The less said about this morning's almost birdless seawatch, the better. By midday the incessant rain eased a bit, and in a misguided moment of optimism I headed out again, this time for a walk around West Bay. It was like birding inside a cloud, and I got very wet. Bird of the day was this...
Sub-adult Yellow-legged Gull on the left, with
Lesser Black-backed (centre right) and two Herring Gulls.
Photographed at considerable range, through dismal rain and murk. |
Again in the field just east of the old West Bay Station car park, this bird looked very much like the sub-adult from May 1st and 2nd. Sure enough, it was...
Too much gull stuff for May? Sorry, but the rest of this post is also about gulls. Or rather, one particular gull...
I have a soft spot for Lesser Black-backed Gulls. LBBG is currently split into three forms. We have Larus fuscus graellsii, the familiar slate-grey one, which includes our breeding population; we have L. f. intermedius - very dark grey, almost black - with its more Scandinavian distribution; and we have the proper black one: L. f. fuscus, or Baltic Gull, which breeds in North Norway and Sweden, Finland, etc.
I love seeing this migratory species pass through our neck of the woods.
Especially welcome is the occasional passage of intermedius birds, with their
extra-dark-and-dangerous plumage. However, the ultimate prize is Baltic Gull.
Officially, Baltic Gull is a British Birds rarity still. I have never knowingly seen one and there are very few
accepted records, mainly because identification is so difficult. By and large,
the best way to ID a Baltic Gull is by its Finnish colour-ring! No ring? Sorry
mate.
In April, Mike and Alan found a Finnish-ringed Baltic Gull at West Bexington, which I think is now set to become Dorset's first official record of the form. As far as I can recall, all my local Lesser Black-backs have thus far been L. f. graellsii, the slate-grey kind, and I've never needed to concern myself with the intermedius/Baltic conundrum. That is, until last Wednesday.
Among the small gull flock on West Bay's River Brit was a dinky, super-dark Lesser Black-backed Gull. Instantly smitten, I don't think I have ever taken more photos of a single bird...
What a stunning gull! |
The black markings on the bill tell us it isn't an adult, and note the dark tail feather. |
That's a standard graellsii LBBG behind it. Very much paler. |
The open wing confirms its age as 3cy or '2nd summer'. Note the tiny speck of white in each outer primary, stronger on the right wing (see next photo). |
My understanding was that you can frequently get some idea whether a small, dark LBBG is a good candidate for Baltic Gull by the state of its wing moult, but I had to turn to more knowledgeable sources to find out the details. My thanks to Thomas Miller of Oxford, who helped me out with this bird and passed on some excellent reference material. Apparently a 3cy Baltic Gull in May should possess both new (inner) and old (outer) primaries, and the fact that this individual's primaries are all the same age - old and unmoulted - suggest that it is L. f. intermedius rather than L. f. fuscus.
Am I disappointed? Certainly not. As is so often the case with tricky birds, by delving a little deeper I have learned new stuff, and that is never a bad thing. And anyway, how could I be disappointed with such a splendid gull?!
Modern methods of bird ID have certainly moved on from a few decades ago, haven't they Gav? The level I operate at; as in,? species, 'because it looks likes one' wouldn't pass muster anywhere. No, the bird species must be proven. We must have evidence, m'lud.
ReplyDeleteStill, thankfully we've moved on from the Victorian method of proof. Where the case was concluded inside a case. One with a permanent glassy stare 😮
Cameras have been such a game changer. The ability to 'freeze' that open wing and thus analyse individual feather markings...
DeleteSeawatching is still a very 'old style' kind of birding though, where jizz and 'because it looks like one' still rule supreme! 😄