www.gull-research.org

Last weekend I saw this adult gull in Groningen, The Netherland, and it left me rather puzzled. At first glimpse it looks like a cachinnans: long-winged, dark-eyed, with a rather thin bill and yellowish legs. The pattern on the bill is not really tipical, but what confuses me the most is the pattern on the primaries; a large white P10 and strong markings on P5 are perfect for cach, but there is no sign of a mirror on P9.
Could this be a Caspian x Herring Gull, or is there an option I happen to miss?

Looks good enough for a Caspian.

Ronald Klein wrote:Looks good enough for a Caspian.

for me too but it's the first full adult type i see without any p9 mirror...

lou