White-winged gulls

By Dominic Mitchell

One of the big birding events of this winter has been the record influx of Iceland Gulls, and anyone with an interest in gull-watching will hopefully have made the most of the opportunity to study this scarce Arctic species. The closely related Kumlien's Gull has been caught up in the influx too, and there have also been reasonable numbers of Glaucous Gulls around Britain and Ireland. There's therefore no better time to get to grips with these large, and largely white-winged, species before they head north-west for the summer.

For this reason Peter Adriaens looks in more detail at the specifics of Iceland v Kumlien's Gull in the April issue, and we'll be uploading more photo resources on the Birdwatch website to supplement this in-depth photo guide. But especially for those with less experience of gull ID, this British Trust for Ornithology video on YouTube offers additional advice on the identification of Iceland and Glaucous Gulls:

A(nother) mystery gull

By Keith Vinicombe

The odd gull (second from right). Note the slate-grey upperparts, heavy dark neck streaking, the heavy bill and dark-centred tertials (despite the adult-like plumage).

I didn’t make a New Year’s resolution, but if I had it would have been to give up looking at gulls. Or to be more precise, big gulls. This is because I’ve come to the reluctant conclusion that they’re more trouble than they’re worth, as the following example will illustrate.

I came across a really odd gull on 23 January – a first for Britain no less. Well, that was my fantasy. To get my retaliation in first, it was probably just another hybrid. It was on Herriott’s Pool at Chew Valley Lake, Somerset, where hundreds of gulls come in to bathe every afternoon prior to joining the 60,000 strong roost. To all intents and purposes, it was a Lesser Black-backed Gull, except that its upperparts were very obviously a shade or two paler than the accompanying British graellsii. I managed to take a few digiscoped photos, some of which are reproduced here.

It was in fact a very distinctive bird: dark leaden grey above with a very thick and obvious white tertial crescent. What was particularly odd was that it retained very distinctive neat brown bases to the tertials, the only signs of immaturity on what was otherwise a fully adult bird. Structurally, it was very similar to a Lesser Black-back, being rather tapered in shape, but it had quite big, almost ‘woolly’ head and its bill looked consistently longer and heavier, with a stronger gonydeal angle.

The mystery gull (right). Note the thick, blunt bill with a strong gonydeal angle, the heavy and extensive head streaking, the dark upperparts and the dark-centred tertials.

The obvious answer to such an ‘intermediate’-looking bird is that it is a hybrid: probably a Herring x Lesser Black-back, or maybe even a Lesser Black-back x Yellow-legged Gull. But, if it was either of those combinations, why did it have heavy and extensive head streaking? It had a profusely and finely streaked head, with the streaks become blacker and much more lined on the sides of the neck. The streaking then spread more diffusely across the upper breast to form quite a definite hood. Having already moulted into summer plumage, virtually all our local argenteus Herring Gulls are white headed and, as the above photos show, our local Lesser Black-backs are rapidly heading the same way (and agentatus Herrings are rare around here).

In flight it showed yellow legs, pale grey under primaries and secondaries (paler than graellsii) and a very thick white trailing edge to the secondaries – thicker than Lesser Black-back– contrasting with the leaden upperwings. It also looked stockier bodied in flight.

Note the pale grey under primaries and secondaries, the very thick white trailing edge to the secondaries and the heavy neck streaking.

It reminded me of photos that I had seen of Heuglin’s Gull – in particular the more eastern taimyrensis, which may be a hybrid form between heuglini and the eastern Siberian Vega Gull L vegae. When I got home, I had a look at the Gulls in Oman website which has some excellent winter images of taimyrensis. The Chew bird looked superficially similar to some of those images, but looking at the books was a different kettle of fish – they are so bogged down in detail that you can’t see the wood for the trees.

