Song Sharing in a Group-Living Songbird, the Australian Magpie, Gymnorhina Tibicen. Part I. Vocal Sharing Within and Among Social Groups

Abstract

In this study we investigate the role of song in the social behavior of a cooperatively living songbird, the Australian magpie, Gymnorhina tibicen (Cracticidae). In this species, kin and nonkin cooperative groups exist in the same population. We sampled the vocal repertoires of 23 magpies in six territorial groups and the nonterritorial flock, and of a tame magpie. Our results include: 1. Description of song. Soft warble syllables and loud carol syllables compose magpie songs, sung in communal choruses in both territorial and nonterritorial contexts. Warble syllables are diverse in physical structure. 2. Song repertoires. Most songs are individual-specific, though some are shared. Song variants could be found within the repertoire of a given individual, produced by various means (e.g., recombining segments). 3. Syllable repertoires. We classified 893 syllable types from our study population; 67% were individual-specific, and few were shared by more than two to five birds. 4. Repertoire sharing in groups. We found the average percentage of the repertoire shared between all pairwise combinations of birds higher (p 0.05, Mann-Whitney rank sum test). 5. Syllable sharing and vocal imitation in a tame magpie. A handreared bird had a repertoire consisting in whistles: some were perfect copies of human whistles, and some were improvisations on the same themes. She learned a new whistle from one of her human group mates, the senior author. We discuss vocal imitation and improvisation as major processes in vocal learning; song sharing as a possible badge of recognition for groups; and the function of song in social cohesion.