| During social communication, animals release irritant signals and then the signal receivers generate special reaction responses. With the advantages of carrying more information, transferring fast and consuming low energy, voice is one of the most important irritant signals. Current researches of voice mainly focused on voice spectrogram, vocal anatomy, neurophysiology, hearing ability and mechanisms, the effect of sonar and noise on animals and the function and meaning of the voice. In a word, previous studies mainly considered the function of different voices during animal communication, and does not explore the meaning of the voices. As research continues, scientists found that some animals could purposefully use the voice and convey specific meaning. Furthermore, the same voice could convey different meanings and the role of the voice receivers was nonnegligible in communication. Considering that the receiving and the understanding of voice signal is a necessary part of voice meaning, we attempts to explain the meaning of the voices when taking the the voice receivers into account. As a kind of social group animal inhabiting forests, primates use voice as the main signal of communication.Furthermore, as close relatives of human beings, evolutionarily advanced primates possess much more directivity in voice. All those characters mentioned above make primates a good model to study voice meaning. Sichuan snub-nosed monkey (Rhinopithecus roxellanae) is a precious primate species endemic to China. Current researches on R. roxellanae mostly focus on ex situ conservation, habitat analysis, social behavior and genetic diversity. Little knowledge has been obtained on the voice of R. roxellanae, let alone the meaning of the voice. Here, we chose R. roxellanaeto study the spectrum and the meaning of its voices under the consideration of receivers’ reaction, and to explore the factors that influence the meaning of the voices. Wild observation method and scan sampling method were used to collect field data in November,2014 and August, 2015 at Dalongtan Sichuan snub-nosed monkey research base of Shennongjia Nature Reserve; statistical method was used to analyse the data. The main results of our study are as follows:(a) The voice spectrum of R. roxellanae was obtained. We totally recorded 19 kinds of voices from R. roxellanae. The spectrum we got was different from previous researches. The voices "or" which taken place when they were fed and the voices "hor-" which happened when the baby and child monkeys were threatened were firstly recorded in our study. We failed to record the voice "bie-" which is called direction alert voice, which may be due to the special life mode of the studied population. We also found that the man-feed group of R. roxellanae has already formed a special answer system after long-term contacting with humans; it is significantly different from the wild-living groups.(b) The voices of R. roxellanae have special meanings; the same voice may express different meanings and different voices can also express the same meaning. We built 20 ASOs (Apparently Satisfactory Outcome) modes with the behavioral response of the senders and the receivers, and conduct the two-factor ANOVA in SPSS to confirm the specificity of the ASOs distributing. We collected 4621 voices with a complete round and classified them to the ASOs, and then we did the chi-square test to get the "explanation" dictionary of the snub-nosed monkey voices. Five kind of the 19 voices were distributed on different ASOs and 10 ASOs contained more than 1 voices.(c) The meaning of voice in R. roxellanae is affected by the gender and age of the voice sender and receiver. For instance, the adult males send the voice "gu" more frequently than the others and the meaning of this voice is the richest among them. Moreover, the meaning of "gu" is also affected by the gender and age of the receiver. When the receiver is a female, the meaning of "gu" could mean "start copulate" which is not exist in other individuals. The male adults send the voice "gu" to announce their dominant status and to maintain the steady structure of the social group. The meaning of the voice "wa" can be changed due to the different receivers. When the receiver is adult male, the sender may be more likely to express the meaning of "embrace and reconciliation" which proves that snub-nosed monkey is a kind of mild species to a certain extend. While the low status males, adolescents and adult females tend to use this voice to mitigate the conflict and tension relation. The meaning of the voice "uga" is much richer in the adolescent individuals than other individuals. The voice "uga" only has one meaning in the adult female, adult male and sub-adult female and male individuals, but it has several meanings in adolescent individuals no matter whether they are the senders or the receivers. |
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