Vega Gull moult timing abnormality

I saw this gull at day's end, the very last light, while looking for a Canvasback to round off a successful twitch for Little Gull on Feb 1.

The Vega is missing four inner primaries on each wing, the innermost secondaries and a few primary coverts. Is it six months early or six months late? The first thought must be that a health issue resulted in suspension of moult. However, if that were the case the outer primaries would be extremely distressed by now, whereas there’s no sign of any wear at all. So, it would appear the bird has commenced moult six months early! Either that or is undergoing an ‘additional’ moult. The possibility that had had spent some serious vagrancy time in the southern hemisphere and had adopted their perverse moult habits before returning north would seem fanciful at best. Needless to say, this is a stage of moult not normally witnessed in Japan.

In the flight images there is a suggestion of pigment deficiency in the flight feathers; if it were a paint job, I’d say the grey doesn’t look evenly applied. However, it’s difficult to rule out photographic artefact under the low light conditions. Even if there is a pigmentation issue, it may indicate some underlying problem that has resulted in this abnormal moult timing. There are two other points to add: firstly that it looks a young adult because of the touch of black in the gonys, but the moult would have synchronized with adult by this age, and secondly that p5 has limited sub-terminal black, unusual but not unheard of for Vega.

2017... how many new birds at the half way point (non-passerines)

Looking back at annual additions to my Japan list over the past 10 years shows some striking ups and downs. 2010 stands out as a miserable effort numerically with just Pied Wheatear and Ferruginous Flycatcher; both on Mishima. While 2014 provided a bumper crop with an amazing 21 new birds.


So how is 2017 faring? Well as we approach the half way stage not too well it has to be said, just the one new bird to date. Mind you Bonaparte's Gull isn't bad, plus it had all the the thrill of a self-find even though it wasn't.


I've realised this is going to be a long post with the number of images involved so I'll split it into two sections. Some of the images I've posted before but others are of birds that didn't fit into any post for one reason or another. I'll start with a couple of shots of that exciting Bonies.

A dinky Black-headed; well done the original finders.

Comparing underwings it suddenly becomes much easier.

Sticking with underwings and this time it's the Black-headed that's the odd man out. Three Saunder's Gulls with a Black-headed for comparison, Saunder's is a more southerly breeder and they acquire their black head (and depart) much earlier.

Still with gulls, this fantastic Thayer's was in its tenth winter on the beach in Tsu city.

Quite approachable on its own.

Here with Vega and Taimyr Gulls.



A better shot of Taimyr Gull.

And the final gull to make the cut is an interesting Vega. In 2013 Peter Adriaens wrote about a useful supportive feature helping to identify American Herring Gull in Europe, stating that European Herring Gulls rarely show an isolated grey mirror in the solid black of p9-10 whereas a larger percentage of American Herring Gulls do. http://birdingfrontiers.com/wp-content/uploads/2013/04/a-new-feature-for-identifying-adult-american-herring-gull.pdf
Here is an example of Vega Gull with the same feature. I'm uncertain what percentage of Vega show this feature because I haven't been looking for it, however it stood out on this bird so I'm guessing not many. Something to look out for in the future.

A clear example of a Vega with an isolated grey mirror on p10.

Moving away from gulls but still on the water this Greater Scaup x Tufted Duck hybrid was only the second I've come across.

Greater Scaup x Tufted Duck hybrid in a large flock of Greater Scaup.

There are plenty of long-legged white birds in Japan, these two species are the rarest of the bunch...

Chinese (Swinhoe's) Egret.

Black-faced Spoonbill.

I started the year in Kyushu, famous for its leggy wintering stuff...

White-naped Crane.

Common Crane.

Sandhill Crane.

Hooded Crane.

American Herring Gulls... or imposters?

I'm too busy at work to get out birding at the moment but the scraps of free time I do have allow me to revisit birds I've planned to post about but haven't. A number of interesting puzzles never make it to the blog because they are overtaken by subsequent birding trips.


