| The Amur tiger is the largest feline in the world,and is also a national Class I protected animal in China.Acoustic communication plays an important role in the information exchange of captive Amur tigers.With the increasing of age,the acoustic communication diversifies from simple to complex,and there are also differences in the acoustic structure of sound signals.Based on the call repertorie of captive Amur tiger cubs,this study quantitatively analyzed the vocal repertoire and behavioral background of captive Amur tiger sub-adults and adults,and we explored the differences in acoustic parameters among different developmental stages and different genders,and we also explored the relationship between acoustic parameters and behavior.From September to November 2019,462 audio samples and 286 video samples of sub-adults,and 482 audio samples and 336 video samples of adult Amur tiger were collected in Hengdao Hezi Tiger Forest Park.247 high-quality sound samples of sub-adults and 316 sound samples of adults were screened out,we comprehensively used principal component analysis,discriminant function analysis,cluster analysis,multinomial logistic regression to analyze the sound samples.The main findings obtained are as follows:(1)We consummated the vocal repertoire of the captive Amur tiger at different developmental stages,and found that there are 7 types of calls used by the sub-adult and adult Amur tigers,namely Ar-2,Er,Chuff,Growl,Hiss,Roar?Hr.Ar-1,eee,and Haer were heard in captive Amur tiger cubs which did not appear in the vocal repertoires of the sub-adults and adults.Hr is a new vocal repertoire that appears in the sub-adult stage,and Hiss and Roar in the sub-adult stage represented warnings to the same kind whereas Chuff expressed kindness at all developmental stages.(2)The difference in acoustic parameters of the sound signals expressed by the captive Amur tigers of the same developmental stage and different genders are as follows:In cub stage,the values of Duration,Freq25,Freq50,Freq75,IQRBW,and MaxFreq of male tigers were higher than female tigers.In sub-adult stage,the values of Freq25,Freq50,Freq75,IQRBW,and SDF0 of male tigers were higher than female tigers,however the Rise Time value of female tigers was higher than that of male tigers.In the adult stage,only the F0 value of male tigers was higher than that of female tigers,other acoustic parameters showed no differences between genders.(3)The difference in acoustic parameters of the captive tigers of the same gender and different developmental stages showed that when the female tiger develops from the cub to the sub-adult stage,the value of the time parameter(Duration and Rise Time)increases,while the values of other parameters decrease.When female tigers developed from sub-adult to adult stage,energy parameter(Freq25?Freq50?Freq75?IQRBW?MaxFreq?SD F0?Duration)increased and Rise Time decreased,while other parameters showed no significant difference.When male tiger developed from cub to sub-adult stage,energy parameters(Freq25,Freq50,Freq75,IQRBW),part of fundamental frequency parameters(F0,Max F0,Min F0)and MaxFreq values decreased,however SD F0 and time parameters showed no significant differences.From sub-adult to adult stages,MaxFreq and Rise Time decreased while other parameters showed no significant differences among stages.(4)In the sub-adult and adult stages of captive Amur tigers,there are different response relationships between the occurrence probability of the five behavioral backgrounds and the changes in the frequency(MaxFreq),fundamental frequency(F0)and sound duration(Duration)at the maximum energy.Our study may provided a basis for the research on voice communication and behavior of the Amur tiger in captivity,as well as a scientific basis for the reintroduction of the Amur tiger. |
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