Sunday, 24 December 2017

Taimyr Gull (3)

As they'll mostly be Taimyr Gulls Larus taimyrensis that follow anyway, I'll persist with the same title (even though it's not entirely appropriate). I can't believe this weekend's gulling, to be honest, as (from just a very small sample) it's been a case of puzzle gull after puzzle gull! This is great, though, as there really can't be that many groups of birds that you find yourself learning an enormous amount from on each encounter. Gulls, however, need re-learning with each one! I'll start with an obvious individual, then, the cracking first-winter Mongolian Gull Larus mongolicus that has been hanging around Dung Shr for some time. This is terrifically 'typical' in every respect, with its slightly faded reddish-brownish wing that is already starting to contrast with the replaced scapulars (which are of a beautiful silvery-grey type) and the big pale panel in the inner primaries (which have white spots near their tips which interrupt the otherwise dark trailing edge).

This bird can be contrasted with the first of the puzzle gulls, a second first-winter Mongolian Gull, but one of a radically different type! It's identity is betrayed chiefly by its scapulars, which are second generation and hence all new. However, although very pale basally (white), these curiously lack the attractive silvery tones of the 'obvious' individual above. The wing is peculiar, too, as there is no strongly contrasting window and you actually have to look quite hard to see pale subterminal spots. However, the greater coverts are patterned throughout their length (just not strongly) and the wing is already showing signs of bleaching, creating a clear contrast between 'old' (wing) and 'new' (scapulars); a characteristic of Mongolian Gull (and not of Taimyr, in which both should be of the same age and/or show signs of feather replacement with darker feathers).

To illustrate just how different this bird is from 'typical' Taimyr Gull, here's a bunch of first-winters also photographed this weekend. The first bird below is the most similar to the second Mongolian Gull above, as it has yet to start replacing its greater coverts. However, just look at its scapulars! These are blue-grey and plain (with nothing more than a weak central shaft-streak for markings) and lack the subterminal anchor-shaped markings of the Mongolian Gull. The inner primaries also show no suggestion of paler subterminal spots (all dark). The birds below the first one all show signs of feather replacement typical of Taimyr Gull at this age, randomly distributed throughout the mantle, scapulars, 'smaller' wing coverts, and greater coverts (so moult in the wing).

Perhaps mercifully, no first-winter Vega Gulls Larus vegae this weekend, but the puzzle gulls did not end there as there was one further individual which defied convenient placement into category. This odd-looking, tubular-shaped, and very brutish gull seemed to suggest Vega Gull on structure and with its grey tones, but lacked patterned greater coverts, any kind of window above, or a dark belly, so Taimyr Gull remains the favourite explanation. Presumably, this is a very fresh juvenile which has yet to replace anything and take on the familiar appearance of the other first-winters.

Of course there were older birds around this weekend, too, of various ages. The first bird below I take to be a fourth-winter Taimyr Gull. This gave me quite a fright whilst on the water as it looked as though its primary moult was complete. Flying, it can be seen that this is not the case, yet it remains frighteningly close to completion! The brown tones to the primary bases and black in the bill suggest that this is not yet a fully adult bird (and the fresh apical spots that there is no need to consider alternatives, i.e. some southerly-distributed taxon), but compare this to another young-looking bird (by virtue of black in the bill) and it is clear that there are some months between them!

The bird below I'm guessing is a third-winter thanks to the extensive black in the primary coverts, a bit much still in the primaries, and some in the bill. Interestingly, each shot of this bird was taken on a different day, but it is likely the same individual. It does well for fish in the harbour anyway!

I was only able to find a couple of second-winter-type birds (though the last bird has whiter tips to its inner primaries, so may in fact be older than the first one, i.e. a retarded third-winter). I'm still not finding enough of these and require many more before I have them anything like 'figured out'.

