Warbler and Reed Warbler.  The head/bill profile seems rather Reed Warbler-like to me but the pale supercilium is broader and more extensive than on Reed Warbler, while less clear than on Sedge Warbler.  The dark eye-stripe is clearer than you would expect on a Reed Warbler and in some photos you can see a narrow lateral crown stripe (upper border to the supercilium).

The upperparts colour tone is close to Reed Warbler but this bird has obviously dark centres to the wing feathers with contrasting pale edges - especially obvious on the tertials which are quite wrong for Reed Warbler.  Note too the strength of colour on the rump.  A hint of dark streaking in the scapulars is visible on one or two of the images, though these are way plainer than they should be on a fresh Sedge Warbler.  It seems to have some pale buffy coloiur extending into the collar which I would not expect to see on a Reed Warbler.  I'm not a ringer so may be misinterpreting the spread wing shot (below), but I think the way the the tip of the second primary (the outermost long primary) falls well short of the adjacent third primary is closer to Reed Warbler than Sedge Warbler (somebody please correct me if I am wrong about that).

It is sometimes said that this hybrid may be misidentified as a vagrant Black-browed Reed-Warbler.  Some hybrids may look more like that species but I don't think you would make the mistake on this individual.  The Sedge Warbler x Reed Warbler hybrid from Finland that featured in British Birds 78: 434-437 (Sharrock, 1985) has a more obvious head pattern and looks like it had plainer wings too, so some individuals may perhaps be more like Black-browed Reed-Warbler than this one.

Probably a tougher ID challenge is separating these from Sedge Warbler x Marsh Warbler hybrids.  That's a hybrid that has been proven to occur in Norway - see Journal of Ornithology 151.2: 513 (Lifjeld, Marthinsen, Myklebust, Dawson & Johnsen, 2010).




Sedge Warbler x Eurasian Reed-Warbler hybrid (same bird as in photo ID 2745 above), Lac de Grand-Lieu (Loire-Atlantique, France), 6th September 2015 - copyright Sébastien Reeber
(photo IDs: 2746-2749)



Sedge Warbler Acrocephalus schoenobaenus
Eurasian Reed-Warbler (Reed Warbler) Acrocephalus scirpaceus
Marsh Warbler Acrocephalus palustris
Black-browed Reed-Warbler Acrocephalus bistrigiceps

Wednesday 9 March 2016

Black-headed Gull x Mediterranean Gull

third-summer (4th calendar-year) Black-headed Gull x Mediterranean Gull hybrid, Christopher Cadbury Reserve, Upton Warren (Worcestershire, UK), 12th March 2017 - copyright John Oates
(photo ID: 3173)


A regularly-returning bird in Worcestershire (central England) has allowed us to see how one example of this hybrid progresses from first-year plumage through to adulthood.  In the following photo when it was in its first summer (second calendar-year) the jet black head and contrasting white eye-crescents recall Mediterranean Gull but the fine bill is more like that of Black-headed Gull.  The shape of the black hood is perhaps intermediate, but certainly doesn't curve up at the rear like it does on Black-headed Gull.  The rather thin-looking reddish legs are more like Black-headed Gull.

Black-headed Gull x Mediterranean Gull hybrid, Christopher Cadbury Reserve, Upton Warren (Worcestershire, UK), 21st June 2015 - copyright John Oates
(photo ID: 2736)


John's flight shot of this first-summer bird (below) shows a wing pattern that is somewhat intermediate between the two species, though perhaps closest to Mediterranean Gull.  There is too much black on the wing-tip for Black-headed Gull, and the grey inner primaries and outer primary coverts are like Mediterranean Gull, yet the band of brown coverts across the middle of the forewing reminds me more of Black-headed Gull.

 Black-headed Gull x Mediterranean Gull hybrid (same bird as in photo ID 2736 above), Christopher Cadbury Reserve, Upton Warren (Worcestershire, UK), 21st June 2015 - copyright John Oates
(photo ID: 2737)


John tells us that the same bird had been at Marsh Lane in April 2015.  What is presumably the same bird returned to Upton Warren in 2016.  As before the blackness of the head recalls Mediterranean Gull, but the shape of the black, with white curving up at the rear, is like on Black-headed Gull.  The wing pattern is perhaps closest to Black-headed Gull with black tips to the primaries, thin black line on outer edge of outer primary and white wedge on outer primaries contrasting with greyer inner primaries.  But there is more black on the tips, which is apparent on the closed wing too, and a long black spot on the outer web of the second outermost primary.



