Interspecific territoriality despite vocal divergence in two sympatric Laterallus crakes

DEPINO EA; ARETA JI

JOURNAL FUR ORNITHOLOGIE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020 p. 1105 - 1120

0021-8375

Territoriality is a widespread behavioral phenomenon that functions for partitioningspace and defending resources. Birds tend to defend territories against homospecificindividuals through long-distance acoustic signals, but some species also exhibitinterspecific territoriality. Two main hypotheses could explain interspecific territorialitymediated by long-distance acoustic signals: (1) misidentification of heterospecifics ashomospecifics (misdirected aggression), or (2) recognition of heterospecifics as threats(purposeful aggression). The sympatric Red-and-white Crake (Laterallus leucopyrrhus)and the Rufous-sided Crake (L. melanophaius) are reciprocally territorial, but themechanism underlying this interspecific territoriality is not known. We assessed thesimilarity of territorial long-distance acoustic signals (duet trills) between these crakesin comparison to more closely related species: Red-and-white vs. Rufous-faced Crake(L. xenopterus) and Rufous-sided vs. White-throated Crake (L. albigularis). Duet trillsare two-parted, beginning with soft initial notes audible at close-range and followed bya loud-trilled portion audible at long-range. We ran univariate comparisons (Kruskal-Wallis), assessed overlap in multivariate acoustic space (PCA), and calculated vocalsimilarities (cluster analysis; Euclidean distances). The loud-trilled portions of theinterspecifically territorial Red-and-white and Rufous-sided crakes occupied completelynon-overlapping acoustic spaces, and were not grouped together by vocal similarity.Their territorial signals were more similar to those of their closest relatives, thanbetween them. Soft initial notes of duet trills were in general very different betweenspecies, and their general structure matched the phylogenetic relationships. We foundno evidence for strong character convergence and partial phylogenetic conservatism insignal explained overall similarities in vocalizations among species. The highlydivergent vocalizations of Red-and-white and Rufous-sided crakes in conjunction withtheir interspecific territorial responses, suggests that recognition of heterospecifics asthreats, and not misidentification of heterospecifics as homospecifics, mediates theirvocal responses. Our study adds evidence showing that interspecific territorialityrepresents purposeful heterospecific aggression and is not the product of misdirectedhomospecific aggression.