A Song and Dance

My winter birding has been absolutely transformed by an unanticipated interest in Sibe Chiffs. I appreciate that many birders have already been down this same road over the years, but for me it's all new really, a fascinating voyage of discovery. The actual birding bit is only part of the attraction. There's also the reading-up-on-it bit, the photography bit, and the audio bit. I love it all, and feel like a detective gathering evidence and building a case...

So it was no surprise to feel the pull of a sewage works once more. Kilmington WTW was just fantastic this morning. The calm, mild air was full of little flies, and everywhere small birds were reaping the harvest. I would estimate 30+ Chiffs at the very least, mostly in trees and bushes adjacent to the works, but also getting along nearby hedgerows too. In addition to several Goldcrests I also saw a Firecrest again, and added Reed Bunting to my Kilmington WTW list by means of a single male. Some Mipits and loads of Pied Wags too, though I didn't see any candidates for White today.

My aim this morning was a decent photo of one or both of the Siberian Chiffchaffs I saw on my initial visit. Within a couple of minutes I spotted one, down the path a way...

Distant Sibe Chiff

Before I got any closer it flicked over some bushes and out of view. Typical...

A few years back, South Devon birder Mike Langman did quite a lot of work with his local tristis Chiffs. One aspect of his investigations involved noting their response to song playback, watching their reaction, and non-reaction, to tristis and collybita song respectively. I have tried this already, back in December, on the Colyton and Chideock birds. My results were positive, but underwhelming, with just a few seconds wing-quivering in response to tristis song, before the birds lost interest and got back to feeding. I am conscious that it is winter and the birds need to feed, so really do not want to overdo it; my efforts in this area have therefore been limited. However, it was a nice, mild morning, one or two collybita were having a half-hearted little sing-song of their own, my tristis had just vanished, so why not...?

The response was amazing! As my phone dispensed a bit of Aves Vox tristis song into the pungent air, not one, but two birds immediately popped into view, their wings quivering like nervous butterflies...

This is one of the two birds mentioned just above. The camera has caught it mid-quiver, and shows you exactly what a lusty tristis will see: sexy yellow armpits. Now there's something to get excited about.

I was completely blown away by this reaction. Compared to what I've had so far, it was almost frenzied! That was good enough for me. These birds were seriously interested in the lovely tristis voice they were hearing. Not a single collybita paid the slightest attention. In addition to the photo above, I recorded a few seconds of video too.

I let them be, and later managed another pretty decent photo of one of the birds...

Barely any yellow-green fringing apparent in the flight feathers of this tristis. Nice.

Not long afterwards I wandered along the cycle path, away from the works, and came across what looked like a pale and interesting Chiff in the top of a tree. The bird was a bit silhouetted, so I tried playing it some tristis song. The reaction was instant, and identical to the earlier pair, and again I recorded a few seconds of video. Here is a still from that video, again mid-quiver...

That is one very excited tristis.

I assume this bird was one of the two seen earlier, but there is a possibility that it could be a third individual. As you can probably tell, my little Sibe Chiff voyage of discovery is leading me towards a solid conclusion. A conclusion which I believe is going to add a great deal of confidence to any future dealings I have with pale and interesting Chiffs. At the end of the day, I simply want to feel comfortable with what I count and what I call it, and be able to explain my position. I'm getting there, but that's for another post...

By the way, I just want to reassure readers that I did not blast these birds willy-nilly, and switched off the recordings within a very short time of seeing a response.

How to Measure Your Caspian Gulls

If you are interested (or think you might be) in the dubious joy to be had from a discussion about Caspian Gull Identification, with particular reference to phenotypic variability and the field characteristics of hybrids, then... Welcome!

The bold print above is taken from the title of a British Birds paper by Chris Gibbins, Grzegorz Neubauer and Brian J. Small, published in December 2011 (BB 104: pp 702-742). Having already published a Caspian Gull ID paper the previous year which dealt with typical individuals, this one focussed on less typical birds and suspected hybrids. The paper provides an objective framework for the treatment of such beasts. Note the word 'objective'...

