ML86194281
Contributor
Date
Location
- Age and sex
- Immature Unknown sex - X
Media notes
SLR image; wing stretch showing very broad white trailing edge to secondaries, broad white terminal tips to inner primaries, and white subapical spots inside of the dark tips on p5 and p6 creating the beginnings of a 'string of pearls' which are the classic field mark for Slaty-backed Gull. The outermost primary has an adult-like mirror and the other primaries had very small apical spots. Note also rich pink legs.
Observation details
***mega; third-winter; 7th Massachusetts and first Middlesex County record found by Jeremiah Trimble and tentatively identified based on distant scope views of bird in middle of pond. MJI arrived to help view and document and was able to get closer view from the tip of the peninsula, with best views of the flock on the ice edge from the rock-lined elevated viewpoint. Identification as Slaty-backed based on: 1) rich reddish-pink legs, substantially darker and more saturated than all nearby Herrings and Great Black-backed, making legs appear dark but with obvious pink tones. Nearby Lesser bLack-backed clearly showed medium-yellow legs; 2) Back color slate gray and intermediate between Great Black-backed and Herring and clearly several shades paler than Lesser Black-backed in direct comparison. Pale brown coverts added to pale appearance of back. 3) Size close to Herring and stocky, with short appearing legs, thick neck, rounded crown, fairly short thick bill, short primary projection with wings about equal with tail tip, and hulking, chesty shape; 4) Irides staring and quite pale, surrounded entirely by dark "mascara" which was especially pronounced behind the eye and accentuated the pale-eyed look; 5) head entirely washed with pale brown, possibly whitish right above bill but no obvious streaks or spots on head itself (unlike all other expected gulls locally?) becoming fairly large pale brown blotching on hindneck and nape; 6) very broad white trailing edge to wing and pale tips on inner primaries "classic" for Slaty-backed and obviously broader than nearby Herring and Lesser Black-backed; 7) faint but obvious "string of pearls" formed by subterminal tips to middle primaries (apparently p5 and p6, based on JRT photos); 8) outer primary with dark outer web and large mirror on p10 (I think, possibly p9?), probably typical for third-winter and maybe not meaningful. The remainder of the primaries had very small apical spots, much smaller than adjacent Lesser Black-backed, but this is expected for third-winter bird. 9) Bill extensively dark (moreso than expected on most species of gulls as third-winter, except Lesser Black-backed) with obvious yellowish tip. Aged as third-winter by obvious pale brown on outer median coverts and tertials and extensively dark bill. Present on ice, in direct comparison with Herring, Ring-billed, Great Black-backed and one Lesser Black-backed for duration of observation, flying once and then circling back, and then flying away at 15:45 and heading off to east with Lesser black-backed. Many photos, both digiscoped (before my phone died) and also with SLR. Unfortunately, the manual focus was not well focused when the bird flew and those images are not in focus.
Technical information
- Model
- Canon EOS 7D
- Lens
- EF400mm f/5.6L USM
- ISO
- 640
- Focal length
- 400 mm
- Flash
- Flash did not fire, auto
- f-stop
- f/5.6
- Shutter speed
- 1/500 sec
- Dimensions
- 914 pixels x 584 pixels
- Original file size
- 315.27 KB