One ray of sunshine was Hadoram Shirihai’s account of heuglini and taimyrensis in the Macmillan Birders’ Guide to European and Middle Eastern Birds. Specific points he mentioned included: the moult (Heuglin’s moults very late, with adult’s primaries often still growing into late winter); the single isolated mirror on the outer primaries (confined to P10); the well-streaked head and neck; and traces of immaturity on otherwise adult-like birds – the last three points all fitted the Chew bird!

It had a single isolated white mirror to P10, something apparently shown by Heuglin’s Gull. Note also the fresh primaries.

But I accept that the bird was probably a hybrid, just like all the others. But the problem is, even if you do get an excellent candidate, such as the Rainham Slaty-backed Gull, how do you prove to the satisfaction of a national records committee that it’s 100 per cent genetically pure? The answer is that, without a DNA sample, you can’t – and even mitochondrial DNA can’t always provide a definitive answer, not least because it only follows the female lineage.

Cackling Geese: a closer look

Richardson’s Cackling Goose Branta hutchinsii  hutchinsii (Blagdon Lake, Somerset, November 2011). Note the square head, tiny bill, dark breast and white neck collar (photo: Nigel Milbourne).

By Keith Vinicombe

On 1 November, Nigel Milbourne discovered an unringed Cackling Goose at Blagdon Lake, Somerset, feeding with feral Canada and Barnacle Geese. He identified it as a Richardson’s Cackling Goose Branta hutchinsii hutchinsii and posted some good photos of it on www.blagdonlakebirds.com. Eventually, the bird came to its senses and moved to nearby Chew Valley Lake, but it soon moved again with the Canada Geese, this time to Torr Reservoir, near Shepton Mallet, where it remains. Disappointingly, the bird information services universally dismissed it as an escape. To rewind seven years ... 

In 2004, the American Ornithologists’ Union separated the seven large forms of Canada Goose from the five small forms, which they lumped together as Cackling Goose. In 2005, this treatment was also adopted but the British Ornithologists’ Union. However, for some reason the BOU decided to rename the two species Greater Canada Goose and Lesser Canada Goose. One problem with this is that Greater Canada Goose now includes the subspecies known as Lesser Canada Goose Branta canadensis parvipes, meaning that this form should, presumably, now be known as Lesser Greater Canada Goose! Given this oxymoron, Birdwatch decided to follow the more sensible American terminology in its Birds of Britain: the Complete Checklist, and British Birds has recently done the same. Given that these geese breed entirely in North America, then we in Britain surely should defer to the AOU’s decision on terminology.

To return to the Somerset bird, there was the inevitable argument about its identity but the issue was quickly put to bed by David Sibley, respected author and illustrator of the Field Guide to the Birds of North America. He came down in favour of it being hutchinsii and, interestingly, explained that this form is actually very variable in both its breast colour and in the presence or absence of a white neck collar; he also sent a very interesting and informative photograph to prove this (for further discussion on the ID of Cackling Geese, see http://www.sibleyguides.com/2007/07/identification-of-cackling-and-canada-goose/).

Richardson’s Cackling Goose Branta hutchinsii hutchinsii (Blagdon Lake, Somerset, November 2011), here with a feral Canada Goose Branta canadensis. It was tiny, estimated to be about 10 per cent smaller than the feral Barnacle Geese it sometimes accompanied (photo: Nigel Milbourne). 

The breeding range of Richardson’s Cackling Goose extends eastwards into north-eastern Canada and includes Baffin Island. Therefore, on geographical grounds it is the subspecies most likely to occur in Britain, and the records so far support this. Greenland Barnacle Geese (and sometimes Pink-footed Geese) act as the ‘carrier species’, the initial vagrancy presumably occurring in the Arctic. This Barnacle population winters in the Hebrides, western Scotland and western Ireland, which is where the majority of Richardson’s occur. But could they also get here on their own? Given that American ducks and even Sandhill Cranes do so, then the answer must surely be ‘yes’.

