Acoustic Identification of Bats in the Southern Western Ghats, India

Claire F R Wordley,John D Altringham,Divya Mudappa,Mahesh Sankaran,Eleni K Foui

doi:10.3161/150811014x683408

Abstract

Bats play crucial roles in ecosystems, are increasingly used as bio-indicators and are an important component of tropical diversity. Ecological studies and conservation-oriented monitoring of bats in the tropics benefit from published libraries of echolocation calls, which are not readily available for many tropical ecosystems. Here, we present the echolocation calls of 15 species from the Valparai plateau in the Anamalai Hills, southern Western Ghats of India: three rhinolophids (Rhinolophus beddomei, R. rouxii (indorouxii), R. lepidus), one hipposiderid (Hipposideros pomona), nine vespertilionids (Barbastella leucomelas darjelingensis, Hesperoptenus tickelli, Miniopterus fuliginosus, M. pusillus, Myotis horsfieldii, M. montivagus, Pipistrellus ceylonicus, Scotophilus heathii, S. kuhlii), one pteropodid (Rousettus leschenaultii) and one megadermatid (Megaderma spasma). Discriminant function analyses using leave-one-out cross validation classified bats producing calls with a strong constant frequency (CF) component with 100% success and bats producing frequency modulated (FM) calls with 90% success. For five species, we report their echolocation calls for the first time, and we present call frequencies for some species that differ from those published from other parts of the species' ranges. This exemplifies the need for more local call libraries from tropical regions to be collected and published in order to record endemic species and accurately identify species whose calls vary biogeographically.

Highlights

Bats are the second most species rich order of mammals, with great ecological diversity, especially in the tropics
Constant frequency calls Using FMAXE and call duration, Discriminant Function Analysis (DFA) classified calls to species with 100% success compared with 25% expected from random assignment
Frequency modulated calls All bats that used a single dominant frequency modulated (FM) harmonic were grouped for analysis along with R. leschenaultii, which uses a low frequency tongue click

Summary

Introduction

Bats are the second most species rich order of mammals, with great ecological diversity, especially in the tropics. They undertake a range of ecosystem services, including seed dispersal, pollination and insect control. A variety of ecologically and commercially important plants rely on bats to some degree as pollinators or seed dispersers (Kunz et al, 2011). The two main methods used for the study of bats are capturing them with mist nets and/or harp traps, or recording their echolocation calls using ultrasound detectors. The use of ultrasound detectors in the tropics has been hampered by the lack of reliable call libraries, which allow identification of bats to genus or species level from their echolocation calls

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Conclusion