On 29 January this year I arrived on the beach in Tsu (Mie) at noon while most gulls were still actively feeding along the tideline and hadn't settled into late afternoon loafing groups dotted along the three-kilometre stretch I usually check. As the afternoon progressed birds began to clump together. If proof were ever needed that the grass is always greener, then the worry that it's always the next flock down the beach that's bound have the more interesting gulls provides it. But frustratingly for the addicted guller there are always new arrivals dropping in on each group plus a toing and froing between groups, so the big find is always just one more short walk along the beach. The beauty of gulling on the Yamatogawa in Osaka is that you can settle comfortably in one spot and let the gulls come to you.


Ultimately the effort was well rewarded and the undoubted highlight was a possible first-winter American Herring Gull. My second possible first-winter of the winter!


American Herring Gull is rare in Japan (how many might go unnoticed is another story) and like other North American taxa, or at least records of them, there is a clear northerly bias to occurrence. Theoretically an adult AHG (I don't have firsthand experience) should catch the eye amongst Vega because of the paler saddle, but I wonder whether this might be less obvious on Kansai's Pacific side because of our generally clear skies and bright sunlight throughout winter. In fact it seems there's been an adult in the area for a while now, though I've yet to connect with it. First-winter types might be more outstanding initially but they could be even trickier to confirm because various features can be shown by three taxa commonly found here.


To identify any potential first-winter AHG these all need to be eliminated; the remarkably variable Slaty-backed, Vega (which can look far more like AHG from my European perspective than do European Herring Gulls argenteus or argentatus), and also some Taimyr Gulls at the brown end of their colour range, these can look very like AHG until they take flight. Then there's the hybrid factor to throw into the mix.


Slaty-backed is an extremely variable taxon at this age, amazingly so in fact, and a few birds do suggest AHG in terms of plumage. However a Slaty-backed's structural differences should be apparent. However any SBG x Vega hybrids could potentially present far more of a challenge. The following hybrid (on this same date) suggested a Vega with a coverts bar when I first saw it, but between bouts of preening (and much to my relief) the head and bill proportions were clearly those of Slaty-backed.

I still haven't seen a certain Vega Gull with such a substantial greater coverts bar but this bird gave me a scare. I may even have passed it over as a Vega had it not been preening and showing off that demanding coverts bar. 

Had I not already seen the coverts bar I could easily have passed this over as a Vega if quickly scanning through the flock, but it had already caught my attention and the head/bill structure and proportions are clearly Slaty-backed rather than Vega. In contrast the long, relatively narrow primary projection isn't something I'd expect to see from any Slaty-backed. In fact, apart from the head proportions and the coverts bar this gull looks a standard Vega.
 

Coming from the UK, but having left before AHG had been recorded, my understanding of the taxon has been fashioned from reports and identification papers heavily weighted towards east coast birds turning up in Europe, stressing overall brownness, uniformity of underparts and frequently an all dark tail and plain tertials to differentiate them from their European counterparts. This probably isn't the best primer when considering AHG from a Japanese perspective. Firstly, though Vega Gull tends to be slightly greyer than the kind of AHG I'd hope to see, it can be uniformly saturated below, anything from cold grey though pale sandy to brown. The greyish variations are commonest. It can also be heavily barred on the rump/upper- and undertail coverts and can more often have an almost entirely dark tail. But reading-up on smithsonianus, I'm led to believe some west coast birds can be less the uniformly brown gull I'd be expecting in Europe; greyer and less uniform overall, some showing more proximal white in the rectrices and  generally edging towards Vega in appearance. Perhaps nailing a first-winter AHG in Japan could be even more difficult than it might be in Europe.


Possibly the most important single feature to separate Vega from AHG is the presence or absence of a prominent greater coverts bar, it's most certainly the feature that's going to grab attention both in flight and at rest. My greatest fear is that some Vega Gulls could show an equally strong coverts bar, I've yet to see an unequivocal Vega with a very prominent bar but such birds could exist. Below are a couple of images of Vega showing a suggestion of a coverts bar, this by no means the worst offender I've seen but, again, they are images of a same-date bird.

