Table 15. Measurements of Phaëthon lepturus from Micronesia
Table 15. Measurements of Phaëthon lepturus from Micronesia
| No. | Wing | Tail | Exposed culmen | Tarsus | |
| Marianas: Asuncion, Guam | 6 | 264 | 107 | 47 | 21 |
| 256-287 | 97-117 | 44-50 | 20-21 | ||
| Palaus: Peleliu | 11 | 257 | 108 | 45 | 21 |
| 242-270 | 98-122 | 40-49 | 19-21 | ||
| Carolines: Ponapé, Kusaie | 11 | 261 | 105 | 47 | 21 |
| 252-271 | 97-114 | 44-49 | 21-22 | ||
| Total: Micronesia | 28 | 260 | 107 | 46 | 21 |
| 242-287 | 97-122 | 40-50 | 19-22 |
Specimens examined.—Total number, 37 (22 males, 10 females, 5 unsexed), as follows: Mariana Islands, USNM—Guam, 5 (June 11, July 21); AMNH—Asuncion, 1 (June?); Palau Islands, USNM—Peleliu, 5 (Aug. 29, 31, Sept. 5, 6); AMNH—exact locality not given, 7 (Oct. 13, 26, Nov. 15, 23, Dec. 18); Caroline Islands, AMNH—Ponapé, 9 (Dec. 8, 9, undated)—Kusaie, 10 (March 1-8, April).
Nesting.—The NAMRU2 party observed nests of the White-tailed Tropic Bird at Peleliu in August and September, 1945. Several nests were seen in hollows of the Australian pine (Casuarina equisetifolia) between 20 and 30 feet above the ground. Birds could be seen in the nest hollows because the plumes of their long tail usually extended well out of the entrance. One nest was found in a dead tree in a battle-cleared area; others were observed in jungle habitat. Coultas observed nesting at Ponapé between November 1 and December 30, 1930, and found nests in the tops of trees and in hollow trees; a few were observed in holes in cliffs. Yamashina (1932a:407) records the taking of one egg at Ponapé on August 18, 1931. At Guam the NAMRU2 party found birds along the high cliffs which edge the beach. There was no evidence that they were nesting from May to July; nevertheless males taken in June had enlarged gonads. The bird is known to breed at Namorik in the Marshall Islands, according to the Hand-list of Japanese Birds (Hachisuka et al., 1942:209).
Food habits.—The NAMRU2 party found small fish in the stomachs of these birds taken at Peleliu.
Parasites.—Uchida (1918:489, 492) records the bird lice (Mallophaga), Colpocephalum epiphanes and Menopon eulasius, from the White-tailed Tropic Bird from Palau.
Remarks.—Birds taken in Micronesia differ only slightly from those from other areas in Oceania. Within Micronesia (see [table 15]) the birds from the Palaus have the shortest wing and shortest exposed culmen.
The White-tailed Tropic Bird appears more numerously in western and northern Micronesia than in the Marshall Islands. This distribution may be correlated with a preference for the "high" islands; especially those which have rocky cliffs, including Guam, Rota, Peleliu, Angaur, and Truk. Reports were received in 1945 that the birds were only infrequently seen at Ulithi, a low atoll. Stott (1947:524) observed birds flying into rocky crevices at Saipan on December 18. Gleise (1945:221) also recorded the bird in the vicinity of Saipan. Borror (1947:416) reports seeing birds at Agrigan on July 29, August 5 and 6, 1945. Coultas (field notes) found tropic birds common at Ponapé in November and December, 1930, in forested regions and along the cliffs. He made similar observations at Kusaie and Palau. At Ponapé and Palau, Coultas noted the use of the eggs, young and adults as food by the natives. At Palau the plumes are used in headdresses worn by the natives, the birds being taken with the blowgun.