短嘴金丝燕回声定位叫声特征

Echolocation calls of free-flying Himalayan swiftlets (Aerodramus brevirostris)

2012年6月,对湖南省石门县壶瓶山国家级自然保护区神景洞短嘴金丝燕的回声定位叫声进行研究,在黑暗山洞内使用录音仪器录制其自由飞行状态的声音后使用声音软件进行分析。短嘴金丝燕捕食归巢时,快速飞入洞口,在洞内有光区域不发声,到达洞内黑暗区域后开始发出回声定位叫声,且飞行速度减慢。声音分析结果表明其回声定位叫声为双脉冲组的噪声脉冲串型(noiseburst),组内脉冲间隔很短[(6.6±0.42)ms],组间脉冲间隔较长[(99.3±3.86)ms],两者差异显著(P<0.01)。对比第一、第二脉冲声音参数发现,主频和脉冲时程差异不显著,第一、第二脉冲主频分别为(6.2±0.08)kHz和(6.2±0.10)kHz(P>0.05);脉冲时程分别为(2.9±0.12)ms和(3.2±0.17)ms(P>0.05);最高和最低频率差异显著,第一、第二脉冲最高频率分别为(20.1±1.10)kHz和(15.4±0.98)kHz(P<0.01),最低频率分别为(3.7±0.12)kHz和(4.0±0.09)kHz(P<0.05);第一脉冲频宽((16.5±1.17)kHz)宽于第二脉冲((11.4±1.01)kHz)(P<0.01);且第一脉冲能量[(32.5±0.60)dB]高于第二脉冲[(35.2±0.94)dB](P<0.05)。另外,短嘴金丝燕在黑暗山洞内的回声定位叫声还包含了部分超声波,最高频率可达33.2kHz。

Here, we present our findings of free-flying echolocation calls of Himalayan swiftlets （Aerodramus brevirostris）, which were recorded in Shenjing Cave, Hupingshan National Reserve, Shimen County, Hunan Province in June 2012, using Avisoft-UltraSoundGate 116（e）. We noted that after foraging at dusk, the Himalayan swifllets flew fast into the cave without clicks, and then slowed down in dark area in the cave, but with sounds. The echolocation sounds of Himalayan swiftlets are broadband, double noise burst clicks, separated by a short pause. The inter-pulse intervals between double clicks （99.3±3.86 ms） were longer than those within double clicks （6.6±0.42 ms） （P〈0.01）. With the exception of peak frequency, between 6.2±0.08 kHz and 6.2±0.10 kHz, （P〉0.05） and pulse duration 2.9±0.12 ms, 3.2±0.17 ms, （P〉0.05） between the first and second, other factors--maximum frequency, minimum frequency, frequency bandwidth, and power--were significantly different between the clicks. The maximum frequency of the first pulse （20.1 ± 1.10 kHz） was higher than that of second （15.4±0.98 kHz） （P〈0.01）, while the minimum frequency of the first pulse （3.7±0.12 kHz） was lower than that of second （4.0±0.09 kHz） （P〈0.05）; resulting in the frequency bandwidth of the first pulse （16.5±1.17 kHz） longer than that of second （11.4±1.01 kHz） （P〈0.01）. The power of the first pulse （-32.54±0.60 dB） was higher than that of second （-35.2±0.94 dB） （P〈0.05）. More importantly, we found that Himalayan swiftlets emitted echolocation pulses including ultrasonic sound, with a maximum frequency reaching 33.2 kHz.