ML227181591

Age

Not specified

Sex

Not specified

Media notes

This image shows the mantle and the tiny white subterminal spots.

Observation details

This morning early there was a flock of at least 34 Ring-billed Gulls and 5 Franklin's Gulls in the impoundment to the northwest. As I counted the RBGUs, one with a darker mantle caught my eye, but I could not get a good look at it in the large flock. Later, as I walked out the east-west spur trail, to that observation deck, the RBGUs and FRGUs had moved a bit further out, but one gull remained and it was clearly a Herring-type gull, in adult plumage. It was standing in the water up to its breast, preening. I used to survey gulls in Florida, now live here, so I'm not very familiar with the California/Western-type gulls, but I knew what field marks I needed to note. Without looking at my field guide I noted the following: an adult dark-mantled gull. The mantle was darker gray than the RBGUs for comparison, and had a white edge or skirt. The gull was larger than the RBGUs and I've included a photo that shows the size relative to an ibis and egret. The primaries were dark with at least four tiny "windows" or subterminal spots. The bill was heavy-set and yellow with a red gonydeal spot and the distal end was slightly dirty yellow. The head and breast were clean white, with no visible streaking on the neck but given the bright white glare contrast any very fine streaking would be hard to see. It looks all clean white to me. I could not see the gape color at this distance. I even took off my sunglasses and zoomed naked-eye (a seabirding trick to minimize the additional lens distortion of eyeglasses), watching the bird through my scope for about 45 minutes. Similarly I could not be sure of the eye color at this distance, although nothing about the color struck me, for example it wasn't bright light yellow nor obviously dark. I knew I needed to see the leg color, that field mark was key, but the bird was sitting in the water. I watched and waited as I said, figuring that as it preened it would eventually scratch or lift a leg. It did and the leg was obviously rich pink, not the light white pink like a Herring Gull (the legs of which always look death-like to me in FL). But I had to be sure it wasn't an illusion so I waited for another leg lift, which happened about 10-15 minutes later. Definitely pink, not yellow, flesh, whitish, or greenish-yellow. The final field mark I noted was that as it stretched its wings the wings appeared very dark and smudgy underneath. I worked to get decent photos but they are all fuzzy with the heat shimmer. So, working through the possibility of large dark-mantled gulls: gulls such as Iceland, Glaucous, and Glaucous-winged are ruled out by the dark primaries; Mew Gull, Ring-billed, and Yellow-footed are ruled out by the yellow legs (and other field marks such as the bill). That leaves Western Gull and Herring Gull. A few photos attached. Note added: I'm leaving my original field notes unaltered above. Two experts independently ID'ed this bird as a California Gull. Not relying on my perception of pink on the unreliable soft parts, this is consistent with the bill spot coloration and structure, head and body shape, mantle color and overall size relative to the RBGUs, habitat and assoc with RBGU etc.

Technical information

Model

COOLPIX B700

ISO

100

Focal length

236.5 mm

Flash

Flash did not fire, auto

f-stop

f/6.3

Shutter speed

1/400 sec

Dimensions

1283 pixels x 941 pixels

Original file size

310.42 KB