Do singing humpback whales (Megaptera novaengliae) favor specific frequency bands?

Abstract

Many species alter their acoustic signals in response to environmental or anthropogenic factors. Differential use of frequency bands may occur as a result of overlapping biotic and abiotic sounds that interfere with communication signals between conspecifics. Singing humpback whales produce units with frequencies ranging from 30 Hz to over 10,000 Hz, but may favor specific frequency bands during song production. We tested the prediction that singing humpback whales consistently produce units with energy focused in specific spectral bands by measuring the consistency of peak frequency bands in the southeastern Pacific stock G population of humpback whales in the Gulf of Tribugá, Colombian Pacific. Preliminary results document extensive use of units with peak frequencies clustered in two different bands between 300 Hz and 1000 Hz for the dominant theme, and additional peak frequency bands between 300 Hz and 3000 Hz for other song themes. These analyses will allow for further spatial and temporal comparisons across distinct population segments, and can be used in future studies to assess whether singers change their use of frequency bands in response to increased anthropogenic noise or as themes evolve over time.