Wednesday, 9 March 2016

A funny Vega

I visited one of my favourite birding areas yesterday, the Matsusaka / Tsu area in Mie; I'm still there in fact, though the continuous rain forecast from just before dawn doesn't bode well for tomorrow.

The best bird of the trip wasn't actually on the trip but about six hours before I set off. As I was standing outside work enjoying a well earned coffee break at 5:30 on Monday evening a bird called overhead. The single note was enough, though the weird context of standing on the busiest shopping street in the centre of Kyoto meant I didn't recognise it at once, I just knew it was rare. I looked up in time to see a short-tailed "wagtail" pass over head as it called again, a clipped double note this time. Richard's Pipit!

Of course Richard's isn't so rare in Japan, even if I don't see them every year, but I've never seen one in Kansai. And Kyoto city centre is the last place I'd expect to! My first Kyoto city tick since Black-throated Thrush in 2012, bringing my city list up to 213 - fantastic!

Jumping ahead 24 hours, I arrived at my final port of call for the day, the beach just to the north of Tsu city to check-out the loafing gulls. I parked and stuck my head over the beach top to see where the gulls were, one flock about 300 metres south and another almost a kilometre in the other direction. Unloading my gear from the van I decided to try the nearest flock first, there was already someone looking at them, but as I made my way down a single gull took off and headed north; white underwing and limited black on the upperside. It had to be an interesting hybrid, definitely worth following up so I did an about face and started the slog up the beach to the other flock.

There was no sign of the gull there and eventually I headed back to the car park with coffee foremost in my mind. Just before I got there a woman asked if I'd seen the Kanada Kamome (Thayer's Gull)... oops. Don't tell me my interesting hybrid had been a Thayer's. Bang went my coffee.

I was about to join 4-5 birders now standing near the original gull flock when I thought better of it,  they didn't give the impression of looking at anything in particular and I knew 'the bird' wasn't in the other flock so I jump in the van and drove to the fishing harbour along the coast. No luck... no gulls in fact. However from the top of the harbour wall I could make out another gull flock further up the coast. Off I went again.

Most gulls were sitting asleep somewhat head-on which didn't help much, it took a while to completely rule out a couple of Vega with no obvious black on the underside of the far-wing, birds with p10 breaking through to the tip aren't uncommon. Then I came across another individual doing a quite reasonable Thayer's impersonation. If only it would stand up, or just put its head up for starters! I've never seen an adult Thayer's and have the fixed image of a "classic" Thayer's in my mind and this bird wasn't ticking all the boxes. Nevertheless, it is most definitely the best Thayer's candidate I've seen.

Over the years I've seen a number of Vega with thayerii-type p9-10, the earlier ones used to arouse a flicker of excitement but repeated disappointment dulled that. There are rather more Vega x white-wing hybrids which never have aroused much excitement, interesting as they nevertheless are. This bird was different, the underside of the primaries really looked clean white, unlike Vega with thayerii-type primaries, and I've yet to see a hybrid in Japan that can mimic Thayer's as the only white-winged gull that can interbreed with Vega is Glaucous and it's genes have an obvious influence and do nothing to create a delicate-billed appearance. Glaucous-winged just isn't white-winged enough to produce a totally white underwing, and don't get me started on that bill.

This gull seems to had a suitable head shape, the bill is decent, the wing looked on the money though I didn't get more than a glimpse, but... but it just didn't have that "OMG Thayer's!" feel to it. Shorter, darker legs would have helped and the saddle was clearly Vega grey. Of course I must say that this might not be the bird that's being touted as Thayer's and that's part of the reason I'm still here, planning to overnight in the van, I want to search again tomorrow. Err, make that in a couple of hours. Which means this post will be out-of-date before I get to finish it.

Anyway, these are the shots I managed to get in the failing light.

Sitting asleep; the far wing was eye-catching.

A Vega the following morning for comparison; though the mirror breaks through to the tip the black on the outer web of the underside of p10 is extensive. Vega with thayerii-type primaries are closer to the Mie gull of course but the overall Vega feel is usually apparent from the outset.

As it struggled to its feet (I'd have been stiff after sitting so long too) I got the only shot showing the underside of the primaries. By this time the light was very poor so the image isn't sharp but apart from a darker p10 the underwing looks white. I've never seen any Vega with this appearance.

In winter Vega bills are normally slightly greenish-based unlike the more uniform yellow of Mongolian or Taimyr Gulls but the yellow of most Vega is intensifying now so the very greenish base of this bill is slightly surprising. 

A glimpse of what appears to be a thayerii-type p10.

As I've already pointed out, I have no reason to suspect this is the gull that had been claimed as Thayer's, this Vega may be no more than coincidental. I hope to have time at the weekend to sift through the flocks again.

No comments:

Post a Comment