Syntactic structure and geographical dialects in the songs of male rock hyraxes

Abstract

Few mammalian species produce vocalizations that are as richly structured as bird songs, and this greatly restricts the capacity for information transfer. Syntactically complex mammalian vocalizations have been previously studied only in primates, cetaceans and bats. We provide evidence of complex syntactic vocalizations in a small social mammal: the rock hyrax (Procavia capensis: Hyracoidea). We adopted three algorithms, commonly used in genetic sequence analysis and information theory, to examine the order of syllables in hyrax calls. Syntactic dialects exist, and the syntax of hyrax calls is significantly different between different regions in Israel. Call syntax difference is positively correlated to geographical distance over short distances. No correlation is found over long distances, which may reflect limited dispersal movement. These findings indicate that rich syntactic structure is more common in the vocalizations of mammalian taxa than previously thought and suggest the possibility of vocal production learning in the hyrax.

Constraints and flexibility in mammalian social behaviour: introduction and synthesis

“…White-faced capuchin monkeys (Cebus capucinus), rstb.royalsocietypublishing.org Phil Trans R Soc B 368: 20120337 for example, exhibit a rich repertoire of group-specific social conventions that appear to serve solely to test social bonds [71]. Across mammals, there is similar group-specific variation in specialized foraging techniques [72,73], tool use [74,75] and communication signals [76,77]. Much of this variation is transient, however, unless there are strong social or ecological pressures maintaining particular behavioural styles [78].…”

Beluga whale (Delphinapterus leucas) vocalizations and call classification from the eastern Beaufort Sea population

“…Dialect differences have been used to indicate structure in many bird species such as mountain white-crowned sparrows (Zonotrichia leucophrys oriantha; MacDougall-Shackleton and MacDougallShackleton, 2001) and yellow-naped amazon parrots (Amazona auropalliata and A. ochrocephala; Wright and Wilkinson, 2001) as well as a diverse array of other taxa including rock hyraxes (Procavia capensis; Kershenbaum et al, 2012), sperm whales (Physeter macrocephalus; Whitehead et al, 1998), fin whales (Balaenoptera physalus; Delarue et al, 2009), killer whales (Orcinus orca; Ford, 1991), and humpback whales (Megaptera novaeangliae; Garland et al, 2013). For example, killer whales display subtle differences in the structure of calls among different matrilines within a pod (Miller and Bain, 2000), while differences in the use and structure of calls exist among pods to produce a group-specific dialect (Ford, 1991).…”

Vocal Flexibility and Regional Variation in Free-Tailed Bat Song

“…Without routine contact with males from other colonies we would expect little or no foreign influence on male songs. Similar patterns of syntactical dialects, which lack a correlation with geographical distance over large scales have been found in other species, including the sage sparrow (Wiens, 1982) and rock hyraxes (Kershenbaum et al, 2012), in the above examples the lack of correlation of dialectical patterns over large distance have also been attributed to reduced mobility and to lack of interaction between individuals belonging to different dialectical groups and do not come into contact with each other.…”

“…cetaceans (Ford, 1991;Whitehead, 1998), elephant seals (Le Boeuf and Peterson, 1969) , rock hyraxes (Kershenbaum et al, 2012), marmosets (de la Torre and Snowdon, 2009), and two species of bats (Davidson and Wilkinson, 2002;Esser and Schubert, 1998). While a growing number of mammals have been shown to have vocal dialects, in most cases the mechanisms of how these dialects arise are still unclear.…”