@article {57884, title = {Performance of Doppler shift compensation in bats varies with species rather than with environmental clutter}, journal = {Animal Behaviour}, volume = {158}, year = {2019}, month = {Jan-12-2019}, pages = {109 - 120}, abstract = {

The performance of vocal motor control is crucial for vocal communication; however, its evolution and ecological drivers are largely unknown. Doppler shift compensation (DSC), which has been found only in bats, represents an excellent model for studying the mechanisms and evolution of vocal control. We tested whether species that are more dependent on DSC for pulse\–echo separation have a more precise DSC and whether changes in environmental clutter would result in adjustments in DSC performance. We recorded the echolocation and flight behaviour of the greater horseshoe bat, Rhinolophus ferrumequinum, and the great leaf-nosed bat, Hipposideros armiger, flying through a corridor and a window in turn. The DSC precision in H. armiger was significantly lower than that of R. ferrumequinum; the offset between the reference frequency and resting frequency, however, was not significantly different between the two species. We also studied the DSC of H. armiger flying through windows of different sizes. Their flight speed decreased significantly with reduced window size. However, DSC precision and the offset did not vary significantly with window size. Our results suggest that DSC is more precise in rhinolophids, which have a higher demand for pulse\–echo separation by DSC, than in hipposiderids. Changes in environmental clutter do not necessarily result in adjustments of DSC performance. Functional importance associated with high-performance vocal control may be critical in shaping the precision of vocal control in the course of evolution. Instead, habitat clutter encountered by vocalizing animals may not play an important role.

}, issn = {00033472}, doi = {10.1016/j.anbehav.2019.10.008}, author = {Zhang, Yu and Lin, Aiqing and Ding, Jianan and Yang, Xinyao and Jiang, Tinglei and Liu, Ying and Feng, Jiang} } @article {53581, title = {Acoustic signalling of aggressive intent in the agonistic encounters of female Asian particoloured bats}, journal = {Animal Behaviour}, volume = {149}, year = {2019}, month = {Jan-03-2019}, pages = {65 - 75}, abstract = {

The signals of animal aggressive intent can communicate aggression levels to competitors, thereby settling conflicts at an early stage and thus reducing energy costs. We tested whether aggressive vocalizations of female Asian particoloured bats, Vespertilio sinensis, encode aggressive intent during agonistic encounters that occur whenever an intruder pushes a resident to obtain a more central roosting spot. Our results showed that the number of noisy/tonal syllables of the disturbed bats met the three criteria used to define aggressive intent. First, the number and ratio of tonal syllables were significantly greater when intruders continued to push, and the number and ratio of noisy syllables were significantly greater when they stopped pushing (context criterion). Second, skin temperature related to emotional arousal during aggressive interaction generally increased when intruders stopped pushing but was unchanged or decreased when they continued pushing (predictive criterion). Finally, bats preferentially selected stimuli with more tonal syllables, and they spent more time approaching more noisy syllables in a two-choice playback experiment (response criterion). Thus, we propose that the number of noisy/tonal syllables within aggressive vocalizations of female Asian particoloured bats functions to signal aggressive intent.

}, keywords = {aggressive intent, aggressive vocalizations, skin temperature}, issn = {00033472}, doi = {10.1016/j.anbehav.2019.01.012}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0003347219300132}, author = {Zhao, Xin and Jiang, Tinglei and Liu, Heng and Wang, Yuze and Liu, Ying and Feng, Jiang} } @article {53527, title = {Bats increase vocal amplitude and decrease vocal complexity to mitigate noise interference during social communication}, journal = {Animal Cognition}, year = {2019}, month = {Oct-01-2019}, abstract = {

Natural background noises are common in the acoustic environments in which most organisms have evolved. Therefore, the vocalization and sound perception systems of vocal animals are inherently equipped to overcome natural background noise. Human-generated noises, however, pose new challenges that can hamper audiovocal communication. The mechanisms animals use to cope with anthropogenic noise disturbances have been extensively explored in a variety of taxa. Bats emit echolocation pulses primarily to orient, locate and navigate, while social calls are used to communicate with conspecifics. Previous studies have shown that bats alter echolocation pulse parameters in response to background noise interference. In contrast to high-frequency echolocation pulses, relatively low-frequency components within bat social calls overlap broadly with ambient noise frequencies. However, how bats structure their social calls in the presence of anthropogenic noise is not known. Here, we hypothesized that bats leverage vocal plasticity to facilitate vocal exchanges within a noisy environment. To test this hypothesis, we subjected the Asian particolored bat, Vespertilio sinensis, to prerecorded traffic noise. We observed a significant decrease in vocal complexity (i.e., an increased frequency of monosyllabic calls) in response to traffic noise. However, an increase in the duration and frequency of social calls, as have been observed in other species, was not evident. This suggests that signal simplification may increase communication efficacy in noisy environments. Moreover, V. sinensis also increased call amplitude in response to increased traffic noise, consistent with the predictions of the Lombard effect.

}, keywords = {acoustic communication, bats, Noise, Social calls, vocal plasticity}, issn = {1435-9448}, doi = {10.1007/s10071-018-01235-0}, url = {http://link.springer.com/10.1007/s10071-018-01235-0}, author = {Jiang, Tinglei and Guo, Xiong and Lin, Aiqing and Wu, Hui and Sun, Congnan and Feng, Jiang and Kanwal, Jagmeet S.} }