02 March 2012

Gull Sit 2012

On Sunday, 26 February 2012, a few birders and I conducted a "Gull Sit" at North Point Marina (Lake County, IL) in an effort to count gulls! Winds were primarily from the south all day at 17-30 mph and temperatures ranged from 26F-48F. Approximately 70% of the harbor was ice-free. The harbor south of the yacht club was monitored continuously from 7:00 a.m. through 5:30 p.m with some interesting results.

First cycle Thayer's Gull. NPM, IL. 26 FEB 2012.
The day's high for "stationary" gulls was approximately 1,150 individuals (~ 970 American Herrings, ~ 180 Ring-billeds). This maximum was reached in the last 90 minutes of daylight, while average numbers throughout the day hovered at or around 800 (over 85% consisting of Herrings).

No "mass exodus" was observed at any one point throughout the day, but rather, 2-3 small groups of 75-100 gulls were noted flying westward early in the morning (very likely to the Zion landfill). Returning numbers from the west consisted of small, loose, groups throughout most of the day. There were two instances when ALL of the gulls got up and were reshuffled, once because of a low-flying helicopter and once because of a Snowy Owl that came in directly over the harbor from south to north. This Snowy was markedly whiter than last week's bird.

Hourly counts verified a constant flow of gulls coming and going, which was expected. For instance, between the hours of 7- 11 a.m., at least 4 adult Lesser Black-backeds were noted, but not one was to be seen again for the entire day shortly after 11:00 a.m.

The Herrings began their evening cacophony of yelps, mews and caws around 4:45 p.m., and at 5:10 p.m., approximately 3/4 of them took wing in unison and flew out quite a distance over the lake. Why some Herrings stayed in the harbor is puzzling, but the majority of Ring-billeds (~ 150) stayed in the harbor as well. With that said, I'd point out that birds noted coming into the harbor during the early morning hours were ones that very likely roosted on Lake Michigan.

An intermediate Thayer'/Kumlien's type, tending towards Kumlien's. NPM, IL. 26 FEB 2012.
A well-marked adult Thayer's.
As for other notable sightings, we did tally all 7 expected gull species. It's difficult to be certain which were counted more than once, so these numbers are ONLY minima at best, accounting for the possibility of recounts:

11 Thayer's Gulls (8 distinct adults, 1 second cycle, 2 first cycle).
4 Kumliens' Iceland Gulls (4 adults. One of these adults showed all white wingtips but with upperparts that matched Herring - see photos).
2 Glaucous Gulls (1 adult, 1 first cycle).
7 Lesser Black-backed Gulls (4 adults, 1 third cycle, 2 first cycles).
1 Great Black-backed Gull (1st/2nd cycle).

Adult Kumlien's Gull with stage zero wingtip pattern. Upperparts matched surrounding Herrings.
Other: 2 adult Thayer's/Kumlien's -type intergrades were observed and are probably best left as "in between" birds. It's always difficult making a quick assessment of these birds in flight, but detailed photographs have made this easier.

Left as an intermediate type although likely a Kumlien's (note the slaty black-ish color on the wintips). The combination of an all white tip to P10, unmarked P5, broken subterminal band on P6, white tongue merging into mirror on P9 and faint dark gray band on underside of primaries are all suggestive of Kumlien's.

Tending towards Kumlien's (same bird as above).
Adult Thayer's.
I find it interesting that LBBGs outnumbered Kumlien's (I think this was the case last year as well), but admittedly, their darker upperparts make them hard to miss. I thought the chances of seeing a GBBG would be slim and I'm still puzzled by why this species is found in decent numbers a short distance to the north in WI, and in great numbers just a ways south in places like Calumet Park, Hammond and Whiting Indiana. Of our "special" winter gulls, Thayer's continues to dominate here and I suspect (gulp) there were at least 2 dozen of them present throughout the day. Overall, I was pleased with the numbers we reported.

Thayer's/Kumlien's in back with dark eye. American Herring in front.
First cycle Ring-billed Gull.

First cycle Thayer's (a bit on the pale end).
A special thanks to Al Stokie for his insightful thoughts on the gull dynamics in this part of Lake County - he and his team had the "harshest" part of the day. I'd also like to thank the Gyllenhaal's, Paul Sweet and Bob Erickson for manning part of the day. A similar two-day, consecutive, "Sit" will be conducted next winter in hopes of comparing Saturday/Sunday numbers. More volunteers will likely be needed -- some for NPM, some for Sand Pond, and some outside the Zion landfill. Please email me if you're interested in helping out.