Autumn 2011 was exceptional for American vagrancy (we have had 17 American birds at Chew alone), a combination of an excellent breeding season in the Arctic and some very strong westerly gales. There has been a significant arrival of at least nine Richardson’s Cackling Geese elsewhere, with four on Islay, one in Mayo, one in Donegal and three in Sligo. In addition, one turned up on the Gwent Levels on 13 November (it was still there on at least 24 December – see www.gwentbirding.blogspot.com). Like the Somerset bird it was unringed, and furthermore it turned up at the same time and place as Gwent’s second-ever Greenland White-front.

Richardson’s Cackling Geese winter in Texas and northern Mexico, but this season there have been a number of wintering records over a thousand miles away in north-eastern Canada, where they do not normally winter. There have also been abnormally high numbers of Canada and Snow Geese lingering there. As in Europe, funny things seem to have been happening with their goose movements. Andy Davis has trawled some North American websites and has come across the following recent records of hutchinsii:

Ontario
* October 27: five near Toronto.
* Early November: two Ottawa (still reported 3 December).
* December 4: eight at Point Pelee and one at Markham.
* December 11: up to five in the Constance Bay area (present for previous 10 days or more).

Nova Scotia
Early November: one (locality not specified).

New Jersey

December 2: seven in Weequahic Park, Newark.

Obviously it’s difficult to be sure about the origins of any vagrant wildfowl, but what are the chances of two unringed Richardson’s Cackling Geese turning up only 15 miles apart at a west coast locality in an exceptional autumn for American vagrancy? Add to this the fact that there has been (a) a significant arrival of the species in western Scotland and Ireland, and (b) apparently abnormal movements in north-eastern Canada and the USA, then surely we have to keep an open mind about these birds.

P.S. Examination of photographs of the Somerset bird revealed that it is a first-winter (not an adult as currently reported by the bird information services). The scapulars clearly show a contrast between the majority of adult feathers, which are square in shape and thickly tipped with buff, and a few lines of remaining juvenile feathers, which are rounded and faintly fringed with dull buff. We have also heard of further reports of unusual winter records of hutchinsii Cackling Geese in Ontario, with up to 30 in one area.

Semi-retrospective Sandpiper

By Keith Vinicombe

On the morning of Thursday 10 November, I discovered a greyish stint feeding with a Dunlin at the mouth of Hollow Brook, in the north-eastern corner of Chew Valley Lake, Somerset. I simply couldn’t get close to it, but it appeared to have a solidly dark crown, with no split supercilium, and a fan-shaped patch behind the eye. It also lacked any trace of a white mantle V, seemed to show a short primary projection and appeared to have a black shaft line on the feathers of the upper row of lower scapulars, expanding into a black blob towards the feather tips. All these features suggested a juvenile Semipalmated Sandpiper.

Semipalmated Sandpiper (smallest shorebird in centre of image, just right of the much-twitched Sharp-tailed Sandpiper, Chew Valley Lake, Somerset, 19 November 2011). The bird's unsplit supercilium is just visible on this photo. By Richard Andrews.

However, it was just too far away to convince me. I went back the following day and watched it for several hours, but I still couldn’t get any closer. I returned again on 15 November, this time armed with an old 60x zoom lens, which I managed to lose in the middle of a reedbed! I spent half the morning trying to find the bloody thing, which, amazingly, I did. Unfortunately, the views were no better, but I did secure 54 rather poor digiscoped images, none of which was sufficiently detailed to provide the proof that I was looking for. Reluctantly, I came to the final conclusion that I had to let it go.

On the weekend of 19 and 20 November, the stint relocated to Herriott’s Bridge at the southern end of the lake, but it was still distant (300 m). The problem now was that everybody was completely distracted by the presence of a juvenile Sharp-tailed Sandpiper that was in the same flock! I decided to try for better views once the crowds died down, but unfortunately, it left overnight on 20th.

Semipalmated Sandpiper (centre bird, Chew Valley Lake, Somerset, 19 November 2011). Note the dark crown and small fan-shaped patch behind the eye, both just visible on this digiscoped image. By Richard Andrews.

