Saturday, 25 February 2012

Glynde, West Rise, Beeding & Burton (25 February 2012)

Saturday 25 February.  A second attempt for the Glynde Great Grey Shrike was almost immediately successful despite light drizzle.  It was along the east then north edges of its favourite field just north of the river.  Next stop West Rise Marsh, Eastbourne where the Black-necked Grebe remained distant and so totally eclipsed by a pair of Great Crested Grebes displaying.  A Cetti's Warbler gave excellent views too but there was no sign of the Goosanders that had been present to Thursday.  At least 5 Cetti's were heard in a walk around Shinewater, a new site for me, but little was seen there other than Gadwall and Shoveler.   Heading back into West Sussex there was no sign of the Bean Geese on Henfield Levels.  Scaning Beeding Brooks from Hillside produced no geese but a look down Smugglers Lane in Beeding was successful with the 4 Bean Geese and 40 Grey Lags.  A Short-eared Owl and another Cetti's was seen on Beeding Levels, 3 Short-eared Owls from Greatham Railway Bridge, 2 Egyptian Geese at Sopham Bridge and finally, at 17:45, a Bittern climbed the reeds and flew a short way in the NE corner of Burton Mill Pond, remaining on view until te light faded at 18:00.  Also seen at Burton was a Kingfisher and 65 Pied Wagtails roosting in the reedbed.

Wet Great Grey Shrike at Glynde.  The apparent white forehead, large wing panel (were it not due to the way the wing is held) and whitish upper tail coverts are features associated with the SE Russian race homeyeri although integrades are not uncommon and the dampness of the bird make its features uncertain.

Black-necked Grebe at West Rise Marsh

displaying Great Crested Grebes at West Rise Marsh

Bean Geese from Smugglers Lane, Beeding
Short-eared Owl on Beeding Brooks
Short-eared Owl at Greatham

Sunday 26 February.  Seawatched from 07.05-08.05 from the end of the West Arm of Shoreham Harbour but little was moving with highlights(?) being Gannet 8E, Tufted Duck 2W, Common Scoter 2E, Black-headed Gull 175E, Razorbill 27 on sea & 1E, auk sp. 23 on sea & 60E and Stock Dove 2W.  At least 7 Purple Sandpipers were feeding at low tide on the rocks halfway down the East Arm (visible, just, from the end of the East Arm) and both Peregrines were on Southwick Power Station chimney.  Lots of gulls all along the beach to Widewatr but nothing stood out amongst yhem and no colour rings were seen.  No sign of the Snow Buntings in a brief look at Widewater but the two juvenile Mute Swans haven't been chased off by their parents yet and the Pintail was still present.

Turnstone on Shoreham Harbour West Arm

Sunday, 19 February 2012

Shoreham Harbour Iceland Gull, Arundel & Greatham (19 February 2012)

Sunday 19 February 2012.  A much more successful day!  I arrived at Shoreham Harbour's West Arm at 07:10 expecting to do a seawatch before going out for the morning with Megan but a first-winter (2CY) Iceland Gull feeding on the beach immediately to the west was a very welcome distraction.  It was a very washed out bird more akin to a second-winter but it had a dark eye.  Also on the beach were two North Thames colour-ringed Herring Gulls HW9T and WR4T.  Offshore Gannets and auks were moving on the horizon and 2 Razorbills were on the sea while 8 Purple Sandpipiers were on the inner arm as the tide peaked.  By now the Iceland Gull, which had been flushed by a dog onto the sea, had apparently flown east.

Iceland Gull on Shoreham Beach
Iceland Gull on Shoreham Beach looking very white in the bright light
Iceland Gull on Shoreham Beach aged as a first-winter by its dark eye

Iceland Gull on Shoreham Beach
Iceland Gull on the sea after being disturbed by a dog
Herring Gull HW9T on Shoreham Beach raising its leg to assist ring reading, except it is upsidedown
Herring Gull WR4T on Shoreham Beach
Six of the 8 roosting Purple Sandpipers (one almost hidden)
Megan and I went to Arundel WWT which was very busy.  I made sure David Cooper wasn't the only Sussex birder to photograph Scaly-sided Merganser this week although Arundel was a very poor second best to Japan!

