Whale Song as Transportation Communication: Temporal Guidance Across Migratory Routes

Humpback whale song exhibits long-term persistence across migratory cycles, punctuated by slow, incremental modification rather than rapid replacement. While often interpreted in cultural or symbolic terms, such interpretations do not account for the strong interannual stability observed when migratory routes remain unchanged, nor for the structured manner in which song evolves when routes shift. Synthesizing longitudinal passive acoustic monitoring studies across ocean basins, this paper examines whale song as a timing-dominant communication system during large-scale movement. We show that song structure remains coherent across seasons when traversal conditions are stable and undergoes gradual, carry-over modification when environmental constraints alter viable routes. These patterns are consistent with song functioning as a directive temporal scaffold that maintains group alignment during migration. Maternal and group-level dynamics further support this interpretation, with corrective signalling expressed through increased temporal precision rather than diversified acoustic content. Appendix A introduces a minimal geometric model linking pulse interval to spatial sampling density in a reverberant medium, generating testable predictions for retuning under environmental perturbation. Together, these findings support whale song as transportation communication: a forward-biased timing architecture optimized for collective navigation under physical and ecological constraints.