Wednesday, 18 June 2014

Black-capped Chickadee x Mountain Chickadee

Black-capped Chickadee x Mountain Chickadee hybrid, Dallesport, Klickitat County (Washington, USA), 9th January 2011 - copyright Steve Mlodinow
(photo ID: 2195)


The first bird shown here prompted a good discussion when one enquirer wondered why it couldn't simply be a Mountain Chickadee.  One thing that came up is the question of the narrow supercilium, and whether or not this can be matched by pure Mountain Chickadee.  It seems that it probably can when the plumage is worn, but that should not be the case for this individual.  Another feature that is contra Mountain Chickadee is the strength of the buff wash on the flanks.  Cathy also pointed out another feature supporting the hybrid identification - on pure Mountain Chickadee, even worn birds with narrow supercilia, the supercilia meet, or very nearly meet, above the bill.  As you can see on the head-on shot, on this bird the black crown comes right down to the bill, broadly dividing the white.


Black-capped Chickadee x Mountain Chickadee hybrid (same bird as in photo ID 2195 above), Dallesport, Klickitat County (Washington, USA), 9th January 2011 - copyright Steve Mlodinow
(photo IDs: 2193-2194)


The next bird was found by Christian Nunes in a flock of Black-capped Chickadees and one Mountain Chickadee, which is locally rather uncommon.  Steve describes its features:
"The broad black throat patch with somewhat ragged edges where it borders with cheek patch is somewhat typical of Mountain Chickadees in Colorado.  The eyeline is similar to that of local Mountain Chickadees, but narrower.  The broad white cheek patch is more like a Mountain Chickadee, but the buff on the flanks is a Black-capped mark.  The lower edge of the the black throat patch is intermediate between the two species."


Black-capped Chickadee x Mountain Chickadee hybrid, Canon City, Fremont County (Colorado, USA), 19th November 2011 - copyright Steve Mlodinow
(photo IDs: 1348-1350)


Steve tells us that the next one was unlike any presumed Black-capped x Mountain Chickadee F1 hybrids he had seen before.  He explains why he nevertheless believes it is such a hybrid:
"Mountain Chickadee traits can be seen in the narrow white supercilium AND the way the white of the cheek curves up in front of the eye (like a Mountain, but not like a Black-capped Chickadee.  And yes, though the photos all show white over the right eye, such existed over the left eye as well.  When Sean Walters and I first saw this bird a few days prior, the larger and more ragged black throat was also evident, not appreciable in these photos."
Black-capped Chickadee x Mountain Chickadee hybrid, Barr Lake State Park, Adams County (Colorado, USA), 22nd January 2014 - copyright Steve Mlodinow
(photo ID: 1112)


Another one from the same location (or is it the same bird?) was equally difficult.  Cathy wondered if it could be just an aberrant Black-capped Chickadee with extra white feathers above the eye, or perhaps an F2 Black-capped x Mountain Chickadee hybrid.
"It seemed to have a different shape to the white pattern on the face than most of the Black-capped Chickadee with the white coming up slightly in front of the eye and curving up a bit more in the back as well.  Feather edging seemed darker than most Black-capped Chickadee and the sides also seemed more pale (not as buff) than the other Black-caps, but in general this bird's feathers were quite worn looking so not sure this can tell us anything."
Steve is confident this bird was indeed a hybrid, noting that other photos show that it had a more extensive black throat than Black-capped Chickadee.

Black-capped Chickadee x Mountain Chickadee hybrid, Barr Lake State Park, Adams County (Colorado, USA), 5th March 2013 - copyright Cathy Sheeter
(photo ID: 1869)


The next bird shows intermediate traits between the two species.  Cathy draws attention to the noticeable, but quite thin white supercillium above both eyes, which did not meet above bill.  The flanks were orange, but not quite as bright as Black-capped Chickadee.  The bill was long and heavy more like Mountain Chickadee.  Its primaries had fairly thick paler edging, however not as contrasting or pale as expected in Black-capped Chickadee.  It called like Black-capped Chickadee and was paired with one too.