Adult-types are looking more consistent to me in terms of appearance than they used to, which I take to be a sign of progress! What did seem unusual to me this weekend was the amount of pale-headed adults around. I seemed to miss any dirty-looking individuals completely, though there were certainly several of these around, too. I'm becoming interested in the appearance of the tongues down the inner webs of P7-6 (for reasons which will become clearer later on); mid-grey merging directly with black or with, at best, 'pencil-thin' white crescents separating the two in Taimyr Gull.

Certainly two (and for my money three) adult (or near-adult) Vega Gulls put in an appearance over the weekend, each one of them being more fascinating than the last. The first of these was the most striking of the three, but never come close enough to get decent images. The combination of such a dirty-looking head and threatening mien can mean only Vega Gull, and just look at those mid-primaries: long pale grey tongues down P6-7 with broad white crescents at their tips (contra Taimyr Gull). Getting better shots of this individual will be a must before the winter is out!

The second adult Vega Gull was arguably more interesting than the first. It shared with that bird the pale mantle and broad white crescents distally on P6-7, and also had a long pale tongue down the underside of P10 (which would be odd for Taimyr Gull). This individual came in very close, allowing me to get clear shots of its head, and to notice something I have never noticed before: Vega Gull (or this one at least) has orange fleshy orbital skin around its eye, unlike the (consistently) deep-vinous-red orbital skin of Taimyr Gull! The last image below compares two adults.

The third Vega Gull of the weekend was arguably the most interesting of all, as it was atypical in terms of its leg colour (orange-toned). Though initially somewhat undecided as to whether or not this might just be some kind of pale-end Taimyr Gull (an explanation completely out of favour with me these days given just how consistent these birds are now starting to look, with any apparent paleness down to bleaching), I am quite convinced that this is in fact a birulai (a Vega Gull with yellow legs), which I come across occasionally but at a rate of no more than one or two per year. In addition to it being a markedly pale bird, the white crescent at the end of the tongue on P6 is too broad for any kind of Taimyr Gull, pale or otherwise, and the bill is also on the dull side.

With all the complexity (and therefore interest) to be found in the puzzle gulls, more obvious birds generate less of an interest in me these days than they once used to (though obviously they still get photographed). The adult Great Black-headed Gull Ichthyaetus ichthyaetus is about as obvious a bird as they come, and it did venture into the harbour for a few minutes late Saturday afternoon. This individual has been returning to winter in the Chiayi area for a great many years now, and is really rather old. Last year, it had obvious wing strain in its right wing when stood, and this year appears to have wing strain in its left wing, too. Given its age, I wonder if this winter might be the last opportunity I will have to play with this striking bird?

As I think I said somewhere above, the more you look at these remarkably complex things, the more there is to learn about them, which I suppose means that my posts about big gulls are likely to get longer rather than shorter! Who knows, there may even be enough in this winter to sustain me until February! Above photos taken at Dung Shr, Chiayi County 22-24/12/17.

Tuesday, 19 December 2017

Taimyr Gull (2)

With so many adult gulls around at Dung Shr Harbour over the weekend, there were also naturally quite a few immatures around, too. The main target for photographs once more was any Taimyr Gull Larus taimyrensis that would stray into range, immatures of which I find really quite astonishing for a variety of reasons. As a northerly breeder, Taimyr Gulls hatch much later than do other, more southerly-distributed big gulls. However, they make up for the 'missing' months by extremely rapid acquisition of adult plumage, becoming ostensibly 'adult' one year in advance of other similarly large taxa. Below is a fairly typical first-winter Taimyr Gull for December. The wing remains fresh and entirely juvenile with nothing as yet replaced. Note especially that there is no real 'window' on the inner primaries, with just a vaguely paler area formed by the paler inner webs of P1-5. The outer greater coverts are also solidly blackish-brown, not patterned (though a variable number of inner greater coverts can be boldly patterned), with no evidence (yet) of any feather replacement. However, there is evidence of replacement in the mantle and scapulars, with some new feathers of a blue-grey 'adult' type mixed in with retained juvenile feathers. The head and body are already very white, contrasting well with the neck 'shawl' typically shown by this taxon. The bill, somewhat surprisingly, is already bicoloured, with a strikingly pale pink base. Depending on the amount of blue-grey present in the mantle, in many ways, first-winter Taimyr Gull looks an awful lot like an oversized first-winter Common Gull Larus canus.

