Vocal behaviour of mates at the nest in the White-throated Dipper Cinclus cinclus: contexts and structure of vocal interactions, pair-specific acoustic signature

Abstract

Birdsong has been extensively studied in the context of sexual selection, and intersexual vocal communication prior to pair formation has been the focus of most interest. With the exception of conspicuous vocal duets of tropical bird species, descriptions of intra-pair vocal communication are missing for most other bird species. This communication can take different forms, fulfil different functions and be more widespread than previously described. Females and males of the White-throated Dipper Cinclus cinclus, a European bird species, have been reported to sing during pair formation, but vocal communication between mates after this phase has not been investigated to date. We report here our study of the vocal behaviour between mates at the nest and describe the specific contexts and structure of the various vocal interactions both during incubation and while brooding hatchlings (N = 23 pairs). Vocal interactions were mainly composed of two vocalization types: ‘trills’ and ‘notes’, with trills being more common at the beginning of the vocal sequence. Both the acoustic features of the vocalizations and the temporal organization of the vocal sequences changed between the two breeding stages. In particular, compared to the trills and notes produced during the incubation period, those produced while brooding were lower in pitch, and female–male vocal sequences were composed of more notes and songs, with a lower overlap rate. This difference may reflect changes in parental activities. Trills and notes carried a pair-specific acoustic signature. This first description of acoustic communication between mates during breeding in the White-throated Dipper lays the basis for future investigation of the functions of the different vocalizations.