Black-capped Chickadee x Mountain Chickadee hybrid, Wheat Ridge, Jefferson County (Colorado, USA), 28th August 2013 - copyright Cathy Sheeter
(photo IDs: 1858-1859)


Chris tells us that the next bird called like a typical Black-capped Chickadee (he heard only 1-2 samples of one type of call). Black-capped Chickadees are common in the Okanagan Valley where Vernon is located; Mountain Chickadee slightly less so but Chris says it's not unusual to see both species in a morning of birding.  They are not separated by altitude here since Mountains occur all the way to the valley floor and Black-caps can be found in deciduous growth near the tops of 5000+ foot mountains.  Chris described it as a hybrid or maybe a Black-capped Chickadee wearing a rare variant plumage.  The latter is often difficult to eliminate with absolute certainty, but as some of the other examples above demonstrate, hybrids do occur and that therefore seems to be a much more likely explanation for its unusual appearance.

Black-capped Chickadee x Mountain Chickadee hybrid, Kalamalka Prov. Park near Vernon (British Columbia, Canada), 12th October 2016 - copyright Christopher Siddle
(photo ID: 2992)



Black-capped Chickadee Poecile atricapillus
Mountain Chickadee Poecile gambeli

Canvasback x Common Pochard

No photos here yet for this hybrid, but Joern Lehmhus has written about them in the German magazine Aves.  The text is in German but non-German speakers may still be interested as it's accompanied by a couple of photos of Canvasback x Common Pochard hybrids.  You can access the PDF of Aves 3 (2012) - the article starts on page 32 with section 5 covering this hybrid beginning at page 38 - the photos captioned "Hybrid Tafelente x Riesentafelente" (Abb. 26 and Abb. 27) are Canvasback x Common Pochard hybrids.  


If you have any photos of this or other hybrids that you would be happy for us to use here, please get in touch (either leave a comment or email).



Canvasback Aythya valisineria
Common Pochard Aythya ferina

Red-crested Pochard x Tufted Duck

Red-crested Pochard x Tufted Duck hybrid, Pontefract Park, Pontefract (West Yorkshire, UK), 14th February 2017 - copyright Philip Ridsdale
(photo ID: 3078)


This is a very striking hybrid when seen in good light, though I guess could be overlooked among Tufted Ducks if not seen so well.  The strong orange tones to the crown feathers are distinctive (though not very dissimilar to those of a Ferruginous Duck x Tufted Duck hybrid), the back is not jet black and the bill is pinkish.  Like Red-crested Pochard x Common Pochard hybrids the rear border of the black breast is sloped down towards the rear of the duck as it is on Red-crested Pochard.




Red-crested Pochard x Tufted Duck hybrid (with Tufted Ducks; same bird as in photo ID 3078 above), Pontefract Park, Pontefract (West Yorkshire, UK), 14th February 2017 - copyright Philip Ridsdale
(photo IDs: 3079-3081)


Joern Lehmhus has written about this hybrid in the German magazine Aves.  The text is in German but non-German speakers may still be interested as it's accompanied by a couple of photos of Red-crested Pochard x Tufted Duck hybrids.  You can access the PDF of Aves 4 (2013) - the article starts on page 21 with section 2.4 on this hybrid beginning at page 25 - the two photos captioned "Reiherente x Kolbenente" are Red-crested Pochard x Tufted Duck hybrids.



