Vocal Repertoire of Cheetah Acinonyx jubatus (Carnivora, Felidae) in Captivity: Sound Structure and Search for Means of Assessing the State of Adult Animals

Vocalization is a rich potential source of information on the internal state of animals. This information is necessary for assessing the animal behavior and ensuring the most favorable conditions for holding and breeding animals in captivity. The sound indicators of animal's behavioral and physiological well-being can be applied without traumatic manipulations, which is especially important for such a rare and endangered species as the cheetah (Acinonyx jubatus). Bight types of sounds were distinguished and attributed to three classes: pulsed, tonal, and noisy. The classification proposed is discussed in relation to mechanisms for producing different kinds of sounds. A hypothetical diagram of the correlation between the sound structure and states of confidence/diffidence and aggressiveness/nonagressiveness in the cheetah is considered. Establishing a correlation between the sound structure and internal state of animals during sound production is one of important issues both in theoretical and applied acoustics (Morton, 1977; Nikolskii, 1984; Hauser, 1996). It has been shown in numerous studies using various methods of independent monitoring of the internal state of animals that animal sounds bear the "honest" information on their emotions and motivations. For example, Weary and Fraser (1995a. 1995b) showed that the call structure of pigs (Sus scrofa L.) is changing depending on the extent of food deprivation and displeasing impact. Jurgens (1976a) presented reliable arguments indicating that the sound structure of the squirrel monkey (Saimiri sciureus L.) is related to subjective displeasing or pleasing feelings of these animals, and sounds of different structure are localized in different areas of vocal centers of the brain. Dessereau et al. (1995) found that structural characters of vocalization in humans also give true information on their internal state: stronger emotional tension is reflected in those sounds, in which the pauses are excessively long as related to frequency. The field of application of vocal indicators of the internal state of animals and humans is potentially very wide. Such indicators, for example, are used in the lie detector, for the emergency stop of machines in response to cry, estimation of reproductive cycle stages of animals in zoos and farms (Smith et al, 1983; Lindburg, 1990; Huang et al., 1994; Volodina and Volodin, 1996). At present, bioacoustic methods for estimating subjective states of animals and humans, such as, e.g., well-being, suffering, etc., attract special attention due to the development of legislation concerning humanistic keeping of animals at farms, laboratories, and zoos, and also in connection will medical programs (Broom and Johnson, 1993; Volodin and Volodina, 1997). The sounds are convenient indicators of the internal state, because they can be easily recorded and analyzed. In addition, bioacoustic analysis does not require traumatic manipulations or immobilizing, which are necessary, e.g., in blood sampling. This is especially important in the work with rare, endangered species, when an investigator is strongly limited in possibilities of manipulating with animals. The cheetah (Acinonyx jubatus Schreber), the object of the current study, just belongs to this kind of species. A description of the vocal repertoire is a necessary premise for the development of non-manipulating bioacoustic approach for estimation of the internal state. Despite the ample body of published data on the vocal behavior of cheetah (Adamson, 1969, 1972; Schaller, 1972; Kingdom, 1977; Movchan and Opakhova, 1981; Peters, 1981, 1983; Frazer Sissom et al., 1991), the vocal repertoire of this species still has not been described satisfactorily, and the terminology for designation of sound types is rich in synonyms. In this paper, I describe the vocal repertoire of adult cheetahs in captivity on the basis of structural charac-