Sunday 6 March 2011

6th March 2011 Beachy Head NE3, Willingdon Levels & Pulborough RSPB

Beachy Head
Grey Heron 1 SE
Brent Goose 19E
Peregrine 1
Lesser Black-backed Gull 6 adults on Birling beach
Red-legged Partridge 1
Skylark c.30
Meadow Pipit 6
Lapland Bunting 1 ex.
Corn Bunting 9
Raven 2

Chalk cliffs south of Birling Gap

Birling Gap Hotel

The most-recent cliff fall at Beachy Head


Birling Gap from the top of the lane

Common, Lesser Black-backed and Great Black-backed Gulls at Birling Gap beach

Green Woodpecker at Birling

Grey Heron over Belle Tout

An acrobatic Raven

Willingdon Levels
Barnacle Goose 7N high
Gull sp. adult 12.10pm - 12.30pm then flew south (see below)

Barnacle Geese flying north high over Willingdon Levels

Gull sp. at Willingdon Levels

Whilst scanning through the Gulls present on a lake at Willingdon Levels the above individual's insipid bill colour suggested it warranted further scrutiny. Helpfully being surrounded by adult argenteus Herring Gulls it was easy to appreciate just how weakly-coloured its bill colour was and it was soon apparent that it's upperwings and mantle were clearly of a shade darker and it was noticeably larger than its congeners. I considered it appeared both very long- and slender-billed that gave it a very snouty appearance enhanced by its long white lores underlined by a long gape-line. Its tiny eyes set amidst its streamlined head gave it a distinctive appearance. I felt I was being gifted a large male Caspian Gull, but then there was a concern, its irises appeared strikingly pale, almost white...

However, I knew Caspian Gull could be pale-eyed. So, could this still be the adult Caspian Gull I had been hoping to find for some time now? Was I just relocating the same adult Caspian Gull Andrew Whitcomb had videod here back in December? Whatever, I felt I clearly needed to concentrate on securing some digiscoped images... almost immediately I'd focussed the camera the bird seemed to co-operate by starting to bathe and preen - both raising its wings and even dancing on the water. And then all too soon it flew off west, being lost, one amongst a number of Herring Gulls to leave the lake.

With a sense of trepidation I reviewed the images with the usual concerns of whether any would prove sharp... they appeared better than I'd dared hoped! I felt they'd captured its overall distinctiveness. On enlarging the top image above I felt sure I could see the hoped-for primary pattern shared by Caspian Gull and argentatus Herring Gull comprising an extensive white tip to p10, a white tip and white mirror on p9 and white tips to the remaining outer primaries. Furthermore I could see long grey tongues projecting far along the inner webs of p9 and p8. Its raised wings appeared long and slender - or so I convinced myself! Another image (fourth from top) showed what I considered were pallid-coloured long thin-looking legs. But then there were those eyes, they were undeniably whitish. But surely this was probably an adult Caspian Gull...

We then noticed an assemblage of Gulls in the fields to the west that were ever-increasing in number. Braving the attention of some Water Buffalo (I'm not kidding!) we made our way across to them although rather unfortunately the Gulls were facing into the cold northeasterly wind standing largely face-on from our viewpoint. On a couple of scans there was no sign of our target bird but then there it was - again located by virtue of its subdued bill colour. Reassuringly its headshape appeared very pear-shaped with a long sloping forehead peaking well behind the eye. It still appeared small-eyed but its irises were clearly near-white being encircled by a dark orbital ring, but were they dark red? I couldn't be sure. Frustratingly for most of the next few minutes it remained stood in longish grass mainly obscured by other Gulls and remained persistently head-on so not allowing for any assesment of its leg length, structure, primary projection but at least it allowed a few more images to be obtained. All the Gulls then took flight with most departing south over the industrial estate.

On re-reading last year's BB paper I still considered there was much to support the identification as a Caspian Gull. Admittedly the images fell short of perfect and I freely admitted I couldn't be sure I was 'reading' its exact primary pattern with total confidence. However, I did feel (probably incorrectly) that I could just determine a dark mark on the outer edge of the underside of p5 on the second image above, and whilst I couldn't be sure that the pattern on the underside of p10 was revealed in any of the images, I did feel long white tongues were visible on what are presumably the undersides of p9 and p8 in the eighth image above. However, on discussing the relative merits of the characters shown in the images with JFC and RJF they both stated they wouldn't have been sure on this individual, both citing their concerns predominently surrounding its white eyes - so not the endorsement I was hoping for!

On trawling the internet I found some interesting opposing views as to the purity of apparent pale-eyed Caspian Gulls http://www.talk.gull-research.org/viewtopic.php?f=14&t=367&start=0

Still awaiting the BB follow-up Part 2 paper dealing with the identification of less typical individuals and hybrids I decided to contact one of the co-authors (whom I won't name as I don't have his permission to do so) of Part 1 to seek his views as to whether Caspian Gulls can ever show such pale irises? I received an extremely helpful reply, virtually by return, for which I am extremely grateful not only addressing my query as to the pale iris but also sharing his knowledge in giving a detailed opinion on the bird in question that I slightly edit as follows: 'Whilst this iris colour is rare, they do occur, although ideally there should be some degree of iris speckling. Whilst in isolation this is not a major issue, but in combination with the lack of any dark on p5 which is very problematic in cachinnans (as the vast majority have a full black bar) and the odd fleshy bill tones for such a mature (otherwise adult) bird and some of the latter images making it look rather large headed and the bill rather robust all add together to make this a worrying suspect individual. However, there is a lot of blurring - you really need very good images to sort birds like this out.'

I also took the opportunity to seek an opinion on my Cuckmere first-winter to which the reply was 'The 1w is a cachinnans, no problem. It is easy in e.g. Romania to find birds a lot more heavily marked than this. So I can't see the problem with this - especially the latter image are easily within the range of variability. They can be very dark.'

Wiston
Common Crane 2 adults - a pair ex.

Pair of Common Cranes at Wiston

Pulborough Brooks RSPB
Eurasian White-fronted Goose 1 adult
Bar-headed Goose 1 ex.
Barn Owl 1

Adult Eurasian White-fronted Goose at Pulborough Brooks RSPB

The only White-fronted Goose present being clearly an adult with white flank-line, extensive black belly barring and blaze. Structurally it always appeared a small Goose never appearing long or straight-necked. At great distance, despite the strong sunlight, it was near-impossible to accurately judge the bill colour with it frequently appearing pink (especially in comparison to its orange leg colour as in top image) but at other times wholly orange! Its head, neck and upperparts were an ashy brown appearing rather uniform in appearance. Its tail feathers were tipped broadly white (lower image).

Bar-headed Goose at Pulborough Brooks RSPB