Spectral Acoustic Niche Partitioning in Three Sympatric Frogs From the Caribbean

ABSTRACT Vocalization is an important behavior in amphibian biology. In the tropics, amphibian diversity is high and calling activity can overlap among various species. The acoustic niche partitioning hypothesis could explain how closely related species coexist in sympatry and not compete within the acoustic niche. In this study, using passive acoustic monitoring, we set out to evaluate whether acoustic niche partitioning occurs within three sympatric Pristimantis frog species from the Caribbean for the first time. Prior evidence suggests there is overlap at the spatial and temporal scales in the acoustic niche in these species. Therefore, we evaluated whether acoustic niche partitioning occurs within characteristics of the signal properties of their advertisement calls at the spectral scale. We collected acoustic data at 15 sites across the island of Tobago to gather quantitative measurements on the advertisement calls for these three island endemics. From 237 calls, we found significant differences within the signal properties among the three frog species. Signal properties were also significantly different between each species, suggesting all three avoid each other at this scale. Our results provide additional evidence of acoustic niche partitioning in tropical frogs, and specifically in these three species on this small tropical island for the first time, including one which is currently classified as Data Deficient on the IUCN Red List. Our findings can contribute towards improving the conservation and ecology of tropical anurans and interspecific competition in sympatric species on islands.