These are adults resting on the mooring ropes of the cruise ship Zaandam before our departure to Antarctica. This species is a long-distance migrant, breeding in the interior North American prairies and wintering primarily along the west coast of South America. This year they were unusually common and we encountered them south all the way to Punta Arenas. This species is unusual in that it has two complete molts each year.
This species was formerly included in the genus Larus, but moved along with other small "hooded" gulls to Leucophaeus in the 49th supplement of the AOU Checklist. New genetic data indicated that inclusion of these gulls in Larus would make the genus paraphyletic. This new arrangement is followed by most authorities including Clements, IOC and Howard & Moore. However Birdlife International and HBW persist in placing these gulls in Larus.
Digiscoped with Panasonic DMC-LX5 | Nikon FieldScope 3 | 30X WA | hand-held (no adapter)