I have not forgotten that my first response to X78C was not very objective at all. I didn't like its heavily marked underparts, or its chequered greater coverts. I did like its white head, its bill, its long legs, its facial expression and various other features. In the end I decided to count it as a Casp, despite knowing it originated from a German colony where hybrids are present [I nearly typed 'where hybrids are rife' but as I have no idea of the demographic composition of these colonies I shall refrain, and try to be...er...objective]. So, I decided to count the bird as a Casp because I liked it sufficiently well.

Is that good enough?

Well, in the end, when pushed (thank you Steve!) I decided it wasn't. What's interesting is that I know why I liked it. Down the pub I could have argued my case with like-minded gull people. Possibly I would have got a bit exasperated when they didn't agree with my argumentation or see how incredibly solid it was. Maybe I'd have been intimidated by their greater experience and knowledge, but stuck to my guns anyway because I really, really liked it for Casp. I don't know... But what I do know is that my opinion would have been almost wholly subjective.

I find it slightly ironic that just a few days ago I wrote a post called The Expert View, all about measuring things, being objective, and yet here was I being the opposite. So this post is all about me rectifying that...

In their paper, Gibbins et al say this:

'There is frequent debate on internet forums over 'problem birds'. In many cases these debates go unresolved because the views put forward lack an objective or quantitative basis - opinion and counter opinion fuel interesting but ultimately inconclusive debate.' (bold type mine)

The paper goes on to outline a process where certain plumage and structure traits are assessed for each bird (in effect measured), scored individually, and then added together to give an overall total score for that bird. The traits chosen for first-winter birds (October to March inclusive) were as follows, with the available scores in brackets:

• Extent of scapular moult (0-2)
• Greater-covert pattern (0-3)
• Ventral bulge (0-1)
• Primary projection (0-3)
• Moult: greater coverts (0-5)
• Moult: median coverts (0-5)
• Moult: tertials (0-3)
• Darkness of head and body (0-4)
• First-generation tertial pattern (0-3)
• Second-generation scapular pattern (0-4)

In their study, the authors found total scores for pure Caspian Gull ranged from 12-25, for pure Herring Gull 29-37 (ie, no overlap) but for hybrids 22-32. Oh dear, there's an overlap, so any bird scoring 22-25 might be either a genuine Casp or a hybrid. Oops. How do you handle that? Gibbins et al explain...

'...we suggest that 21 should mark the upper limit of safe first-winter Caspian (as birds with scores of 22-25 could be either pure Caspian Gulls or hybrids).' (bold type and underlining mine)

And I would just like to highlight another point made in this fascinating paper...

'Particularly for first-winter birds, the data show that some traits, traditionally thought to be useful for separating the species, are not wholly reliable on their own because of the degree of overlap. Rather than necessarily seeing this overlap as a problem for field identification, we prefer to use it to suggest that certain criteria used in record assessment should be relaxed. Perhaps most obviously, it is clear that a virtually unmarked white head and body should not be a prerequisite for a record of first-winter Caspian Gull - many Caspian Gulls (16% of our sample) were actually rather well streaked (trait score 3). Similarly, some first-winters had heavily chequered greater coverts, so this feature alone should not automatically rule out a candidate bird.'

One aspect of using the total of all the trait scores means that undue weight is not given to any particular trait, and the above quote indicates why this is a reasonable approach.

So, how did X78C fare? That bird returned a trait score of 19. Which is objective enough for me.

What about yesterday's bird? Well, it came out as 18.

The mean score for Caspian Gull in the study was 18, so both birds were more-or-less average. I am guessing this will be a bit surprising to some readers. It was to me. Also surprising was how close their scores were.

Above: 7th Jan bird   Below: X78C (18th Dec)

Here's a fact. X78C comes from a German colony where there are hybrids, as well as pure Caspian Gulls. Provenance of the 7th Jan bird is unknown; it may be from the hybrid zone, it may not. But because we know about this possibility it is very tempting when we see traits in a bird that are a bit more Herring than Casp to effectively downgrade the bird as having had its genetic purity diluted, rather than just accept that such traits are within the variability of Caspian Gull and treat the bird as a whole. In reality the bird may be genetically spot on, and its less-than-classic appearance nothing whatsoever to do with any Herring Gulls in its dark, embarrassing ancestry.