Scaly-sided Mergansers, sadly not taken in Japan
Harlequins at Arundel, another I'd rather have been watching in Japan
Long-tailed Duck at Arundel, I rarely see them anywhere else these days ...
I finished the day with an excellent couple of hours at Greatham were 2-3 Shot-eared and finally a superb Barn Owl performed very well. 

pale silent Chiffchaff at Greatham, warm ear coverts but very white below
Stonechat at Greatham

Short-eared Owl at Greatham, probably my best views this winter!
Barn Owl at Greatham

Saturday, 18 February 2012

Birling, Glynde, Beeding & Adur (18 February 2012)

A day perhaps best forgotten.  200 auks west off Birling and 40+ Gannets but only a Sparrowhawk aound the gardens there and a Treecreeper and 4 Long-tailed Tits in Belle Tout Wood.  A couple of hours wandering along the river bank at Glynde failed to produce the Great Grey Shrike, although I did flush a Woodcock from a nearby copse.  Simon Linington then appeared and following the old maxim that two pairs of eyes are always better than one, especially if they include Simon's, we tried the river bank for another hour or so but to no avail.  I then went to Beeding Brooks, arriving just as the rain did.  An hour and a half walking around produced two flocks of Greylags but no sign of the 4 Bean Geese that had been present at least until Thursday (weekend birding due to work has a lot to answer for).  Now thoroughly wet I called in at the Adur as it was low tide.  A North Thames colour-ringed Herring Gull was seen but by now the light was too poor to be sure of its ring number.

Sunday, 12 February 2012

Shoreham area and points west (11-12 February 2012)

Saturday 11 February.  A morning at Shoreham Fort, Widewater and the Adur before doing a few chores in town, I then tried Burton Mill Pond for Bitterns but despite staying to 17.45 none were seen.  A red-head Smew, Kingfisher and 7 Mandarins were at Burton with over 150 auks off Shoreham Harbour of which the nearer half were Razorbills.  A Knot was seen on Widewater and then the Adur.  A quick look for the Snow Buntings proved unsuccessful.  The only colour ring noted, despite a number of gulls on the Adur, was what was almost certainly Black-headed Gull R3 at Widewater, unfortunately in water just deep enough to cover half of its ring.

Knot on the ice at Widewater
Gulls on the Adur at low tide
Sunday 12 February.  John King and I had a day in West Sussex.  We stated at Pagham Lagoon where the red-head Smew was on one of the few patches of open water, sharing it with at least 28 Little Grebes, while a Water Rail crept along the edge of the reeds behind.  We moved on to the North Wall where a Bittern had been glimpsed earlier and I heard then saw in flight a Bearded Tit.  We then walked north to North Homer Farm where we were unable to pick the Black Brant out of a flock of about 1650 Brent Geese although not all the flock was viewable.  We eventually tracked down the Whooper Swans a bit further north and also saw a superb male and rather drabber female Marsh Harrier and flushed a Jack Snipe.  We timed out return to the North Wall to coincide with the Paddyfield Warbler's first appearance for over 24 hours although it was very distant and rather brief and we were very glad to have seen it previously.  We headed into Hampshire calling in at Warblington to look for the Cattle Egret but couldn't even find the cows!  Next stop Hayling Oyster Beds where the Shore Lark was still performing and 9 distant Black-necked Grebes were scoped out in Langstone Harbour.  Back to Thorney via Warblington again (some cows were found this time but no Cattle Egret).  We'd hardly arrived at Thorney when the Great White Egret flew overhead high and off towards Prinsted.  Two Avocets were scoped on the Great Deep and we registered a third dip on the Cattle Egret before heading home after a very enjoyable day out.

Whooper Swans north of North Homer Farm, Pagham

Shore Lark at Hayling Oyster Beds

Wednesday, 8 February 2012

Newhaven Caspian Gull trait scores

Caspian Gulls in Sussex are often reported but with very few exceptions rarely are they fully documented.  On a high at having finally found one in the county that I am completely happy with (and have got reasonable images of) and the recent publication of a detailed British Birds article the temptation to try and rectify this was too great to resist.  Without digiscoping this bird may well have got away.  It would certainly have been hard to prove to the counties cynics (of which I'm one)!  Digiscoping doesn't have to be expensive if one has a telescope already and is only interested in a blog or getting images for identification purposes.  My camera cost £85 (although it is an unfashionable yellow!) and I made an 'adaptor' out of a pill box lid and a couple of washers costing 50p that works reasonably well most of the time.

