01 October 2010

Sabine's Gull - Carlyle Lake, IL

Every fall in late September, the Illinois Ornithological Society (IOS) offers an "inland pelagic" field trip to Carlyle Lake, with Sabine's Gull being the primary target bird. Carlyle Lake is the biggest inland reservoir found in Illinois and has indisputedly provided more state records for this species than any other site. More so, Carlyle now produces more Sabine's Gulls than Miller Beach in Gary, IN. Ken Brock predicted this over a decade ago in his Sabine's Gull paper that assessed this species' footprint in the Midwest:  "Although Gary, Indiana at Lake Michigan's southern tip currently boasts the largest total, based on current observation rates Carlyle Lake will claim the title in the near future (Meadowlark, V7 N1)". I'm unsure of current data, but if I had to make a prediction as to which state will claim the title next, I would put my money on Iowa, particularly from the large reservoirs in the Des Moines River Valley area (Saylorville and Red Rock Lakes).

Anywho, the IOS trip to Carlyle finds birders traversing the lake for several hours using a flotilla of 2-3 pontoon boats. Bread and popcorn is used to chum the gulls and eventually a Sabine's is discovered by one party which then alerts the other boats.


This year, I had the pleasure of attending this field trip for a 2nd time and I was not dissapointed in the results. In fact, I've attended this trip the last 2 out of 3 years with Sabine's gone unrecorded on the trip I missed. Are you thinking what I'm thinking? Yes, I should attend this trip every year so that other birders get a chance to see this species :) Tim Kussel for instance, has had a 4 out of 8 success rate and so it's not gravy every time you get on those boats.
Our search for Sabine's Gull took less than 30 minutes when one of our crew members, Anthony Friend, spotted a Sabine's flying right towards us. As expected, the bird was a juvenile that was probably no more than 3 months old. I should mention that in Brock's data from 1998, out of 111 aged birds, only 13 were adults. These numbers should have significant meaning to the vigilant birder (not I).

Juvenile Sabine's Gull by Amar Ayyash, Carlyle Lake IL, 25 SEP 2010
Same individual as above.
The day ends with an evening lakewatch from the Hazlet Olympic Pavillion on the west side of the lake. Here, we were again treated to extensive but somewhat distant views of two Sabine's feeding out at mid-lake with hundreds of gulls, tens of Black Terns and a Parasitic Jaeger. An interesting observation that I won't soon forget is the feeding style of this agile gull. While flying low, it would bank and come to a sudden stop where it would  then dip to snatch its food from the water. I commented to the folks around me that the behavior was very tern-like, although the wing-beat pattern was much more stiff compared to a Bonaparte's Gull or Black Tern.

Last month, I was reflecting on the uniuqeness of Sabine's Gull's molt strategy but I failed to put two and two together when watching this species from the Olympic Pavillion. For a brief moment, I thought I may have had an adult Sabine's out on the lake. I kept this thought to myself and studied the bird a bit more. Lighting conditions were less than ideal and from afar the brownish/gray mantle seemed solid gray as expected in an adult. There is no parallel as in the adult/juvenile Black-legged Kittiwake or adult/juvenile Bonaparte's when it comes to the upperpart pattern of Sabine's; Both ages are virtually identical from above.


The smoky wash to the nape and breast was undetectable to my inexperienced eyes. Since the bird I was watching did not have a black hood I thought, "Oh, why can't that be a basic adult"? Although knowing what to expect from earlier in the day during the boat trip, I squinted and squinted until I made out the thin tailband. The tailband was very hard to make out and I think that if lighting conditions were any worse, and had I not had a biased expectation from a few hours prior, I may have missed it completely.

Fortunately, a most humble birder from St. Louis rightfully reminded birders of Sabine's molt strategy in a recent thread on the Illinois Birders' Forum (IBF). Unlike other gulls that breed in the northern hemisphere, Sabine's is a high-Arctic breeder with a taxing migration. It does not have the time and energy to manage a complete prebasic molt on the breeding grounds or en route while migrating. Rather, this molt is delayed, or "suspended", until it arrives at its wintering grounds. Although limited head and body feathers may be molted during migration, an adult Sabine's seen in the interior states in fall will almost always have a full hood effect. In fact, Olsen estimates that over 90% of Sabine's Gulls seen in the northern hemisphere will have full summer hoods from August through early October. This implies that one should expect to see one of two plumages in Illinois: First Basic or Definitive Alternate, with the latter being much less common.

Note the black subterminal tailband, dusky ring around the neck, scaling on the 
contrasting mantle and secondary covert feathers.


Full hood with black border, solid gray mantle, white tail and tips to primaries.
BirdsofIreland.com

My two photos above are somewhat of an oversimplification that may give the impression that identifying these two ages is a nonissue. Maybe, but not when viewing conditions are less than ideal and more than 1/2 a mile sits between you and this agile -sometimes erratic - flying beauty. I know this from firsthand experience (i.e., my mistake).

From the Olympic Pavillion out to mid-lake, using a 60 power scope, one
could expect to make out less detail than what is seen in the photo above.

It should also be mentioned that any sighting of 1st summer birds is considered extraordinary and quite rare. These sightings should be well documented since it's believed that this age group remains primarily on or around the wintering grounds without migrating through the interior. I'm currently discussing a bird with Indiana birder Mike Clarke who observed a Sabine's in the Bloomington area on 30 SEP 2010. He describes a bird with no juvenile-like dusky wash on the neck and sides of the breast, a medium-gray manlte and an all black bill. The bird had no adult hood but had an extensive white area on and around the neck as a 1st summer bird. Could this be another distant juvenile? It was observed at less than 1/4 of a mile in excellent light with a 80 power scope.

  A more serious ID issue is confusing young kittiwakes with Sabine's in flight. Keep in mind that Black-legged Kittiwakes form M-patterns through their ulnar bars and Sabine's does not.

Photo by Amar Ayyash
Photo by Ross Ahmed

This photo is a great picture, but I don't expect on seeing these specieis side-by-side. In the Great Lakes region, Sabine's is an earlier transient than Black-legged Kittiwake, with little overlap. However, one never knows what to expect. Last year, there was an early Black-legged Kittiwake sighted in September at the confluence of the Illinois, Kankakee and Des Plaines Rivers. While searching for the kittiwake the next day, birders happened upon a Sabine's Gull.  

Thanks to St. Louis birder Charlene Malone for forcing me to review the particulars that make Sabine's such a special gull. I hope to be watching Sabine's Gull tomorrow with thousands of Franklin's from the dam on Saylorville Lake in Iowa. I'll have to quiz those Iowa birders on "expected plumages in the Midwest". That's all for now.
A plumage not familiar to the interior states: http://www.youtube.com/watch?v=T9s-qVJly-M&feature=related

A juvenile in flight:  http://www.youtube.com/watch?v=aj_jK9LNQ1Y&feature=related

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