Thursday morning before 8 am I saw a bonanza of birds on the south edge of the North Basin: Black Oystercatchers, White Pelicans, Greater Yellowlegs, Long-billed Curlew, Western Sandpiper, Double-crested Cormorants, Willets, Snowy Egrets, and a young Western Gull. That’s enough for a whole week of daily postings. But pride of place belongs to this rare Pigeon Guillemot that birder-with-camera Sam Zuckerman spotted and identified, no mean trick. The adults of this species are fairly easy to identify when in breeding plumage. They’re solid black with a white wing streak and bright red legs. This one is not a grownup, or if it is an adult then a non-breeder, and shows a bit of wear and tear. The Merlin bird ID app wasn’t at all sure what this might be, but a close look at the photos of the bird in different stages of development strongly supports Sam’s ID. Sam reports that the bird was diving energetically and coming up with edible bits, as shown here. They’re very capable divers, able to go down to 45 meters (147 feet). They use their wings underwater for propulsion, and their feet mostly as rudders. They eat a wide range of marine proteins: little fish, crabs, shrimp, snails, and the like.
I surveyed the area where Sam saw this — near the Schoolhouse Creek outfall — the day before and didn’t see it, and again two days later, the same. This bird didn’t stay long. They’re rarely seen here. The last one recorded on eBird in Chavez Park was in 2011. I personally never saw one here. But I did see quite a few of them on a recent boat trip to the waters just off the Farallon Islands. Several thousand of them breed there, and right now is the end of their breeding season, with the young well launched and in the air. Chances are this bird was in an egg a month or two ago, in a crevice on the shores of the Farallons, and on one of its exploratory flight adventures the prevailing westerly breeze carried it here.
If this is a first year bird, its parents cooperated in incubating the egg or eggs in the nest — rarely more than two. Males and females look identical, and both have a brood patch on their chest, a soft feathery spot perfect for sitting on a pair of eggs and keeping them warm. The eggs are hardy, and some have been known to hatch successfully even if left alone for 24 hours or briefly flooded. The parents are monogamous, although the females and some of the males have to fend off repeated sexual advances by horny unpaired males. Both parents cooperate in feeding the hatchlings. They’ll need to be 3 years old or older before they can breed successfully. The majority of birds in one study didn’t live long enough to get to that point, but once they are successful breeders they have an average life expectancy of 4.5 years. The oldest reached 14 years. They fall victim to pollution, oil spills, mammal predators, and entanglement in gill nets, but the main danger to their survival is climate variations that warm the water, reducing the populations of young fish on which they feed, and so they starve.
Pigeon Guillemots live in the North Pacific on both sides. There are breeding populations in Russia and Japan as well as in Alaska and the west coast of Canada and further south into Washington, Oregon, and northern California.