Bird Hybrids: February 2016

Sunday, 21 February 2016

Recent updates

(photo ID: 2594)

Here's another of our regular posts letting you know what pages have been updated in the project recently. As always, a big thanks to all who have contributed photos and/or insights, and if you haven't done yet or have more to offer then please get in touch. You can comment on any thread if you have anything to say about the hybrids or topics covered, and if you have any photos you would be willing for us to use, please let us know (e.g. by emailing us).

The recent updates are summarised below but remember you can find an index list linking you to ALL the bird hybrids featured so far here:

Index of bird hybrids

And an index list of all the bird hybrid topics covered so far here:

Index of bird hybrid topics

So, the recent updates are:

New Bird Hybrid pages added for:

New photos added to:

Text updated in:

Lesser White-fronted Goose x Ross's Goose

Don't forget you can now follow us on Twitter at @BirdHybrids

Enjoy browsing - and please do contribute where you can!

White-cheeked Pintail x Chestnut Teal

possible White-cheeked Pintail x Chestnut Teal hybrid, Victoria Park (Surrey, UK), 3rd November 2012 - copyright David Darrell-Lambert

(photo ID: 2700)

The identification of this bird is not easy and so far we have not reached a confident conclusion. Provisionally I've labelled it as possible White-cheeked Pintail x Chestnut Teal as of all the ideas that have been presented so far this one seems to me to be the best, but we are by no means sure.

The rather long pointed tail with white sides suggests White-cheeked Pintail to me, though there are other species with relatively long tails and other species with white edges to the tail, so this is not a certainty. The pale cheeks fit with that too, though of course there are many other hybrids that show pale cheeks, so this is not a strong supporting factor. The brown body plumage suggests to me one of the ducks that lack bright body colours, which again fits White-cheeked Pintail (among other species), but of course we do not know that this bird is fully adult, or if it has completed its post-eclipse moult, or indeed if it is intersex. So White-cheeked Pintail is a tentative starting point for me, not a conclusion.

If right, then the second parent must have black under the tail and a green head. Probably a wholly green head as the green looks quite extensive, though hybrids involving Wigeon or Teal have also been suggested. We have seen Wood Duck x White-cheeked Pintail hybrids recently and these have looked quite different, but one of my first ideas was Mallard x White-cheeked Pintail. But this idea did not convince me, or others I asked. Mallard hybrids usually show some hint of the curved central tail feathers, whereas this shows nothing of that. A Chiloe Wigeon x White-cheeked Pintail hybrid looked very different with, among other things, very different pattern to the tertials and scapulars.

It was Joern who first suggested White-cheeked Pintail x Chestnut Teal, though he has been clear that he is not sure and some things seem wrong for this ID. But the tertials and scapulars of Chestnut Teal are rather close to this bird, and the pattern of the flanks (if not the colour) could easily lead to a pattern like the one shown by this bird. And it has a green head and black vent of course, and the bill is not dissimilar either. But should we not expect to see chestnut colour on the body if Chestnut Teal was involved? Certainly some of their hybrids show chestnut on the body. Well, there's a photo of a Cape Teal x Chestnut Teal hybrid in one of the Gillham books (Hybrid Ducks: the 5th contribution towards an inventory, plate 68) and that shows only a hint of chestnut on its breast, not at all on the flanks - so rather like this bird in that respect. We might have expected to see a redder eye on a Chestnut Teal hybrid, but at least it is not darker than that of White-cheeked Pintail (it's actually quite similar to White-cheeked Pintail's eye colour I think).

We've considered other ideas too, involving Teal, Wigeon and even Black Duck, but for me at this point White-cheeked Pintail x Chestnut Teal is the best fit. That doesn't mean it's right though, so please get in touch if you can help clear this mystery up!

possible White-cheeked Pintail x Chestnut Teal hybrid (same bird as in photo ID 2700 above), Victoria Park (Surrey, UK), 3rd November 2012 - copyright David Darrell-Lambert

(photo IDs: 2701-2702)

White-cheeked Pintail Anas bahamensis
Chestnut Teal Anas castanea

Wednesday, 17 February 2016

Yellow-legged Gull intergrades

possible Yellow-legged Gull intergrade, Hyde Park (London, UK), 16th December 2006 - copyright Dave Appleton

(photo ID: 1567)

The Azorean form of Yellow-legged Gull (atlantis) is sometimes considered to be a distinct species (sometimes known as Azorean Gull), and appears to be a rare vagrant to north-west Europe with several credible claims from the UK and Ireland in recent years. The individual shown here showed many features consistent with this taxon but some observers felt that not everything was quite right. Specifically they felt that the tone of the upperparts was a bit too much like michahellis Yellow-legged Gull and the structure was not as it should be. It is possible that it was an odd atlantis, and it is possible that it was a Yellow-legged Gull originating from one of the other Atlantic island populations, but perhaps an intergrade or hybrid between the two might be the most satisfactory explanation.

possible Yellow-legged Gull intergrade (same bird as in photo ID 1567 above), Hyde Park (London, UK), 16th December 2006 - copyright Dave Appleton

(photo IDs: 1567-1570)

Yellow-legged Gull Larus michahellis
Azorean Gull Larus (michahellis) atlantis

Wednesday, 3 February 2016

Herring Gull x Caspian Gull

probable Herring Gull x Caspian Gull hybrid, Millennium Green, North Hykeham (Lincolnshire, UK), 22nd September 2015 - copyright Dean Nicholson

(photo ID: 2652)

Dean thought this bird was going to be a first-winter cachinnans (Caspian Gull) when he first saw it but after a longer view he started to have doubts and suspect mixed genes. He writes:

"Size and proportions were spot on for cachinnans, head and bill shape and position of eye all good, long primaries and tertial pattern was absolutely perfect for cachinnans and the whitish head with subtle mask around eye also fitted cachinnans nicely... I never particularly liked the well barred greater coverts but occasionally some pure Caspian can show this pattern but generally it is much more a feature of young Herrings. I was more concerned by the retarded state of moult... it was still in full juvenile plumage which would be remarkable for a Caspian Gull on this date and should really be showing several second generation scapulars now as well as some renewed coverts. The oak-leafed patterned scapulars were also a bit more Herring-like than I would have liked although when it flapped the underwing/axillaries looked nice and white thus Caspian-like. When I got home I forwarded the pics to my usual gull contacts and they all agreed that this was no pure Caspian and was in all probability a Caspian x Herring which is a common hybrid pairing in western Europe now (especially East Germany and Poland) where Caspians are spreading west."

probable Herring Gull x Caspian Gull hybrid (same bird as in photo ID 2652 above), Millennium Green, North Hykeham (Lincolnshire, UK), 22nd September 2015 - copyright Dean Nicholson

(photo ID: 2653-2654)

Here is another Caspian look-alike. Dean tells us:

"I initially called it a Caspian when I first saw it at range in heat haze but over the following days when I saw it at closer range I realised it wasn’t quite right (slightly odd tertials, dark underwing/axillaries, random scapular moult), so I circulated to my gull contacts for opinion and although there is a lot of guesswork involved with such birds, the general consensus was that it is more than likely a Caspian x Herring hybrid. A common mixed pairing on East Germany and Poland."