A Puzzler

There was a strong south-westerly blowing this morning, so I made the effort to wrap up in multiple layers and waterproofs in readiness for a protracted seawatch. I don't know why I bother. I endured 30 minutes of infinite direness, peeled off a couple of layers and went for a short, uneventful walk at Cogden. Three Chiffs and a Blackcap are not enough meat for a full NQS post, so I'm going to pad it out with something which I've been wanting an excuse to write about...

After the morning Wryneck two weeks ago I went to work over in Seaton. As is often the case, at lunchtime I found myself picking through the Axe Estuary gulls. A preening first-year bird on the far bank caught my eye, mainly because I glimpsed the tail pattern and thought it looked extremely contrasty. A strongly black-and-white tail is a good indicator for Yellow-legged or Caspian Gull. Unfortunately it turned out to be neither, but was nevertheless interesting enough to hold my attention for a while. A few photos...

On the water it looks quite unexciting. The tertials and greater coverts look pretty bog standard Herring Gull, as do the head and bill. However, moult-wise it seems to have a lot more 2nd-generation (ie, first-winter) scapulars than you would normally see on a Herring Gull of this age in Devon in early(ish) September.

And that underwing is strikingly pale. If it had been a Caspian Gull I would have been pointing that out as a feature in its favour!

Again, not many of those scaps are still juvenile feathers. Quite a strong inner primary window though, which suggests Herring Gull to me more than Casp, and definitely more than YLG.

But look at that tail pattern! Again, if it had been a Casp I would be highlighting how the crisp, black terminal band contrasting strongly with a vivid white uppertail supports the identification!

So, what is it? When I posted these pics on Twitter I got very little feedback. Probably nobody fancied sticking their neck out. One birder whose opinion I respect suggested it was just a Herring Gull. And he may well be right. However, in my own experience I cannot recall ever seeing a juv/1st-winter HG display such a striking tail. Combine that feature with the rather advanced scapular moult and the pale underwing, and I cannot help thinking that this is a hybrid beast. I doubt it's a pure HGxCasp, but would be surprised if there were not some Caspian Gull genes somewhere in the mix.

All good fun. And a reminder that gull ID is frequently not a done deal. It's funny, I am conscious that some birders think I'm quite good at gulls, an 'expert' even. Nothing could be further from the truth. I am a learner.  Please be aware, when asking for my opinion on a bird you are doing the birding equivalent of asking the keen DIY-er to build your two-storey extension. He might gamely have a go, but...

Anyway, here are a couple of pukka Axe Caspian Gulls for comparison...

December 2011. Although this bird has quite a strong inner primary window, note how dark the outer webs of those inner primaries are in comparison to the bird above.

March 2012. Photo by Dave Land. Note wing and tail patterns.

So, apologies for such an early gull post. Hopefully some proper autumn fare will get things back on to a more appropriate footing soon...