[All photographs copyright, Gary Nunn 2015] – Flying in from the north, low over the ocean, a large shorebird quickly got my attention at Point La Jolla early this morning since a Western Gull was chasing right behind it. Weird! Things made more sense however as it approached closer and the large body and shallow stiff wingbeats soon added up to an incoming oystercatcher! As it came flying in I started to see the white belly which lifted my interest level much higher! I was hoping for a circle flight around below my viewpoint, for photography, but instead it bee-lined to a rocky perch right in front of me. Luckily it then decided to move a few yards, in a short flight, allowing a few upper and under wing photographs.
Referencing information given in Pyle (1997) and additional material at the website of the American Oystercatcher Working Group this individual seems, so far as I can tell, to match the description of a frazari form of American Oystercatcher Haematopus palliatus. It has a well demarcated black bib with a little black mottling at the sides, white underparts, white undertail coverts, almost complete white underwing, and a white greater secondary coverts wingbar on the upperwing. The uppertail coverts are mottled black and white, but this also seems consistent with descriptions in the reference literature.
I did make a preliminary score using the system described in the publication by Jehl (1985) on hybridization in oystercatchers in Baja California. The scoring instructions from Table 1 of this publication can be found, rather usefully, at the Western Field Ornithologists Rare Birds of California entry for American Oystercatcher. This individual scores high in the range, about a 33, and would be attributed to American Oystercatcher using this system. I had to make a guesstimate on the white wingbar width, I conservatively put it in the middle of the range but it does look pretty wide to me!