Bay-Breasted Warbler Off California Coast
Bay-breasted Warbler off California Coast.-On the morning of October 6, 1956, a specimen of the Bay-breasted Warbler (Dendroica castanea) was obtained 24 miles south-southeast of San
Clemente Island, almost due west of San Diego, California. This location is out of sight of any land mass, and the bird, after circling the ship for approximately ten minutes, attempted to land. The crew
of the vessel, a commercial chartered fishing craft, indicated that it was not uncommon to find small land birds off the COI!St, and that "many were picked up and released when they returned to port."
This bird, following unsuccessful attempts to land on the rigging, slipped into the water and was netted by the crew.
The specimen, now number 134974 in the collections of the Museum of Vertebrate Zoology, was checked for identification by Dr. Harrison B. Tordoff. The bird is an immature, as shown by the
plumage, having only a faint suffusion of buff on the breast, and by the skull, which was only partly ossified. It was a male, and it was considerably emaciated.
No reference can be found to the occurrence of this warbler in the western United States, although numerous reports are available concerning vagrant warblers taken or seen at sea near the California
coast and on the Channel Islands off southern California. It would seem most likely that passerine birds would appear away from shore during conditions of unusual wind velocity. At the time the
Bay-breasted Warbler was taken, there was no storm, nor had there been high winds. The bird was alone; no other passerines were observed on this particular day.
One must concede that, particularly among migrants, the mortality is great because of straying from regular migration routes. Grinnell (Auk, 34, 1922:373-380) discusses such vagrants carefully,
and we can but conclude with him that this Bay-breasted Warbler was a "pioneer ... sacrificed in the interests of the species."-M. DALE ARVEY, Long Beach State CoUege, Long Beach, California,
February 20, 1957.
