Food-begging calls in African parrots [abstract]

V. Venuto, R. Massa and L. Bottoni (2002). Food-begging calls in African parrots [abstract]. Bioacoustics, Volume 13 (2): 179

Food begging calls are highly stereotyped innate vocalisations whose structure is very similar in quite different species. It usually consists of a series of homologous harmonic pulses. To understand species-specificity and relationship to the adult sounds, using Canary ,software we recorded and processed food begging calls from five different species of African Poicephalus parrots pertaining to two different superspecies (P.  gulielmi, supersp. robustus), and P.  senegalus, P. meyeri, P. rufiventris, P. cryptoxanthus, supersp. meyeri) from birth to 60 days of age. As the food begging call is an innate vocalisation type, it also qualifies as a useful taxonomic character. In fact, it is evolutionarily slow to change, apparently because it is unlikely to be affected by those external pressures that more quickly shape morphological characters. The general principle is that in all Poicephalus species studied, the call is structured in a series of harmonic pulses. These increase in number in the first four weeks of age, then decrease. However, at all times, a clear-cut difference among all the species is maintained up to the tenth week of age, when the differences disappear and the pulse number is two for all species. For all species studied, the main specific character appears to be the utterance rate, that is the pause duration between the different pulses. By applying a correlator analysis routine to the different species' spectrograms and subsequently a multidimensional scaling to correlation values, it clearly appears that all species' parameters segregate neatly. Within the superspecies meyeri, it also appears that P. meyeri and P. senegalus are phylogenetically the most apart, bioacoustically confirming recent molecular results.