33.

Japanese Pipistrelle

Pipistrellus abramus

French: Pipistrelle abramusi / German: Japan-Zwergfledermaus / Spanish: Pipistrela japonesa

Other common names: Japanese House Bat

Taxonomy. Vespertilio abramus Temminck, 1840,

“les environs de Nagasaki,” Kyushu, Japan .

Pipistrellus abramus is in the Eastern clade of Pipistrellus, but its exact relationship to other members of this clade is uncertain because very few species from Asia have been sequenced. Pipistrellus abramus has been included as a subspecies of P. javanicus but is clearly distinct based on morphology and karyotype. There is high genetic divergence among populations on Hainan Island and mainland China. Monotypic.

Distribution. SW Russian Far East (Ussuri region), North and South Korea, Japan including many offshore Is (Tsushima, Yakushima, Tanegashima, Kuchinoshima, Takarajima, Amami-Oshima, Kakeroma-Jima, Tokunoshima, Okinawajima, Miyakojima, Irabu, Ishigakijima, Iriomotejima, and Yonagunijima), C, E & S China, Taiwan and Hainan Is, N Myanmar, N Laos, N & C Vietnam (including Cat Ba and Kaitien Is), and scattered records in NC, SC & NE India (Uttar Pradesh, Arunachal Pradesh, and Andhra Pradesh); there is a record from Sakhalin I, but this requires confirmation.

Descriptive notes. Head-body 38-60 mm, tail 27-45 mm, ear 8-13 mm, hindfoot 6-10 mm, forearm 29-36 mm; weight 3-8-5-8 g. Dorsum ofthe Japanese Pipistrelle is grayish olive to grayish brown, with slightly frosted appearance; venter is light grayish brown; and young are darker than adults. Ears are thin, dark, and rounded at tips; tragus is barely one-half the height of ear. Wings and uropatagium are dark, and uropatagium extends nearly to end oftail (only extreme tip is free). Baculum is very long (exceeding 9 mm) and S-shaped, similar to that of Mount Popa Pipistrelle ( P. paterculus), but thinner and more sinuous. Skull is very wide; zygomatic arches are slender; rostrum is wide and flat; braincase is barely inflated or convex above frontal region; palate is narrower than in the Javan Pipistrelle ( P. javanicus); I’ is more than one-half as high as I’, and both upper incisors are bicuspid; C' is strong, with weak secondary cusp; P? is visible and within tooth row; upper molars are less robust than in the Javan Pipistrelle; and lower molars are nyctalodont. Chromosomal complement has 2n = 26 and FN = 44.

Habitat. Favoring disturbed habitats and avoiding montane regions and forests, the Japanese Pipistrelle is often associated with houses and buildings. Its preferences in non-anthropogenic habitats are uncertain and difficult to establish because it is most common in anthropogenic habitats. It often forages for insects under streetlights.

Food and Feeding. Japanese Pipistrelles eat various insects depending on area and season. In urban areas of Fukuoka, southern Japan, they eat Lepidoptera, Diptera, and Hemiptera, butin ricefields in Kyoto prefecture, central Japan, they eat Diptera, Hemiptera, and Hymenoptera . Diet reportedly change throughout the year in Japan; main prey changes from Coleoptera in July to Diptera in October in Fukuoka prefecture and from Diptera in June to Hemiptera in September in Kyoto prefecture.

Breeding. Japanese Pipistrelles are seasonally monoestrous, with delayed fertilization after copulation. In Japan, mating season begins in October, but spermatogenesis has been observed as early as September. Copulation occurs in October, but sperm is stored in the uterus and oviduct. Fertilization does not occur until ovulation occurs after females awake from hibernation. Gestation lasts ¢.70 days, and littersize is 2—4 young (mean 2-6-3 young). At birth, young weigh 0-86 g. They open their eyes at 8-9 days old and are completely furred with black hair at 14 days. Young become volant after 25-30 days. First curve of baculum starts developing after ten days and second at ¢.34 days. Baculum is completely developed after 110 days (also when testes are mature). Young reach adult size in about late August. During their first year, females enter estrus and mate in their natal colony. Rate of disappearance after weaning to one year of age is 18-29% for females and 85-96% for males. Oldest individuals have been five-year-old females and three-year-old males; malestypically do not live more than ten months, whereas females often live much longer. Female mortality rate is relatively low at 1-3 years of age but increases at 4-5 years. Male mortality always seems to be higher than females, but reasons forthis are uncertain.

Activity patterns. Japanese Pipistrelles begin foraging 10-30 minutes after sunset in summer, with major peak in activity soon after sunset and minor peak just before sunrise in May-August. In October, foraging was recorded only after sunset, probably because of cooler temperatures through the night. Emergence time changes based on energy consumption and needs at specific life stages, ambient temperatures, and abundance of insect prey. When ambient temperatures were lower than 15°C in Fukuoka prefecture and lower than 12°C in Kagawa prefecture, individuals rarely emerged. Japanese Pipistrelles enter hibernation for winter at some point from late October to November and remain in hibernation until March. Body weight increases from summerto late autumn before hibernation by an average of 30-6% in females and 29-2% in males. During hibernation, weights decrease: 21:3-25-3% in adult females, 20-26% in yearling females, and 24-3-27-1% or 32% in yearling males. Japanese Pipistrelles roost primarily in anthropogenic settings, including narrow spaces in buildings, under rooftiles, parapet caps, small roof covers over windows, inside sliding wings, and under bridges. There are also a few reports of roosts in caves and nests of red-rumped swallows (Cecropis daurica). Call shape is FM/QCF in search phase and FM in scanning phase (or in back-cluttered space). Average peak frequencies were 43-4 kHz in Hokkaido prefecture and 42-9 kHz in Kanagawa prefecture, and peak frequencies of 42-5-52 kHz were recorded in Kagoshima prefecture. End frequencies were recorded at 43-3—45-2 kHz in Kagoshima and 40-43 kHz (mean of 41-2 kHz) in Kyoto prefecture. The besra (Accipiter virgatus) and the peregrine falcon (Falco peregrinus) prey on Japanese Pipistrelles.

Movements, Home range and Social organization. Japanese Pipistrelles do not often move between roosts, even during mating season, and stay in the same roost throughout much of their lives. Make-up of colonies, however, does change throughout the year. In September and late October when mating begins, a colony had males and females, with sex ratio of 1:1. After hibernation, colonies have all or mostly females (July). In late August, adult females and young roost together, without adult males. Males might be more mobile than females and switch between roosting localities more, but lack of males in maternity colonies might also be due to higher mortality of males. Colonies are generally small (1-26 individuals in Tokyo and 4-36 individuals in Fukuoka prefecture) before young fly, but colony of more than 100 individuals have been found in some cases. After young fly, colony size seems to increase (1-61 in Tokyo and 11-27 in Fukuoka and Kagawa prefectures).

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Japanese Pipistrelle is common throughout its distribution and in disturbed and urban environments. People commonly encounter them because they roost in buildings and other man-made structures.

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