It is thought-provoking that one or two fellow birders felt that yesterday's Axe Casp was a really nice example, or words to that effect. I am not so sure. In the field I thought it looked much darker on top than I would like, and not that great really. Definitely a Casp, yes, but far from a classic one in my opinion. For example, in the comparison shots above, it's pretty clear that X78C has a more Caspy bill. Using a selection of the best photos I could find, the length/depth bill ratio of X78C was almost 3.0, compared with 2.5 for yesterday's bird. Again, using several photos, it looked like X78C just pipped yesterday's bird for primary projection too. A tiny bit more Caspy. Mantle and scaps much more Caspy.

My gut feeling is that those NQS readers who are a bit into their gulls much prefer yesterday's bird to poor old X78C. If, after reading this, that's still the case, well, fair enough, but I really like that lovely white-headed weirdo. In an objective way of course...

Jam is Sweet

My pre-work intentions today involved Sibe Chiff worship, but with the cloud base just above head height and Kilmington WTW therefore totally shrouded, I went straight to the Axe instead. Which turned out more fortuitous than I would have anticipated...

Driving along the estuary I spied very few gulls, and most were small ones. Turning at the bottom end, I pulled up and half-heartedly raised my bins. A handful of freshly-arrived birds were floating along just off the far edge, washing vigorously. One of them looked very interesting, with a clean white head and very Casp-ish feel. I jumped out for a proper look. One or two of the big gulls were already leaving and I realised I was going to get caught out if the Casp-ish one did likewise, so I fumbled around, trying to dig out scope and camera simultaneously, and panicking slightly. It was at this point I noticed some mild trembling. Oooooohhh...it still gets me...

Anyway, enough story-telling. It was a cracking Caspian Gull in 1st-winter plumage, and it remained for about 90 minutes. Best of all, I got to share it - not always an easy thing with an Axe Casp. After about five minutes of photographing it I suddenly realised that Steve might be in his new office, which overlooks this very spot, and gave him a call. He was! Score! Unfortunately no other local birders were able to arrive before it departed.

A few snaps...

The first shot I took, while it was still bobbing about in the water. If you can see what it was that caught my attention, beware, you might be in danger of becoming as sad a gull-victim as I am.

Although much of it is hidden, this is one of the best shots of the tail band. Truly black, sharp, and even with some crisp white tips on it still. Very characteristic. The rest of the tail very sparsely marked.

Portrait shot. Very plain greater and median coverts, with the remains of some light notching on the inner GCs. The mantle and scaps are quite dark for a Casp, with rather strong shaft-streaks and some bold anchor shapes. But that white ground colour to the underparts is nice, and only modestly-streaked/mottled darker on the flanks and belly.

A nicely pale underwing

Dark tertials with diffuse pale tips. Spot on.

Great comparison with similar-aged Herring Gull. A very different look.

Full underwing. Perfect for Casp. Beautifully pale.

All the above were taken with the Nikon P900 of course, but I'm experimenting with 'P' mode, or 'Programmable Auto' at the moment, and had forgotten that I'd left the camera set on it. Even so, I'm very happy with those pics. Apart from the first one, they were all at 2000mm zoom, with the camera supported lengthwise on the scope. The bird was probably 80+ yards away at its closest, and frequently further. Most of the shots here were at the closest range.

The bird was so obliging that I was tempted into trying a video recording. Nothing fancy, I simply pressed the red button on the back of the camera...

Wow!!

I am blown away by the quality! On my laptop it looks amazing. A major asset is the ability to play back your video on the camera's monitor, and extract single frames as a still image. It's like this camera was designed specifically for birders or something...

This post was due to be about X78C, but I think the loyal readers of NQS have suffered enough for one day. Another time.

I can't believe how jammy I've been just lately...

Is It or Isn't It?

Most birders will be at ease with the idea that not all birds can be identified with certainty. Regular seawatchers, for example, will be used to recording 'commic' terns, and will frequently leave distant auks, and even divers or skuas, unidentified. The balance of probability may well suggest that Great Northern is far more likely than Black-throated, but the bird will still go down as 'unidentified diver' because that is the safest call. When you cannot see diagnostic features, mere probability is not good enough.