It's normal for Vega to have a small group of brown outermost feathers, this bird also has three coverts where the visible dark spots visibly link up to form a solid internal area however there's still a broad white fringe. There's also a certain amount of peppering towards the bases of the outer feathers creating a slightly muddy appearance.

The right wing is distinctly darker but hardly qualifies as a coverts bar. I have seen birds with a more prominent bar than this and the questions really are how substantial can a Vega bar get and how rare are such birds? 

The first of my possible AHGs, and much the better candidate, was two months earlier back on 18 November. I only saw it briefly late in the day and unfortunately missed it fly off while I was changing battery in the camera!

Even head-on, and despite the overlapping flank feathers, dark greater coverts are clearly visible.

Second generation scapulars are already in place and the pale patches on the breast are probably also evidence of moult. The underparts are uniformly dark brown, the vent and undertail coverts densely barred. The solidly dark outer greater coverts and more heavily marked bases inwards, along with the carpal and lesser/marginal coverts create a strong frame to already dark median coverts panel. To me this as much as anything suggests this really is AHG rather than Vega.

A glimpse of the very dark undertail coverts. A few Vega are equally dark.

A 'good' coverts bar, densely barred rump and uppertail coverts plus almost solidly black tail. Because each individual feature can be matched by Vega (apart from a strong coverts bar, I hope) a perfect storm of features on a single gull may make all but the most extreme AHG unidentifiable in Japan. That said, a Vega showing a full suite of AHG features is likely to be much rarer than the real thing!

A closer view and there's no doubt the vent is solidly dark brown and the rump/uppertail coverts show more brown than white.

It looks a particularly long-winged gull at rest, longer at least than the average Vega, but that's pretty subjective. I haven't mentioned the rather uniform blackish tertials as that's yet another feature Vega can match but there's a very obvious difference between this bird and the first-winter Vega in the background. The Vega in the foreground is a sub-adult hence the full primaries at this date (18 Nov), the adult at the rear is typical at this time, as is the adult Taimyr with its retained outer primaries and new inners not yet visible beyond the tertials.

I've significantly lightened this image to try to show the underwing coverts.

And another lightened shot here.

The other taxon to eliminate is Taimyr Gull. Like most, if not all, large gulls they range from overall grey colouration to overall brown. Below is a bird very much at the browner end of the colour range.

On the ground this Taimyr shows a striking superficial resemblance to AHG, it also has a strong brown frame to dark median coverts but even in this partially obscured view the rear belly is contrastingly pale, unlike AHG.

The vent is whitish and sparsely marked.

Once in flight things become much easier. The whiter vent with large brown spots in the longest undertail coverts forming a horseshoe seems typical of the Taimyr I see here.

The rump and uppertail coverts are also mainly white with a horseshoe of bold arrowheads around the uppertails and lines of arrowheads in the middle; no hint of cross bars. The out rectrices are basically white with sub-terminal black, the reverse of AHG. The inner primary window is very subdued with the wings less spread.

The primary window is fairly dark with a strong contrast between the inner and outer webs.

Of course the lack of obvious window and the lack of venetian blinds in the outer primaries also rules out Slaty-backed Gull. So does the long-winged structure of course. If anything you could say Taimyr has the so-called venetian blind pattern on the inner primaries.

So now coming to the recent bird. It would fit in nicely with many images of AHG in California I've seen online. But making a strong case for a bird like this in Japan might be a lot to ask. In the field (29 Jan) I felt it was a strong contender for AHG but checking the images at home doubts crept in. However now that I'm preparing images for this post I'm swinging back towards AHG and feel this meets the criteria for identification as such. Obviously it would be unusual as a Vega otherwise it wouldn't have caught my attention and suggested AHG in the first place. That said, to be 100% certain about the identification is an entirely different matter.

Even at first glance Slaty-backed can be ruled out structure, that long primary projection is wrong. It isn't a Taimyr as the retained scapulars will attest. So Vega or AHG? 

On the pro-AHG side it has a very prominent dark frame to the median coverts panel with a strong greater coverts bar and very dark, uniform marginal coverts. The upper- and undertail coverts are no more heavily barred than many Vega but wouldn't look out of place on many AHG either.