Red-crested Pochard Netta rufina
Tufted Duck Aythya fuligula

Red-crested Pochard x Rosy-billed Pochard

No photos here yet for this hybrid, but Joern Lehmhus has written about them in the German magazine Aves.  The text is in German but non-German speakers may still be interested as it's accompanied by a couple of photos of Red-crested Pochard x Rosy-billed Pochard hybrids.  You can access the PDF of Aves 4 (2013) - the article starts on page 21 with section 2.5 on this hybrid beginning at page 25 - the five photos captioned "Peposakaente x Kolbenente" are Red-crested Pochard x Rosy-billed Pochard hybrids (and I think the sixth one captioned "Wahrscheinliche R├╝ckkreuzung eines Hybriden Peposakaente x Kolbenente mit der Kolbenente" translates to "probable backcrossed hybrid (Red-crested Pochard x Rosy-billed Pochard) x Red-crested Pochard)".


If you have any photos of this or other hybrids that you would be happy for us to use here, please get in touch (either leave a comment or email).



Red-crested Pochard Netta rufina
Rosy-billed Pochard Netta peposaca

Tuesday, 17 June 2014

Barn Swallow x Cliff Swallow

Barn Swallow x Cliff Swallow hybrid, near Kersey, Weld County (Colorado, USA), 15th July 2012 - copyright Steve Mlodinow
(photo ID: 1265)


Steve tells us that this bird was among a flock of about 1000 birds, mostly Cliff Swallows, but also a fair number of Barn Swallows.  They were near a bridge under which both species breed.  The hybrid heritage here is pretty obvious.  When the bird spread its tail more widely, even more white spots could be seen.

Steve had seen two Barn Swallow x Cliff Swallow hybrids previously but neither had the odd (and slightly asymmetric) white throat shown by this individual.



Barn Swallow x Cliff Swallow hybrid (same bird as in photo ID 1265 above), near Kersey, Weld County (Colorado, USA), 15th July 2012 - copyright Steve Mlodinow
(photo ID: 1262-1264)


Barn Swallow is pretty clear in the next bird too, though whether the other parent was Cliff Swallow or Cave Swallow is less obvious.  Steve thinks the dark blue on the throat indicates Cliff Swallow.

Barn Swallow x Cliff Swallow hybrid, north of Cameron Prairie NWR, Cameron Parish (Louisiana, USA), 25th April 2015 - copyright Steve Mlodinow
(photo ID: 2237)


Steve didn't find the next one quite so easy at first:
"I initially glanced at this bird and thought 'Cliff Swallow' given the nicely demarcated dark orange throat.  Of course, it was at some distance, on a wire, lined up with a bunch of Barn Swallows and one Tree Swallow.  It took me quite some time to realize how dark the forehead was, that there was only light streaking on the undertail coverts, and that there was some buff down the flanks.  That sent me off in the Cave Swallow direction.  But the throat was wrong for Cave Swallow.  And I stood stuck.  Michael O'Brien and Peter Pyle kindly unstuck me with the Duh (nicely put) revelation that it was a Barn x Cliff/Cave Swallow.  That would explain the rather extensive buff beneath, the tail nearly reaching the wingtips (whilst perched, of course), and the minimal dark throat markings.  The dark throat, with a hint of dark markings at lower edge, strongly suggests Cliff x Barn Swallow."



Barn Swallow x Cliff Swallow hybrid (same bird as in photo ID 1265 above), near the Logan County entrance to Prewitt Reservoir (Colorado, USA), 15th September 2012 - copyright Steve Mlodinow
(photo ID: 1251-1254)



The next bird is another tricky one.  Dave thinks it may be a hybrid on account of (1) the white forehead recalling Cliff Swallow, (2) the under primaries and secondaries appearing white like Cliff Swallow not dark like Barn Swallow (and not merely made too translucent by sunlight) and (3) the wide breast band possibly showing Cliff Swallow heritage (unlike European Barn Swallows, American birds have only a very narrow and incomplete breast band).

possible Barn Swallow x Cliff Swallow hybrid, Grand Isle, Lake Champlain (Vermont, USA), 11th-12th August 2013 - copyright Dave Hoag
(photo ID: 1802)


Personally I find the underwing colour quite a difficult feature to use as it can look quite pale on Barn Swallow too, depending on the angle and light.  Of interest and possible relevance this link shows a North American Barn Swallow with a not dissimilar forehead patch and a broadish breast band (admittedly not as broad as Dave's bird).  That link came from a discussion about a brown-backed Barn Swallow on the ID-Frontiers listserve and I see that bird also shows a broad breast band, though it differs from Dave's bird in other ways.  I'd be interested in other people's views about this bird... please use the comments to let us know what you think.



