Pipistrellus tenuis subsp. westralis Koopman 1984

47.

Northern Pipistrelle

Pipistrellus westralis

French: Pipistrelle de Koopman / German: Mangroven-Zwergfledermaus / Spanish: Pipistrela Koopman

Other common names: Koopman'’s Pipistrelle, Mangrove Pipistrelle, North-western Pipistrelle, Western Pipistrelle

Taxonomy. Pipistrellus tenuis westralis Koopman, 1984,

“Cape Bossut, (ca. 18°40’S, 121°30°E), Western Australia,” Australia.

Pipistrellus westralis was originally described as a subspecies of P. tenuis but is considered a distinct species based on morphology. Although similar to one another, P. westralis and P. adams: are considered separate species based on morphological and genetic distinctions. Monotypic.

Distribution. Along Australia’s N coastline from Cape Bossut in Western Australia to Karumba in W Queensland, including Melville, Bathurst, and some other offshore Is.

Descriptive notes. Head-body 34-4-42-2 mm, tail 29-37-2 mm, ear 8-1-11 mm, forearm 27-4-31-3 mm; weight 2-7-4-8 g. Like the Forest Pipistrelle (P. adamsi), the Northern Pipistrelle is very small and one of the smallest bats in Australia. Dorsal pelage is dark brown; ventral pelage is buffy grayish brown. Muzzle, ears, and forearms are generally brown to light brown; wing membranes and uropatagium are dark brown. Ears are broadly triangular, with less rounded tips than in the Forest Pipistrelle; tragus is less than one-half the ear height, with small basal lobe and less convex posterior side than in the Forest Pipistrelle. Uropatagium stretches nearly to end oftail (only extreme tip free), and postcalcarial lobe is elongated. Glans penis is slightly flared, with central circular depression at tip that has many small fleshy spines. Baculum is shorter than in the Forest Pipistrelle, with wider base, and shaft is straight, with bifurcated tip (for 10% of its length rather than 30% in the Forest Pipistrelle). Skull is small and fragile; sagittal crest is absent; lambdoidal crest is weak; zygomatic arches are weak; I” is bicuspid, and I’ is unicuspid and subequal in height to second cusp of I?; P* is slightly outside tooth row but well developed; and lower molars are nyctalodont.

Habitat. Primarily mangrove habitats but also adjacent thicket habitats and riverine forests, generally associated with water. Northern Pipistrelles are found in a broader variety of habitats in the Top End region of northern Australia, although they are still primarily found in mangroves. They also can be associated with Melaleuca (Myrtaceae) swamps, areas dominated by Pandanus (Pandanaceae), freshwater Barringtonia (Lecythidaceae) mangroves, and within pindan thickets.

Food and Feeding. Diet contains various arthropods, including moths, small beetles, ants, bugs, and cockroaches, and occasionally spiders. In northern Australia, diets reportedly include Coleoptera (29-2% by volume), Hymenoptera (24-7%), Lepidoptera (23:7%), and Hemiptera (16-:3%), along with a few other arthropod food items (6-1%).

Breeding. Births of Northern Pipistrelles have been recorded in dry season (June-July), but they probably breed year-round like some Pipistrellus in New Guinea (e.g. the Lesser Papuan Pipistrelle, P. papuanus). Litter size seems to be one.

Activity patterns. Northern Pipistrelles are nocturnal. Although no roosts have been reported, they probably roost in tree hollows. They have fluttering, acrobatic flight that allows them to follow irregular contours of forests’ outer foliage as they forage 2 m off the vegetation. Search-call shape is FM/QCEF, with characteristic frequency averaging 46-6 kHz (44-49-3 kHz).

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Northern Pipistrelle is common in suitable habitats, although its habitats are relatively limited. It does not seem to face many threats currently, but destruction of mangrove habitat might be a future threat.

Bibliography. Adams et al. (1987), Churchill (2008), Hill & Harrison (1987), Kitchener et al. (1986), Koopman (1984b), McKenzie & Hall (2008), McKenzie & Milne (2008), Milne (2002), Milne, Armstrong et al. (2005), Milne, Burwell & Pavey (2016).