86.

Pygmy Long-eared Bat

Nyctophilus walkeri

French: Nyctophile de Walker / German: WalkerLangohrfledermaus / Spanish: Nictofila de Walker

Taxonomy. Nyctophilus walker Thomas, 1892,

“Adelaide River, Northern Territory, Australia.”

Nyctophilus walkeri is tentatively in the macrotis species group, but its exact relationships to other species of Nyctophilus are unresolved and require additional analysis. Monotypic.

Distribution. NE Western Australia, N Northern Territory, and NW Queensland, N Australia.

Descriptive notes. Head-body 38-44 mm, tail 26-36 mm, ear 10-7-14-1 mm, forearm 30-1-36 mm; weight 3-7 g. The Pygmy Longeared Bat is the smallest species of Nyctophilus, with relatively large ears and unique simple noseleaf consisting of two ridges, one further on muzzle and another immediately above nostrils, with vertical groove in middle and furred trough between them. Dorsal pelage is pale orangish brown to fawn; venter is cream or buff. Wing membranes are blackish brown, and face, ears, and wing bones are pinkish brown. Rostrum is short and blunt, with ridge across muzzle over nostrils that is well developed with deep but thin medial notch. Ears are large and broad, with bluntly rounded tips but are much smaller, narrower, and more tapered at tip compared with other species of Nyctophilus, having horizontal ribbing on inner surfaces, inward curved anterior edges, and smooth posterior edges (ears can fold back at top of thick part of anterior edge); interauricular membrane typical of the genus is either missing or barely present and covered by fur; tragusis almost rectangular, being straight or very slightly convex on anterior margin. Baculum has distinct distal notch, curves downward at base,is bifurcated basally, and is straight for the rest of shaft. Skull is robust, tympanic bullae are small, and M? and lower molars are not reduced.

Habitat. Riverine Melaleuca (Myrtaceae) and Pandanus (Pandanaceae) forests, monsoon rainforest patches, open savanna woodlands, tall open forests, and mixed shrublands, generally associated with permanent water sources.

Food and Feeding. Pygmy Long-eared Bats forage by aerial-hawking and gleaning off the ground and foliage. They usually fly within 1-2 m of the ground or water surface and are highly maneuverable in cluttered vegetation. Their flight is jerky and irregular, with 2-3 wing flaps before a glide, which might be an adaptation to avoid predation. Diet consists mostly of moths and beetles in the Top End region, but cockroaches, termites, mosquitoes, leafhoppers, lacewings, and spiders were also eaten.

Breeding. A female Pygmy LLong-eared Bat captured in September in the Northern Territory was in early pregnancy with twins, and three females were captured in late pregnancy in mid-October. A pregnant female with a fetus in each uterine horn was captured in October in the Kimberley region. Young are likely born around early November.

Activity patterns. Pygmy LLong-eared Bats spend the day roosting in foliage and forage throughout the night. They have been reported roosting in dead fronds of large Livistona (Arecaceae) palms and have been seen emerging from Pandanus thickets at dusk. Call shape is steep FM sweep, with peak frequencies of40-7-50-8 kHz (mean 45-8 kHz) in the Top End region. In Western Australia, peak frequencies were 54-58 kHz (mean 56 kHz) and were noteasily distinguished from other species of long-eared bat.

Movements, Home range and Social organization. Pygmy [Long-eared Bats reportedly roost in large enough colonies that they can be heard squabbling with each other during the day, but no specific numbers are available. They appearto be long-lived because captured individuals commonly have teeth worn down to nubs that are virtually flush with gums.

Status and Conservation. Classified as Least Concern on The IUCN Red List, as it is locally common in much ofits distribution and does not seem to face any major threats.

Bibliography. Bullen & McKenzie (2002a), Churchill (2008), Churchill et al. (1984), McKenzie, Lumsden & Parnaby (2008), Milne (2002), Milne etal. (2016), Parnaby (2009).