 Black-headed Gull x Mediterranean Gull hybrid (presumed same bird as in photo IDs 2736-2737 above), Upton Warren (Worcestershire, UK), 26th March 2016 - copyright Craig Reed
(photo IDs: 2759-2761)





Black-headed Gull x Mediterranean Gull hybrid (presumed same bird as in photo IDs 2736-2737 and 2759-2761 above), Upton Warren Nature Reserve (Worcestershire, UK), 24th April 2016 - copyright John Oates
(photo IDs: 2788-2791)


It has been seen again in 2017, now in its fourth calendar-year. The wonderful photo at the top of this page was taken at the same time as this next one and both show the distinctive wing-pattern well.

Black-headed Gull x Mediterranean Gull hybrid (presumed same bird as in photo IDs 2736-2737, 2759-2761 and 2788-2791 above), Christopher Cadbury Reserve, Upton Warren (Worcestershire, UK), 12th March 2017 - copyright John Oates
(photo ID: 3174)


There were quite a few reports of this type of hybrid in the UK during the 90s when Mediterranean Gull was spreading in to the UK as a breeding bird.  More recently, as Mediterrean Gull becomes more established as a breeding bird, I get the impression that records have become scarcer again, a pattern that is typically seen when a recent coloniser becomes established.



Black-headed Gull Chroicocephalus ridibundus
Mediterranean Gull Larus melanocephalus

Mute Swan x Black Swan

Mute Swan x Black Swan hybrid, West Midlands (UK), 13th January 2012 - copyright John Oates
(photo ID: 2734)


John tells us that this first-winter bird was the only surviving offspring of a male Mute Swan & a female Black Swan that nested at Marsh Lane Nature Reserve in 2011.  It disappeared shortly after this photo was taken.



Mute Swan Cygnus olo
Black Swan Cygnus atratus

Chiloe Wigeon x Cape Teal

probable Chiloe Wigeon x Cape Teal hybrid, Trittiford Park (West Midlands, UK), 3rd March 2016 - copyright Jenny Renowden
(photo ID: 2742)


One parent of this hybrid seems easier to resolve than the other, though arguably is not the only possibility.  The reddish pink colour on the bill extends well down the bill suggesting a species with a mainly red bill, and Cape Teal fits that bill.  There are other red-billed species, and some Wigeon hybrids are known to show a pinkish bill, but the general appearance of this bird recalls Cape Teal a bit, so that seems a good starting point.  The shape of the bill, quite flattened near the tip, also fits Cape Teal, as does the black base of the bill (although the latter could come from the other parent).  Cape Teal also shows black along the edge of the bill in the distal third, like this bird, and that for me is the clincher.

But Cape Teal doesn't have so much black on the nail, it doesn't have the dark patch round the eye (the eye itself would be pale too) and it is a greyer bird overall.  A number of people have suggested a Wigeon species as the second parent, and that was my idea too.  The dark patch round the eye on an otherwise fairly plain head suggests this, as do the white tertial edges.  But which Wigeon?  Neither Eurasian nor American Wigeon have so much dark extending above the eye to the top of the head, but Chiloe Wigeon does.  The flanks are a bit orangey, which supports Chiloe Wigeon.  I wondered if such a plain bird could be produced from a Chiloe Wigeon, that being such a striking species even in female plumage, but Joern has confirmed that it can.  And what's more he tells us that there have been examples of Chiloe Wigeon x Cape Teal seen in the UK that have looked much like this.

Apparently Chiloe Wigeon x White-cheeked Pintail can also look surprisingly similar to this, so it would be helpful to get a view of the wing pattern to be 100% sure, but for now it seems very likely indeed that this is a Chiloe Wigeon x Cape Teal hybrid.



Chiloe Wigeon Anas sibilatrix
Cape Teal Anas capensis