“I am a conservation biologist at the Gorongosa National Park in central Mozambique, where I focus on bats and their social vocalizations. In this photo, I’m photographing a colony of fruit-eating bats (Eidolon helvum) that live in the Tunduru Botanic Garden in the capital, Maputo.
As we learn about the different types of vocalization, we can understand the phases of a bat’s life better and perhaps be able to conserve species with fewer interventions than now. For instance, there are vocalizations specific to the mating season, and some species have only one reproductive season over two or three months of the year. We can better quantify and recognize that time period if we focus on the sounds bats make.
There are a lot of unanswered questions. Do the male bats use vocalization to mark and defend their territory, for instance? During my master’s degree, I worked on two species: the Egyptian slit-faced bat (Nycteris thebaica) and Sundevall’s leaf-nosed bat (Hipposideros caffer). For one of them, I was able to identify 11 distinct vocalizations, and for the other, I identified 6.
Our basic equipment is a bat detector, which records the ultrasound calls emitted by bats. I use specialist software, including Kaleidoscope Pro and Raven Pro, to visualize these sounds in a sonogram, which graphs sound as a wave. (Kaleidoscope even has a bat mode.) We then use frequency, duration and other harmonic details to identify the vocalizations.
