Acoustic space in an anuran (Amphibia) assemblage from southeastern Brazil

Abstract

This study describes the acoustic space used by anuran species in a permanent pond at the Serra de Paranapiacaba, in the Municipality of Ribeirão Branco, South of the State São Paulo (approximately 24013’S, 48046’W; ca. 800m above sea level). Field work was carried out between January and December 1993, totaling 40 nights of observation. Seven preliminary visits were made before this period, and four additional ones after December 1993. Naturalistic observations usually began before sunset, and terminated around 24:00-1:00h. Nineteen anuran species were recorded in the pond or at its margins. The most species in the pond and margins presented distinct advertisement calls. Different advertisement calls were probably enough to avoid hybridization. Phyllomedusa distincta and P. tetraploidea were the only species presenting the same specific call and activity schedule, as well as calling site, season, and reproductive mode. These factors resulted extensive hybridization between these two species. The frequency of the advertisement call, the duration of the note and call, as the physical structure of the call, might provide species specific recognition.