Miniopterus aelleni, commonly known as Aellen’s long‑fingered bat, belongs to the order Chiroptera and the family Miniopteridae. It is endemic to Madagascar and the nearby Comoro Islands, where it occupies a range of elevations from sea level up to 1,200 m. The species prefers karstic limestone landscapes, roosting in caves, tunnels, and abandoned mines, often forming colonies of several hundred individuals. Outside the roost, it forages over forest edges, savanna mosaics, and agricultural fields, exploiting the rich insect fauna of these habitats. Morphologically, M. aelleni displays the characteristic long, narrow wings of the genus, enabling fast, agile flight in open airspace, and a well‑developed tragus that aids in echolocation. Its fur is a uniform dark brown on the dorsal side with lighter ventral coloration. The IUCN currently lists the bat as Least Concern, reflecting its relatively wide distribution and presumed large population, although localized threats may be causing gradual declines.

Aellen’s long‑fingered bat is highly colonial, with individuals clustering in tight groups within dark, humid caves during daylight hours. It is strictly nocturnal, emerging at dusk to hunt insects in the air column above forest canopies and open fields. Roost fidelity is strong; colonies may occupy the same cave system for many years, though seasonal movements to alternative sites occur when microclimatic conditions change. Social interactions are mediated by a repertoire of ultrasonic calls used for navigation and prey detection, as well as lower‑frequency social calls that maintain group cohesion and coordinate emergence. Territoriality is limited to roost sites, where dominant males may defend preferred perching spots, while foraging ranges overlap extensively among colony members, reducing competition through temporal partitioning of hunting activity.

Miniopterus aelleni is an insectivore that captures prey on the wing using aerial hawking techniques. Its diet is dominated by moths (Lepidoptera), beetles (Coleoptera), and dipterans such as mosquitoes and midges, which constitute up to 70 % of stomach contents in seasonal studies. Occasionally, it consumes small orthopterans and occasional arachnids. Foraging occurs at heights of 5‑30 m above ground, often along forest edges where insect abundance is highest. The bat employs frequency‑modulated echolocation calls ranging from 30‑50 kHz to detect and track prey, adjusting call intensity based on ambient light and clutter. Energy intake is estimated at 0.8‑1.2 kJ per night, sufficient to sustain its high metabolic rate and support reproductive demands during the breeding season.

Sexual maturity in Miniopterus aelleni is reached at approximately 10‑12 months of age, with males and females attaining reproductive capability after their first winter. Breeding is seasonal, typically occurring from November to February, coinciding with the rainy season when insect prey is abundant. After a gestation period of about 70‑80 days, females give birth to a single pup, which is altricial and weighs roughly 1.5 g at birth. The mother nurses the pup for 4‑6 weeks, during which time the juvenile remains in the roost attached to the mother’s fur. Weaning occurs around 45 days, after which the young bat begins to accompany the mother on short foraging trips, gradually developing flight proficiency. Juveniles attain independence by the end of the first summer and may join the colony as subadults the following year.

Although classified as Least Concern by the IUCN, Miniopterus aelleni faces several anthropogenic pressures that could affect its long‑term viability. Habitat loss due to deforestation for agriculture and charcoal production reduces foraging grounds, while mining and quarrying disturb roosting caves. Human intrusion into caves during tourism or guano collection can cause colony abandonment. Pesticide use in adjacent agricultural fields diminishes insect prey availability and may lead to bioaccumulation of toxins in bats. Climate change poses a risk by altering precipitation patterns, potentially affecting insect emergence cycles. Current population estimates suggest a stable to slightly declining trend, with roughly 150,000 mature individuals across its range, but precise numbers are uncertain due to limited survey effort.

• Aellen’s long‑fingered bat can fly at speeds exceeding 50 km/h, making it one of the faster insectivorous bats in Madagascar.
• It uses a unique echolocation pattern that includes a rapid frequency sweep, allowing it to detect prey in cluttered forest environments.
• Colonies often consist of mixed‑sex groups, but females dominate the roosting sites during the breeding season.
• The species has been observed sharing roosts with other Miniopterus species, indicating a degree of interspecific tolerance.
• Its name honors the Belgian zoologist Fernand Aellen, who contributed extensively to African bat taxonomy.