It seemed doomed to remain ‘the one that got away’, but about a week later, I had a light bulb moment. On 19 November, Richard Andrews had photographed the Sharp-tailed Sand from a ringing ride near Herriott’s Bridge. I phoned him and asked if, by any chance, he had the stint in any of his photos. To my amazement, he did, and promptly sent me 14 quite reasonable shots of it. As I opened his email, there right before my eyes, was the confirmation that I had been looking for: it was indeed a juvenile Semi-p, just beginning its moult into first-winter plumage!

Needless to say, I felt both elated and vindicated, but I also felt a little uneasy about claiming a bird retrospectively from a series of digital images. Call me old fashioned, but I prefer to identify my birds in the field. Thinking it over, I decided on a belt and braces approach: I sent the photos to Killian Mullarney, who very kindly and very promptly replied with a strong endorsement of the ID as a Semi-p.

This was the lake’s 10th BB rarity and the 16th American bird of a truly remarkable autumn. Even the ‘Good Old Days’ weren’t that good!

Wilson's Snipe

Now split from Common Snipe Gallinago gallinago, Wilson's Snipe G delicata is the lookalike Nearctic counterpart. For decades distinctions between the two have been murky, with much variation and similarity clouding the picture, but in recent years the ID criteria have become clearer and Wilson's - although still bestowed with mega rarity status - is being identified with increasing confidence and regularity in Britain. It surely remains under-recorded here, however, given that 115 have now been recorded in the Azores (for full details see the Birding Azores website).

A major photo ID guide in the January 2012 issue of Birdwatch looks at this problem, with extensive photos of both Common and Wilson's Snipe and discussion of the ID criteria for the rarer species. These videos, shared from YouTube with due credit to those who shot the footage, supplement the still images in the magazine.

 The above clip has interesting 'song' on the soundtrack.

Wilson's Snipe: accepted British records

• 1998: Lower Moors, St Mary’s, 9 October 1998-7 April 1999 (British Birds 101: 539-540).
• 2007: Lower Moors, St Mary’s, a first-winter on 3 October, with the presumed same bird from 1 October to 22 April (British Birds 103: 587); also three juveniles moulting to first-winter plumage at the same site, 21 October-26 December (British Birds 104: 582).
• 2008: Wingletang, St Agnes, 11 October (British Birds 104: 582).

In addition, it seems highly likely that the autumn 2011 bird, present at Lower Moors from September into November and documented so thoroughly with photographs, will become the seventh accepted record in due course.

References and further reading 

Bland, B. 1998. The Wilson’s Snipe on the Isles of Scilly. Birding World 11: 382-385.
Bland, B. 1999. The Wilson’s Snipe on Scilly revisited. Birding World 12: 56-61.
Reid, M. 2008. Identification of Wilson’s and Common Snipe. British Birds 101: 189-200.
Rowlands, A, Small, B J, and Bradshaw, C. 2009. From the Rarities Committee’s files: Identification of Wilson’s Snipe and assessment of the first British record. British Birds 102: 425-434.

Continental Greylag Geese

Three of the continental Greylags at Chew Valley Lake.

By Keith Vinicombe

As many people will be aware from the various bird information services, recent weeks have seen a major displacement of Tundra Bean Geese into Britain, as well as flocks of White-fronted Geese occurring in areas where they are not usually seen. However, a third species of goose, Greylag, seems to have fallen below the radar, despite unusual records at a number of places, such as Portland Bill in Dorset.

Being a common feral species, it would be easy to assume that these records lack significance. However, on 17 November, I came across a party of five at Blagdon Lake in Somerset, an unusual record there for the time of year. When I looked at them through the scope, there was something distinctly odd about them, although I couldn’t put my finger on what it was. However, they seemed very fresh and immaculate and both their upperparts and flanks were very heavily barred with white.

