EAC 4, Shearwater, February-March 1967
Page 48
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Transcription
- 11 - Western (9), Ring-billed (16), Heerman's (1), Bonaparte's (1), Glaucous-winged (1), and Black-legged Kittiwake Gulls were recorded, many following from time to time. The age composition of these gulls is unknown except for the Kittiwakes (4:1 adults). One flock of Ring-billed and one of California Gulls was observed, otherwise gulls were scattered except for 4 large flocks (50-200) of Gull sp. distantly seen along the shore line. These were probably mixed compositions of California, Western, and Ring-billed Gulls. In the southern section great differences occurred in comparison with the northern section, primarily concerning the numbers, age composition, and activ- ity of the Black-legged Kittiwakes. From sunrise until sunset Kittiwakes were dense, mainly sitting and feeding flocks. Altogether 40 flocks were sighted. Such a large concentration of Kittiwakes (1109) along with other birds indicates a prime area of feeding. One might assume migration a possible explanation for such a congregation, but when one takes into account the 9:1 ratio of immatures to adults, a prolific food source can be the only reason for this aggregation. The following numbers of Kittiwakes were logged: 544 immatures, 67 adults, and 498 of unknown age. It is interesting to note that among the predominant flocks of immatures, one totally adult flock of 30 was recorded. Other gulls in the southern section were Glaucous-winged (1), California (6), and Western Gulls (3). The California Gulls (one flock) were observed 90 miles and the Western Gulls 30 miles southwest of San Clemente Is. Alcids Three Ancient Murrelets represent the only alcids sighted in the northern section. In the southern section, on the other hand, alcids were common. Twenty-six were identified as Rhinoceros Auklets while 10 were logged as Alcid sp. All were on the water indicating that they were feeding or had been doing so. One flock of 5 Rhinoceros Auklets was observed.