Larynx and vocalization of the Takin (Budorcas taxicolor Hodgson, 1850-Mammalia, Bovidae)

The head of an adult male Takin (Budorcas taxicolor) was dissected with spe cial reference to the larynx. Compared to a typical bovid larynx, the laryn x of the male B. taxicolor is clearly enlarged. The enlarged larynx is supp orted ventrally by the very broad parotidoauriculares muscles as if lying i n a hammock. Enlargement of the larynx is mainly due to the great size of t he thyroid cartilage, which caudoventrally forms a distinct inflation, the thyroid bulla. and of the cricoid cartilage, the dorsal muscular plate and the arcus of which are strongly extended. In contrast to a typical bovid la rynx (as exemplified by cattle) a tough cartilaginous connection between th e arytenoid cartilages is found dorsomedially. Both, the muscular and the m edial process articulate with the rostral edge of the cricoid cartilage. Co mpared to the typical situation in bovids the vocal process of the arytenoi d cartilage is distinctly extended. With respect to these characters the la ryngeal structure of the takin bears a greater resemblance to that of cervi ds (especially to rot deer) than to that of bovids. The vocal fold consists of two portions which differ in mass and flexibilit y. Formation of a median synchondrotic connection between the arytenoid car tilages, the double articulation of both arytenoid cartilages with the cric oid cartilage and the long, lever-like vocal process presumably are caused by the great width and mass of the voluminous vocal folds. These make highe r demands on the tensor apparatus of the vocal folds than it is the case in a typical bovid larynx with narrow vocal folds. This interpretation is sup ported by the considerable size of the thyroarytenoid muscle. Male takins vocalize mainly during the mating season, whereas females addit ionally vocalize to call their young. Calls of the female are as low in fre quency as those of the male and cannot be distinguished by ear. From this i t may be inferred that the larynx of female takins is enlarged to a similar degree like in males. This was confirmed by the dissection of the larynx o f a female neonatus which, basically, has the same structure as that in the male sex. The bellowing calls last for about one second. Frequencies are l ow and mainly cover the range between 0,1 and 4 kHz. Low frequencies are fa vourable for a communication on longer distances as they are less attenuate d than higher ones. In the sonagram two maxima of frequency of the bellowin g call are distinguishable: a) at c. 0,24 kHz; b) at c. 0,41 kHz. The highe r one is not a harmonic of the lower maximum suggesting the occurrence of n onlinear oscillation dynamics. The male muskox (Ovibos moschatus) possesses an enlarged larynx very much r esembling that of the male takin with respect to its external shape. In convergence to the takin and the muskox, the African water chevrotain (H yemoschus aquaticus. Tragulidae) probably in both sexes evolved an enlarged larynx which, except for its different proportions, is similar to that of the takin. The frequencies of the vocalizations of the water chevrotain cov er the same low range as those of the takin, although the larynx of H. aqua ticus reaches only one quarter of the takin's laryngeal size. In the reinde er (Rangifer tarandus). males and females possess a median inflatable sac w hich obviously functions: as a resonance organ for vocalizations which, lik ewise, lie in the low frequency range.