Soundscape Analysis and Wildlife Presence in the Vicinity of a Wind Turbine

The present work uses sound recordings to evaluate wildlife presence in the vicinity of a wind turbine. The setting is a rural nature park in Chevetogne, Belgium, where a single 800 kW wind turbine has been in operation since 2007. Two weeks of continuous sound data at 12000 Hz sampling frequency were collected at three positions around the turbine. Bird vocalizations from relatively common species are present throughout the audio records. Color-composite spectrograms, assembled from acoustic indicators that target wildlife detection, allow a direct visualization of 24 hours of sound data at once. Passerines are well detected by the acoustic complexity index and a modified spectral entropy; the latter also captures the voices of birds with more monotonous songs. A third dimension, derived from the sound pressure level, gives a sense of the weight of human activities on the soundscape, namely through road traffic. The final spectrograms display the musical composition of the day, showing birds singing on and off, captured with different color nuances. Wind turbine noise is present in the recordings although by design it does not appear on the wildlife spectrograms. No evidence was found of negative interactions between the turbine and the birds. However, generalization of this result is limited by the restricted timeframe of observations.