Pair duets in the yellow-naped amazon (Amazona auropalliata): Phonology and syntax

Abstract

AbstractPair duets are acoustically complex communication signals formed jointly by members of a mated pair. Duets may serve multiple communication functions; quantitative studies of the acoustic structure and organization of notes (or 'syntax') within duets are an important step in identifying these functions. This study examined duets of the yellow-naped amazon (Amazona auropalliata) at two sites in Costa Rica to determine the syntactical rules underlying duet variation. Duets were composed of contact calls and three other note types found only in duets. These latter note types were sex-specific, with one type performed by females and the other two types by males. Sex-specific notes were delivered antiphonally and in distinct pairs, with the male note following and often overlapping that of the female. Note types appeared in a strict sequential order in which each note could be repeated a variable number of times or omitted entirely, a pattern previously termed 'combinatorial syntax'. Additionally, there was considerable variation in acoustic parameters of notes within types. Many of these parameters varied significantly with note order within a duet. These syntactical features suggest a preliminary hypothesis that males and females encode different, and possibly multiple, messages in their respective contributions to duets.