Jan 7, 2013

Caspian Gull in Bergen

The 5th of January is with out doubt one of the highlights in our gull ringing career. We managed to ring a gull we think is a Caspian Gull (Larus cachinnans). The possibility of a Caspian x Herring Gull hybrid have not been ruled out yet, but this will be very good bird here in Western Norway anyway. Our gull year started on the 4th of January when we ringed a 2 cy Iceland Gull (Larus glaucoides) at Osøyro. Yesterday we searched our local spots for more white-winged gulls. We managed to find a new 2 cy Iceland Gull in a freshwater outlet in the fjord outside Bergen which was not interested in bread at all. However, back to the Caspian gull. When we threw bread to the around 150 Herring Gulls (Larus argentatus) in the city centre lake in Bergen a white headed gull draw our attention. Could it be a Caspian or was it just an odd looking Herring Gull. We took a few snapshots and decided to catch the bird to get in hand documentation, measurements and a blood sample. The bird was very hungry, so the catching was relatively easy. Well at home that evening we started to read the available Caspian Gull identification papers and contacting the gull experts we know. As the evening tuned to night we was quite convinced that the bird could be a Caspian Gull.

This bird is our second bird to be ringed in 2013, so if the experts agree for a Caspian Gull we have a really good start to the new year. Also if accepted as a Caspian Gull this will be the first ever ringed in Norway and also the second observation of this species in Hordaland county.

Second winter Caspian Gull JN879. Note the venetian-blind pattern visible on the inner primaries where the outer webs are dark contrasting with pale grey inner webs. This contrast is much less marked in Herring Gulls.

The almost totally white under wing is typical Caspian Gull. Axilliares are also unmarked on this bird which is another good CG character.

The tail pattern is a black narrow sharp defined tail band against a near white upper tail and rump.

White head is one of the best known CG characters

The CG before ringing. The venetian-blind pattern is even more visible on this picture so are the pale lozenges on the outer web of P3 and P2 on the right wing.

The comments from the national and international experts are so far promising. Chris Gibbins the author of two extensive identification papers on Caspian Gull think the bird looks like a Caspian Gull. The other comments can be seen at the gull-research forum.

We are greatful to Morten Helberg, Kjeld T. Pedersen, Alf Tore Mjøs, Frode Falkenberg, Chris Gibbins, Theo Muuse and Jan Jörgensen for comments and help with the identification of the bird.

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