27 November 2015

Third Cycle Kumlien's - New Buffalo, Michigan

One of the joys of watching gulls in the Lake Michigan region in winter is encountering individuals from the Thayer's/Kumlien's/Iceland complex. My personal estimate is that there's 6-7 Thayer's for every Kumlien's Gull that we see here on the southern rim of the lake. We've never knowingly seen nominate glaucoides on Lake Michigan.

Much more intriguing though is the number of individuals that, if found on the Pacific or Atlantic, would be readily identified as the expected taxon in that region. Given the opportunity to "overthink" some of these birds, one may look at the same photograph months later and "aptly" assign a different label.

Here's one of these so-called "Lake Michigan Gulls"; 25 November 2015, New Buffalo, Michigan:

I first spotted this bird in flight, and immediately called it a Kumlien's Gull due to the muted an relatively pale wingtip. My first impression, I've learned, is usually the best impression (given neutral lighting and sufficient views of the upperwing).

I feel a similar-aged Thayer's Gull would average darker primary tips - more blackish than the dark slaty-gray seen here. Here's a 3rd cycle type Thayer's from the same region, from this time last year:

Michigan City, Indiana. 27 November 2014.
Although it may be splitting hairs, the Thayer's has darker wingtips and more pigmentation on both webs of p7-p10, lacking the large white tongue tips shown by the Kumlien's. This is not to say a similar-aged Kumlien's wouldn't, or couldn't, show darker inner webs on those primaries. The overlap is tremendous.

Now for something a bit lighter - a crisp juvenile Herring Gull showing immaculate plumes for late November:

Herring Gull. 25 November 2015.
And an adult BOGU:

A few black marks on the outer tail feathers on an otherwise perfect looking adult.