Thursday 21 August 2014

Caspian Gulls

I had a good time gull watching (not gulling) at Shawell over the last couple of days. I read a total of 16 colour rings and saw three Caspian Gulls and quite a few Yellow-legged Gulls. 

In The photo below the 1CY looks slightly odd structurally, but its bill ratio and primary projection seem OK. It is still too young to use the trait scoring system, but the traits that can be used are OK. It can make your head hurt trying to work out if a particular Caspian Gull is pure. Any opinions on this gull are welcomed, as I'm always keen to learn. You can either comment directly to the blog or email me. Comments on Blogger don't always seem to work, but I've found if you click on Preview after writing the comment it helps.

This 1CY is the same as the one seen on both the 9th and 13th August - see comments below.

1CY Caspian Gull

Nice White Underwing

The underwing is creamy white apart from a little bit of brown on the underwing coverts. This is typical of 1CY Cachinnans. Yellow-legged Gulls can show pale underwings, but not as pale as this. The clean white axillaries are also a good feature, as other juvenile large gulls should have heavily marked axillaries, or at least grey brown markings. 

Same as Above

Just prior to seeing the 1CY Casp, I spotted an adult, which landed reasonably close and stayed long enough for me to get a few images. Its plumage is spot on: you can see the underside of the longest primary on the far wing and the pattern is text book good. The bill is also good, although its eyes are a little pale, but not as pale as Herring or Yellow-legged Gulls. Its legs are long and thin and the right colour.

Close Up

The final one is a 2CY.

2CY Caspian Gull (at the back)

In addition to the three pictured here, I saw a very distant 2CY, which looked OK for Caspian Gull plumage wise, but structurally it was obviously not pure and had plenty of Herring Gull genes. 

Below is one of the more interesting YLG's.

Beast of a 2CY Yellow-legged Gull
Colour-ringed LBB Gull (J7MM), ringed as a chick during July 2010 in Norway


  1. Nice birds Carl. The 1cy looks good to me, and in fact looks like the same bird in the last three posts (ie since the green-ringed bird). Similarities in scaps, tertials, and blotchy neck sides seem too much of a coincidence in the pics anyway... But I could be wrong

  2. Thanks Tom, I'm sure you are right that it is the same 1CY that I have seen three times. I was of that opinion on Wednesday night, but when I reviewed the photos I talked myself out of that being the case. The birds structure seems to alter each time I see it and I was thrown by the tertials looking very faded one day and very blackish another. Of course light has a massive effect. The very distinctive scapulars didn't look so obviously pale edged in the bright light on the day I saw it with the colour-ringed adult. In the end you have to go with the fact that it is such a distinctive bird and what's the likelihood of there being more than one so similar?

    Thanks once again,