In the fall of 2009, a Black-tailed Gull (Larus crassirostris) showed up roosting on a log boom on the east side of Commencement Bay, near Tacoma. It was found on October 13 by Charlie Wright and remained for about a month, seen almost daily until November 7. I remember that date well, as it was seen that morning. That afternoon, Netta Smith and I were finally able to accompany Shep Thorp in his boat, the best way to see the gull, but we were unable to find it. It had presumably headed south with the large numbers of California Gulls that had been present until that time.
In the fall of 2011, presumably the same bird showed up at the same spot. First seen by Shep on September 14, it was still present as of November 4 but may have departed soon after that. During both of its visits, this bird was seen by many enthusiastic observers, mostly at a distance of several hundred yards, spotting-scope range. By far the best way to see it was to go out in a small boat and circle the big log boom on which it roosted daily with hundreds of other gulls.
On November 4, Netta and I brought our kayak down from Seattle and launched it from the Gilmur access point on the bay. Very quickly we found the Black-tailed Gull and captured a few mediocre photos. Then something spooked them, and a bunch of the gulls took off. We saw our bird head across the bay and disappear in the distance, very disappointing. But we weren't discouraged, as the day, although threatening rain, had turned beautiful, with the low afternoon sun illuminating the maple-covered hillside in front of us.
We maneuvered the kayak around the log boom and found a place to enter it, giving us better light for photography. The boom was covered with gulls over much of its length, with photo ops abounding. Double-crested Cormorants roosting on it didn't like us at all, and they took off when we were a hundred yards away. Harbor Seals watched us but stayed put until, in a few cases, we got too close for their comfort level. The gulls just mostly sat and watched us paddle or drift past as close as 30 feet from them. They are surely used to curious kayakers by this time.
The most abundant gulls on the boom were Bonaparte's and Mew, at least several hundred of each. Among them were dozens of California and a few Thayer's and Glaucous-winged. We scrutinized the flock carefully and were able to find no other species. While slowly moving around the boom, we found to our delight that the Black-tailed had returned. We were able to get photo after photo of it as it watched us; it often rested with eyes closed, comfortably napping. When we got a little too close several times, it hopped onto another log, giving us the opportunity to photograph it with a different species.
Among the hundreds of gulls, the lack of immatures was noteworthy. There were no immature Bonaparte's and only a few immature Mew and California, a far lower proportion than would have been in their populations. Obviously immature gulls were not using Commencement Bay, or perhaps they weren't roosting. Do they have a harder time finding enough food and therefore have to continue foraging for a longer time? That makes sense, and the timing of mature vs. immature gulls at roost sites would be an interesting research project.
Another point of interest was the variation in leg color in the adult gulls. We noted such variation in Bonaparte's, Mew, California, and Thayer's, usually from duller to brighter. Bonaparte's varied from pale pink to red-orange, California from yellow-green to blue-gray. Thayer's are supposed to have rather bright red-pink legs, but one adult had very pale whitish-pink legs.
In any case, my luck had changed; it turned out that this was probably the last time the gull was seen!