39.

Least Pipistrelle

Pipistrellus tenuis

French: Pipistrelle gréle / German: Winzige Zwergfledermaus / Spanish: Pipistrela diminuta

Other common names: Indian Pygmy Bat

Taxonomy. Vespertilio tenuis Temminck, 1840,

Sumatra, Indonesia .

Pipustrellus tenuis included P. adamsi, P. angulatus, P. collinus, P. papuanus, P. watts, and P. westralis, but all are recognized as distinct species based on morphology. Subspecies mimus was originally described as a distinct species but has generally been included under P. tenuis, although recent authors have chosen to continue to recognize mimus as a distinct species. As currently recognized, P. tenuis might represent a species complex, but additional research is needed. Recently extinct P. murray: has been included as a subspecies of P. tenuis but is recognized as a separate species based on morphology. Six subspecies recognized.

Subspecies and Distribution.

P.t.tenuisTemminck,1840—Sumatra.

P.t.mimusWroughton,1899—NWAfghanistan(NangarharProvince),Pakistan(KhyberPakhtunkhwa,Punjab,andSind),India,W&SSriLanka,Nepal,Bhutan,Bangladesh,andNMyanmar.

P.t.nitidusTomes,1859—Borneo(includingLabuanI),thePhilippines,Sulawesi,SeramI,AmbonI,andTimorI.

P.t.portensisJ.A.Allen,1906—SChina(includingHainanI),Myanmar,Thailand,Laos,Vietnam,Cambodia,andPeninsularMalaysia(includingPenangI).

P.t.sewelanusOey,1960—Java,Bali,andLombokIs.

P. t. subulidens G. S. Miller, 1901 — Serasan I in the Natuna Is.

Descriptive notes. Head-body 33-45 mm, tail 20-35 mm, ear 5-11 mm, hindfoot 3-7 mm, forearm 25-31 mm; weight 2:9-4-2 g. Muzzle ofthe Least Pipistrelle is broad, and smaller than that of the Indian Pipistrelle ( P. coromandra) but otherwise nearly identical. Pelage is fine, dense, and silky. Dorsum is medium to dark brown; venter is paler (hairs buffy with dark brown bases). Ears, muzzle, and membranes are dark brown. Ears are narrow and broadly rounded; tragus is more or less same thickness throughout and narrow, with broadly rounded tip. Uropatagium stretches from calcar to nearly tail tip (only very tip is free). Penis is short (less than 8 mm). Baculum (3-1-3-7 mm long) is very similarto that of the Indian Pipistrelle in that it hasstraight or slightly sinuous shaft, bifurcated tip, and ventrally deflected basal lobes. Skull is small and delicate; zygomatic arches are thin and lack processes; I? is bicuspid, and I’ is unicuspid and exceeds height of secondary cusp of I*; C' is bicuspid; P? is subequal in crown area to I? and usually within tooth row; and lower molars are nyctalodont. Chromosomal complement has 2n = 38 and FN = 48 (India, Sri Lanka), with one record of 2n =42 (India).

Habitat. Various habitats in forests and rural and urban areas; secondary hill, montane, or montane mossy forests in South-east Asia in arid and humid regions; mangrove forests in some regions (e.g. Sabah in northern Borneo) at elevations of 800-2650 m in the Philippines but from sea level to 769 m in much of the distribution.

Food and Feeding. Least Pipistrelles eat various insects including coleopterans, hymenopterans, dipterans, and lepidopterans. They forage by aerial-hawking, low in understories earlier in the night and moving higher to canopies near the end of the night in India. Fecal samples from southern India contained coleopterans (26-3% by volume), dipterans (20-4%), homopterans (17-5%), lepidopterans (136%), formicids (10-6%), hemipterans (5-7%), and isopterans (5-1%). It seems to be a relatively generalized feeder, and its diet varies markedly throughout the year based on prey availability. In winter (December—February) in Rajasthan, north-western India,it fed mostly on beetles (66-6%) along with cockroaches and wingless ants; in summer (March—June), it fed on a wider variety of insects, including grasshoppers, crickets, termites, beetles, and moths. During monsoon season (July-September), it primarily ate soft-winged termites (45-5%) along with moths, Hymenoptera, and Orthoptera averaging 10-15% of their diet. In post-monsoon period (October-November), beetles became more prevalent in diets (31-4%), but it still ate other insects, including winged ants and wasps (31%), crickets, grasshoppers,flies, and mosquitoes.

Breeding. The Least Pipistrelle apparently has two peaks in reproductive activity. In Rajasthan, one occurred in February-March and the other in July-August, both correlated with peak prey abundance. Nevertheless, reproduction can occur year-round, and pregnant and lactating females have been recorded throughout the year in China and India. Males remain fertile year-round but to a lesser extent in winter. Sperm storage in female reproductive tracts is also evident (November—December in Uttar Pradesh, northern India). Litter size is 1-3 young (average 2-2 young). Young are weaned after 30-40 days. In Maharashtra, central India, reproductive activity peaks in May-June and September—October just before and after maximum rainfall. Pregnant females were collected in November-December in West Bengal, northern India, with juveniles recorded in May, September, and December. In Sri Lanka, females with young were recorded in March—June and again in December.

Activity patterns. Least Pipistrelles emerge just around sunset. They are quick and erratic fliers and make many twists and turns when foraging. In Rajasthan, they did not hunt during heavy rain or when ambient temperatures dropped below 15°C at night. They roost in trees, leafy canopies, and walls or ceilings of buildings in urban and suburban settings. Call shape is FM/QCEF, and calls recorded in southern India had maximum frequencies of 51:4-73-6 kHz (average 60-8 kHz), minimum frequencies of 31-5—42 kHz (35-1 kHz), frequencies of maximum energy of 32.8-47-5 kHz (37-8 kHz), and durations of 7-6—10-3 milliseconds (8-6 milliseconds).

Movements, Home range and Social organization. Least Pipistrelles are often found in colonies of 1-25 individuals. Adult females and juveniles roost together year-round, but males generally roost alone in secluded locations. There is a higher ratio of female Least Pipistrelles to males throughout the year, indicating that males have higher mortality than females (possibly due to their more solitary lifestyle). In India, Least Pipistrelles occasionally roost with Indian Pipistrelles, remaining isolated from each other while in the same roost.

Status and Conservation. Classified as Least Concern on The [UCN Red List. The Least Pipistrelle is common throughout its wide distribution and does not seem to face any major threats.

Bibliography. Advani (1981b, 1983), Bates & Harrison (1997), Bates et al. (2005), Benda & Gaisler (2015), Bhunya & Mobarty (1975), Corbet & Hill (1992), Francis (2008a), Francis, Rosell-Ambal, Tabaranza, Lumsden et al. (2008), Gopalakrishna et al. (1975), Heaney et al. (2016), Hill & Harrison (1987), Isaac & Marimuthu (1996), Isaac et al. (1994), Javid, Mahmood-ul-Hassan, Afzal (2012), Krishna (1984, 1985), Kruskop (2013a), McKean & Price (1978), Pathak & Sharma (1969), Phillips (1980), Raghuram et al. (2014), Sinha (1980, 1986, 1999), Smith & Xie Yan (2008), Sreepada et al. (1996), Thapa, Subedi et al. (2012), Topal (1974), Volleth et al. (2001), Wang Yingxiang (1982), Whitaker et al. (1999).