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QUIZ GULL #3 WITH ANSWER BELOW: what is this in the lower left?
bonus: what's that in the upper right?


ANSWER:

The correct answer to Quiz Gull #3 is Black-tailed Gull-- maybe. Actually, we don't know exactly what it is because no one saw the bird at the time of the photo-- it was only noticed after the film was developed! This photo, which was supposed to have only the shearwaters in it, was taken in September 1998 by Don Desjardin (copyright 1998) off southern California, where there is only a single previous record of this species.

The distinct black tail band, the adult gray mantle (of medium shade), and the lack of mirrors on the primary tips is a most striking combination. Franklin's and Laughing Gulls have tail bands like this in first winter plumage, but the wing pattern is different then and the terminal white band much narrower on those birds. In fact, the large white terminal band is very distinctive on this bird. Band-tailed/Belcher's has a similar tail, but a much darker (almost black) mantle. The mantle shade is within the range of California and Western Gulls-- could this bird be one of those species? Given the tail, it would have to be a second or third year bird; based on the developed adult gray on the wings and lack of primary mirrors, probably third year. However, these birds (and most other species as well) have more solid dark tails in second year and a scattered broken tail band in third year; they never acquire a well-defined tail band like this. It would have to be a second year Black-tailed, as the band goes to the outer retrices. Compare this bird with the Black-tailed Gull in flight at cras1.htm as well as the second year Western Gull at wyma2.htm. Some have proposed Heermann's Gull-- which is common in the area and does look like this bird, except for the tail. One person hypothesized that, because the photo is out of focus, the white areas bled into the other areas, making them look larger. Others can't buy this argument.

Also, note the bird is in moult (which is to be expected for most species in late summer), evidence by the white spots on the upper wing and the tattered edge of the secondaries.

The bird in the upper right is a Pink-footed Shearwater.

comments to shampton@ospr.dfg.ca.gov