Pitch of Cat Calls Varies with a Cat Species' Territory

From BBC news via neatorama
Why lions roar and wildcats miaow
by ELLA DAVIES
The low roar of a lion, or the miaow of a wildcat, has more to do with where a cat lives than its size.

Scientists analysed the calls of 27 cat species, investigating how they vary in habitats from open sandy deserts to thickly planted jungles. Cats living in open areas have deeper calls than those in dense habitats, the researchers found. Previous research suggested a cat's size determined the pitch of its calls, made to find mates or defend territory.

Forest dwelling wildcats call at a higher pitch
Dr Gustav Peters and Dr Marcell Peters at the Alexander Koenig Zoological Research Museum in Bonn, Germany analysed the average frequencies of long-distance calls made by 27 different species of cat. These included the great or "roaring" cats, such as lions, tigers and jaguars, which are able to roar due to the specialised structure of their throats. They then looked for any relationships between the cats' calls and their size, and the habitats in which they live.

Cat species that live in more open types of habitat, such as lions and servals, have deeper calls. Cats living in dense habitats, such as wildcats, clouded leopards and the little known marbled cat, communicate at a higher pitch, the researchers found.

The findings are published in the Biological Journal of the Linnean Society.

The results are unexpected. "Most studies of sound transmission of animal acoustic signals found that lower frequencies prevail in dense habitats," says Dr Peters. For example, previous research has found that high pitch calls are disrupted by dense vegetation. Low pitch calls meanwhile are disrupted by air turbulence in open spaces. But that does not explain why lions roar so deeply, for instance. Another suggestion is that big cats simply produce sounds at a lower frequency. That would explain a lion's roar compared to a smaller cat's miaow, but when the researchers took into account the genetic heritage of each species studied, they found body weight has no effect on the dominant frequencies of its call.

Members of the cat family Felidae occur naturally on all continents except Australia and Antarctica, and with the exception of lions, they live solitary lives. Due to this isolation, both males and females use long-distance calls to communicate, to attract mates and deter competition.

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reference
Peters G & Peters M (2010) Long-distance call evolution in the Felidae: effects of body weight, habitat, and phylogeny. Biological Journal of the Linnean Society 101(2): 487–500

ABSTRACT
Long-distance calls used for mate attraction and territorial spacing are distinctive signals in the felid vocal repertoire. Their evolution is subject to natural and sexual selection, as well as various constraints. Body size is an important morphological constraint, with the scaling of the spectral characteristics of a species' vocalizations with its body size being established for several vertebrate groups. Alternatively, the structure of long-distance calls may have been optimized for transmission in species' habitats (acoustic adaptation hypothesis). The present study assessed whether the mean dominant frequency of long-distance calls in the Felidae (approximately 70% of all species incorporated) is influenced by the species' body size and/or conforms to the acoustic adaptation hypothesis. After controlling for phylogenetic relationships, we found a significant correlation between mean dominant frequency of a taxon's long-distance calls and conditions for sound transmission in its habitat type (‘open/heterogeneous’ versus ‘dense’), although no significant influence of body size. Taxa living in more open habitat types have long-distance calls with significantly lower mean dominant frequencies than those living in dense habitats. The result obtained in the present analysis is fairly robust against random removal of single or few taxa from the data, and also against the use of different branch-length transformation models in phylogenetic regression. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 487–500.