Population Status and Natural History of Pteropus mariannus on Ulithi Atoll, Caroline Islands

Abstract

A census of fruit bats (Pteropus mariannus ulthiensis) was conducted on Ulithi Atoll, Caroline Islands, in March 1986. We observed 715 bats in 3.2 km2 of habitat on 14 of 43 islets, yielding a minimum average density of 210 bats/km2. The population of the entire atoll was estimated to be about 1200bats at an overall density of 280 bats /km2. During the day, most (89%) bats roosted in colonies of > 5 animals. Colonies, which were typically composed of harem groups and bachelor males, occurred most commonly in two species of trees, Pisonia grandis and Artocarpus altilis. We recorded nine species of plants eaten by bats , with the fruit of Pandanus tectorius and the fruit and leaf stems of Guettarda speciosa and A. altilis fed on most frequently.