Because it is located next to a landfill, the parking lot of the Lake County Fairground attracts many gulls that come to rest and preen. Most abundant are Herring Gulls and Ring-billed Gulls, but Amar was mainly going to show me Thayers Gulls and Kumliens Gulls, species that I had never seen before and were one of the reasons why I had come over to the States.
While scanning a group of gulls from the car, Amar spotted a large, dark-backed gull coming in to land nearby. Even before it had fully settled, Amar asked: “Is that an adult Slaty-backed Gull?!?”
Adult Slaty-backed Gull among adult American Herring Gulls.
Adult Slaty-backed Gull among adult American Herring Gulls.
I have to admit that the exact characteristics of an adult Slaty-backed Gull Larus schistisagus didn’t immediately sprang to mind because I had never seen one and wasn’t anticipating on seeing one any time soon either.
However, this gull was very striking with its dark back, broad tertial crescent and especially the white skirt (created by the white tips of the secondaries when the bird is in rest).
One of the key identification features of an adult Slaty-backed Gull is its white ‘skirt’, created by the broad tips of the secondaries that protrude from underneath the greater coverts when in rest.
We could hardly believe our eyes but were immediately 95% certain of what it was. In the mean time, the gull had sat down and we had to wait for it to stand up to confirm the pink color of the legs. A few moments later we were also able to see the characteristic ‘string of pearls’ created by the white tongues on the primaries P5 to P8. Textbook adult Slaty-backed!
Adult Slaty-backed Gull in basic (non-breeding) plumage. Note the streaking on the head and neck. A small black mark can be seen on the orange/red gonys spot.
The white tongues on P5 to P8 form what is referred to as a ‘string of pearls’.
The white tongues on P5 to P8 form what is referred to as a ‘string of pearls’.
Just to put some context to what we were seeing: Slaty-backed Gull originates from Asia and is a rare visitor to the USA; for Illinois it was only the 4th record and the first for Lake County. Only a handful of records exist for Europe.
What followed were incredible close up views while it was resting and various opportunities to make the all important flight shots. And all of this in perfect light conditions.
And what a beautiful gull this was. I don’t think I’ve ever said “wow” and “unbelievable” so many times in a day.
Note that in one of the photos below it can be seen standing next to an adult Lesser Black-backed Gull, Herring Gull and Thayers Gull. What a combination!
Adult Slaty-backed Gull.
Adult Slaty-backed Gull.
Adult Slaty-backed Gull.
From left to right: Thayers Gull, American Herring Gull, Slaty-backed Gull, and Lesser Black-backed Gull. At the bottom of the photo 3 first-winter Herring Gulls.
Stretching its wing.
Preening its feathers.
Giving its feathers a good shake.
Videos
In the following video it can be seen trying to regurgitate something:
Other links
Me and my Slaty-backed
How often do you get the chance to have your picture taken with a Slaty-backed Gull?
Lake County Fairground, Libertyville, Illinois:
Gulls to the Horizon 