Barn Swallow Hirundo rustica
Cliff Swallow Petrochelidon pyrrhonota

Violet-green Swallow x Cliff Swallow

Violet-green Swallow x Cliff Swallow hybrid, Port Susan Bay, Snohomish County (Washington, USA), July 2010 - copyright Steve Mlodinow
(photo ID: 1498)


The green colour in the wing-coverts (or are they not scapulars, Steve?) is pretty clear when you look closely at the top image here, and Steve notes other Violet-green Swallow features including the small white dash over the eye and the short forked tail.  Cliff Swallow is evidenced by the orange-toned rump and collar.  The back has a mixture of green and blue feathers.





Violet-green Swallow x Cliff Swallow hybrid (same bird as in photo ID 1498 above), Port Susan Bay, Snohomish County (Washington, USA), July 2010 - copyright Steve Mlodinow
(photo IDs: 1495-1497)



Violet-green Swallow Tachycineta thalassina
Cliff Swallow Petrochelidon pyrrhonota

Tree Swallow x Violet-green Swallow

Tree Swallow x Violet-green Swallow hybrid, Port Susan Bay, Snohomish County (Washington, USA), 1st August 2010 - copyright Steve Mlodinow
(photo ID: 1494)


This hybrid has not been reported before although a mixed pair once attempted to nest in Illinois.  The lack of reports probably has more to do with how difficult they are to detect than their actual rarity but Steve did really well to pick this one out.  He describes the intermediate rump pattern, the Violet-green like markings on the face that is dark with a masked effect like Tree Swallow and dark along the flanks like on Tree Swallow.  Its tail is shorter than on Tree Swallow (central rectrices barely extending past the upper tail coverts in flight) and no Tree Swallow should show this much white on uppertail coverts. Pointing away from aberrant Violet-green Swallow are the dusky flanks,  limited white on its face and the odd rump patch shape.



Tree Swallow x Violet-green Swallow hybrid (same bird as in phot ID 1494 above), Port Susan Bay, Snohomish County (Washington, USA), 1st August 2010 - copyright Steve Mlodinow
(photo ID: 1492-1493)


Tree Swallow Tachycineta bicolor
Violet-green Swallow Tachycineta thalassina

Carrion Crow x Hooded Crow

Carrion Crow x Hooded Crow hybrid, Svedala (Sweden), March 2008 - copyright Carl Gunnar Gustavsson
(photo ID: 1056)


Carrion Crows and Hooded Crows have in the past been considered to be different races of the same species, although most authorities now treat them as distinct species.  Part of the reason for treating them as the same species was the extensive zone of hybridisation, at least in Scotland.  Some texts I have read seem to play down this overlap zone suggesting it is quite small in reality, but at least in my own experience I have commonly encountered hybrids across a large range within Scotland. Their ranges adjoin elsewhere in Europe too and we have examples of hybrids here from Sweden and Germany.

Some hybrids are superficially similar to Hooded Crows and are sometimes mistaken as such when they turn up in places where Hooded Crows are scarce visitors.  Others are much darker, and easier to overlook among Carrion Crows.  As hybrids are fertile they may backcross with either parent species leading to some individuals that can be very hard or even impossible to detect.  Presumably those hybrids that most closely resemble one or other parent species are backcrossed, but it would be interesting to establish the extent of variation within first generation hybrids - if you have images of birds where the circumstances (not merely the birds' appearance) lead you to believe they are the offspring of a pure Carrion Crow and a pure Hooded Crow, we'd like to hear from you.

