Figure 66. Gleaming white on the rump and lateral undertail coverts, and projection of feet beyond the folded tail peg this as a Wilson’s Storm-Petrel. In California this species is best known as a regular fall visitor to Monterey Bay, but Cordell Bank in Marin County has also hosted large numbers on rare occasion, including this individual, photographed on 19 September 1993 (James Lomax).

 

Figure 67. Distribution of 129 Wilson’s Storm-Petrels accepted through 1989. More than 85% were found at either Cordell Bank or Monterey Bay.

 

 

WILSON’S STORM-PETREL Oceanites oceanicus (Kuhl, 1820)

Accepted: 129 (99%)	Treated in Appendix H: no
Not accepted: 1	CBRC review: records through 1989
Not submitted/reviewed: 7	Color image: none

This storm-petrel, among the world’s most abundant bird species, breeds along the coast of Antarctica and on subantarctic islands. The species’ taxonomy is unsettled, with up to three extant and one extinct subspecies recognized. Following Grinnell and Miller (1944), the AOU (1957) attributed California specimens to O. o. chilensis, but this may be subject to change. During the austral winter (April–September) most of these birds migrate to the northwestern Atlantic Ocean, although some head to the Indian and tropical Pacific Oceans. The species is rare in the Gulf of Mexico and accidental inland—mostly after tropical storms—with records from southern Ontario, southwestern Quebec, upstate New York, and Pennsylvania. Migrants are encountered sparingly in the tropical Pacific Ocean (Pratt et al. 1987), and small to moderate numbers occur regularly north to Japan. This storm-petrel is considered a casual or very rare visitant in the eastern Pacific Ocean between Panama and Washington, except for small numbers found regularly off central California.

An adult Wilson’s Storm-Petrel collected on 24 August 1910 at Monterey Bay, Monterey County, provided the first record for California and the North Pacific (Grinnell 1915). Records were then spotty for several decades, but the species has been recorded every fall since 1972. Apart from unseasonal records of presumed non-breeders on 1 May 1978, 13 July 1986, and 10 June 1989, the Committee-endorsed records fall between 7 August and 14 November; more than 85% come from Monterey Bay and Cordell Bank (Figure 67). Numbers at the latter spot during November 1985 were unprecedented, with as many as 45 birds recorded, and this area again hosted large numbers—by California standards—in 1987 and 1989.

 

RINGED STORM-PETREL Oceanodroma hornbyi (Gray, 1854) – see Appendix H

 

[WHITE-BELLIED STORM-PETREL Fregetta grallaria (Vieillot, 1818) – see hypothetical section]

 

[BAND-RUMPED STORM-PETREL Oceanodroma castro (Harcourt, 1851) – see hypothetical section]