Wilson's Storm-Petrel (Oceanites oceanicus)

Wilson's Storm-Petrels breed in the Antarctic and disperse during the austral winter into the N Atlantic and, less commonly, the N Pacific (Crossin 1974, Cramp and Simmons 1977, Harrison 1983, AOU 1998, CBRC 2007, Spear and Ainley 2007, Howell 2012). Huber (1971) collected 58 specimens at Enewitok I, Marshall Is, from 17 Apr to 29 May 1969 (USNM), apparently migrating north, and they are regular in small numbers off California in July-November (CBRC 2007, Howell 2012). They appear to be uncommon transients through Northwestern Hawaiian Island waters, with all records to date occurring in fall at sea. Three individuals recorded about 9 km SE of Gardener Pinnacles 3 Nov 1984 were the first reports for Hawaiian waters (Pyle and Eilerts 1986). The HBRC accepted this species to the Hawaiian Island Checklist based on this record, despite no photographic or specimen evidence from the islands. During 336 days of observing in 2002 and 2010 (168 days each in Northwestern and Southeastern Hawaiian Island waters), HICEAS observers recorded 18 Wilson's Storm-Petrels ranging in dates from 21 Sep to 22 Oct (Rowlett 2002; HICEAS data). Sixteen of these occurred in waters among islands between Pearl and Hermes and Kaua’i, while only two were recorded farther east, about 350 km SE and SW of Hawai'i I, 8 Oct and 13 Oct 2010, respectively. The HBRC did not accept these records due primarily to lack of detailed descriptions rather than questions about the identifications. Given the amount of coverage in Southeastern Hawaiian Island waters (including CRC data) with only two observations, it seems Wilson's Storm-Petrels may follow a migration route largely through Northwestern rather the Southeastern Hawaiian waters, although, among several observations and specimens recorded by the POBSP in the C Pacific during the 1960s, one Wilson's Storm-Petrel was recorded (without description) about 325 km E of Hawai’i I. (Crossin 1974). The subspecies (of two recognized; Spear and Ainley 2007, Pyle 2008) of Wilson's Storm-Petrels recorded in Hawaiian waters remains undetermined. Only one of 66 specimens collected at Eniwetok and in the c. Pacific appears to be of the smaller O.o. chilensis breeding in South America (USNM 544414, Eniwetok, 8 May 1969; PP examination), and birds off California also appear to be of nominate oceanicus (Howell 2012) so it seems probable that individuals reaching Hawaiian waters would be predominantly of the nominate Antarctic subspecies as well.