Spatial pattern of song element sharing and its implications for song learning in the chowchilla, Orthonyx spaldingii

The extent and spatial pattern of song similarity in the chowchilla were examined to determine at what scale song similarity changes, and whether this pattern is indicative of the timing of learning and dispersal strategy of this rainforest passerine. We recorded songs from across the species' entire range in the Wet Tropics of Australia. Songs were divided into their syllables, and a syllable catalogue was created for the whole population. Pairwise comparisons of syllable sharing were used to calculate a similarity index for each recorded group as well as for neighbours and non-neighbours. Chowchillas have a single-song repertoire, which is primarily used in territorial defence. Chowchillas show exceptional spatial variation in their song, and song similarity was significantly correlated with distance. Song similarity decreased sharply at 1 km, confirming the existence of song neighbourhoods that share near identical songs. Neighbours shared significantly more syllables than non-neighbours. Our results are consistent with the idea that chowchillas learn their songs after dispersal when settling into a new group.