“…However, an information-carrying signal that is produced almost constantly and is freely available is a likely candidate to be used for communication. Signals emitted by an animal, voluntarily or involuntarily, provide useful information, for example about feeding grounds and suitable roosts (Barclay, 1982;Ruczynski, Kalko, & Siemers, 2007), the presence of mates (Behr & Von Helversen, 2004;Leippert, 1994), prey (Page, Ryan, & Bernal, 2013;Siemers, Kriner, Kaipf, Simon, & Greif, 2012), a threat (Mariappan, Bogdanowicz, Marimuthu, & Rajan, 2013;Russ, Jones, Mackie, & Racey, 2004) or attributes of the sender (Fenton, 2003;Siemers et al, 2005) and its behavioural state (Bastian & Schmidt, 2008). Nevertheless, the communicative function of echolocation can only arise or be fine-tuned if it does not compromise the primary functions of echolocation which are fundamental to the bat's survival.…”