Gull - Lake Geneva, Switzerland (1 Viewer)

[SternaParadisaea]

Hello,

One month ago, I saw this gull in Lake Geneva, Switzerland.



It was a second winter gull, as the tip of the tail was still very black. In this area, the most common species is the YLG. When I saw this one, it immediately looked different to neighboring YLG and for me, looked like a big male Caspian gull (it was actually bigger than YLGs). However, when I look at the pictures, I am more cautious; there is somethings which sounds wrong with a Caspian. I have experience with first winter and adult Caspians, but not much with 2nd winter ones.

Here is my analysis:

Arguments in favor of Caspian:

• The global shape/jizz: high chest, ventral bulge, receding forehead (but it depends of the picture; the last one shows a better jizz than previous ones)
• Legs relatively long
• Beak relatively long
• Advanced plumage for a 2nd winter, especially in October: scapulars seem totally grey and coverts are also globally grey. However, the light and the distance did not allow to go into detail.
• The tertiary pattern seems good for Caspian
• Neck more striated than the area around the eye

Arguments against Caspian/for YLG:

• Beak and legs not that long (overlap possible with some YLG)
• Beak fairly thick (but possible in male Caspians)
• Primary projection short for a Caspian
• More pronounced, coarser striations on the neck than in a typical Caspian, which has a more subtle pattern
• The date is also quite early. Caspians gull become more common since November here, but are rare in October

What do you think?