I doubt many Vega (if any?) will have as clear-cut a coverts bar as this. I certainly hope not anyway, put that on a dark Vega and identifying AHG in Japan just became a lot more difficult. 

Even though most  single features wouldn't be out of place on Vega the combination, on top of the bold coverts bar, definitely make this a gull of interest. 

The undertail coverts and vent are heavily marked but the bars are also widely spaced.

The vent is an even brownish. The tertials could go either way but those of Vega are usually far more notched than these. Likewise the primaries aren't convincing; though AHG is meant to have a longer, blacker primary projection I'd defy them to be any blacker than some Vega I see.

A good view of the forewing, the marginal and many lesser coverts are uniformly dark unlike Vega.

My best flight shot; more AHG than Vega on this view. Nevertheless, all I can say with certainty is that the uniform primary window (no contrast between webs) is quite unlike any Taimyr I've ever seen.

So, how many American Herring Gulls? Two...  one...    or none?

A few interesting recent gulls

This is just a quick post to show some of the gulls I thought interesting (for one reason or another) recently. I have mountains of gull images that never see the the light of day, in fact there are files full of images I haven't got round to checking at since the day I took them! Most of these gulls I saw during my last two visits (January) to Mie.

A presumed female Taimyr judging by size. This gull really caught the eye because not many have such yellow legs at this time of year. The moult is at the faster end of the progress scale but not unusual, a couple of other birds had p8 as the longest new feather. Towards the other end of the scale I noticed one gull that hadn't dropped its old p8 yet. 

P8 effectively black to the coverts, it's just becoming blackish-grey proximally though this probably wouldn't be obvious at a any distance. P7 is also extensively black and the black notch on p4 is also fairly standard.

A remarkably small p10 apical spot which at this moment is twinning a tiny p9 mirror.

It's a smallish gull, here with Vegas, I think it's going to have very long primary projection in relation to the rather short tail length when the primaries are fully grown.

With a first-winter Taimyr in the background. Thoughts of possible barabensis crossed my mind at the time but being realistic the fresh primaries due to much later and ongoing moult plus the lack of expected bill markings rule that out. 

The same first-winter Taimyr. The narrow pale tips have worn of the tertails, and fringes from the inner greater coverts, creating a very uniform appearance.

Another adult Taimyr, this still with three retained outer primaries. In the field the legs were pinkish overall as they seem in this image but less so than Vega, on closer inspection however the back of the knee was distinctly yellow and the rear of the tibia only slightly less so. This is closer to the norm at this time of year rather than the bright yellow of the earlier bird.

Mongolian Gull? Here as part of the flock and a couple of heavily cropped individual shots below.

A white head in the flock is always worth checking but a number of Vega can stay surprisingly white-headed through winter. However this bird's structure and extensive black towards the bases of the primaries all looked good for Mongolian (I didn't get flight views) so I was really taken aback to see it hadn't completed its primary moult. All but the very earliest arrivals in November seem to have already completed their moult, perhaps not unexpected in a southern breeder. This bird was even behind the vast majority of Vega in its timing. I still think it is a Mongolian, but one with a noteworthy late moult. 

Vega with a white band through the sub-terminal black of the tail are very scarce rather than rare but this bird wins first prize for style; I've never seen such a well banded tail on any other gull. As for it being a pure Vega... well, it's at the whiter end of the spectrum but nothing to write home about, the oddest features (other than the tail) are its very short legs and small size.



If I had that tail pattern, I'd want to keep it into maturity!

There's nothing in the plumage to indicate it's a hybrid as far as I can see, it's simply a very distinctively patterned bird.

For me this is a particularly dark Slaty-backed, I see a small number like this but they aren't the norm in this region at least.

The same bird in the foreground later in the day. The other Slaty-backed has a more typical saddle colour, in this region certainly. 

This was another dark bird last winter, in flight there was almost no contrast between the outer primaries and the rest of the wing. 

First-winter Slaty-backs show enormous variation but this gull looks good for Glaucous-winged, a bird I rarely see in Kansai.