Sunday, October 12, 2014

Black-vented Shearwaters on San Diego pelagic trip

Black-vented Shearwater
Black-vented Shearwater. Off San Diego, California. September 20, 2014. Greg Gillson.
This shearwater is rather unique in that it feeds inshore, and is often seen from shore. It nests on islands off Baja, Mexico, and is common off southern and central California in summer and fall.

It was formerly considered a subspecies of Manx Shearwater. Like that species it is smaller with rapid wing beats and short glides in commuting flight. Unlike the striking black-and-white Manx Shearwaters, Black-vented Shearwaters are smudgier and grayer where the dark upper parts meet the white under parts. Manx Shearwaters have white vents--the body feathers between and back from the legs and to the base of the tail. As you can see in the above photo, the body feathers under the tail are dark on Black-vented.

Really, though, in plumage this species looks like a miniature Pink-footed Shearwater--including the wide variance in under wing mottling and dusky "hooded" look to the head of many individuals. The Pink-footed Shearwater, however, is bigger with longer wings and deep, slow wing beats that gives a flight described as "lumbering" with long glides between. In photos you can't judge wing beats, so one must compare the all-dark bill of Black-vented Shearwater with the big pink bill and dark tip of Pink-footed Shearwater.

The following photos are of Black-vented Shearwaters off San Diego, California on September 20 and October 4, 2014.

Black-vented Shearwater
This Black-vented Shearwater shows white "saddle bags" on the side of the rump. This is more often
associated with other small black-and-white shearwaters like Townsend's and Newell's.
Black-vented Shearwater

Black-vented Shearwater

Black-vented Shearwater
Pale-headed individual with larger bill.
Black-vented Shearwater

Black-vented Shearwater
Very pale headed individual.