Temporal bone anatomy in Panthera tigris

Abstract

Preliminary findings suggest that members of Panthera tigris subspecies may rely on low-frequency acoustic cues when communicating with conspecifics either in the field or in captivity. This view is supported by the observation that individuals are sensitive to tone bursts in the 300–500-Hz range and produce significant acoustic energy in an overlapping frequency band in the case of close encounter roars. Other utterances within the vocal repertoire of tigers also contain, and are often dominated by, low frequency acoustic energy that can extend into the infrasonic range. Efforts to determine temporal bone correlates of P. tigris bioacoustical features were recently initiated using computerized tomography to assess key aspects of middle and inner ear morphology from a small set of adult Siberian tigers (P. tigris altaica) and one neonate. Obvious peripheral auditory specializations were not observed and structures comprising the auditory periphery were consistent with the anatomical character of felids generally. Although cochlear dimensions appeared to be adultlike, or nearly so, in the case of the neonate, other temporal bone features were grossly immature. The relationship between acoustic sensitivity, the spectral character of a subset of close encounter calls and cochlear dimensions will be considered.