133.

Heller’s Serotine

Neoromicia helios

French: Vespeére soleil / German: HellerZwergfledermaus / Spanish: Neoromicia de Heller

Other common names: Helios Pipistrelle Bat, Heller's Pipistrelle, Heller's Pipistrelle Bat, Samburu Pipistrelle, Samburu Pipistrelle Bat

Taxonomy. Pipistrellus helios Heller, 1912,

Merelle Water, 30 miles (= 48 km) south Mount Marsabit, Kenya.

Traditionally treated as a race of N. nanus, but split as a separate species based on the shape of the baculum. Monotypic.

Distribution. Extreme S South Sudan, S Somalia, NE & E Uganda, Kenya, and N Tanzania; isolated record from Djibouti needs confirmation.

Descriptive notes. Head-body ¢.34-41 mm, tail 26-34 mm, ear 5-11 mm, forearm 26-30 mm; weight 2-6 g. Males average larger than females. Pelage of Heller’s Serotine is dense and soft; dorsally pale brown to pale yellowish brown (hairs tricolored, with basal one-quarter blackish brown, central onehalf pale creamy fawn, and terminal one-quarter pale brown; mid-dorsal hairs 5-7 mm long); ventrally paler (hairs blackish brown for basal three-fifths, with pale brown tips). Wings are dark brown to blackish, with very narrow to moderate white hind border; interfemoral membrane is semi-translucent and paler than wings. Ears are pale brown, with rounded tips; tragus is about one-half ear length, broadest above midheight, hatched-shaped, with anterior margin slightly to distinctly concave, posterior margin with abrupt, obtuse angle above mid-height, and rounded tip. Most adults of both sexes have a pair of glands (1-2-3-8 mm in diameter), one on each side oftail, in proximal region of interfemoral membrane; function of these glands unknown, and in males there is no correlation with testis size. Skull is small for an African pipistrellelike bat (greatest skull lengths 10-4-11-4 mm); profile of forehead is strongly concave; there is no occipital helmet. I? is bicuspid and broad; I’ reaches posterior cusp of I*; P? is present and well developed, displaced lingually, but visible in labial view; lower molars are myotodont. Dental formulais12/3,C1/1,P 2/2, M 3/3 (x2) = 34.

Habitat. Widely reported from dry habitats, but also from East African coastal forest mosaic, Isoberlinia (Fabaceae) woodland, undifferentiated montane vegetation, and mosaics of lowland rainforest and secondary grassland, at 400-1333 m.

Food and Feeding. Heller's Serotine feeds on small insects, foraging by slow hawking 2-5 m aboveground.

Breeding. In Masalani, eastern Kenya, Heller’s Serotine shows restricted seasonal monoestry, with births in November, and lactation until late December or early January. There is no evidence of testicular activity until March, when testes descend, remaining in scrotal position from April through September. Based on this, copulation may occur from May to August, when males are more vocalat their roosts, and ovulation and fertilization in late August. In Masalani, the overall ratio of males to females was 2:1. A seasonal phase of dispersal was observed in late May to mid-June, when some adults left and other joined the population. Litter size is two.

Activity patterns. Heller's Serotine roosts by day, and intermittently during the night, between overlapping, vertically hanging fronds of wild date palms ( Phoenix reclinata, Arecaceae), in small crevices around edges of roofs thatched with bundles of palm fronds, and in crevices in vertical sections of thatch used to cover walls. Enters torpor during the day. Echolocation parameters recorded as: search-phase call shape steep FM/QCEF, intensity high,start frequency c.115 kHz, and end frequency 65 kHz. Predators include Heart-nosed False-vampires (Cardioderma cor) and possibly tree snakes.

Movements, Home range and Social organization. Heller’s Serotines roost singly or in groups of 2-12; during most of the year, most adult males roosted singly or with one female or, less frequently, with two or more females. Adult females roosted with one male, but sometimes with two other females and without a male. Adult males almost never roosted with other males. Females showed roost fidelity, competing aggressively for prime roosts (those large enough to accommodate one male and one or two females), fighting intruders and chasing them in flight. Bats were active in and near roosts throughout the night. While some bats rested, territorial males patrolled outside their roosts, chasing other males away. Males vocalized at their roosts and females were attracted to the most vocal males. Females roosted with several males sequentially, showing preference for certain individuals. Prior to parturition in November, all females left the study area, presumably to establish a maternity colony. These data suggest a mating system based on resource-defense polygyny.

Status and Conservation. Classified as Data Deficient on The IUCN Red List.

Bibliography. Happold & Van Cakenberghe (2013), Hayman & Hill (1971), Hill & Harrison (1987), Koopman (1975, 1993), O'Shea (1980), O'Shea & Vaughan (1980), Peterson (1987), Simmons (2005).