I went to Highline Lake SP around 4 this afternoon and saw a lone gull that seemed unusual. I studied it floating in the water in great detail through my scope and watched it fly numerous times and finally concluded it was an adult Black-legged Kittiwake.
Here are the field marks:
While floating on the water, the the bird showed a yellow bill( thicker than a Bonaparte's bill), white forehead, dark gray arc behind a dark eye, lighter gray hind neck, dark gray body bordered by white with black wingtips (no white spots).
In flight the top of the bird showed dark gray mantle, lighter gray primaries, with black wingtips (no white spots evident). The trailing edge of the wing showed narrow white edge and the tail was all white.
The flight seemed swift and buoyant and the bird would dive into the water, float for a short while, than take off again.
Would be great if someone could get out tomorrow morning and take some photos.