Tuesday, September 24, 2013
Birds I'm Watching: Unusual Heermann's Gull
There have been a number of Blue-footed Boobies in the San Francisco Bay area this autumn, including around Bodega Bay, the area we set out from. We saw nothing so rare as a booby, but we did get to see an unusual variant of the Heermann's Gull, which is a fairly common visitor in Sonoma County during autumn migration and over the winter months. A few of these birds have a white patch in the wings that is not normally present and that I'd never seen before. I've heard various estimates of the frequency with which the variation occurs, ranging from one in a hundred to one in a thousand. I don't know, but I thought this bird very interesting. This particular individual has white in the secondaries, not just in the upper primary coverts, which is where the white normally occurs in birds that show this variation. Happily, the water was comparatively calm on this (my second) pelagic tour. On the first one, the water was so rough that many on the boat were sick the whole time, including me.
For more about bird watching in Sonoma County, see my website Sonoma County Bird Watching Spots