This individual photographed by Carl Gunnar seems to be fairly typical of the type that more closely resemble Hooded Crow. In the picture above Carl Gunnar notes the relatively broad black streaks at the bottom of the breast.  In the photos below you can also see black centres to the undertail-covert feathers and also the mantle and scapulars - these feathers would be plain pale grey on a pure Hooded Crow.




Carrion Crow x Hooded Crow hybrid (same bird as in photo ID 1056), Svedala (Sweden), March 2008 - copyright Carl Gunnar Gustavsson
(photo IDs: 1052-1055)


The next one from Germany has a similar pattern but the dark centres of the feathers seem a bit broader making the bird appear darker.

Carrion Crow x Hooded Crow hybrid, Magdeburg, Saxony Anhalt (Germany), 1st May 2013 - copyright Joern Lehmhus
(photo ID: 0549)


Many hybrids are darker such as the one below that shows a dark belly, dark scapulars and a dark back, although the grey on the mantle, sides of the neck and breast is very obvious.


Carrion Crow x Hooded Crow hybrid, Magdeburg Zoo (Germany), 3rd March 2012 - copyright Joern Lehmhus
(photo IDs: 0614-0615)


Next up is another paler bird more closely resembling Hooded Crow, though it has a bit more black on the rear belly compared to Carl Gunnar's bird at the top of this page (photo IDs 1052-1056).



Carrion Crow x Hooded Crow hybrid, Magdeburg Zoo (Germany), 3rd March 2012 - copyright Joern Lehmhus
(photo IDs: 0616-0618)


On the next bird although the grey extends to the back and scapulars it is rather heavily marked dark across the whole area including the mantle.

Carrion Crow x Hooded Crow hybrid, Three Lochs Forest Trail (Stirlingshire, UK), 29th April 2007 - copyright Dave Appleton
(photo ID: 0538)


Next another one with extensive black on the belly but still obvious Hooded Crow influence.

Carrion Crow x Hooded Crow hybrid, Loch Ryan (Dumfries & Galloway, UK), 30th December 2003 - copyright Dave Appleton
(photo ID: 0539)


The next bird is much more like Hooded Crow, and perhaps a backcrossed bird, but it has too much dark at the bottom of the breast and under the tail.  Also when compared to the apparently pure Hooded Crow to its left the grey parts are a shade darker.

Carrion Crow x Hooded Crow hybrid (right, with Hooded Crow to left), near Tain (Highland, UK), 24th February 2012 - copyright Dave Appleton
(photo ID: 0540)


The next two are much darker, though still obviously hybrids.  Interestingly on the first of these the mantle feathers seem to be palest in the centre with darker fringes.  This is perhaps unexpected given that many hybrids show grey feathers with dark centres.


Carrion Crow x Hooded Crow hybrids, near Tain (Highland, UK), 24th February 2012 - copyright Dave Appleton
(photo IDs: 0541-0542)


The next bird is much closer to Carrion Crow than most, so is perhaps a backcrossed bird.  The mantle, scapulars, upper belly and (though you can't tell from this photo) lower breast feathers were distinctly greyish though, albeit far less obviously so than on most of the other birds shown here.  It's another bird where on the mantle and scapulars the feather fringes are dark and the centres are greyer.

Carrion Crow x Hooded Crow hybrid, Arderseier (Highland, UK), 16th March 2014 - copyright Dave Appleton
(photo ID: 1609)


The next few photos were taken from among a large flock of corvids consisting mostly of Hooded Crows but containing a small number of apparently pure Carrion Crows and quite a few hybrids.  In the first photo you have an obvious hybrid back left, a pure-looking Carrion Crow in the centre flanked by two pure-looking Hooded Crows.  I'm not sure the Carrion really was pure though as it seemed to have dark grey centres to the mantle feathers, only a shade paler than the black edges.  I suspect it was a second or even subsequent generation backcrossed hybrid.

