Techniques for studying the spatio-temporal distribution of animal vocalizations in tropical wet forest

An array of four microphones was set up in two rain forest locations in Costa Rica, and 12-14 hours of sound were recorded over a 24-hour period at each location. Using this acoustical location system, the distribution of animal signaling in time, space and frequency could be assessed. This study demonstrates the feasibility of localizing some animals acoustically even under difficult field conditions in a highly reverberant and noisy environment. Primates seem to be particularly easy to track using this method, while birds seem more problematical. We also advocate the use of long-term indiscriminate acoustical sampling of all vocalizers, in order to give information about the synecology of animal communication. Long-term spectral analysis and data reduction by Principal Components Analysis provide tools for comparing acoustical samples over time and space.