Dominant frequency of loud mew calls of felids (Mammalia: Carnivora) decreases during ontogenetic growth

Abstract

1 A negative correlation between body weight and frequency characteristics of a species' vocalizations exists in mammals, due to the acoustics of vocal sound production ('source-filter theory'; source = larynx; filter = supralaryngeal vocal tract) and the strong positive correlation between body weight and vocal tract length. 2 A negative correlation is hypothesized to exist between increasing body weight and frequency characteristics of calls during ontogeny as well. 3 This hypothesis is tested for mean dominant frequency (maximum spectral energy peak) of intense mew calls in juveniles of five species of the Felidae: lion Panthera leo, jaguar Panthera onca, leopard Panthera pardus, tiger Panthera tigris and puma Puma concolor. 4 In the five felid species in which the hyoid is incompletely ossified (genera Panthera and Uncia), the larynx undergoes a considerable ontogenetic descent, resulting in a proportionally longer vocal tract in adult individuals than in all other species of the family, which have a fully ossified hyoid without a descent. 5 In all five species studied here, mean dominant frequency decreases as body weight increases during growth. In the four Panthera species (with laryngeal descent) dominant frequency is determined by the vocal tract (the filter), and dominant frequency is largely similar at similar weights, indicating a similar correlation between the ontogenetic increase in body weight (and vocal tract length) and the decrease in mean dominant frequency. In the puma (without laryngeal descent) dominant frequency is determined by the larynx (the source), it is considerably higher than in the Panthera species, and the course of its ontogenetic decrease differs considerably from that in Panthera. 6 The data do not support a uniform scaling relationship between body weight and mean dominant frequency of intense mew calls in the Felidae during ontogenetic growth. © 2010 The Author. Journal compilation © 2010 Mammal Society.