torsdag 25. oktober 2012

Hybrid herring gull x caspian gull?

This striking adult gull was seen in pouring rain for a few minutes october 3rd 2012. It is not easy to exclude caspian gull on the standing gull. Amber eyes - mostly white face with head streaking mostly concentrated in the neck - long, slender greenish bill with little pronounced gonys angle (and the gonys angle very close to the tip) - pale yellowish legs - head shape and general build all point towards caspian gull. The open wing, however, reveals black on outer web only on P5. This wouldn't exclude caspian within the caspian range since about 10 % lack a complete band on P5 (according to Gibbins et al 2012). In a norwegian context, however, a complete band on P5 is probably a prerequisite for claiming caspian gull. Apart from the P5 pattern, the eye is in the pale end for caspian, the bird is maybe a little bit short legged, a tiny bit too streaked in the head and perhaps not extreme enough in the body shape to be a true caspian? Sooo, a hybrid?

Compare build with the herring gulls. Really easy to pick out from the crowds...

Black on outer web only on P5 probably excludes caspian gull in a norwegian context.


I guess there is no point asking for comments...

fredag 28. september 2012

Caspian gulls from Sweden part II

We continue with our presentation of caspian gulls seen in Scania, Sweden 14th of september. This day was spent checking harbours for gulls since strong southerly gales put an effective stop to our main purpose for our trip to Sweden - the famous migration of raptors at Falsterbo. As usual, we've put in a lot of photos to show the different individuals in as many situations as possible...This time we start with long distance photos of a rather dark 1cy. The variation exhibited by this taxon is really bewildering and almost matches argentatus...All photos in this entry were taken in Skillinge, south east Scania. Click on photos for larger versions.

 Here, a single photo of a large male that gave great black backed gulls a tough match for food. A bit "fishy" perhaps?..

Then these three birds where standing side by side. Three is about the total number seen in Norway annually...From left to right: ad (or near ad = 4cy+), 3cy and 1 cy. The 1cy is a bit darker than the typical 1cy CG, so we've added quite a few photos of the bird...In our opinion it's within the variation of CG, but maybe a hybrid cannot be excluded? Comments are welcome.

Here are photos of the underwing

Note the strongly marked breast and flanks



Nothing to worry about with the next one, though...

Here are a few photos of the 4cy+. Note that the iris, on a closer look, is really amber, not brown or black. Note very typical body shape and stance. The "back line" - from wing tip to nape - forms an almost straight line, like it was made with a ruler...

 As usual, when you see a caspian gull next to a herring gull, you are struck by how much whiter the caspian seem to be, and it's not just the head. Note also difference in leg length, especially above the tibia. Pale yellowish legs seem to be common in this age group and note also the greenish bill.

onsdag 19. september 2012

Caspian gulls from Sweden

In a couple of entries we will present pictures of (mostly) caspian gulls from a recent trip to Scania, Sweden. The main purpose for the trip was raptors in Falsterbo, but as always, the weather may make you change plans. We present many pictures of the same individuals to show the birds from different angles if possible...The weather was very changing throughout the day which reflects on the quality of the photographs. Hope you'll enjoy them. We begin with a big male that gave excellent views in the small harbour of Smygehamn, the southernmost point in Sweden. (Co-observers: Magne Pettersen, Harald Mørken and Roar Olsen). SEN

Next a 2cy in a field just west of Smygehamn. Long distance shots only..

 Note the mirrors of the growing P10's

Next one up is a 4k(+) in a field west of Hörte hamn..

 The last ones for this time are two beautiful 1cy's in Abbekås. Here's #1

 # 2:

 More to come later when photos have been processed...