Acoustic deterrents influence foraging activity, flight and echolocation behaviour of free-flying bats

Data for Research Article in Journal of Experimental Biology. Including trajectory measurement dataset, acoustic bat call count dataset and echolocation call parameter dataset. Abstract: Acoustic deterrents have shown potential as a viable mitigation measure to reduce human impacts on bats, however, the mechanisms underpinning acoustic deterrence of bats have yet to be explored. Bats avoid ambient ultrasound in their environment and alter their echolocation calls in response to masking noise. Using stereo thermal videogrammetry and acoustic methods, we tested predictions that i) bats would avoid acoustic deterrents and forage and social call less in a ‘treated airspace’; ii) deterrents would cause bats to fly with more direct flight paths akin to commuting behaviour and in line with a reduction in foraging activity, resulting in increased flight speed and decreased flight tortuosity; iii) bats would alter their echolocation call structure in response to the masking deterrent sound. As predicted, overall bat activity was reduced by 30% and we recorded a significant reduction in counts of Pipistrellus pygmaeus (27%), Myotis spp. (probably M. daubentonii) (26%) and Nyctalus and Eptesicus spp. (68%) passes. P. pygmaeus feeding buzzes were also reduced by the deterrent in relation to general activity (by 38%), however social calls were not (only 23% reduction). Bats also increased their flight speed and reduced the tortuosity of their flight paths and P. pygmaeus reduced echolocation call bandwidth and start frequency of calls in response to deterrent playback, probably due to the masking effect of the sound. Deterrence could therefore be used to remove bats from areas where they forage, for example wind turbines and roads, where they may be under threat from direct mortality.本数据集为《实验生物学杂志》（Journal of Experimental Biology）研究论文配套数据，包含轨迹测量数据集、蝙蝠声学呼叫计数数据集以及回声定位呼叫参数数据集。 摘要：声学驱避措施（acoustic deterrents）已被证明可作为减轻人类对蝙蝠负面影响的可行缓解手段，但其驱避蝙蝠的核心机制仍有待探究。蝙蝠会规避所处环境中的环境超声，并会因掩蔽噪声调整其回声定位呼叫（echolocation call）。本研究采用立体热成像摄影测量法与声学方法，对以下三项预测展开验证：其一，蝙蝠会规避声学驱避措施，在“干预空域”内的觅食与社交呼叫行为均会减少；其二，驱避措施会使蝙蝠采用更趋直线的飞行路径，类似其往返通勤行为，该变化与觅食活动减少的结果一致，进而导致飞行速度提升、飞行曲折度降低；其三，蝙蝠会因掩蔽性驱避声调整其回声定位呼叫的结构。 如预期一致，蝙蝠整体活动水平降低30%。研究记录到侏伏翼（Pipistrellus pygmaeus）、鼠耳蝠属（Myotis，大概率为道恩顿鼠耳蝠Myotis daubentonii）以及夜蝠属（Nyctalus）与棕蝠属（Eptesicus）物种的飞行过境次数分别显著减少27%、26%与68%。相较于整体活动水平，侏伏翼的觅食嗡鸣次数也因驱避措施减少38%，但社交呼叫次数仅减少23%，未出现显著变化。蝙蝠同时提升了飞行速度并降低了飞行路径的曲折度；侏伏翼还会因驱避声回放调整其回声定位呼叫，具体表现为呼叫频带宽度与起始频率降低，这可能源于声音的掩蔽效应。 因此，声学驱避措施可用于将蝙蝠从其觅食区域（如风电场与道路区域）移除，这些区域正是蝙蝠面临直接致死威胁的高发地带。