Bats of a remote island: integrated genetic and bioacoustics monitoring confirms species occurrence in Flores (Azores, Portugal)

Abstract. Island ecosystems often harbour unique and vulnerable species, yet many remain poorly documented. In the Azores archipelago, two extant bat species are known to occur: the endemic Nyctalus azoreum and the Macaronesian endemic Pipistrellus maderensis. On Flores Island, part of the remote western group, only unidentified pipistrelle bats had previously been recorded. Here, we combined acoustic monitoring and genetic analysis to assess the occurrence, identity, and ecological patterns of bats on Flores. A pipistrelle specimen was genetically analysed, confirming its identity as P. maderensis and providing the first publicly available genetic reference for the Azores. Acoustic surveys at ten sites detected both species. Pipistrellus maderensis occurred across the island and accounted for 99.6 % of recorded bat passes. Nyctalus azoreum was confirmed for the first time on the island but showed very low activity and was detected only at a few sites in the central and southern parts of Flores. Activity patterns were consistent with nocturnal foraging, with no diurnal activity recorded during the study period. The detection of N. azoreum at previously sampled sites suggests that earlier non-detections may reflect low detectability rather than true absence. These findings improve knowledge of bat distribution in the Azores and highlight the importance of continued monitoring and conservation of small island bat populations.