Circumstances of observation. As reported on my blog, Frank Lambert and I found a first-winter (2CY) Caspian Gull about half-way along the West Arm of Newhaven Harbour on Sunday 5 February. It was present from at least 10.15-11.10am. Although it was rather distant, and the light poor for photography, the digiscoped images copied below show most of the necessary features. It was also seen briefly in flight, by both of us, and showed a very pale whitish underwing, white rump and solid black tail bar. John Cooper saw the same bird the following day when it, or a bird appearing similar, was also seen by Tony Cook, Matt Eade and Paul James.

Newhaven Caspian Gull when first picked out
Identification. This appeared a classic individual in every respect with a long, parallel sided predominantly dark bill, small white head with small forward placed dark eye, hind neck streaking, 4 coloured body (white head/underparts, grey mantle, brown coverts and black primaries), all dark tertails with white thumb-nails, long this legs and attenuated rear. It also had the ventral bulge, long primary projection and in flight a very pale/whitish underwing, white rump and black tail bar. However an apparent gull ‘expert’ is alleged to have expressed concerns about it not having sufficient grey on the mantle for this stage of the winter for it to be a Caspian Gull.   This, if true, is nonsense in relation to the bird photographed here if a quick internet check revealing similarly plumaged birds photographed at this time of year is to be believed. Further, in Caspian Gulls “moult is suspended for the winter – most birds complete post-juvenile moult by October with no (or only exceptional) further replacement of feathers beyond this point. Moult commences again in spring from April onwards.” (British Birds 104:709-10). Photographs of a bird taken in March showing less grey on the mantle than the Newhaven Caspian Gull (British Birds 104:plate 420) and another taken in January showing more (British Birds 104:plate 421) add weight to this as once a bird suspends its moult (by October) it will remain more or less unchanged until April (bar any normal wear).

The Newhaven Caspian Gull – a classic in every respect. Long, parallel sided predominantly dark bill, small white head with small forward placed eye, hind neck streaking, 4 coloured body (white head/underparts, grey mantle, brown coverts and black primaries), all dark tertails with white thumb-nails, long this legs and attenuated rear. It also had the ventral bulge, long primary projection and in flight a very pale/whitish underwing, white rump and black tail bar.
Trait scoring. Several highly competent observers have expressed no concerns at all with this birds identification, considering it a classic, but would it stand up to the latest criteria – trait scoring? Identification of Caspian Gull – part 2 by Gibbins, Neubauer & Small (British Birds 104:702-742) is the essential reference for this analysis.

For first-winters seen between October and March the above paper provides a system of scoring based on certain ‘traits’ to differentiate most pure Caspian Gulls from Hybrids. When added up these trait scores will indicate whether a bird is a Caspian Gull (combined score 12-25), Hybrid (22-32) or Herring Gull (29-37). Birds in the overlap zone are best left indeterminate. For a safe Caspian Gull identification a score below 22 is required although the lower the score the better.

Trait 1. Extent of scapular moult. On this bird no first-generation feathers are present. This feature is exhibited in 92% of Caspian Gulls but only 13% of Herring Gulls and 78% of hybrids (based on samples of 63, 85 and 12 respectively). Score = 0.
Newhaven Caspian Gull showing all second generation scapulars.

Trait 2. Greater-covert pattern. This bird had white edges with delicate notches or vermiculations or dark brown centre with white tip to 1/3rd of length. This is shown by 63% of Caspian Gulls, 0% of Herring Gulls and 12% of Hybrids. Score = 1.
Newhaven Caspian Gull showing delicate greater-covert pattern. This also shows the very long, thin legs. Not a trait feature for first-winters but it is for adults where it would score 0.
Trait 3. Ventral bulge. This bird showed a ventral bulge, as did 62% of Caspian Gulls, 14% of Herring Gulls and 34% of Hybrids. Score = 0.
Newhaven Caspian Gull showing ventral bulge

Trait 4. Primary projection. This bird showed a very long primary projection (>0.6). Consistent with 72% of Caspian Gulls but only 6% of Herring Gulls and 56% of Hybrids. Score = 0.
Newhaven Caspian Gull showing primary projection of about 0.65 (roughly 6/9). Note also small head, forward placed eye and parallel sided bill, all features associated with Caspian Gull but not ‘traitable’. This image also shows the long thin legs, attenuated rear (with long primary projection) and 4-toned plumage. In every way the classic Caspian Gull!

