Advertisement Calls and Calling Habits of Frogs from a Flooded Savanna of Venezuela

Abstract

Knowledge of the calls and reproductive biology of the anurans inhabiting Venezuelan lowlands is scarce. The advertisement calls and calling habits of 17 anuran species (Bufonidae, Hylidae, Leiuperidae, Leptodactylidae and Microhylidae) from a locality in the Central Llanos of Venezuela are described here. Advertisement calls were recorded in the field and analyzed. The abundance of active males was estimated through call surveys performed in natural and anthropogenic habitats and ecotones; the microhabitat at calling positions was also described. Calls were divided into pulsed and non-pulsed frequency modulated. There was substantial variation in call traits between species, thus acoustic segregation was well defined. Patterns of acoustic similarity among pulsed calls were related to call duration, number of notes per call and pulse duration, and to modulation type (downward or upward) and rate of modulation among non-pulsed frequency modulated calls. The most abundant species in the community were Physalaemus fischeri, Pseudis paradoxa and Engystomops pustulosus. Temporal (monthly) segregation was not evident. Engystomops pustulosus was the most generalist species, occupying both anthropogenic and natural habitats. Leptodactylus bolivianus and Dendropsophus minusculus were habitat specialists. Moderately flooded grassland (herbaceous bajío) was the most diverse habitat and the sand hill was the least diverse. Analysis of acoustic characteristics and habitat preferences indicated that call similarity in some traits was opposed by segregation in others, and also by habitat and/or microhabitat segregation. Qualitatively, the results showed a pattern found by several previous studies on anuran communities in the tropics.