63.

Northern Cave Bat

Vespadelus caurinus

French: Vespertilion du Kimberley / German: Nérdliche Hohlen-Waldfledermaus / Spanish: Vespadela de Kimberley

Other common names: Little Brown Bat, Little Northern Cave Bat, Northern Brown Bat, Western Cave Bat

Taxonomy. Eptesicus pumilus caurinus Thomas, 1914,

“Drysdale, Kimberley, N. Australia [= Western Australia, Australia].”

This species is monotypic.

Distribution. N Australia in Kimberley region of N Western Australia (including Bonaparte Archipelago), N Northern Territory (including Groote Eylandt I), and NW Queensland.

Descriptive notes. Head-body 32-1-40 mm, tail 24-4-34-8 mm, ear 8-3-12-3 mm, forearm 26-6-31-7 mm; weight 2-3-4-2 g. Dorsal pelage is brown or gray brown (hairs dark brown, nearly blackish, at base with brown tip), whereas ventral pelage is slightly paler. Face is mostly naked and dark brown (nearly black) in pigmentation, along with ears, wings, uropatagium, and forearms. Ears are small and rounded triangular with a smoothly convex anterior edge; tragus is narrow, anteriorly straight or slightly concave, posteriorly convex, and with a rounded tip and slight posterobasal lobe. Wings and uropatagium are dark brown, nearly black and uropatagium stretches to end of tail. Glans penis is cylindrical and laterally compressed; urethra is covered by narrow strip of skin projecting upward from ventral tip. Baculum is moderate in length (mean 2-9 mm) and rodlike (base and distal end gently curved ventrally) with a bifurcated, gently expanded base. Skull is short; lambdoidalcrest is weakly to moderately developed; anterior narial notch is generally V-shaped and occasionally U-shaped; rostrum is short. IZ is bicuspid and I’ is unicuspid; P* is much smaller than C!, and within tooth row; crista linking base of metacone and hypocone on M' is moderate to large, and slight or moderate on M2.

Habitat. Present in a wide variety of habitats, including Melaleuca (Myrtaceae) forest, monsoon forest, tall open forest, open woodland, savanna, spinifex hill woodland, mixed shrubland, floodplains, and deciduous vine thickets, often in or adjacent to rocky outcrops.

Food and Feeding. Northern Cave Bats forage by aerial-hawking below the canopy in wooded areas. Diet generally consists of beetles, moths, spiders, flying ants, leathoppers, bugs, and caddisflies. Stomach contents in Kimberley included moths, bugs, and caddisflies; individuals in Top End region ate mainly ants and beetles, with a few other insects in smaller amounts (flies, moths, mayflies, and leathoppers).

Breeding. Northern Cave Bats may produce two or more litters per year. Males with enlarged testes have been recorded from May to July, and pregnant females in June, September, October, and November. Births occur in October and November:litter size is usually two, but occasionally single young. Most females caught in November are lactating. For some time after birth, young are carried on the mother while she forages; when they increase in size, they are left in small créches at the roost. Volant young have been captured in mid-November.

Activity patterns. Northern Cave Bats emerge at dusk to forage, and are most active during the first three hours after sunset. In flight, they are highly agile and will change direction quickly when foraging. Roosts are often in volcanic, sandstone, or limestone caves, small cracks and crevices, unused mines, and occasionally buildings, road culverts (sometimes as maternity colonies), and bird nests within road culverts. Roosts have been recorded at variable temperature (20-34-5°C) and humidity (23-98%); however, females with young have more restricted microclimates, with warmer temperatures (28-5-34-5°C) and more moderate humidity (25-62%). Call shape is FM/ QCF with peak frequencies recorded at 57-5-61-7 kHz (average 59-6 kHz). Average peak frequency was recorded at 61-3 kHz, and call duration at 4-9 milliseconds, in Kimberley.

Movements, Home range and Social organization. The Northern Cave Bat is found either solitarily or in small groups averaging 8-12 individuals, although 1-45 in nonmaternity colonies. Maternity colonies may contain several hundred individuals.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Northern Cave Bat does not currently seem to face any major threats, although its maternity colonies are especially sensitive to human disturbance.

Bibliography. Churchill (2008), Kitchener et al. (1987), McKenzie & Bullen (2012), McKenzie & Lumsden (2008), Milne, Armstrong etal. (2005), Milne, Thomson & Burwell (2008).