Carrion Crow x Hooded Crow hybrid (back left), probable backcrossed (Carrion Crow x Hooded Crow) x Carrion Crow hybrid and two Hooded Crows, West Tarbet (Argyll & Bute, UK), 15th March 2014 - copyright Dave Appleton
(photo ID: 1610)


In the next three photos the second and third images certainly show the same individual.  I think the first image is also the same individual, but if not it is a very similar bird.



Carrion Crow x Hooded Crow hybrid, West Tarbet (Argyll & Bute, UK), 15th March 2014 - copyright Dave Appleton
(photo IDs: 1611-1613)


There are at least two hybrids in the next couple of shots.  The bird in the front is fairly obvious but the more Hooded Crow like bird at the back right is also a hybrid.  The other birds are possibly pure (Carrion on the left and two Hoodies on the right).


Carrion Crow x Hooded Crow hybrids (front and back right, with apparently pure Carrion Crow left and 2 Hooded Crows right), West Tarbet (Argyll & Bute, UK), 15th March 2014 - copyright Dave Appleton
(photo IDs: 1614-1615)






Carrion Crow x Hooded Crow hybrids, West Tarbet (Argyll & Bute, UK), 15th March 2014 - copyright Dave Appleton
(photo IDs: 1616-1620)


The next bird was in the same flock but seems rather unusual in having the palest area on the flanks and lower belly.  Often these parts can be dark on hybrids even when the mantle and upper belly are much paler.  This bird is leucistic, having a pale wing-bar (just visible at the bases of the primaries in these images) and a pale band across the base of the tail (also visible in the first photo).  I suppose the pale flanks could also be down to leucism, but corvids with pale bars in the wings and tail are quite frequent and most such birds don't also express the leucism elsewhere on the body.  Even if it is due to leucism I still think the bird is a hybrid as it shows a ghost of the Hooded Crow pattern, albeit very much darker.


leucistic Carrion Crow x Hooded Crow hybrid, West Tarbet (Argyll & Bute, UK), 15th March 2014 - copyright Dave Appleton
(photo IDs: 1621-1622)


The next photos from Germany all show the same bird which was paired with a Carrion Crow.



Carrion Crow x Hooded Crow hybrid, Braunschweig, Lower Saxony (Germany), 12th June 2014 - copyright Joern Lehmhus
(photo IDs: 1633-1635)


Another clearly intermediate bird from Germany:


Carrion Crow x Hooded Crow hybrid, Frankfurt, Hesse (Germany), 3rd March 2015 - copyright Joern Lehmhus
(photo IDs: 2322-2323)


The front bird here looks pretty good for pure Hooded Crow but the vent is too dark.  Presumably it is a backcrossed bird.

Carrion Crow x Hooded Crow hybrids, Berlin (Germany), 14th January 2016 - copyright Joern Lehmhus
(photo ID: 2624)


The next one is a bit more obvious with extensively dark underparts and back.


Carrion Crow x Hooded Crow hybrid (with Hooded Crows), Berlin (Germany), 14th January 2016 - copyright Joern Lehmhus
(photo IDs: 2621-2622)


The next one isn't so solidly dark where a pure Hooded Crow would be pale, but it does have fairly obvious dark feathering throughout much of the pale part of the plumage.

Carrion Crow x Hooded Crow hybrid, Berlin (Germany), 14th January 2016 - copyright Joern Lehmhus
(photo ID: 2623)


Joern reports that the majority of Carrion/Hooded Crows he saw during a short stay in Vienna were hybrids and backcrosses with birds showing a wide variety of appearances, some close to Carrion Crow and others close to Hooded Crow.  Below is a composite of some of them.  There were also phenotypically pure examples of both species present, not shown here.

Carrion Crow x Hooded Crow hybrid, Vienna (Austria), October 2016 - copyright Joern Lehmhus
(photo ID: 2887)



Carrion Crow Corvus corone
Hooded Crow Corvus cornix