Yellow-footed Gull

Larus livens

ML51129091


©
Curtis Marantz
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eBird Checklist S35165885
Los Angeles River--Alondra Blvd. to Artesia Blvd.
Los Angeles, California, United States
Search this location, Illustrated Checklist
Latitude and Longitude 33.8815, -118.1887 Map

Age
Adult
Sex
Unknown
Behaviors
Breeding
Tags

Comments

Adult Yellow-footed Gull photographed by Curtis A. Marantz on 12 March 2017 along the Los Angeles River above Atlantic Avenue, Compton, Los Angeles County, California. This bird had been seen daily at this site since first found on 9 March 2017 by John Garrett.

Observation details

This was a large, heavy-bodied gull that I estimated to be 10-15% larger than adjacent Western Gulls. The head was proportionately large and the bill was both larger and conspicuously deeper than those of the nearby Western Gulls. I estimated both that the bill would have extended backward on the face to the rear edge of the auriculars and that it was about two-and-a-half times as long as it was deep at the base. The culmen was straight for about the basal two-thirds before curving smoothly downward to a blunt tip, and the lower mandible was weakly curved inward basally yet with a conspicuous angle at the gonys that produced an expansion just before the tip of the bill. The forehead was sloping and the crown was gently rounded back to a more sharply rounded junction where it met the nape. The neck was relatively short and stocky, at least when retracted. The body was conspicuously plump and full-chested, and the posture when the bird was standing was slightly more upright than horizontal with the tail held slightly below the horizontal. The medium-length wings had a primary projection that was comparable to the entire length of the exposed tertials, if not slightly longer. The tips of four primaries were visible beyond the longest tertial, with the two longest feathers grouped near the wingtip and the two inner feathers about equally spaced between the wingtip and the longest tertial. The wingtips extended beyond the tip of the tail a distance that appeared to be slightly less than the length of the bill. The tail appeared to be about half the length of the body without the head and neck, and it seemed to be square-tipped. The legs were moderately stout and of unremarkable length, and the feet were relatively large and with the front three toes fully webbed. This bird’s plumage patterns were essentially identical to those of the nearby adult Western Gulls. The head, neck, underparts, and what I could see of the tail were entirely white and unmarked. I noted no dark markings on the face, crown, nape, or the back or sides of the neck. The white of the neck was sharply demarcated from the slate-gray of the back, behind which, the mantle, scapulars, wing coverts, and what I could see of the tertials and secondaries were, with a few exceptions, the same shade of slate-gray as those of nearby Western Gulls. I saw no obvious difference in the shade of gray between these species in direct comparison, nor did I see brown tones anywhere on the upperparts or wings. Contrasting with the slate-gray color described above was a moderately conspicuous “scapular crescent” that represented relatively broad, white tips to the rear scapulars. Complementing the scapular crescent was a conspicuous “tertial crescent” that was produced by broad and sharply demarcated tips of white to the longest tertials, and yet again, in direct comparison, this crescent was no broader than those of nearby Western Gulls. The marginal wing-coverts were white and the underwing coverts were at least mostly white. The exposed primary tips were dull black from the tertial crescent to the wingtip; however, the four primaries visible in the wingtip each had a small and relatively inconspicuous spot of white at the tip that facilitated my counting the exposed primaries. Evident on the underside of the far wing was a large, white mirror near the tip of what I suspect was the outermost primary. The distal part of the tail, visible around the closed wings, appeared to be uniformly white. The bill was deep yellow apart from a rounded spot of scarlet-red near the tip of the lower mandible just beyond the gonydeal angle. The eyes were cream-colored with a contrasting black pupil and encircled by an orbital-ring that was a deep, bronzy-yellow. The legs and webbed feet were lemon-yellow, and thus not as rich in color as the bill, yet they lacked any suggestion of flesh or pink. The black claws contrasted conspicuously with the yellow toes.

Technical Information

Model
Canon EOS 7D Mark II
Lens model
EF100-400mm f/4.5-5.6L IS II USM
f-stop
f/8.0
Focal length
400 mm
Shutter speed
1/2000 sec
ISO
160
Flash
Flash did not fire, auto
Original file size
452KB
Dimensions
1992 x 1325

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