ML618323412

Age and sex

Adult, Unknown sex - 1

Behaviors

Flying

Media notes

Adult. Wingtip underside shows interesting pattern. Not enough dark on inner web of p9-p8 for LBBG, kind of "confused" pattern at the border of the dark tips and gray tongues in these feathers.

Observation details

Adult and subadult associating with each other in the gull roost at the south end of the beach. My first impression of these birds was that they looked larger and stockier than typcial Lesser-black Backed, without the small head or long, tapered look to the body in sitting position owing to slim midsection and long primary projection. I considered hybrids of LBBG x HERG, but was confused that the upperparts did not appear lighter or intermediate, and I was not certain if the shape differences were just variation in “pure" LBBG, so I tried to get detailed photos of the bare parts and wingtip patterns. The shape features point away from LBBG, while the bare part coloration, wingtip, and upperpart shade point away from both LBBG and LBBG x HERG hybrids, instead favoring Kelp x Herring hybrids, aka “Chandeleur Gulls." Shape: more obvious in the sub-adult, the large heads and thick bills with pronounced gonydeal angle are not typical in LBBG, nor are the more rounded wingtips, noticeable both in flight and sitting (short primary projection). These shape features are much more pronounced in the sub-adult individual. Bare part coloration: neither bird shows the saturated red orbital typical of breeding aspect LBBG at this time of year, and the gape colors are also not typical for LBBG. The orbital of the adult bird is hard to discern but appears somewhat orange, with a pinkish gape, while the sub-adult has a dull yellow orbital and gape. The legs of both birds are mostly dull yellow, with hints of green in the upperleg and joint, and some pink in the webbing of the feet. LBBGxHERG hybrids in breeding aspect tend to have more saturated yellow or sometimes pinkish leg color, more similar to LBBG or else intermediate between LBBG and HERG. The dull yellow leg color here with a hint of green is suggestive of Kelp influence. Wingtip pattern of adult (subadult wingtip patterns generally darker and more variable in gulls): the inner webs of p8 and p9, visible in the underwing flight photos, show less dark and longer gray tongues than LBBG. LBBG would have much more dark in these inner webs (especially p9), creating a more solid dark wedge appearance on the underside of the outer primaries. The adult also shows a noticeable and round white tongue tip to p7, uncommon in LBBG. Upperpart shade: the dark gray upperparts here appear to be in line with the shade of LBBG, which may cause confusion with that species, but actually helps to rule out LBBG x HERG hybrids. In the article by Donna Dittmann and Steven Cardiff on Chandeleur Gulls (available online), they noted that the upperparts of the first generation of known Kelp x Herring hybrids is actually in line with LBBG and Yellow-footed Gull. LBBG x HERG hybrids would presumably show noticeably paler upperparts, more intermediate between LBBG and HERG.

Technical information

Dimensions

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Original file size

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