Interspecific Recognition Behaviors Of Echolocation Calls Within Four Sympatric Constant Frequency Bat Species And Its Influencing Mechanisms

Interspecific recognition is the product of species coexistence, and has direct effects on survival and reproduction of animals. Bats are able to discriminate between sympatric different heterospecifics based on their echolocation calls, which has been shown both in free-flying and captive bats. To date, however, the factors that may determine the behavioral responses of bats to echolocation calls from sympatric heterospecifics have rarely been tested, especially under well-controlled conditions in captive bats. Hence we aimed at tackling this question by performing playback experiments (habituation-dishabituation) with three horseshoe bat species within the constant-frequency (CF) bat guild, which included big-eared horseshoe bats(Rhinolophus macrotis), Blyth’s horseshoe bats (R. lepidus), Chinese horseshoe bats (R. sinicus), and Stoliczka’s trident bat (Asellisus stoliczkanus). We played the echolocation calls of conspecies and of the rest three heterospecies respectively to three horseshoe bat species. We quantified interspecific recognition behaviors, determined the differences and causes of interspecific acoustic recognition, and proved the communication function of echolocation calls. Study the mutual recognition between sympatric species, which helps to understand the species coexistence mechanism and the dynamic formation process of animal community. This also could provide theoretical and scientific basis for animal communication culture and biodiversity protection. The main results were as follows:1. In our experiments, bats’ reactions depended on the heterospecific identity that the echolocation calls represented, but not the simple reactions to the differences of call characters between two playback files.2. The ratio of reaction bats≥75%when the three horseshoe bats species discriminated the echolocation calls from each other or A. stoliczkanus, and there was no significant between them (Pearson Chi-Square test; χ2=7.55, df=8, P＝0.479).3. The three horseshoe bats species displayed a series of same behaviors (leg movement, wing stretching, nodding, body movement and echolocation) to echolocation calls from each or A. stoliczkanus. But the strength of the behaviors differed significantly when each horseshoe bat discriminated different heterospecies (nodding:Friedman test; Rm, Fr=6.13, P=0.046; Rs, Fr=8.06, P=0.018; RM ANOVA; R1, F=5.50, P=0.012; body movement:Friedman test; Rm, Fr=15.96, P<0.001; RM ANOVA; Rs, F=4.70, P=0.025; R1, F=5.41, P=0.010).4. The morphological similarity and the genetic relationship between species had only a minor effect on bats’ reaction. Moreover, our data showed that there was no significant canonical correlation between the degree of bats’reaction and the interspecific difference of echolocation call characters (peak frequency, duration, and bandwidth)(canonical correlation=0.846, p=0.629), and the component of calls also had a minor effect on bats’reaction.5. We found a statistically significant positive correlation between the interspecific trophic niche overlap index and the number of nods (r=0.882; P=0.002), body movements (r=0.688; P=0.041), and echolocation pulses emitted (r=0.854; P=0.003) when bats discriminated echolocation calls from each other or A. stoliczkanus.