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Résumé :
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Birds that do not possess vocal learning exhibit contrasting styles of vocal development. For some Anseriformes, Galliformes and Charadrii species, gradual changes of call-frequency variables throughout development have been reported, while for some Gruiformes, Procellariiformes and Coraciiformes species, the changes are jump-like. The distribution of the vocal development types among other bird taxa, however, is poorly known. We analyzed early vocal development in three auk species (Alcidae): Crested Auklet (Aethia cristatella), Tufted (Fratercula cirrhata) and Horned Puffin (F. corniculata). All three species have semi-precocial chicks that stay in nest-burrows until fledging. We recorded calls from 26-35 chicks of each species at 4-5 ages between hatching and fledgling at a breeding colony on Talan Island, Sea of Okhotsk, and compared main acoustic variables of calls across ages and with common adult calls. In all species, we observed the lack of a gradual change in the fundamental frequency of calls between hatching and fledging despite a considerable increase in body size. Fundamental frequency actually increased slightly over development and was always higher than that of adult calls. We also observed two-frequency calls at the beginning of voice breaking in two Tufted Puffin chicks just before fledging. Thus, we confirm the presence of jump-like vocal development in Alcidae and speculate that such a pattern of vocal development is widespread among bird species from altricial spectrum.
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