ML56005261

Age

Not specified

Sex

Not specified

Observation details

Continuing. The bird was like an Iceland Gull by structure. Dorsally, p10-6 had extensive dark coloration on both sides of the rachis mid-shaft, and complete dark terminal bands. The outer vane of p9 was continuously dark. The right p5 had a small smudge on the outer vane, toward the tip. The left p5 was completely pale. The legs were pinkish, the eyes were dusky though showing some dark yellow coloration, and the orbital ring was purple-pink. The mantle, in direct sunlight, was a similar color as that of nearby Herring Gulls. My own personal reservations for calling this bird thayeri are two-fold. 1) The dark coloration on the much of the primaries, particularly on p10 and p9 was noticeably paler than the deep black of the primaries on nearby Herring Gulls. Thayer's should be closer to a deep black like a Herring. I think the bird found in this checklist is comparable to the bird in this link- http://www.anythinglarus.com/2015/01/a-mostly-thayers-gull-whiting.html. 2) While the right p5 had a dark smudge, the smudge was quite small, and only present on one of the wings. Thayer's Gulls typically have more dark coloration present on both p5's. I readily concede that the bird could be a fine Thayer's. However, given their rarity on the east coast, I personally am looking for birds that are a slam dunk across the board. Such birds occur regularly around the Great Lakes, so I'll wait patiently for one of those. Finally, I must add that Thayer's Gull may not represent a reproductively isolated taxon. Dunn and Remsen make compelling arguments to discredit Smith (1966; the seminal Thayer's Gull paper that the current treatment hinges upon) in proposal #7 of proposal group 2017-C- http://checklist.aou.org/assets/proposals/PDF/2017-C.pdf.

Technical information

Model

Canon EOS 7D

Lens

EF400mm f/5.6L USM

ISO

200

Focal length

400 mm

Flash

Flash did not fire, auto

f-stop

f/5.6

Shutter speed

1/4000 sec

Dimensions

2058 pixels x 1484 pixels

Original file size

1.66 MB