As an aside I should mention that there are a few birders who will be able to identify absolutely everything they see by jizz alone. But such birders are either dodgy or red-hot (you decide) and we're not going to be talking about them any more. No, this post is about you and me, the everyday birder.

So, birds being unidentifiable is a concept with which most of us are comfortable in certain circumstances. However, the notion is not so easy to swallow when the bird is right there in front of you, giving crippling views. Just occasionally though, the everyday birder is faced with a situation where an easily-viewable, well-photographed bird might not be safely identifiable. And when that happens, every fibre of our being screams in protest, because such a bird simply must be identified. So when might this happen? Well, there are a few scenarios, but I'm going to pick just one, because it is painfully relevant right now...

Gulls. More specifically, putative Caspian Gulls. Even more specifically, X78C.

In THIS post some experienced gull-watchers had reinforced my view that the bird was a Casp, and unsurprisingly I was delighted. I am acquainted with several other very capable birders down here in the southwest who, while perhaps having less first-hand experience with Caspian Gull, are thoughtful, analytical observers, and I value their opinions. Matt Knott had already expressed his view that certain features suggested Herring Gull gene influence, and it was Matt's idea to seek some help from the London contingent. But since their input it's all gone rather quiet. Are my fellow SW birders in agreement with their diagnosis, or not...?

Well, until very recently I didn't know. And then Steve Waite got in touch. I think Steve knows I'm always up for a debate, so here's a potted version of his take on this bird...

• The hybridisation issue with Casp, and how they could look, is unknown.
• How can we be sure that the chequered greater coverts, dirty underparts and less-than-impressive size are actually okay for Casp? And to say they are okay is a guess. 
• We don't know what the bird will look like as an adult. [Steve showed me an example of a bird which had been deemed okay for Casp as a first-winter, but showed obvious hybrid traits in adulthood.]

In a nutshell there are too many red flags for Steve's liking, and for him it's in the hybrid zone. He then apologised for disagreeing with me, as we never have before on a gull's ID. At which I smiled, because if I'm honest I needed challenging on this. Here's why...

In some areas of bird ID I am a bit cavalier. Not with a poorly-seen bird. No, I'll almost always let them go. A late-May probable Short-toed Lark on Beer Head still grates, but I really didn't get enough to claim it. But with birds like X78C this tendency comes out. An obvious hybrid like some of the vile Aythya duck things I have no problem with, but something like this gull brings out the worst in me. For some reason, "Have it!" is my default position.

I'm in danger of going the same cavalier route with the Sibe Chiff issue, which is exactly why I am trying to research it properly. I hope to reach a point where I can safely call a pale winter Chiff a tristis, but I'm not there yet. Not quite.

Anyway, Steve's challenge to my complacency has prompted me to revisit something I should have thought of ages ago...

British Birds 104 - December 2011 - pp702-742

This superb 41-page paper not only analyses the various plumage and structural traits of Caspian Gull, but also provides a scoring system for each, so that you can assess individual birds. In addition it suggests a threshold score, outside which a bird may not safely be identified as Caspian. Assuming my photos provide enough detail I shall duly put X78C through this process, and report back.

Personally I enjoy being challenged on things like this. Hopefully I am open-minded enough to respond positively, and I'm always willing to learn. I try to avoid presenting myself as some kind of 'expert' on anything, because it must be very hard when you have to climb down from such an elevated position to acknowledge a mistake. In my book, good debate drives knowledge.

With grateful thanks to Steve for prodding my conscience thus.

Be Careful HOW You Read!

Somewhere, way off to the east of us, the Chiffchaff subspecies you probably know as Scandinavian Chiffchaff (Phylloscopus collybita abietinus) peters out, and Siberian Chiffchaff (Phylloscopus collybita tristis) takes over. Needless to say, there is no neat, crisply-defined border where abietinus ends and tristis begins. There is an overlap. A contact zone.

And this contact zone (and what goes on there) seems to be the mischievous cause of much of the apparent Sibe Chiff controversy. The unrestrained sexual activity of its Chiffy inhabitants appears to have messed with some of them, both their appearance and their voice, as well as producing all sorts of DNA-related subspecific identity issues.

