Thursday, January 29, 2009

Glaucous x Herring Gull hybrid?

Yesterday when I searched through the Herring Gulls on the rubbish dump of Köping my eyes got stuck on a first winter gull. Seen from the front it was even coloured in a lighter shade than young Herring Gulls of the same stage. The bill was as dark as in Herring Gull with a hint of pink from the base to the nostrils. When it turned around and the primaries were shown I started thinking of a possible hybrid Glaucous x Herring Gull. They were not as dark as that of a normal Herring Gull and had quite broad light brown edges. Very much like the ones of the following gull, photographed by Chris Gibbins in Scotland this winter. Press here to see the image.
In the evening Hans Larsson noticed the light eyelids on the images, normally shown by Glaucous Gull.

The wing coverts had a lot of off-white markings and the scapulars weren't contrasting against the wing coverts. I don't know wether some were moulted or not. In the image to the left a few scapulars look moulted, but it's hard to tell. Sadly, I never managed to remember the appearance of the tertials and sadly the bird quickly dissapeared. From what I could see the bird had a tail-bar resembling that of a Herring Gull.

I can add that I saw a light gull in flight maybe ten minutes before I saw this one on the ground. It's quite possible it was the same gull. My impression of the gull in flight was someting like this presumed Herring x Glaucous hybrid (except for the red hue), press here.
By that I mean a light and diffuse appearance. But again, I'm not sure it was the same gull.

What suggest a hybrid on the standing bird is the pattern of the primaries, the even body colour and the very clear light eyelids.

Maybe you have experience of this kind of hybrids or just some thoughts? Write a comment!

Sunday, January 25, 2009

Thayeri patterned Herring Gulls

Roughly said, the normal wing pattern of argentatus Herring Gulls is described by black subterminal markings on P6-P10 with well defined white primary tips (on P9 a mirror too). On P10 the white mirror is more often grown together with the white primary tip. This type of wing pattern is shown to the left.

Some of the Herring Gulls show a pattern like the one to the left. Note the thayeri patterned P10 where the white has burned through the black on inner web and combined the white tip with the white on the inner part of the primary. Also on P9 the white has burned through the black on inner web, connectig with the mirror.

Here is another thayeri patterned Herring Gull. Note the pattern of P10 as well as P9. There is only a very thin black line separating the mirror and the white tongue on P9.

According to an article on 30 percent of the Latvian inland breeders show long white tongues on P9 and P10 that often connects with the mirror on P9 while 10 percent of the breeders at the coast of the Gulf of Finland do so. Press here to see the article.

On the website of the University of Glasgow,, it's said that 27 percent of the Herring Gulls from northern Scandinavia and NW Russia show thayeri patterned P9. Here's the article.

Monday, January 19, 2009

Differences in tail pattern of young Herring Gulls

This image shows the normal tail pattern of a first winter Herring Gull. The black bond is broad in the middle and gets narrower towards the sides, with quite a lot of barring on inner part of rectrices, upper tail-coverts and rump.

Some of the Herring Gulls show tail pattern like the gulls on the images to the left and below. A very thin and even broad black bond, with some barring on inner parts. Could recall the one of Great Black-backed Gull.

In this image the tail is really hard to see but it's possible to imagine the tail has the same type of pattern as the one above.

Ringed GBbG JET5

Since we only have about three Great Black-backed Gulls present in Köping I was quite stunned when I saw that one of the adults was ringed. I got even more happy when I saw the bird was ringed in Norway! After reporting it on our Swedish bird system I got an e-mail saying the gull has been a regular winter guest earlier years in Västerås, about 35 kilometers to the east. It was first seen there in 2003 and it's ringed as an adult female in northern Norway. I'm waiting for more information! It would be really fun if the bird has been seen in summer time on a breeding spot any of the years between 2003 and now.

Sunday, January 18, 2009

Ringed Herring Gull C0V22

On the 18th of December 2008 I observed the ringed adult Herring Gull C0V22 at the rubbish dump of Köping, Sweden. It was ringed on the 22nd of June the same year as an adult at Pori, Finland by Erkki Haukioja.

Ringed Herring Gull KV17

This Herring Gull was ringed as a youngster in nest in Kandalakshskiy Nature Reserve, Murmansk, Russia. The date was 9th of July in 2005 which makes it a 4cy bird when seen on the 3rd of October 2008 on the rubbish dump of Köping, Sweden. The distance between the ringing place and Köping is 1165 kilometers.
Press here to see the ringing location on a map. Here's Köping.
In this image the age is suggested by fleshy inner part of the bill in combination with the black subterminal markings. Note also the dark mantle of this north-eastern bird.

Ringed Herring Gull C52CU

The first winter C52CU was seen on the 26th of December 2008 in the harbour of Köping, Sweden. Information is on it's way from Finland, where it's ringed! Three Finnish-ringed birds of 700 in total indicates that a lot of the gulls where Finnish.

Ringed Herring Gull C0H08

An adult Finnish-ringed Herring Gull seen on the 26th of December 2008. More information will come!

Ringed Herring Gull C57UU

This very normal looking first winter Herring Gull was seen on the 26th of December 2008 together with C0H08 and C52CU in the harbour of Köping. I'll put up information when I recieve it!

Ringed Herring Gull C6V34

On the 16th and 17th of January I saw the ringed Herring Gull C6V34 on the rubbish dump of Köping who's. I have reported the bird to the Finnish Ringing Center and I'm still waiting for the information. As soon as I have it I'll put it up here! A pic of the bird is shown to the left and another one in the Herring Gull gallery. Note the complete (but not even broad) black bond on P5.