Volodin Ilya A, Matrosova Vera A, Frey Roland, Kozhevnikova Julia D, Isaeva Inna L, Volodina Elena V
Department of Vertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Vorobievy Gory, 12/1, Moscow, 119234, Russia.
Scientific Research Department, Moscow Zoo, B. Gruzinskaya str., 1, Moscow, 123242, Russia.
Naturwissenschaften. 2018 Jun 11;105(7-8):40. doi: 10.1007/s00114-018-1567-8.
Non-hibernating pikas collect winter food reserves and store them in hay piles. Individualization of alarm calls might allow discrimination between colony members and conspecifics trying to steal food items from a colony pile. We investigated vocal posture, vocal tract length, and individual acoustic variation of alarm calls, emitted by wild-living Altai pikas Ochotona alpina toward a researcher. Recording started when a pika started calling and lasted as long as possible. The alarm call series of 442 individual callers from different colonies consisted of discrete short (0.073-0.157 s), high-frequency (7.31-15.46 kHz), and frequency-modulated calls separated by irregular intervals. Analysis of 442 discrete calls, the second of each series, revealed that 44.34% calls lacked nonlinear phenomena, in 7.02% nonlinear phenomena covered less than half of call duration, and in 48.64% nonlinear phenomena covered more than half of call duration. Peak frequencies varied among individuals but always fitted one of three maxima corresponding to the vocal tract resonance frequencies (formants) calculated for an estimated 45-mm oral vocal tract. Discriminant analysis using variables of 8 calls per series of 36 different callers, each from a different colony, correctly assigned over 90% of the calls to individuals. Consequently, Altai pika alarm calls are individualistic and nonlinear phenomena might further increase this acoustic individualization. Additionally, video analysis revealed a call-synchronous, very fast (0.13-0.23 s) folding, depression, and subsequent re-expansion of the pinna confirming an earlier report of this behavior that apparently contributes to protecting the hearing apparatus from damage by the self-generated high-intensity alarm calls.
非冬眠的鼠兔会收集冬季食物储备并将其储存在干草堆中。警报叫声的个性化可能有助于区分群体成员和试图从群体干草堆中偷取食物的同种个体。我们研究了野生阿尔泰鼠兔（Ochotona alpina）对研究人员发出的警报叫声的发声姿势、声道长度和个体声学变异。当一只鼠兔开始呼叫时开始录音，并尽可能长时间持续。来自不同群体的442个个体呼叫者的警报叫声序列由离散的短（0.073 - 0.157秒）、高频（7.31 - 15.46千赫）和调频叫声组成，间隔不规则。对每个序列中的第二个442个离散叫声进行分析发现，44.34%的叫声没有非线性现象，7.02%的叫声中非线性现象覆盖不到叫声持续时间的一半，48.64%的叫声中非线性现象覆盖超过叫声持续时间的一半。峰值频率在个体之间有所不同，但总是符合对应于估计45毫米口腔声道计算出的声道共振频率（共振峰）的三个最大值之一。使用来自36个不同呼叫者（每个来自不同群体）的每个序列8个叫声的变量进行判别分析，正确地将超过90%的叫声归属于个体。因此，阿尔泰鼠兔的警报叫声具有个体特异性，非线性现象可能会进一步增强这种声学上的个体特异性。此外，视频分析显示耳廓有叫声同步、非常快速（0.13 - 0.23秒）的折叠、凹陷以及随后的重新展开，证实了此前关于这种行为的报告，这种行为显然有助于保护听觉器官免受自身产生的高强度警报叫声的损害。
