ML133077131

Age

Not specified

Sex

Not specified

Observation details

This was a relatively small gull, yet it appeared to be maybe 20% larger than the Bonaparte’s Gulls with which it was associated. Despite its having proportions like those of the other birds, this bird also had a somewhat larger bill and seemingly a slightly stockier overall appearance. I thought the bill would have extended backward on the face to a point near the rear edge of the auriculars, which made it appear a little longer in proportion to the head than those of the Bonaparte’s Gulls. I nevertheless felt its heavier mass was more conspicuous than its greater length, given that this bird’s bill was maybe 20% longer than those of the other birds yet maybe double the depth from top to bottom. I further noted that the culmen was straight through most of its length before curving downward distally, and that it had a gonydeal angle that was subtle yet clearly evident. The forehead was relatively steep and the crown was smoothly rounded on a head that was proportionately similar to, if not slightly larger than, those of the Bonaparte’s Gulls. The neck was unremarkable in length for a gull of this size, but I thought it was slightly stockier than those of the smaller birds. The plump body sat high on the water and this bird’s overall shape and posture were not unlike those of the Bonaparte’s Gulls. I saw at least enough of the tail when this bird was on the water to note that it was relatively short and seemingly square-tipped. Largely obscuring the tail when the bird was on the water were the conspicuously long wings that tapered to pointed tips that were held slightly above the horizontal and extending some distance beyond the tail. I had no more than fleeting glimpses of the legs and feet when the gull took flight. When seen in flight, this bird appeared similar in overall proportions to the Bonaparte’s Gulls, given a slim bill, a head that extended only a short way beyond the leading edge of slim wings that were relatively long and tapering to pointed tips, and a short, square-tipped tail. This bird’s plumage coloration and patterns were almost identical to those of the Bonaparte’s Gulls. The head and neck were white and essentially unmarked apart from a small, black spot on the lower, rear part of the auriculars that was rounded and relatively well-defined. I overlooked in the field some limited dark markings around the eyes and a grayish wash to the cap, both of which are evident in my photos. Contrasting with the white neck, the back, scapulars, and most of what I could see of the wings was a shade of light gray that may have been ever so slightly lighter than those of the Bonaparte’s Gulls. I noted no markings whatsoever on the back, scapulars, or wing coverts, but I cannot now recall if there were white tips to the generally light-gray tertials. The exposed primary tips were black with what appeared to be a small, white spot at the tip of each feather. We also noted, at least at times, that one of the primaries was misarranged, which resulted in a feather with an entirely white inner-web sitting atop the black uppersides of the other feathers. I saw enough of the tail to note that it was white and without a black tip. When seen on the swimming bird, the breast had a faint, pinkish cast, and when this bird took flight, I thought the underparts were extensively washed with light pink. My views of the bird in flight were not very good, yet I was able to see that the tail was white and that there was a white wedge on the outer primaries as seen on the upperside of the wing. The underwing pattern is obvious in my photos, but I did not notice this in the field. Immediately conspicuous on this bird was a deep, coral-red bill that darkened distally, with a diffuse demarcation that appeared to cut straight across the bill near the gonydeal angle. I noted in the field only that the eyes were dark, and I had no more than an impression that the feet were webbed and dark in coloration.

Technical information

Model

NIKON D810

Lens

200.0-500.0 mm f/5.6

ISO

800

Focal length

500 mm

Flash

Flash did not fire, auto

f-stop

f/8.0

Shutter speed

1/2500 sec

Dimensions

4000 pixels x 2667 pixels

Original file size

6.05 MB