“om ” / - “ an 7 . , The total absence .of natural predation on theislets has allowed the | population to soar and‘be limited only by population pressure, ’ i , . ‘ : ee se ee competition between species and food/harborage availability. With *°4 the exception of the islet of Enewetak the rat population reached the sy maximum carrying of the islets surveyed. , Mice, though not taken in traps, are present on the islets. "Evidence ma -used to determine their presence was the collection of frass and signs of damage. The population of mice on the individual islets is! probably low’due to successful corpatition from the rat population. . Ectoparasites found on rats were limited to mites of undetermined | species. No ticks or fleas were found. Three methods were used to -.: obtain ectoparasites from the rats. mo vs oe 1) Combing. 2) Washing. 3) Visual examination of the bocy and hair with the aid ¢of magnifying F: optics. ; oe “ a Lack of higher ectoparasitic population is attributed to extremely. limited contact with other mammalian species. Various species of stinging (aculeate) wasps are present on all of the islets. Polistes _ ‘bem fuscatus “var. aurifer is the most aggressive. Ropalidia marginata and an unidentified species in the family Vespidae are also present. Parasitic wasps of the family Sphecidae were also collected. 1) 7 In all cases the wasp populations per islet is low. However, where present the wasps tend to be concentrated in small areas. For example, on the islet of Jedrol (Rex) a P. fuscatus colony - was located in a refrigerator building. The colony was old but viable and nests varied in size from the diameter of a quarter to the size of a football. 2) About 25 wasps were present in the refrigerator building and a 3) - Limited natural food sources and high winds have severly restricted the numbers of wasps capable of surviving on the islets. Normal fdods such as lepidopterous larvae, nectar etc, are extremely limited. Colonies are therefore small and focal. They may usually number were observed foraging in the area. The estimated living population of the colony is between 100 and 150 wasps. ww be located in dense foliage, well shielded from the wind and close to the ground. Some R. marginata were observed nesting up to six feet above ground onthelee side of the foliage. : Co Caenwile rb a r~ wh EsiMAES i . we Re eae A ——