11 December 2012

More Intermediate Thayer's/Kumlien's and a 2nd Cycle Thayer's

Greg Neise and I teamed up for some Lake County gulling on Saturday. We hit the LC Fairgrounds first where we were treated to this:

Adult Kumlien's. Lake County, IL. 08 December 2012.
We went back and forth about the possibility of it being an intermediate Thayer's/Kumlien's, and although it may be, I leaned towards Kumlien's because of the limited markings on the primary tips, but especially because of the unmarked P5 - this has not been documented in the leading identification papers on Thayer's Gull:

Note the large, all white, tip to P10 and unmarked P6. This individual exhibits a pattern similar to PLATE I in Howell and Dunn, but the shade of darkness is much more extensive.
We then headed for North Point Marina, running into some nasty snow/rain mixture along the way, but just as we were approaching our destination, the rain stopped and it cleared up with partial sunshine!

We found 2-3 Kumlien's types and 2-3 Thayer's - no Glaucous or LBBGs,  which was somewhat of a surprise.

2nd cycle Thayer's Gull. Lake County, IL. 08 December 2012.

Although P10 is with a large white tip, P6 is with a full subterminal band. This individual resembles PLATE P in Howell and Dunn. I thought it was best to keep this one in the "intermediate" category, but to my eyes, the under pattern suggests Thayer's.
We also had this beast of a 2nd cycle Herring with an almost completely unmarked bill:
The adult-like bill pattern is just another example of the infinite variation found at the species level with Herring!