Female reciprocal calling of pearly tree frog (Nyctixalus margaritifer Boulenger, 1882) in West Java, Indonesia

Less than 1% of female anurans vocalize (Gerhardt & Bee 2007; Köhler et al. 2017). In some species, females emit calls as a response to male calls. This behaviour has been referred to as a reciprocal call (Schlaepfer & Figeroa-Sandí 1998). As most female frogs respond to male calls only when they are at the peak of reproduction (Bush et al. 1996), experimental playback becomes a beneficial method for revealing their acoustic signal (Capranica 1965). Nevertheless, the study of female calls often receives less attention from researchers because the behaviour is challenging to observe (Willaert et al. 2016). However, a reference collection is needed for taxonomy purposes to provide clear guidelines for species identification or delimitation (Köhler et al. 2017).