环境噪声对蝙蝠回声定位叫声及飞行活动的影响

Effect of ambient noise on the activity and echolocation calls of bats

环境噪声影响动物的活动及其叫声特性,已成为动物面对的一种重要选择压力。为应对噪声的干扰,多数动物类群会远离噪声区域和改变其叫声的频谱时间结构,如延长叫声持续时间、提高叫声频率等,但有些动物的活动和叫声频谱时间结构并不受环境噪声的影响。本研究在自然条件下,研究不同环境噪声强度对蝙蝠活动和回声定位声波的影响。选取噪声强度有差异的12个样点,分别录制各样点大卫鼠耳蝠、西南鼠耳蝠、亚洲长翼蝠及未知蝙蝠的回声定位声波,分析其持续时间、起始频率、峰频、终止频率和带宽,统计蝙蝠通过次数。回归分析结果显示:环境噪声强度与大卫鼠耳蝠、西南鼠耳蝠、亚洲长翼蝠及未知蝙蝠的活动无显著相关性(P>0.05),与回声定位声波的脉冲持续时间、起始频率、峰频、终止频率及带宽均不显著相关(P>0.05)。暗示低频低强度(<20 k Hz,<67.5 d B)的环境噪声可能对高频回声定位蝙蝠的叫声及活动没有显著影响。

Ambient noise affecting the activity and vocalization of animals has been an important environmental selection pressure. Many vertebrates use a number of strategies to avoid ambient noise, including avoiding noisy areas, prolonging call duration and increasing call frequency. However, some animals do not make any response to ambient noise. Here, we conducted a natural experiment to investigate the potential effects of ambient noise on the activity levels and echolocation calls in bats. We recorded the echolocation pulses and activity from bats while flying in twelve areas with different ambient noise levels whose equivalent continuous A-weighted sound pressure levels were 47.5 dB, 47. 7 dB, 54.4 dB, 54.9 dB, 55.1 dB, 55.1 dB, 58. 0 dB, 60. 6 dB, 60. 8 dB, 62. 5 dB, 62. 8 dB, 67.3 dB respectively. A total of 1 017 pulses and 4 124 bat passes were analyzed at the twelve areas during all experimental trials over 12 successive nights. The results from linear regression models showed that changes in the number of bat passes and call parameters including pulse duration, starting frequency, peak frequency, ending frequency and bandwidth did not differ significantly among twelve areas （ P 〉 0. 05）. The results may indicate that low frequency and low level （ 〈 20 kHz, 〈 67.3 dB） ambient noise may have no significant effect on the echolocation calls and activity of bats producing high frequency calls.