31 January 2015

A Thayer's-Kumlien's Gull: Whiting, Indiana

I got out to the Indiana lakefront today. It didn't take long for me to be reminded of what great gull-watching we have here on Lake Michigan in the winter season. It's not so much the number of gulls, but rather the variety that impresses me. In less than an hour I had Thayer's (4), Kumlien's (1), Glaucous (4), GBBG (32) and LBBG (2) checked off for the day. There was also a Thiceland Gull. Yes, a Thiceland...

An intermediate bird showing both Thayer's and Kumlien's features on the wingtip. Whiting, Indiana. 31 January 2015.
Looks mostly like a Thayer's Gull, but the two outer primaries are suspiciously pale. The mirror on p9 also extends across both vanes from edge to edge. All of this would've been fine until I saw it side-by-side with Herrings and Ring-billeds.

That wingtip is too pale for my taste and I don't feel compelled to call such birds Thayer's Gulls. So why not a Kumlien's? Mostly because of the full band on p5. Of 345 sampled Kumlien's, Howell & Mactavish noted only 17 with subterminal markings on p5, "but never a complete subterminal band". They go on to say that altough none of their sample showed a complete band, it does occur, "albeit rarely". My bird also shows black bleeding onto the inner web of p9, and the "fullness" of the subterminal bands from p8 down to p6 make me even less willing to call it a Kumlien's. So by Lake Michigan standards, we'll keep this bird in the "intermediate" file.

I also had a neat 3rd cycle Thayer's with pale eyes - my 24th third cycle type Thayer's in the Lake Michigan region this season.

Thayer's Gull (3rd cycle type). Whiting, IN. 31 Jan 2015. Photo 1 of 3.
Photo 2 of 3.
Photo 3 of 3.

I have big hopes for February...big hopes. The Black-tailed Gull population is approximately 750,000 individuals. There has to be one out there with my name on it. Bring it!