Thursday, 8 February 2018

Caspo Number Ten!

There's been really good numbers of large gulls on the Estuary today, including notably more Great Black-backed Gulls which is always a good sign (means they're coming in from the sea). I was really hoping for a white-winger, but a text from Gav informing me of a Caspian Gull just before 3pm had me hurrying down to the Estuary.

Just as I pulled up at the lower end of the Estuary Gav informed me it had flown south, but luck was on my side as I could see it flying towards me low over the water. Pleasingly it landed again and remained here until at least 5pm...

First-winter Caspian Gull

Front to back; first-winter Herring Gull, first-winter Caspian Gull, second-winter Great Black-backed Gull

Front to back; second-winter Herring Gull, first-winter Herring Gull, first-winter Caspian Gull


Although I marvel at every Caspian Gull I see, as first-winter Casps go this isn't the best. It's bill in particular is pretty feeble, being only slightly narrower and longer than the nearby Herring Gulls. Also note how mottled the flanks are and it even has a bit of a shadow around it's eye.  Still a striking looking thing though.

It's definitely not the whiter than white bird I saw on the Axe on 9th January, but it clearly is the other Casp that's been seen here this year.  Gav thought he'd found this bird on 22nd January, but a few days later it came to light Tim White had photographed it on the Axe back on 17th January.  This bird is distinctive enough from all the points I listed in the paragraph above (bill size and mottling), but it shows a couple more characteristic plumage traits too...

First-winter Caspian Gull


The red arrow is pointing to my favourite feature on this particular Caspian Gull, that lovely little pale line formed by the tips of the median coverts. It's really noticeable on this bird at rest.  Then we have the two red 'circles'. The top one highlights the contrast between the lower moulted tertials, and the upper two unmoulted ones, which look completely knackered and are much browner in colour. The lower 'circle' highlights all that white in the greater coverts, inline with where they meet the lower tertials. This feature is really noticeable, even on distant pics of this bird. Most first-winter Casps show a neat and even white line along the tips of all the greater coverts. 

You can see pretty much all these features on all the previous photos of this bird, which Gav has put together in a blog post HERE.

So this is my tenth Caspian Gull for the Axe, I can't wait for number eleven!

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