Vocalizations and morphology: interpreting the divergence among populations of Chough Pyrrhocorax pyrrhocorax and Alpine Chough P. graculus: Capsule Differences in vocalizations among populations are mostly explained on morphological bases, but historical factors may have played a significant role in differentiation processes.
Authors: Paola Laiolo1; Antonio Rolando1; Anne Delestrade2; Augusto De Sanctis3
Source: Bird Study, Volume 51, Number 3, 1 October 2004 , pp. 248-255(8)
Publisher: British Trust for Ornithology
Abstract:
Aims To investigate the relationships among vocal and morphological variation in two corvids: Chough and Alpine Chough.Methods We used data from 11 populations of Chough and seven populations of Alpine Chough spanning the Palearctic distribution of the two species. Three data sets (morphometry, spectrotemporal parameters of trill calls and acoustic repertoire) were analysed and their variation compared with uni- and multivariate techniques.Results In both species, morphological differences among populations were correlated to spectro-temporal variation of trills; in particular, frequencies of calls were negatively correlated to wing length (an indicator of body size). By considering only co-existing populations of the two species, the magnitude of morphological and spectrotemporal divergence was similar.Conclusions In both species, birds from populations with similar morphology uttered similar call types and trills with close spectrotemporal features. In particular, larger-sized populations, as expressed by wing length, emitted lower pitched calls. However, the fact that dissimilarities in repertoire and morphology were correlated cannot be explained only by appealing to functional explanations, as the observed intraspecific morphological variability does not seem to be high enough to promote consistent changes in the pool of calls. In this case, historical factors might have contributed to the present pattern of differentiation.Document Type: Research article
Affiliations: 1: Dipartimento di Biologia Animale e dell'Uomo, Via Accademia Albertina 17, 10123 Turin, Italy 2: Centre de Recherches sur les Ecosystèmes d'Altitude, 400 Route du Tour, Montroc, 74400 Chamonix, France 3: C.A.R.F, c/o WWF-Abruzzo, C.P. 317, 65100 Pescara, Italy


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