So, how big a problem is this? Well, the range of tristis is vast. And so is the range of abietinus. So if the contact zone was, say, the size of your local Tesco car park, well, the problem would be microscopically small, wouldn't it?

In the web book Catching the Bug (2019) by Mark Constantine, Nick Hopper and The Sound Approach, there is a fascinating chapter (entitled 'Drab') about using song and calls to identify tristis Chiffs. It acknowledges that there are problematic birds in this contact zone, but then states that according to a study by Marova et al (2009) the contact zone is less than 65km wide, compared with the total east-west range of tristis of some 4000km, and proceeds to use this 'fact' as a basis to minimise the problem. In other words, think 'Tesco car park'.

I'll be honest here. I want to minimise the problem too! So I liked what I was reading. But just to be on the safe side I thought I should check that paper by Marova et al (2009) and see exactly what it said. Well, in searching for it I came instead upon this paper...

Marova et al (2017): 'Interaction between Common and Siberian Chiffchaff in a contact zone' 
Published in Ornis Fennica 94: 66–81. 2017

In the paper is a map, from which I've cropped this bit...

The contact zone is the grey shaded area in the middle

So, is that grey shaded area really less than 65km wide? No. A quick, and very rough, muck-about with Google Maps shows it to be a good 500km at its widest. Also, it's over 2000km long. That equates to very approximately the area of England, Scotland and Wales combined. Times two!

So my hopes of a Tesco car park scenario have been dashed. And it goes to show that what you read must not be taken for granted. Verify. Verify. Verify! I could so easily have repeated that 65km figure right here in NQS, in good faith, and inadvertently misled readers.

Anyway, if you fancy having your brain sucked from your head and liquidised, I heartily recommend that paper by Marova et al. Seriously, it is fascinating.

We read on...

The Expert View

Including the recent pair of birds at Kilmington WTW my winter tally of Siberian Chiffchaffs is now five. Or is it? Are these five birds actually Siberian Chiffchaffs? What exactly is a Siberian Chiffchaff? What about fulvesecens? Is a fulvescens a tristis? What about so-called 'intergrades'? And so on, ad nauseum. To be honest, reading about all this stuff could easily drive you nuts. Why? Because you are constantly presented with one expert view after another, and they don't all tally. So who is correct?

Here's a completely different scenario...

A golfer is standing by his ball in the middle of the fairway, trying to decide how far it is to the hole, and which club he will therefore need. He invites ten expert golfers to offer their opinion. All ten do the same thing. They peer towards the green, estimate the yardage to the hole and offer their view. Some reckon he'll need a six-iron, some a five-iron, one thinks he'll manage with a seven-iron, and so on. So, several different views. Another expert comes up, asks our friend how far he reckons he can hit a ball with each club, then takes a surveyors tape and measures the distance to the hole before offering his opinion. Which expert view would you take?

I am still mid-research with a lot of reading yet to do, but one thing I can say. When it comes to how a bird looks, well, the assessment of colour and tone is a bit subjective, and photographs may or may not tell you the truth. But there are a couple of things you can effectively 'measure', and would therefore seem to me more useful if you want to make an objective assessment. And they are DNA and sonograms. Going on what I've learned so far I would say all my pale and interesting Chiffs would likely return tristis DNA, and if I were to hear them call (just the one so far) and record it, the resulting sonogram would probably be a nice, almost-flat bar at around 4.5 kHz, which would match typical tristis.

I suppose my point is this. When gauging which expert view to listen to, ask yourself what it's based on. For example, how much 'measurement' has been involved, and how recently? Expert views change - or should do - when new criteria or data present themselves. Even our golfing expert with the tape would need to change his opinion if a monstrous headwind began to blow.

How are you on white-winged gulls? Not too tricky, you think? Allow me to present you with an expert view on the field identification of Iceland and Glaucous Gulls...

This is from the 1946 London Bird Report

So, in 1946 one expert view maintained that Iceland Gull was not reliably separable from Glaucous. I don't know how long that view held sway, but hands up who agrees with it now... What, nobody? Of course not. Since then much has been added to our collective knowledge, and it'll be a very rare occasion that the identity of a white-winger is not immediately apparent.

So far then, this is where I've got to...

