Red-footed Booby The increase from six birds of this species seen in March to 71 seen in April is explained by two factors. First, a feeding flock of 40 was seen in the company of 200 Sooty Terns on the first day out of Oahu, and, second, 28 birds were seen within sight of Oahu on the last morning. This area was passed during the night on the March cruise. Great Frigatebird Only two birds of this species, both along the western edge of the grid area, were seen in April, indicating a very small but possibly regular occurrence in the western portions of the grid area in the spring. Sooty Tern Numbers of this species increased 30% from 1261 in March to 1633 in April. The difference can be accounted for by the numbers seen during the last morning of the April cruise to the north of Oahu, the same area having been covered at night in March. Three density centers were found; first, within 100 miles of Oahu, second, along the western side of the grid, and third, in the southeast corner. Noddy Tern All 165 Noddy Terns seen during the April cruise were seen within 50 miles of Oahu where there is a large breeding colony. Hawaiian Noddy Tern All 420 of this species seen during the April cruise were seen within ten miles of Hilo harbor. This species nests along the rocky cliffs of the coast of the island of Hawaii.