Vocal recognition between parents and young of ancient murrelets, Synthliboramphus antiquus (Aves: Alcidae)

Abstract

Vocalization is a conspicuous feature of the departure of family groups of ancient murrelets, Synthliboramphus antiquus, from their colonies. The nocturnal timing of departure and the temporary separation of adults and chicks, followed by their reunion among many conspecifics, suggest that they recognize one another by their vocalizations. In this study, the calls of adults showed greater betweenthan within-individual variability indicating their potential for use in recognition. The calls of sibling chicks were similar and chick calls showed greater variability between broods than within broods. In a playback experiment in a water-filled arena, chicks given the choice of parent's and non-parent's calls preferentially approached the parent's calls and responded to them vocally. In two trials, playback of chick calls in a cove containing many adults seeking chicks attracted the correct parents. It is likely that both parents and chicks recognize each other's calls and that this ability is based on their experience with the calls prior to departure. The chicks hear their parent's calls each time a parent returns to the burrow to relieve its mate. Parents hear the calls of their two chicks after they hatch, a few days before departure. A system of mutual recognition may be fundamental for the success of the colony-departure strategy of ancient murrelets.