Pteropus pselaphon, Lay, 1829

Don E. Wilson & Russell A. Mittermeier, 2019, Pteropodidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 16-162 : 156

177.

Bonin Flying Fox

Pteropus pselaphon

French: Roussette des Bonin / German: Bonin-Flughund / Spanish: Zorro volador de Bonin

Taxonomy. Pteropus pselaphon Lay, 1829 ,

“Island of Bonin [= Ogasawara Islands],” Japan.

This species is monotypic.

Distribution. Ogasawara (Bonin) Is (Chichijima and Hahajima) and Iwo Is (Kita-Iwoto, Iwoto, and Minami-Iwoto) of SJapan. Sightings, GPS recordings, or traces of foraging are reported for Mukojima, Nishijima, Anijima, Ototojima, and Higashijima Is.

Descriptive notes. Tailless, ear 23-29 mm, hindfoot 42-50 mm, forearm 131-145 mm; weight 353-616 g. Muzzle of the Bonin Flying Fox is short, tapering, and sparsely haired, with black shortly tubular nostrils. Eyes are moderately sized, with brown to chestnut-brown or reddish brown irises. Ears are short, concealed in fur, roughly triangular, semicircular, and hairy at bases, with rounded tips. Head and body pelage is uniformly seal-brown to blackish brown, very long, dense and coarse, and erect on head, collar, and mantle, spreading or loosely adpressed on back and rump; everywhere underfur is mixed with longer hairs, densely sprinkled with glossy grayish white, silvery, or golden hairs, more so on sides of head, chest, and rump. Forearm, tibia, and foot are thickly furred dorsally. Wing membranes are jet-black. Uropatagium is reduced at center and laterally concealed in long overhanging hairs; calcar is short. Skull is typical pteropine, generally stout, with marked basicranial deflection; forehead is strongly sloping; and zygoma is strongly arched. Dorsally, rostrum is wide, interorbital space is narrow, postorbital foramina are present, postorbital process is strong with thick root and tip projected laterally, postorbital constriction is very narrow, temporal lines are joined immediately behind orbits in obvious but low sagittal crest, and nuchal crest is sharp. Ventrally, palate is flat and long, premaxillae project; tooth rows are almost parallel, post-dental extension is wide, palate is concave, ectopterygoids are large, and zygoma is widely open. Mandible is stout and thick, coronoid steeply ascends, condyle is well above lower alveolar line, and angle is round. Palatal ridges 5 + 5 + 3. Dentition is heavy; upper incisors are large, with strong lingual cingulum; C' is short and recurved, with broad cingulum and tubercles; P!' is rudimentary (lost in old adults); posterior cheekteeth have strong posterior basal ledge, marked by notch; and M? is small but with traces of cusps. I is smaller than I; C, has marked cingulum; P|is comparatively large, with low triangular crown well differentiated; posterior cheekteeth are strong, with rectangular occlusal outline and strong posterobasal ledge marked by notch, and M,is very small and displaced lingually. Chromosomal complement has 2n = 38 and FN = 72.

Habitat. Subtropical moist forests.

Food and Feeding. The Bonin Flying Fox feeds on a variety of plants as a sequential specialist. Thirty-one species offruit, including native and cultivated species, are used with strong preference for the native endemic Pandanus boninensis (Pandanaceae) . Flower products of 17 plant species including Freycinetia (Pandanaceae) , Pandanus , and Syzygium (Myrtaceae) , and leaves, such as fronds of the bird-nest fern ( Asplenium setoi, Aspleniaceae ), are also eaten. It disperses seeds, pollen, and spores of native and exotic species. Cultivated fruit is taken from orchards. It reportedly feeds on the ground and drinks from streams.

Breeding. Mating system of the Bonin Flying Fox appears to be female-defense polygyny. Mating occurs in winter roosts in December—April; females give birth mainly in June. Littersize is one. Sex ratio is 1:1. Longevity is unknown in the wild; greatest life span in captivity was 18-6 years. Non-reproductive sexual activity includes erect penis licking between males in winter roosts.

