Behaviour 2019
Social information differs among contact calls of three vocal learning species
Grace Smith-Vidaurre1, Marcelo Araya-Salas2, Timothy F. Wright1. 1Department of Biology, New Mexico State University, Las Cruces, NM, United States; 2Universidad de Costa Rica, Puntarenas, Recinto de Golfito, Costa Rica

We know little about how social dynamics influence vocal learning processes in natural populations. The social group membership hypothesis assumes socially learned calls can signal group membership over various social scales, or hierarchical mapping. We asked if monk parakeets (Myiopsitta monachus) exhibit hierarchical mapping in contact calls. For comparison, we analyzed calls of thick-billed parrots (Rhynchopsitta pachyrhyncha) and yellow-naped amazons (Amazona auropalliata). We used spectrographic cross-correlation and supervised random forests to measure acoustic similarity. Matrix regression was used to assess acoustic similarity over social and geographic scales. We found strong individual signatures in monk parakeets that outweighed acoustic convergence at a higher social scale (sites), and no clear pattern of geographic variation. These patterns matched those in thick-billed parrots, but not yellow-naped amazons, a species with well-defined vocal dialects. The distinct social information encoded in these species’ contact calls suggests vocal learning is linked to social dynamics. Future research addressing this compelling link can lead to novel insights on vocal learning.