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C. H. GILBERT CRUISE 74, August 1964 This cruise was designed to study the fish species present in ocean currents at this time of year. The fish were to be found by observing bird flocks, especially terns, which seem to follow fish schools more closely. Dayle Husted (S. I. personnel) boarded ship at Kaileua, Hawaii, August 14, 1964. The cruise covered the area around Hawaii, north of the Hawaiian chain to Kauai, the channel between Kauai and Niihau, and northwestward to south of Nihoa, then back to Honolulu on August 23. Dayle Husted was to observe the feeding behavior of the birds of the various flocks. FEEDING BEHAVIOR OF BIRDS IN FLOCKS Wedge-tailed Shearwater Wedgetails were observed feeding in two major ways -- either sitting on the water and dabbling or flying above the water and diving into the water. When sitting on the water they keep the wings folded, paddle around and put their head and neck under water to feed. When flying above the water, they dive to just above the water and put their head and neck under the water. During this action their wings are continuously beating. After sitting on the water they take off by lifting their heads out of the water and run along the surface until becoming airborne. The dives were not very deep-- probably less than a foot-- and lasted 3 or 4 seconds or less. Some Wedgetails were observed to alight on the water, keep their wings beating, or raised above their bodies, thrust the head and neck under water, and then take flight after a short run.
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Newell's Shearwater Only one flock of Newell's was observed feeding. These birds fed in similar fashion to the Wedgetail, but between dives to the water they do not arc up as high between dives to the water. Most of the arcs observed were under 15 feet above water level. They also turned on their sides more often, similar to Petrel flight. Newell's is also more maneuverable than the Wedgetail. When it dives down to the water it keeps its wings beating, puts its head and neck under water, then takes off with a much shorter run than a Wedgetail, or almost no run at all. No Newell's were observed sitting in the water in this particular flock, but they were observed sitting in the water singly or in pairs. Noddy Tern In the flocks observed, Noddy Terns stayed low to the water, usually 8 feet at the highest. When feeding they dove to just above the water and hovered above it. With wings beating continually, they put their heads into the water to feed. They then rose almost vertically above the water. Noddy Terns were also observed sitting on the water just dabbling around. Noddy Terns also followed along behind the ship as bait was being thrown out. The Noddies would grab the bait almost as soon as it hit the water. Noddy Terns were more maneuverable than the Shearwaters. Hawaiian Noddy Tern Hawaiian Noddies fed almost identically like Common Noddies. They stayed low to the water and were also very maneuverable. Both occurred in the same flocks and from a distance it was very difficult to distinguish the two species.