Is the expert view based on something measurable?
Is it current?

Yes, and yes again? When it comes to expert views then, give that one, at least, some weight.

Fresh Approach For a New Decade

Twitter has been alive today with birdy reports about who has been where and seen what. Me? I had to wait until mid-afternoon for my chance to join the fray. I chose West Bexington, and walked W along the beach to the end of the mere, and back again, slowly...

The entrance to West Bex Nature Reserve is currently a wellies job. Or waders maybe...

I saw singles of Sparrowhawk, Red-throated Diver and Guillemot, 6 Great Crested Grebes, and many gulls. On the mere were Shovelers, Tufties, Teal, Gadwall and more gulls. Whenever I spotted a Med Gull I lingered for a few seconds, and was pleased to realise I've not quite relegated them to dross yet. Water Rails squealed, a Cetti's Warbler did its thing. All in all I was content with my little walk and its outcome.

What I didn't do was write anything down. Nor go out of my way to count anything. I had no expectations, but was happy just to be out there. Since rekindling some enthusiasm for this hobby I've been wondering what I can do to keep the fire burning a bit. Because I need an approach that is going to work long term...

Twitching is one approach. In my younger days I was a pretty keen twitcher. Despite many terrific birds, and a lot of fun, twitching all became a bit meaningless eventually, and is a rare thing today. So no, not twitching...

Another approach is local patching of course, and one that I have tried several times. But for some reason it has never kept me going long term. I'm not sure why. I like the idea of it, but many of the elements that patchers commonly employ to give depth and meaning to their local birding leave me cold. Various kinds of survey, for example. No thanks, I find it a chore. Diligent record-keeping and submission thereof. No thanks, and ditto. Even the simple act of listing doesn't do it for me...

Am I a lost cause? Maybe you've read that last paragraph and judged me a bit of a birding waster. No surveys? And what?! No records either?!! Well, I have tried both, and at one time would have championed the submission of records, but experience has taught me to go with what I've got, not what I would like to have. And though I would like to have that consciencious, contributing-type birder in me, he really isn't there. Sorry.

So what do I like? Well, I like this...

West Bexington this afternoon. Relative solitude.

I also like finding stuff. Now when it comes to finding good birds I know I am not the world's best, but when it does happen I love it. I love the thrill of it. By now most NQS readers will be aware that I love places that are off the beaten track too. I love the feeling that I'm on some kind of 'pioneer trail', even if that's just in my head.

Solitude. Finding stuff. The road less travelled. Put those three things together and what have you got? Possibly, hopefully, a recipe for birding longevity. I am dead fortunate to live in W Dorset. I am surrounded by acres and acres of barely-birded countryside and underwatched coast just begging to be exploited, and not constrained by the self-imposed limitations of a patch.

But am I just a selfish, birding hedonist? a NON-contributor? This thought has crossed my mind, but I am reassured by a couple of things, which I'll illustrate by relating a message that appeared on the Patch Birding WhatsApp group chat today. The gist of it was this:

Kilmington WTW: 100+ Pied Wags, 20 Chiffs, 1 Sibe Chiff, 1 Firecrest and some Goldcrests.

Someone else had visited Kilmington WTW on the strength of my visit yesterday, and scored. I was absolutely delighted to see this message, and (I think) for all the right reasons. Firstly, it felt great to have shared some good birds. If I hadn't visited yesterday, that wouldn't have happened. And secondly, it felt great to have promoted a good birding location, and particularly that one. When I first began birding in the Seaton area, Phil put me on to Kilmington. Apart from the sewage works, there was also a disused quarry that held the occasional Jack Snipe. So, originally Kilmington was part of the Axe patch. And then - around 2006 or so - we deliberately reduced the size of the 'official' patch, and Kilmington, as well as one or two other good spots, fell outside the boundary and have since received far less attention. My 2020 approach to birding is no longer fettered by the confines of a patch, or even a county, and a neglected spot like Kilmington WTW fills my needs perfectly.

Despite how I may come across, I do like to feel I have been helpful and enhanced someone else's birding experience in some way. And I'm hoping my fresh approach will occasionally allow me to feel I have in some way contributed, after all. So far, so good...