Interspecific territoriality despite vocal divergence in two sympatric Laterallus crakes

ARETA JI; DEPINO EA

Congreso; XI Neotropical Ornithological Congress; 2019

Territoriality is a widespread behavioral phenomenon that functions for partitioning space and defending resources. Birds tend to defend territories against homospecific individuals through long-distance acoustic signals, but some species also exhibit interspecific territoriality. Two main hypotheses could explain interspecific territoriality mediated by long-distance acoustic signals: (1) misidentification of heterospecifics as homospecifics (misdirected agression), (2) recognition of heterospecifics as threats (purposeful agression). The sympatric Red-and-white Crake (Laterallus leucopyrrhus) and the Rufous-sided Crake (L. melanophaius) are reciprocally territorial, but the mechanism underlying this interspecific territoriality is not known. We assessed the similarity of territorial long-distance acoustic signals (duet trills) between these crakes in comparison to more closely related species: Red-and-white vs. Rufous-faced Crake (L. xenopterus) and Rufous-sided vs. White-throated Crake (L. albigularis). We characterized acoustic signals by measuring nine parameters in 10 different pairs of each study species. We ran univariate comparisons, compared signal overlap in multivariate acoustic space (PCA), and performed a cluster analysis (Euclidean distances). The interspecifically territorial Red-and-white and Rufous-sided crakes occupied completely non-overlapping acoustic spaces, and were not grouped together by vocal similarity. Their territorial signals were more similar to those of their closest relatives, than between them. We found no evidence for character convergence and partial phylogenetic conservatism in signal explained overall similarities in vocalizations among species. The highly divergent vocalizations of Red-and-white and Rufous-sided crakes in conjuntion with their interspecific territorial responses, suggests that recognition of heterospecifics as threats, and not misidentification of heterospecifics as homospecifics, mediates their vocal responses. Our study adds evidence showing that interspecific territoriality represents purposeful heterospecific aggression and is not the product of misdirected homospecific aggression.