Lesser Long-eared Bat

Identification

The lesser long-eared bat is a medium-sized vespertilionid, weighing 6 to 12 grams with a forearm length of 30.6 to 41.7 mm. Its most distinctive feature is a unique Y-shaped groove behind the nostrils, formed by a nose ridge approximately 1.5 mm high split and connected by an elastic membrane of skin. The bat's fur is light grey on the back, contrasting sharply with lighter to white underbelly fur. The hair is bi-colored, dark at the base fading to light at the tips. Long ears measuring 17.6 to 25.3 mm are characteristic of the species, though coloration varies considerably—bats from arid regions are notably paler than their forest-dwelling counterparts.

Range & Habitat

One of Australia's most widespread endemic bats, Nyctophilus geoffroyi is highly adaptable and occupies diverse habitats ranging from arid deserts to tropical rainforests, alpine woodlands, mangroves, sclerophyll forests, and agricultural areas. The species has successfully colonised urban environments, including buildings and city parks. It is recorded at elevations up to 1600 metres, though more commonly found at lower altitudes. The species is notably absent from northeast tropical coasts and Cape York Peninsula. Where water is available, lesser long-eared bats inhabit arid regions, commonly roosting near bore wells, livestock dams, and pools in association with other microbat species.

Behaviour & Diet

These nocturnal bats employ highly specialised and diverse hunting techniques to capture prey. They forage at remarkably low speeds—as slow as 4 km/h when hunting through understory vegetation—yet demonstrate exceptional manoeuvrability, diving vertically from 6–10 metres above ground to catch insects. In open areas, they spiral around bushes and can land on ground prey before launching almost vertically. The species employs three distinct hunting methods: echolocation (peak frequency 47.7 kHz), passive listening without echolocation or sight, and visual hunting of aerial prey. This acoustic sophistication includes a subtle whispering technique that evades detection by moths that have evolved to sense typical bat calls. Grasshoppers, crickets, and moths form their primary diet, supplemented by lacewings, beetles, flies, nymphs, cockroaches, and spiders. Lesser long-eared bats roost in small crevices including tree hollows, caves, buildings, peeling bark, and even unconventional sites such as rolled swags, brick piles, and tractor exhausts. They range from solitary individuals to small groups of 2–3 bats, though maternity colonies may contain 10–15 individuals with a single mature male.

Best Time & Places to See It

Active year-round, these bats are nocturnal and best observed during evening foraging sessions. They are particularly common in agricultural areas, urban parks, and nature reserves, with established populations near Canberra (in buildings and tree hollows) and Perth (Kings Park). The species is fairy common throughout most of Australia in suitable habitats. Listen for their characteristic low flight speeds and sudden directional changes when hunting near vegetation margins and over open ground at dusk and night.

Photography Tips

Photographing lesser long-eared bats requires patience and low-light capability. Focus on their distinctive Y-shaped nose ridge and proportionally large ears—key identification features in field images. Capture their characteristic foraging behaviour: low-altitude hunting through vegetation, hovering, and ground-level prey capture. Evening sessions near known roosts and water sources (dams, bore wells) offer the best opportunities. Use high-speed flash and fast film speed to freeze their erratic flight patterns, particularly the sudden vertical dives and directional switches they employ when hunting. Urban populations near Canberra and Perth offer accessible opportunities for documentation.