EAC 13, Shearwater, May-June 1967
Page 55
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Transcription
Boundary area A -- roughly centered at day 4 (mouth of the Gulf of California) is the approximate convergence area of the southeast-flowing California Current and the west-flowing north Equatorial Current. Boundary area C, determined at days 10-11 at about 9°N, is at the region where the Equatorial countercurrent bifurcates to stream north and south. Boundary area B is evidently an area of upwelling caused by the north- ward flowing tongue of the Equatorial countercurrent meeting the continental shelf. It is evidently rich in food as large schools of tuna and "dolphin" were associated with the bird flocks 10-20 miles off the coast. Some current charts would lump these hypothesized A and B divisions as being the two sides of a broad current transition area. SPECIES ACCOUNTS Black-footed Albatross Total Observations - 17 One to six birds followed the ship for the first five days. Two birds were seen last about 1200 of 3 June (22°30'N, 110°00'W). Laysan Albatross Total Observations - 1 One "White Goony" was reported by the chief engineer on 31 May. I take the observations as valid. Sooty Shearwater Slender-billed Shearwater Total Observations - 49 ? "Numbers" of Sooty Shearwaters were observed shortly out of San Francisco and around Monterey Bay. None were recorded during 30 and 31 May, perhaps due to the greater distance from the coast. Birds were fairly regu- lar again off Baja, California, and down to about 15°N along the Mexican cost. Sooties were regularly mixed in with the large Manx Shearwater flocks and many were seen from the skiff on 5 June. With little hesitation I feel 95+ percent of the Sooty/Slender-bill types were indeed Sooty. A single bird, glimpsed in a flock on 5 June, was probably a slender-bill; but this was the only one observed during careful scrutiny of the Sooties. Wedge-tailed Shearwater Total Observations - 619 The first Wedge-tail appeared in boundary zone A at the mouth of the Gulf of California (ca. 23°N). The bulk of the observations were made in the Manx Shearwater flocks off the Manzanilla-Acapulco area on 5 June. In this area light-phase birds outnumbered dark-phase (5 to 1). Birds were seen as far south as Panama where a light-phase bird was recorded. Pale-footed Shearwater Total Observations - 81 A flock of ca. 80 birds was following 20 + whales off the coast of El Salvador on 9 June. Another single bird, thought to be this species, was seen off Panama on the 11th.