64.

Finlayson’s Cave Bat

Vespadelus finlaysoni

French: Vespertilion de Finlayson / German: Finlayson-Waldfledermaus / Spanish: Vespadela de Finalyson

Other common names: Inland Cave Bat, Little Brown Bat, Little Cave Eptesicus

Taxonomy. Eptesicus finlaysoni Kitchener, B. Jones & Caputi, 1987,

“Cossack, Western Australia (20°41’S, 117°11’E) at altitude ca. 5 m, from roof of ‘Customs House’,” Australis.

This species is monotypic.

Distribution. Arid and semiarid regions of N, C & W Australia, including Tiwi, Groote Eylandt, and Edward Pellew Is.

Descriptive notes. Head-body 34-3-46-4 mm, tail 30-7-42 mm, ear 9-3-13-2 mm, forearm 29-8-37-6 mm; weight 3-7 g. Finlayson’s Cave Bat is somewhat morphometrically variable throughoutits distribution. Dorsal pelage is very dark brown, nearly black, with a yellowish or reddish tinge (hairs with either dark rust-brown or yellow-brown tips), whereas ventral pelage is slightly paler. Bare portions offace, ears, forearms, and membranes are blackish. Ears are small and rounded triangular with a smoothly convex anterior edge; tragusis narrow, anteriorly straight orslightly concave, posteriorly convex, and with rounded tip and slight posterobasal lobe. Uropatagium stretches to end oftail. Head of glans penis is laterally compressed, and rod-shaped, and has narrow strip of skin projecting upward from ventral tip; dorsal surface has a deep longitudinal groove, and ventral surface a slight keel; urethra is at distal end of penis. Baculum is moderately long (mean 3-2 mm in central-eastern range, 2-8 mm in central-western/Pilbara range, and 2: 2 mm in north-western coastal range) with a dorsally rod-shaped shaft, and slightly bifurcated and expanded base; gently curved ventrally at base and tip (base more so than tip). Skull is short; lambdoidal crest is weakly to well developed; anterior narial notch is narrow U-shaped to V-shaped; rostrum is short. I? is bicuspid, I is unicuspid; P* is much smaller than canine, and within tooth row; crista linking base of metacone and hypocone on M' is absent, slight, or moderate, and absent or slight on M?.

Habitat. Found in a wide variety of habitats, including grasslands, spinifex grasslands, savanna woodlands, open forests, mulga ( Acacia, Fabaceae), and a number of other shrubby and arid desert habitats, generally close to rocky outcrops or caves.

Food and Feeding. Finlayson’s Cave Bats are insectivorous, and forage in cluttered areas of vegetation, canopies, escarpments, scree slopes, and other surfaces. They are often observed foraging over water.

Breeding. Timing of reproduction varies throughout the range: in northern portion of the range, Finlayson’s Cave Bat appears to breed year-round, with peaks in births in March and September to October; but in south, the species has a single breeding season, with births in November or December. Mating has been observed in late June: male couples with female from rear, while hanging from ceiling. Litter size is one or two, with more single young in north (20% are twins) and more twins in south. Females carry their young for first week but then begin to leave them at the roost at night. Nursing females are typically found further into their cave or mine roosts, where temperature is more constant. Young start attempting flight at 2-3 weeks, and are volant by 3-4 weeks old.

Activity patterns. Finlayson’s Cave Bats leave their roosts at dusk, to forage at night. They roost primarily in caves, crevices, and abandoned mines (typically close to the entrance). They are also occasionally reported to roost in abandoned nests of fairy martins ( Petrochelidon ariel). Call shape is a steep FM/QCF with characteristic frequency recorded at 53 kHz, in the Top End region.

Movements, Home range and Social organization. Finlayson’s Cave Bat has been recorded at speeds of 19-5 km/h during straight and level flight, although it often zigzags, rapidly changes direction, and performs alternating series of near vertical rolls in opposite directions. Colony size is generally 2-20 individuals but can exceed 500; unlike several other cave-dwelling bats, it does not create maternity colonies. It rarely switches roosting sites. Females and males have distinct roosting habits, with females typically roosting in large clusters and males usually in smaller groups (often in inaccessible crevices). The species seems to prefer roosts with low humidity (under 30% relative humidity) and a temperature range of 16-35°C. A colony that contained over 200 young roosting separated from the adults was observed by S. K. Churchill in western Queensland, in 2008. The young roosted in tightly clumped groups in the warm part of an abandoned mine. Interestingly, when disturbed, they flew off and separated, joining the small clusters of adults that were scattered throughout the mine. The species has been recorded sharing caves and mines with Taphozous species, as well as the Ghost False-vampire (Macroderma gigas), which is also one ofits few natural predators.

Status and Conservation. Classified as Least Concern on The IUCN Red List. There do not currently appear to be any major threats to this species. Finlayson’s Cave Bat is relatively common throughoutits distribution.

Bibliography. Churchill (2008), Ford & Le Brocque (2000), Kitchener et al. (1987), Maddock & McLeod (1976), McKenzie & Muir (2000), McKenzie & Reardon (2008), McKenzie et al. (2002), Milne, Armstrong et al. (2004), Milne, Fisher & Pavey (2006), Reardon, Milne et al. (2008), Young & Ford (2000).