Typically, there is some variation, though this is generally produced by moult progression rather than by any other variable, meaning that first-winter Taimyr Gull is actually quite consistent in terms of its appearance. As with adults, it is also quite distinct amongst its congeners. Below are a few more first-winters which show some of the variation possible at this time of year. The last bird in the set is really quite remarkable as it is already actively replacing its greater coverts, this in December (though an increasing number of birds will resemble this one by February).

Sadly, there were no juvenile Vega Gulls Larus vegae to play with this weekend, but a major target of mine did venture into the harbour: a first-winter Mongolian Gull Larus mongolicus. Immature Mongolian Gulls are usually very worn by the time I start to look at them in February, and I had been hoping to get shots of a relatively fresh one while still early in the season. The bird below is remarkably fresh, and for my money is just stunning! Obvious differences between this and the Taimyr Gulls above are the boldly-patterned greater coverts (throughout their length), the large pale window P1-5, and the gorgeous silvery base tone to the replaced scapulars. Note also how 'brown-toned' everything in the wing is (i.e. the primaries, the primary coverts, the dark bars running through the greater coverts, the 'smaller' upperwing coverts) compared to the 'blacks' of Taimyr Gull.  All of these areas bleach rapidly over the winter, and very quickly Mongolian Gull starts to show a clear contrast between a silvery saddle and a faded brownish (and tatty) wing.

Whilst first-winter and adult Taimyr Gulls are pretty straightforward to deal with, other age classes I find a bit more problematic (though this problem is not restricted to just the one taxon). As Taimyr Gulls acquire adult plumage rapidly, (standing) third-winter birds appear essentially adult, albeit ones with black in the bill and reduced (or no) apical spots at the primary tips. It takes a spread wing to see still more traces of immaturity, these largely in the primary coverts. Birds with a general mix of adult and immature features (extensive grey saddles, grey and brown in the coverts, blackish primaries, tail bands) I take to be second-winters, and two typical birds are shown below.

Both of these have extensively pink bills, whitish heads, contrasting dark nape 'shawls' (extensive and 'dirty' in both, with a 'dusting' of dark around the eye in the right-hand bird), a mix of adult-type and brownish feathers above, immature-patterned primaries, and complete tail bands. P10 seems a little short in both, and is likely still growing.These two were photographed at my 'inland' site, where birds are more distant, and only two second-winters would enter the harbour where they could be photographed more closely this weekend. The first of these was a dark/dirty-extreme individual, with a filthy-looking neck shawl spilling out across the breast, almost in the pattern of Vega Gull. However, the dark inner primaries (and dark saddle) tell us that this cannot be Vega Gull, and the late moult (P10 is still growing) tells us it must be Taimyr Gull, despite other 'oddities' (chief among these being a dark base to the upper mandible).

The second second-winter in the harbour this weekend was about as different as they come, being a clean-bodied individual with few neck streaks. It is too dark for any kind of Mongolian Gull, which the dark inner primaries also eliminate. So, whilst there is limited variation in first-winters and adults, the variation in second-winters is more vast, but this is the case with all of the big gulls!

I got a final treat on my way home from Dung Shr Sunday when I found a beautiful third-winter Vega Gull feeding next to the road as I exited town. This bird bears a very strong resemblance to the 'dirty' second winter Taimyr Gull above, but has much more adult-like outer primaries (as well as fully adult inners) than that individual, and is also way too pale for that species. I tend to associate dark eyes with Vega Gull, too, and this one appeared to be almost completely black!

This will certainly not be the last of the big gull posts, and my enthusiasm for them grows stronger with each one that I see. Hopefully, I'll be fortunate enough to run into a whole lot more of these delightfully puzzling immatures as the winter progresses! Above photos taken at Bu Dai and Dung Shr, Chiayi County 15-17/12/17.