Tuesday 8 September 2015

Caspian Gull

The above photo shows my initial view of this bird - the new'ish first-winter mantle and upper scapular pattern coupled with the cream-tipped tertials immediately pointed to it being a yellow-legged gull-type. The finely marbled, pale-tipped greater covert pattern raised my pulse rate! They looked, if anything, better for Caspian Gull but I was cautious because of the variability shown by Yellow-legged Gull. Eventually the bird stood up and its incredibly long wings and long thin legs meant it surely had to be Caspian Gull. I sent out some 'prob' texts but wanted to see the underwing and tail pattern. Meanwhile, the head profile was looking better and better, although it's amazing how much this can change, depending on the bird's posture. The harsh light meant the viewing conditions were far from ideal, but eventually I moved around to the new bird screen on the other side of the railway line where I was able to confirm a pale-looking underwing and a black tail band of even-width, contrasting with gleaming white tail bases and uppertail coverts. The bird was still present off Mudbank when I left at 5pm and I was chuffed that Dave and Terry managed to get down for it. All my previous Caspians have been more distant and brief so I was particularly pleased to be able to study this bird at such close quarters

Note the really long wings and long spindly legs in the above photo. The greater covert pattern shows dark bases and a fairly subtle marbling with nice cream tips.

In this pose the bill looks long and lacks a significant gonydeal angle. The small pear-shaped head, with long, sloping forehead looks obvious but in other postures the head shape could look very different and the bill much shorter.

This shot gives some idea of the tail pattern with the black terminal band of even width.

I found it really hard to get a proper view of the underwing but it always looked pale. This shot give some idea.

In this photo you can see how long the whole bird looks. Note also the streaked nape that is characteristic of this species, giving the effect of a shawl.

A different posture and a different look to the bird. This was a large individual - bigger than adjacent Herring Gulls but with noticeably thinner and longer legs.


  1. Nice one Matt and thanks for the text - I had a quick look off MB at lunchtime today but had no luck...

  2. Looks like a Yellow-legged Gull to me.

  3. Hi Brett - have to admit it has been troubling me having spent a long time looking at my photos, and I'd kind of reached the same conclusion. The long tibia length and oddly thin spindly legs, compared to adjacent Herrings coupled with very white-looking underwing kind of took me away from the fact that the eye seems wrongly placed for Caspian Gull. Also thought diffuse greater covert pattern and tertials better fit Casp - I'm so used to seeing crisply marked tertials and strongly marked grt coverts on the yellow-leggeds that pass through in July/August. Interesting bird tho. All the best and thanks for getting in touch.