The Status of Fruit Bats on Guam

Two species of fruit bats are known from Guam in the southern Mariana Islands. Pteropus mariannus mariannus has declined greatly in abundance since the early 1900s. Its numbers decreased from an estimated 3,000 animals in 1958 to fewer than 50 individuals in 1978. However, by 1982, the population of this species increased to about 850 to 1,000 bats, probably through immigration of fruit bats to Guam from the island of Rota. Since then , P. m. mariannus appears to be declining once again with only 425 to 500 counted during a February-April 1984 census . A second smaller species, P. tokudae, has always been rare since it was first discovered in the early 1930s. It has not been recorded since 1968 and now is thought to be extinct. Overhunting of Pteropus for use as a delicacy is the main cause for their decline on Guam. Forest clearing and predation by brown tree snakes may be other contributing factors. Both species of Pteropus were listed as endangered on Guam by the U.S. Fish and Wildlife Service in August 1984. O VERH UNTING AND HABITAT DESTRUCTION have reduced the populations of man y islanddwelling fruit bat species in the Pacific and Indian Ocean s (Wodzicki and Felton 1975, 1980, Racey 1979, Cheke and Dahl 1981, Cox 1983, Fal anruw in prep.). Similar declines have occurred in the southern, inhabited portion of the Mariana Islands where two species of Pt eropus occur, the Marianas fruit bat (P. m. mariannus) and the little Marianas fruit bat (P. tokudae) (Wheeler and Aguon 1978, Wheeler 1979, 1980, Wiles et al. in press). P. m. mariannus inhabits the island s from Guam northward to Saipan (perhaps even further north to Maug, depending on the validity of the subspecies description for P. m. paganensis) while P. tokudae is endemic to Guam. Fruit bats or " fanihi" (their Chamorro name) are highly sought after by Chamorro residents, who serve them as a delicacy on special occasions. Both species of bats were listed as endangered on Guam by the U. S. Fish and Wildlife Service in August 1984. P. m. mariannus is protected throughout the remainder of its range but is rare on Saipan, 1 Manu script accepted March 1986. 2 Division of Aquat ic and Wildlife Resources, P.O. Box 2950, Agana, Guam, 96910, USA. Tinian , and Aguijan, and declining on Rota because of heavy illegal hunting (T. O. Lemke , pers . comm.). The purpose of this study was to document the abundance and distribution of fruit bats on Guam prior to their endangered listing and to complement other bat surveys recently completed in the remainder of the Marianas (Wiles et al. in press , T. O. Lemke, pers. comm .).