Activity patterns. The Bonin Flying Fox is nocturnal, but diurnal activity occurs on uninhabited islands (Minawi-iwo-to). It roosts in trees.

Movements, Home range and Social organization. On Chichijima Island, Bonin Flying Foxes disperse on the island in summer when individuals roosted alone or in female— young pairs. In winter, they concentrate in traditional roosting areas with up to 100 individuals. Three types of winter roosts were recognized: multiple females with a few males, multiple males, and subadults of both sexes. In all winter roosts, individuals formed ball-shaped clusters of 6-20 individuals to conserve heat. Average home range is ¢. 9 km? (range 1-3-20- 6 km?*). GPS-collared individuals on Chichijima Island were active on neighboring Ani and Ototo islands.

Status and Conservation. CITES Appendix II. Classified as Endangered on The IUCN Red List. Classification of the Bonin Flying Fox will likely be upgraded to Critically Endangered soon, especially because the population of Hahajima Island might become extinct. Total population is 300-400 individuals, with only ¢.200-250 mature individuals fragmented atfive island locations and total extent of occurrence of only ¢. 60 km?*. Genetic data indicate that the population is fragmented on islands without recent gene flow, but genetic variation is distributed across islands so the entire population is a single management unit. It was hunted for food in the past, but this practice has ceased. Main threats are disturbance at roosting site, deforestation, and conflict with fruit growers, but fruit damage appears negligible. Accidental killing is frequent in nets set by farmers. Feral cats and dogs prey on Bonin Flying Foxes. The Bonin Flying Fox has been a Natural Monument ofJapan since 1969. Ogasawara Islands have been a UNESCO Natural World Heritage Site since 2011. Kita-Iwo-to and Minami-Iwo-to are also protected but uninhabited. It occurs in a National Wildlife Protection Area established in 1980. A conservation plan for its survival was established in 2010 by the Ministry of Environment, but conservation efforts appear limited to Chichijima Island.

Bibliography. Abe et al. (1994), Almeida et al. (2014), Andersen (1912b), Inaba et al. (2005), Kinjo & |zawa (2009), Nakamura et al. (2008), Okada et al. (2014), Ota (1992), Sugita (2016), Sugita & Ueda (2013), Sugita, Inaba & Ueda (2009), Sugita, Ootsuki et al. (2013), Vincenot (2017b).

Figures

174. Livingstone’s Flying Fox (Pteropus livingstonii), 175. Pemba Flying Fox (Pleropus voeltzkowi), 176. Ryukyu Flying Fox (Pleropus dasymallus), 177. Bonin Flying Fox (Pteropus pselaphon), 178. Little Golden-mantled Flying Fox (Pleropus pumilus), 179. Lyle’s Flying Fox (Pteropus lylei), 180. Indian Flying Fox (Pleropus medius), 181. Rodrigues Flying Fox (Pteropus rodricensus), 182. Large Flying Fox (Pteropus vampyrus), 183. Aldabra Flying Fox (Pleropus aldabrensis), 184. Malagasy Flying Fox (Pteropus rufus), 185. Seychelles Flying Fox (Pleropus seychellensis), 186. Greater Mascarene Flying Fox (Pteropus niger), 187. Aru Flying Fox (Pteropus aruensis), 188. Kai Flying Fox (Pleropus keyensis), 189. Black-bearded Flying Fox (Pleropus melanopogon), 190. South Moluccan Flying Fox (Pteropus chrysoproctus), 191. North Moluccan Flying Fox (Pteropus caniceps)

Distribution. Ogasawara (Bonin) Is (Chichijima and Hahajima) and Iwo Is (Kita-Iwoto, Iwoto, and Minami-Iwoto) of SJapan. Sightings, GPS recordings, or traces of foraging are reported for Mukojima, Nishijima, Anijima, Ototojima, and Higashijima Is.