Echolocation calls of Rhinolophus ferrumequinum in relation to habitat type and environmental factors

The present experiment was carried out in Luotong Mountain Natural Reserve in Jilin Province of China in 2007. We recorded and analyzed the echolocation calls of Rhinolophus ferrumequinum in different habitats by using Avisoft Bioacoustics USG 116 and Avisoft-SASLAB PRO (Avisoft Bioacoustics, Berlin, Germany). Our results showed that R. ferrumequinum foraged in diverse habitats in the study area, and their echolocation calls were significantly variable in different habitats (One-Way ANOVA, P < 0.05). Vegetative, climatic and topographical factors were selected by using the principal component analysis and the correlations between the parameters of echolocation calls and these environmental factors were analyzed. The results indicated that although R. ferrumequinum always emitted FM/CF/FM echolocation calls in different habitats, the parameters of echolocation calls varied with variable environmental factors. Significant negative correlation existed between FM1 bandwidth and arbor height (r = −0.948, P < 0.05), FM2 bandwidth and arbor height (r = −0.825; P < 0.05), FM1 starting frequency and canopy area (r = −0.967, P < 0.05), FM2 ending frequency and canopy area (r = −0.958, P < 0.05), FM1 starting frequency and air relative humidity (r = −0.776, P < 0.05), FM2 ending frequency and air relative humidity (r = −0.875, P < 0.05), peak frequency and air relative humidity (r = −0.794, P < 0.05), pulse duration and average shrub height (r = −0.911, P < 0.05), and inter-pulse interval and average shrub height (r = −0.990, P < 0.05). Significant positive correlation existed between peak frequency and number of plants (r = 0.756, P < 0.05), and pulse duration and height below the canopy (r = 0.870, P < 0.05). Our results suggested that many kinds of ecological factors (such as vegetation factor, climatic factor and topographical factor) affected the structure of echolocation calls and made them diverse in different habitats, i.e., echolocation calls of bats had phenotypic flexibility and eco-adaptability. These characteristics determined the degree of available habitats and natural resources for R. ferrumequinum.