Pteropus pselaphon is found mainly in forests. This species is mostly nocturnal, yet diurnal activity has been reported on uninhabited islands. It forms colonies of up to several dozens of individuals that return to the colonial roost to sleep during the day. When resting, individuals often gather on branches and form ball-shaped clusters of ~6-20 individuals. These clusters improve thermoregulation and incidentally impact the mating system, which has been described as female-defence polygyny (Sugita and Ueda 2013).

Pteropus pselaphon is a dietary generalist (or more precisely a sequential specialist), switching food source at the individual level depending on availability. Fruits of the endemic Takonoki tree (Pandanus boninensis) are particularly favoured by this flying fox, which also regularly feeds on a variety of leaves and nectar. It is also known to feed on fallen fruits on the ground and to drink from streams. On inhabited islands, orchards are also targeted, resulting in this species being seen as a pest by some farmers (Vincenot, unpub. data). The limited extent of damages, however, does not support this characterization.

This species is known only from the Bonin Islands in Japan, which are located on the Izu-Bonin-Mariana arc, about 1,000 km south of Tokyo and halfway to the Mariana Islands. It has been observed in the Ogasawara archipelago (Chichi-jima and Haha-jima) and in the Volcano archipelago (Kita-Iwo-jima, Iwo-jima, and Minami-Iwo-jima) (Abe et al. 2005). It was also once observed flying on Muko-jima (Harata 2010) and traces of foraging were found on other islands of the chain (Nishi-jima, Ani-jima, Ototo-jima, and Higashi-jima), but no local population has been reported at these locations.

This species was designated as a Natural Monument in 1969 under the Law for the Protection of Cultural Properties and as National Endangered Species” in 2009, whereby capture and disturbance without permission are prohibited. A National Wildlife Protection Area that includes the species' habitat was established in 1980. This species is categorized as Endangered (EN) on the Tokyo Red List (Tokyo Metropolitan Government 2014) as well as on the national Japanese Red List (Ministry of Environment 2012). A conservation plan has been officially devised by the Ministry of Environment (2010), yet remains poorly implemented. At the international level, P. pselaphon is listed on the Appendix II of CITES, and the Ogasawara Islands, to which this species is endemic, have been a UNESCO Natural World Heritage since 2011.

The remote islands of Kita-Iwo-jima and Minami-Iwo-jima are protected and uninhabited. Iwo-jima hosts a military base and is not accessible to civilians, which significantly hinders research and conservation.

There is an alarming lack of rigorous scientific research on P. pselaphon to support conservation policies. Moreover, monitoring of the subpopulations, which is of paramount importance, is not carried out in a regular and transparent manner and results are not disclosed publicly. Furthermore, conservation efforts on other islands than Chichi-jima (especially on Haha-jima) remain inexistent.