Comparison of Shannon–Hartley-based sub-unit classification of Pacific humpback whale feeding and song vocalizations

Humpback whale communication studies have primarily focused on holistic unit classification methods to identify thematic patterns of song structure. These various whole-unit, spectral-feature-extraction and classification procedures have resulted in low information entropy estimates of songs. A recent Shannon–Hartley-based sub-unit classification study of high complexity, voiced, target-frequency-modulated song units shows that unit diversity and information entropy of song units is much higher and variable across regions of the Pacific and the Atlantic breeding grounds. Here we present a new analysis, using the same sub-unit-level target-frequency feature extraction and sub-unit classification methodology, applied to a variety of Southeastern Alaska feeding calls and social sounds. The scope of the analysis is expanded to include low-frequency-voiced and unvoiced units for a comprehensive comparison of unit diversity and information entropy metrics across the seasonal and behavioral spectrum.