Individual variation in the advertisement calls of a Neotropical treefrog (Scinax constrictus)

Studies of the variability of signals at different levels are important to resolve issues related to the evolution of a species' recognition system. We analysed the variation within males, among individuals, and among three breeding seasons in the advertisement calls of Scinax constrictus, a Neotropical hylid frog endemic to the Cerrado of Brazil. We assessed the influence of different temperature ranges and different body condition ranges over a three-year period of breeding season on the acoustical features of the advertisement calls of 62 individuals. Air temperature had negative relationship with call duration and note number. Body condition had a negative relationship with the dominant frequency and positive effects on pulse number and note duration. The acoustic parameters of S. constrictus were stable across breeding seasons. Temporal parameters were highly variable within individuals, whereas the dominant frequency was the most stereotyped property of advertisement calls. Individuals of S. constrictus have sufficient among-male variability, especially for temporal parameters (call duration, number of notes, and note duration), to permit discrimination between conspecific calling males at a reproductive site by statistical analysis. The results highlight the informativeness of non-invasive bioacoustic features for population-level studies and biological conservation.