About Nyctophilus geoffroyi Leach, 1821
Nyctophilus geoffroyi, commonly called the lesser long-eared bat, is a medium-sized bat species. Individuals weigh 6 to 12 grams, have a forearm length between 30.6 and 41.7 mm, and have long ears ranging 17.6 to 25.3 mm in length. Its back fur is light grey, while its underbelly has lighter to white fur. All fur is bi-colored, dark at the base and light at the tips. Fur color varies widely across individuals, with bats from arid regions being notably paler. The species' key distinguishing feature is a roughly 1.5 mm high nose ridge, which is split and connected by an elastic skin membrane that forms a Y-shaped groove behind the nostrils. This species is highly adaptable to a wide range of habitats, making it one of the most widespread endemic bat species in Australia. It occupies deserts, tropical to alpine woodlands, mangroves, agricultural land, urban areas, wet to dry sclerophyll forests, and rainforests. While it has been recorded at elevations up to around 1600 metres above sea level, it is more common at lower altitudes. It is the most widely distributed species in the genus Nyctophilus, found across arid to wet regions, though it does not occur on Australia's northeast tropical coasts or Cape York Peninsula. It can survive in Australia's arid regions when water is available, and is commonly recorded at bore wells, pools, and livestock dams. In these arid inland areas, it is found in association with the inland free-tail bat Mormopterus petersi, and the little and inland forest bats Vespadelus vulturnus and Vespadelus baverstocki. It is especially common in agricultural areas near Canberra, where it roosts in both buildings and tree hollows. It is one of several bat species that resides within Canberra itself, foraging in nearby parks and reserves. It also occurs at Kings Park near Perth, Western Australia, alongside other microbat species: the wattled bats Chalinolobus morio and Chalinolobus gouldii, and the tiny endemic freetail bat Mormopterus kitcheneri. For male lesser long-eared bats, spermatogenesis begins in November, peaks in March, and ends in May. After spermatogenesis ends, sperm is stored in the epididymides while the testes retreat. Mating typically begins in April; over winter, females store retained sperm in the oviduct and uterine lining. Ovulation and fertilization occur in late August to September, and gestation lasts between 72 and 93 days. Births occur from late October through November, occurring later at lower latitudes and lower elevations. Mothers most often give birth to twins. Young bats are able to fly by December, and lactation ends in early February. Observations of the species in Tasmania have recorded shorter lactation periods. Mature females do not necessarily give birth every year, and this species exhibits sperm competition.
