First characterisation of bat echolocation calls in Argentina

Abstract

Bioacoustics is a non-invasive method and an important complementary tool because, in combination with other methods such as mist nets, it allows us to characterise more completely the assemblage of bats in a given place. However, a description of echolocation calls in local conditions is required to use it. This study presents the acoustic characterisation of bat species from northwestern Argentina using different recording techniques. Between April 2022 and November 2023, surveys were carried out with mist nets in different locations in the province of Tucumán (Argentina). The captured specimens were recorded with an Echo Meter Touch 2 device using four techniques: hand release, zip-line, flight cage, and emergence recordings. A total of 209 echolocation calls were recorded from 13 species belonging to the families Phyllostomidae, Molossidae, and Vespertilionidae. The phyllostomid species showed frequency-modulated calls (FM) of low intensity with multiple harmonics; molossids calls exhibited quasi-constant frequency, long duration, and narrow bandwidth; while in vespertilionid bats the calls have pulses with descendent FM (FMd), short duration, and greater bandwidth. This research provides the first acoustic reference data for bats from Argentina, helping to facilitate the acoustic identification of bats in the region.