Acoustic identification of five insectivorous bats by their echolocation calls in the Sahelian zone of Far North Cameroon

Despite their abundance and ecological importance, bats are under significant threat worldwide. There is little information about their distribution, roosting, and habitat requirement for most species, making assessing which species is threatened or in need of special conservation measures difficult. The knowledge gap may partly be due to limitations of the old methods of studying bats which mainly involved capture/or observational techniques. In order to evaluate the potential of identifying insectivorous bats by their echolocation calls in the Sahelian zone of northern Cameroon, 65 bats belonging to five species were captured using standard mist netting: Mops condylurus , Chaerephon major , Mops niveiventer , Scotophilus dinganii , and Scotophilus leucogaster . The bats were identified by using morphometric measurements. An Anabat SD1 detector was later used to record echolocation calls of each individual bat in flight after it was hand-released. The sonogram of each individual bat was analyzed using Analook and categorized into two call types (frequency modulation and frequency modulation/quasi constant frequency) in order to develop a library of bat reference calls that could be used for a qualitative acoustic survey and species identification. Discriminant function analysis (DFA) was applied to search phase calls of the 65 individual bats in order to evaluate the potential for classifying calls into five species groups. Seven parameters calculated from each search phase call were used to classify calls. Bats where place into two groups according to the structure of calls: FM bats ( Mops condylurus , Chaerephon major , Mops niveiventer ) and FM/QCF bats ( Scotophilus dinganii and Scotophilus leucogaster ). The DFA resulted in a correct overall classification of 69.7%. This preliminary study showed that DFA of call parameters is a feasible method that can be used to identify insectivorous bats in the region by their echolocation calls.