QUIZ GULL #10 (with answer below)

ANSWER:

The correct answer is California Gull. This is a funny looking bird, obviously a juvenile by the brown tones and nicely edged scapulars and coverts.

The extensive pale areas to the bill help us rule out most species. In fact, the only species that are likely to show this much pale in the bill while still a juvenile are Mew, Kamchatka, Common, Ring-billed, California, Black-tailed, and Glaucous. It's clearly not the later, due to the dark tones and black wing-tips. The bill seems much too thick for Mew, Kamchatka, or Common. Ring-billed is an interesting option, though they typically have coarse scaling across the breast, sparsely marked undertail coverts, and well-defined gray streaks on the head and face, among other things. That narrows us down to California or Black-tailed.

Superficially, this bird does seem most like a first year Black-tailed Gull. Examine the two juveniles at http://plaza8.mbn.or.jp/~aiseisin/kamome/kamome.htm or the first winter bird at www.west.net/~dj/taim1.htm in Figure 1. Something's wrong, however; those birds have a dark brown wash across the breast and much paler vent areas than our bird. The upperparts and head, however, are reasonably similar. (Though by first winter, note how faded the scapulars of Black-tailed Gull become.) So is the overall structure of the bird. Perhaps the most important difference is the bill shape. The Black-tailed Gulls show unusually long bills, not unlike Laughing Gull, with a long, almost drooping (but not really) tip. Our quiz bird has a much more stout bill in comparison, and fine for California Gull.

But this is a funny California Gull! This is said to be an extreme example of a "cinnamon morph" juvenile, with a white breast and underparts. I'm not sure this extreme is reported in the literature. I'm told they can be regularly found in any large juvenile group of California Gulls (I often don't see that many this early in the season). Note the bill is still dusky at the base, as young juveniles have solid black bills for a brief period (see Quiz Gull #1 for an example of that). This bird was photographed August 10, 1998 in Goleta, CA by Don DesJardin, copyright 1998.

Once again, a plurality was correct but the majority got it wrong. Band-tailed and Brown-headed are good guesses, but since they're not covered in my gull pages, they automatically are not possibilities.

GUESS	# OF VOTES
California Gull	8 (35% correct)
Black-tailed Gull	6
Band-tailed Gull	3
Mew Gull	2
Western Gull	1
Ring-billed Gull	1
Brown-headed Gull	1