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.

No comments:

Post a Comment