A couple of hours later, I was at nearby Chew Valley Lake when, at about 13.30, I heard some Greylags calling. A flock of nine appeared high over the lake and dropped in just to the north of the hide. Their behaviour was strongly suggestive of wild birds and, like those at Blagdon, there was something ‘odd’ about them. I took a large number of digiscoped photographs, and a couple of the better ones are shown here.

Note the pink bills and subtly different bill shape.

According to BWP, there are two subspecies in Europe, nominate anser and eastern rubirostris. Anser occurs in Iceland, Scotland and coastal Norway and has a shorter, thicker and rather triangular bill, predominantly orange in colour (with just some pink behind the tip). Also, it has a pale buffy-grey head and neck and finely barred upperparts and flanks. Our feral breeding birds seem to correspond with this race. Rubirostris, however, is slightly larger and generally paler than anser, with stronger and whiter transverse barring and a longer bill that is wholly pink, apart from the white nail. Birds in central Europe are apparently intermediate.

The Chew birds were indeed heavily and contrastingly barred, they also had longish and rather thin bills, perhaps recalling the bill of Taiga Bean Goose in shape. Their bills were predominantly pink, although at least some had orange at the base. Also distinctive was that the white nail at the tip of the bill was very obvious and contrasting. From BWP, it was clear that they did not fit nominate anser, although, given the orange at the bases of their bills, they did not fit pure rubirostris either. However, they were clearly some way along the spectrum towards that subspecies.

Since then, Nigel Milbourne sent me a good photo of two of the Blagdon birds, and this shows that the left hand one did indeed have an all-pink bill (see ‘Latest news’ at www.blagdonlakebirds.com for 17 November). On re-checking my own photos, it appeared that some of the Chew birds also had all-pink bills. That being the, case, I can’t see any reason why these particular individuals should not be regarded as pure rubirostris. Whatever their exact racial assignment, the important point is that it's safe to conclude that they arrived from continental Europe and were not feral or Icelandic birds. This is the first firm evidence of wild Greylags occurring at the lakes, although the late Bernard King saw a bird at Steart, Somerset, in April 1952 that resembled rubirostris.

Apparently, there has been a big movement of Greylag Geese on the French side of the English Channel, with 200 past Jersey this month and “thousands” past various sites in Normandy. These are thought likely to be Swedish birds deflected westwards en route to Spain (www.guernseybirds.or.gg). It would seem that, like the Tundra Beans and European White-fronts, there has also been a major arrival of continental Greylag Geese - right under our noses!

Roosting Caspian Gulls

By Keith Vinicombe

On a recent trip to East Anglia, one of our target species was Caspian Gull, and a report of six at Minsmere persuaded us to pay a late afternoon visit to the RSPB’s flagship reserve.

A lot has been written about Caspian Gulls in recent years, but this has tended to polarise birders into two camps: those who fully embrace the subject and those who steer well clear of it – many people are simply put off by all the detail.

Among all the talk of black bars on P5 and white tongues on P10, one thing that tends to get overlooked is the species’ jizz. Or to put it another way: how would you notice a Caspian Gull in the first place? Our experiences at Minsmere may help to clarify this. On our arrival, a quick scan through the gulls soon revealed a strong candidate. It was sitting down, front on, with its neck hunched into its body, as shown in the digiscoped photo below.

The adult male Caspian Gull is the bird at the front sitting down. Photo by Keith Vinicombe.

It stood out from the nearby Herring Gulls due to its pure white head, its beady black eye, its long down-turned gape line and its rather long, slim, washed-out, yellowy bill. It was a large, bulky bird, with a deep and well-rounded breast, but it also had a gently rounded head and, unlike the other large gulls, a rather benign, gentle character.

Front on, the combination of its woolly white head and beady eyes reminded me of an albatross, something that has struck me on previous occasions. The colour of the upperparts varied, looking similar to the accompanying Herring Gulls when front on, but a darker, flatter shade of grey when side on, more similar to Yellow-legged Gull.