Trait 5. Greater-covert moult. Scored from 0-5 depending on the extent of moult (0 almost all, 5 none). Images of this bird and my ability to recognise replaced feathers make this very hard to assess. I can perhaps excuse my incompetence in this area as by early February all second generation feathers would be 4-6 months old and so subject to some wear. It appears that none have been replaced which would be consistent for 35% of Caspian Gulls, all Herring and 78% of Hybrids and would give a score of 5. 
Newhaven Caspian Gull appearing to show all first generation greater coverts
Trait 6. Median-covert moult. Scored from 0-5 depending on the extent of moult (0 almost all, 5 none). As above, images of this bird and my ability to recognise replaced feathers make this very hard to assess, more so as second generation feathers would be 4-6 months old, but juvenile median coverts would be darker with more contrasting centres so many may have been replaced. Assuming the worst, that none have been replaced, would be consistent for 19% of Caspian Gulls, 99% of Herring and 67% of Hybrids. This would give a score of 5 although its true score is probably lower?
Newhaven Caspian Gull not really showing enough detail of median coverts so the worst trait score was assumed (that no feathers have been replaced) although some might be second generation as replaced feathers will be 4-6 months old and so perhaps not stand out that well. The small head and protruding breast show well in this image.

Trait 7. Tertial moult. Scored from 0-3 depending on the extent of moult (0 three or more new tertials, 3 none). Hard to judge but all tertials are assumed to be old. This is consistent with 66% of Caspian Gulls, 100% of Herring Gulls and 89% of Hybrids. Score = 3. 
Newhaven Caspian Gull showing what appear to be old tertials. Also evident the dark tail bar and impressions of the sides of a white rump.

Trait 8. Darkness of body and head. This bird has reduced greyish wash or streaking confined to flanks and single streaks around the neck. 41% of Caspian Gulls show this but none of the sampled Herring Gulls or Hybrids. Score = 1. 
Newhaven Caspian Gull showing reduced streaking confined to flanks and nape, although a score of 0 is almost deserved in this image. Also long legs, small head, predominantly all dark bill and protruding breast are noticeable in this image.
Trait 9. First generation tertial pattern. Shows a diffuse white tip like a Common Gull. Consistent with 65% of Caspian Gulls, 1% of Herring Gulls and 33% of Hybrids. Score = 0.
Newhaven Caspian Gull showing thumb-nail white tips to tertials

Trait 10. Scapular pattern (second generation). Shows strong, contrasting shaft streaks on less than half of feathers. Consistent with 30% of Caspian Gulls but none of sampled Herring or Hybrids. Score = 2. 
Newhaven Caspian Gull showing contrasting shaft streaks on less than half scapulars with the odd diamond-shaped dark centre just about visible in this image
Trait summary. The above trait scores, assuming the worst for covert moult (traits 5 & 6), total 17. An average median-covert score reduces it to 14. The average overall trait score for first-winter Caspian Gulls in the sample was 18.2, within the range 12-25. The range for Hybrids is 22-32. This bird, even with the worst median-covert score has a trait score below the average for the species putting it towards the more distinctive end of the range. This is no surprise given its classic appearance.
Newhaven Caspian Gull - the complete package.
Non-traitable features. Other features noted that are not 'traitable' were the whitish underwing, white rump and dark tail band (seen by both Frank and myself in a brief flight view but sadly not documented), an almost completely dark bill, bill shape (L:D ration of about 3, trait score = 0 were it an adult), small head with small forward placed eye and bulging upper breast. Most of these features are evident in the following images.
Caspian Gull at Newhaven showing a suite of classic features, in particular its very long thin stilt-like legs, protruding breast, small head and forward placed eye

Caspian and Herring Gulls at Newhaven Harbour.  Again the Caspian Gull shows a suite of classic features. Its relatively small size suggests that it is probably a female although this might be over-emphasised as the second gull from the right appears to be a good contender for an adult argentatus Herring Gull with its dark mantle, white primary tips and menacing size.

Caspian Gull at Newhaven showing a suite of classic features, in particular its small head, forward placed eye, lack of appreciable eye mask and in this view a bulging upper breast and ventral bulge

Newhaven Caspian Gull showing a suite of classic features, this angle showing its attenuated rear end