Monthly Archives: March 2012

Juvenile Thayer’s Gulls from breeding grounds

Wing-tips

Like the teenage dream of the imaginary perfect boyfriend or girlfriend I sometimes wonder if the search image some folk have a vagrant juvenile Thayer’s Gull in Britain, is a bird which doesn’t actually exist!

So to spice up the discussion here are 2 juvenile Thayer’s Gulls. The primaries are still growing, so I think its fair to assume that where they were collected very near to where they hatched (might even be from same brood?). They are from Igloolik, in the northwest corner of Foxe Basin, Nunavut, Canada.  This is core range Thayer’s zone according to the maps. Both birds indeed look basically very similar, both like juvenile Thayer’s Gulls (as I have seen them in Pacific North west).

Critically, one has obviously paler primaires than the other, paler tertials and when I looked carefully at the secondaries they are paler and don’t seem to contrast at all with the rest of the wing. I think a dark secondary bar would not be apparent in the field.

That, as I have argued many times, is the normal variation which can be ascribed to juv. Thayer’s Gulls. The bird I saw in Derbyshire, considered ‘acceptable’ or not- looked just like…a juvenile Thayer’s Gull. The  parsimonious explanation is that it was one, as are most of the other ones which have occurred in recent years in western Europe, even though they vary somewhat in appearance- (just like the juveniles of all large gulls)!

Can of worms or closer to the truth?! Great article by Peter Adraiens b.t.w. in latest Birdwatch mag. Well worth a read. Not what some might expect!

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juvenile Thayer’s Gulls, copyright NHM

End of season: Gull Masterclass Days

Thanks!

The winter season has now finished for Gull Masterclasses in the UK, though I expect plenty of learning for myself as I head off to Israel. Then of course there is Varanger and the Gullfest coming soon! Just wanted to say thanks for all those who attended and made each event such an enjoyable time for me.

Stubber’s Green, West Midlands in February 2012

The most overlooked,interesting gull plumage in the UK? This one on the West Midlands gull day in Feb. 2012. Can you work  out what it is?

Finishing at the Chasewater Roost. Thanks especially to Kevin Clements and Graham Evans

North Wales gang, 3rd march 2012. Thanks especially to Marc Hughes, Julian Hughes and Conway RSPB reserve.

North Cheshire, 17th March after scoring on Arpley Tip. Thanks especially to Bill Morton, Mark Payne, Paul Cassidy (and Waste Recycling Group) and for background info Jason Atkinson, Tom McKinney, Pete Kinsella and Ian McKerchar.

Siberian Gull in Lincolnshire?

pale heuglini/ taimyrensis or lookalike?

Most gull photos I receive to comment on usually fall into one of several ‘expected categories’. Not this one. Dean Nicholson’s regular search of the gulls flocks in Lincoln’s southwest corner (North Hykeham) produced this bird.

Seen briefly on 16th March 2012, very well on 19th March (most photos taken) and again briefly on 21st March and not since. It seemed to associate most especially with Lesser Black-backed Gulls (ranging from typical adult graellsii to black looking intermedius types). Dean described it as:

“An adult – too dark mantled for michahellis or cachinnans but too pale for even the palest graellsii (and with a noticeable blueish tinge), head and hind neck streaking rather odd for time of year, the hind neck streaking forming a ‘shawl’ like on a winter Caspian…no other adult LBB present today had as significant streaking as this. pics shows the mantle tone in comparison with argenteus Herrings and graellsii/intermedius LBB’s.
The bird had single white mirror on p10, there was a thick black band on p5
Although not in the same frame for direct comparison there was a 3W michahellis present today which was seen to be obviously paler than this bird. It really didn’t fit anything particularly well……so what is it?”

and he went on to say:

“and there are some frighteningly close Heuglin’s (of the form taimyrensis) pics knocking about the various gull sites(!)”

A couple of days after main sighting he comments:

“Spent 2 hours this afternoon grilling c40 adult LBB’s and was quite surprised at just how worn the majority of the birds primaries were compared to my bird, most birds showed reduced white tips where the ends had started to wear and a couple of birds already showed totally worn tips making the primaries appear all black. Similarly the head streaking was nonexistent on all but 2 birds which showed just faint ‘pencil thin’ lines around the eyes on to the crown….neither of these birds showed any streaking to the hind neck at all.”

Well I agree. Indeed I was immediately impressed by the birds’ appearance. That is, to me, its looks frighteningly like some pale heuglini- or dare I say example of taimyrensis (whatever that is). In terms of the bird’s appearance:

* droopy billed, dopey look of some ‘Siberian Gulls’ (hard to explain!)