After a while it became active and its entire shape was transformed. The head appeared small and rather rounded (although, surprisingly, it could also look very square), the bill seemed long, slim and tapered (lacking a strong gonydeal angle) and the neck was very long too. One of the most distinctive things about the extended neck was that it seemed to have an extra curve, producing a prominent bulge at the front, which gave the impression of a full crop (see the photo below).

When active, the male showed the classic Caspian gull shape, with its small rounded head, beady black eye and long, slim, tapered, washed-out bill. Note the prominent bulge in its long neck, resembling a full crop. Photo by Keith Vinicombe.

Its facial expression was completely different from the Herring Gulls, with its black eye and a narrow white upper eyering – a combination that imparted a soft, almost dopey look. The bill was a washed-out, dull yellow with small black marks behind the red spot. When walking around, the legs looked long and spindly, and they were a rather insipid greyish-pink.


After a while, a second bird glided in and sat down next to it. It was pretty much identical, except that it was distinctly smaller in every respect. The birds seemed comfortable in each other’s company and it was clear that they were a male and a female, perhaps even an established pair.


Much of the excellent work on Caspian Gulls has been carried out on rubbish tips, where the birds may be very active in their search for food. Consequently, what tends to be emphasised in the literature is their long, slim, tapered bill, the small pear-shaped head and the long, thin neck. However, their structure often looks quite different at nocturnal roosts, where the birds are relaxed and ‘ready for bed’. Instead, the head looks woolly and rather rounded and they appear short necked when the head is sunk into the shoulders. Also, because the relaxed feathers makes the head look larger, the bill does not stand out as being that different from other large gulls, in either its length or its structure.

For birders searching for Caspian Gulls in evening roosts, this relaxed, rounded pose is the normal default posture. At Minsmere, this was particularly true of the female, which often looked surprisingly Herring Gull-like in its structure and overall appearance, as shown below. In fact, at rest, the female reminded me of a giant Common Gull, with that same gentle expression, a high, rounded crown and a full, rounded breast. Also, it was not as long billed as the male.

The female Caspian Gull (middle, next to a Lesser Black-back) was distinctly smaller than the male and, as this photo shows, could like rather Herring Gull-like. Photo by Keith Vinicombe.

When relaxed, the female had a rounded body (with a full breast) and a very rounded head. The bill was shorter than the male's and did not look particularly long. Photo by Keith Vinicombe.

This is the same female, side on. In this photo, you can make out the darker grey upperparts, the dark eye and the slim, tapered bill. It also shows the flat crown and low forehaead, which are more typical of active Caspian Gulls. Photo by Keith Vinicombe.

Having soaked up the birds’ characters, we did, of course, look at the important primary pattern. Adult Caspian Gulls have much less black in the open wing than both Herring and Yellow-legged Gulls, with the black is, to all intents and purposes, confined to the rim.

At rest, the important feature to look for is the pattern of the underside of the outer primary, which is readily visible on the ‘opposite’ underwing, especially when the bird is preening its primaries. Caspian Gulls have a large white mirror at their wing-tip but there is also a long lobe of white on the inner web of the outer primary and this is separated from the white mirror by a relatively short area of black. This white-black-white pattern is very distinctive.

Three final points are worthy of clarification:
• Although the above account emphasises the black eye, when carefully scrutinised in good light, both these Caspian Gulls showed pale eyes, albeit a dull ivory colour. This is in fact perfectly normal in good, close range views – I once checked hundreds in the Ukraine!
• Although winter Caspian Gulls are often said to be white headed, they do in fact acquire grey head streaking just like other large gulls. It’s just that this streaking is so fine, so pale and so delicate, that it is often not visible except on very good views. Believe it or not, both the birds illustrated above had this streaking, but it normally manifested itself as a light dusting of grey that was not immediately apparent.
• It is also worth remembering that there is complete overlap in the bill measurements of Caspian, Herring, Yellow-legged and Lesser Black-backed Gulls.

Just before we left Minsmere, a third Caspian Gull dropped in, completing an excellent couple of hours of educational gull-watching!