Biology of the flying foxes in American Samoa: Pteropus samoensis and Pteropus tonganus

Brooke, Anne

Describes the characteristics of the flying foxes (Pteropus samoensis and P. tonganus) surveys conducted in American Samoa, post-hurricane population growth, past monitoring problems, roost sites, and diet... The Order Chiroptera is divided into two sub-orders, the Microchiroptera which has a worldwide distribution and the Megachiroptera which is limited to the Old World tropics. The Megachiroptera consist of a single family, the Pteropodidae or old world fruit bats, found from the eastern Mediterranean, African sub-tropics throughout southeastern Asia, Australia and islands in the Pacific ocean. Within the Pteropodidae, there are 41 genera consisting of 161 species (Koopman 1993). The largest and best known genera, Pteropus, has 57 species commonly known as flying foxes. 55 ofthese species (or 96.5%) are island dwelling, with some or the entire species' range on islands in the Pacific ocean. There are a large number of island endemics, 35 species, that are confined to a single island group or a single island. Nine species are found on continental areas, five in Asia, five in Australia. Only two species are found on continents but not on islands (Mickleburgh et al. 1992). Megachirpoteran bats are generally more robust and possess a suite of physical characteristics that distinguish them from Microchiropterans including large eyes, small, simple ears lacking a tragus, a small claw on the third finger, and large, well developed thumbs. Megachiroptera rely on vision rather than echolocation for navigating at night. The diet of Megachiroptera consists primarily of fruit, nectar, pollen, and leaves (Mickleburgh et al. 1992) although there are reports of Megachiroptera occasionally eating sap (P. Craig; P. Trail personal communication), insects, (Funakoshi et al. 1993) and fish (Ghose and Ghosal1983). The evolutionary history of bats is not well known and the fossil record scant. Whether the order has a diphyletic origin or is monophyletic is contested. (Pettigrew et al. 1989; Baker et al. 1991). The earliest known occurrence of P. tonganus and P. samoensis (subspecies unknown) are from Eua, Tonga, and predate the human colonization of Polynesia (Koopman and Steadman 1995)