December 1964 - BCF cruise Red-tailed Tropicbird This species decreased from 14 in November to a new low of six birds in December, all in the southern and western parts of the area. White-tailed Tropicbird This species increased to 17 in December from 9 in November. None were seen south of 16° North, and most were in the general vicinity of the high Hawaiian Islands. Brown Booby One bird was seen near the entrance to Pearl Harbor on 1 December. Red-footed Booby Five of the 77 Red-footed Boobies observed in December were immature birds seen at a considerable distance from land, as far south as 11° North. Evidently, in winter a small population of immature birds is to be found far out to sea in the area. Great Frigatebird Numbers dropped to 9 in December from 22 in November. Four were seen at the southern end of the area and the rest were found in the general area of the high Hawaiian Islands. Sooty Tern Numbers of this species remained constant from November to December, 557 to 566. Again, greatest concentrations were found in the vicinity of the high Hawaiian Islands and toward the southeastern corner of the area. Numerous immatures were observed. Nearly all of the birds were seen in flocks.