Ranging patterns and habitat use of a solitary flying fox (Pteropus dasymallus) on Okinawa-jima Island, Japan

Most flying fox species (genus Pteropus) exhibit strong coloniality. They are highly mobile animals and commonly forage over vast areas. Only a small number of species are solitary, and their foraging and roosting patterns are not well understood. Here, we examined ranging patterns and habitat use of Orii's flying fox, Pteropus dasymallus inopinatus, a solitary fruit bat, using radio-tracking from April 2002 to January 2006 on Okinawa-jima Island, Ryukyu Archipelago, Japan. The daily home range size for this species was very small (mean 52.5 ha) compared to other Pteropus species, although home range size was highly variable among individuals and seasons. The distance between a day roost and feeding trees was 621 m on average, with a maximum of 6,875 m. Day roost site shifted frequently (every 1.6 +/- 0.8 days) to a nearby site in the current foraging area. The distance between consecutive day roost sites was 792 m on average, with a maximum of 6,000 m. These bats favored forest habitats for roosting sites, whereas they often used residential areas as feeding sites. Our results suggest that they regularly shifted the location of their personal activity range, a small home range with roost switching, probably to track changes in food availability and to avoid local competition for food. The solitary roosting system of this species links to its flexible foraging system, which likely provides an advantage for using limited food resources on a small island, even when food is patchily distributed in urbanized habitats.