A new study in Global Change Biology argues that conservation urgently needs acoustic baselines to detect ecological changes that satellite images cannot capture. The Soundscape Baselines Project, led by Zuzana Buřivalova and colleagues, is recording the sound signatures of intact forests across six pilot sites in Brunei, Ecuador, Gabon, Germany, Peru, and the United States. Passive recorders collect continuous audio data for at least a year at each location, generating massive datasets that reveal daily acoustic rhythms of birds, insects, frogs, and other wildlife. Acoustic monitoring can detect changes in animal communities even when the forest canopy looks intact from above. In Gabon, logged forests showed similar coarse acoustic measures to intact forests, but the timing and structure of dawn and dusk choruses differed significantly. The project uses acoustic indices like Power Minus Noise and Soundscape Saturation to analyze soundscapes without needing to identify every species. This approach avoids the limitations of species-by-species monitoring, especially in tropical forests where many animals are hard to identify by sound. Bioacoustics has limits. The equipment generates about 1.5 terabytes of data per month for a six-recorder network, requiring careful data management, local team involvement, and transparent handling of uncertainty. The project stores data locally at each site and at the University of Wisconsin-Madison. The goal is to establish reference points before shifting baselines make it harder to recognize what has been lost.