* streaking still present on head, especially concentrated on lower nape

* upperpart tone between graellsii and michahellis

* only one white mirror in outer primaries and at notable distance from feather tip

* extensive black appears to be cover most of p10-p8 and good amount seemingly on p4

Yep. That combination to my eyes is very like taimyrensis. Whether it is one or not is another matter. Now some may be inclined to come rushing in and say that taimyrensis/pale heuglini) only head southeast from breeding ground to winter in Southeast Asia. The great majority of the population may, but I have never been convinced that they all do. The presence of similar birds in the gulf in winter (pers obs, a while back so probably need a refresher) and  passing through Azerbaijan in autumn (C. Gibbins pers comms) suggests otherwise; and why not? Most fuscus head SE- but not all (some go SW). Most mongolicus head east- but not all (some go west). I think most thayeri head SW but not all (some go SE!).

Have a look at the pics and the combination of characters. Interesting no? Certainly got my ‘possible vagrant gull taxa’ juices flowing.

All photos, North Hykeham, Lincolnshire, 19th March 2012 by Dean Nicholson

bit of droopy-billed, ‘dopey’ look. streaking still present concentrated on lower nape

looks like black is present at least on outer web of P4

same features again

all black looking p10- single mirror on p10 and of noteworthy distance from feather tip

’tis the bird on the right- compared with 2 adult Lesser Black-backed Gulls on left

Marsh or Willow Tit

and other fine ‘garden birds’

Nice one- all almost all who had declared were right: it was a Marsh Tit. One of at least 2 coming to feeders right outside the kitchen window of our accommodation at Minsmere RSPB reserve (9-11 March). Good chance to check the features, and much discussed was the ‘new’ feature of pale spot at the base of the bill. This feature was very obvious on one and often hard to see on the other. Willow Tits have an all black bill with no pale bill spot. They called a fair bit and neither had an obvious pale panel over the secondaries as often seen on Willow Tit.

The ‘white spot’ feature…

… seems to be percolating through British birder consciousness. Some of us in the cottage new about it and others didn’t. In a nutshell: Marsh Tits have it, Willow Tits don’t. Aside of the white spot, Richard Broughtons’ study places calls and song, and cheek pattern as the most reliable features for separating these 2 tricky species.

Marsh Tit showing obvious white spot at bill base. one of the most reliable visible characters for separating Marsh and Willow Tits in Britain.

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Marsh Tit,  Minsmere, March 2012. The pale bill spot is weak on this one, but there is pretty obvious contrast in this shot between the small area of white cheek and pale buffy/beige area behind the ear coverts. Willow Tits look more ‘all-white’ here and so give impression of ‘bigger cheek’.

Marsh Tit,  Minsmere, March 2012. White spot at bill base looks bit more obvious here.

Glossy or Matt Black Cap?

Must admit I never got that one. Looked for it as supposed feature and never seemed to see it. For me identifying these 2 species usually boiled down to call differences and the presence or absence of an obvious pale wing panel. The papers highlighted above have certainly sharpened things up and I am please to say, down graded the glossy/ matt feature of the cap!

same Marsh Tit: Above as sun catches= glossy. Below in shadow= matt. Won’t be looking for this character anymore!

could be sometimes trickier to see the white spot with bill full of food…

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Nice plain brown wings, the way Marsh Tits are supposed to look according to my old books!

The more often seen garden birds, showed very nicely at the same feeders:

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Marsh Warbler in November

to compare…

The Linosa acro remains a fascinating bird and one which it seems doesn’t quite resolve, either for those of us who saw it and at least some who have subsequently seen the photos. There are new comments well worth looking through…

Meanwhile, in response, Paul Baxter sent an excellent set of images of what does appear to be a first winter Marsh Warbler from north-east Scotland at the same time of year. A remarkably late record, and v. helpful comparison with the Linosa bird. The images and video below providing lots of learning.

“Just thought, whilst its topical, to share with you some images (and video) of an acro from Aberdeenshire last autumn – a Marsh Warbler in November (unheard of!). I reckon about 3 weeks later than any other Scottish record. When I first clapped eyes on it, I thought this was going to be a BRW, date, behaviour et al. But…. when I started to look at the bird, it didn’t add up. Thank heavens for digital photography :-) Just shows that we have to wide open to all possibilities all of the time.  The bird turns out to be one of our rarest of the year. 

This bird showed a long primary projection.  At least 8, possibly 9, exposed primary tips were visible beyond the tertials.  These primary tips appeared to show very faint white crescents but this could have been an effect of the light.  The tips were evenly spaced.  Several of the images show the emargination to primary 3, but not primary 4.  The emargination on P3 is roughly in line with P7. Also, the tip of P2 falls level with P4. Wing point = P3.

You will see how phyllosc like it was on the video – hovering under sycamore leaves taking aphids like crests. I guess they adapt to whatever food source there is, particularly in late autumn. Always learning!

Paul”

all images: Marsh Warbler, Old Church Kineff, Aberdeenshire, 5th November 2011 (Paul Baxter)

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Video of the bird:

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all images: Marsh Warbler, Old Church Kineff, Aberdeenshire, 5th November 2011 (Paul Baxter)