Potential changes in the communication space of humpback whale social sounds in increasing wind and vessel-dominated noise

An animal communication network involves complex acoustic interactions between multiple senders, receivers, and eavesdroppers. Any reduction in communication space, due to signal masking, may have detrimental effects on their ability to obtain social information. Humpback whales use social sounds (vocal and surface-generated percussive sounds) for within-, and between-, group communication. To generate masking models, and infer communication space, changes in signal-above-noise and frequency content of received humpback whale social sounds were modelled with the combined effect of increasing background noise (wind or vessel-dominated) and distance from the source (signalling whale). Results suggest that the signaler’s communication space in increasing wind-dominated noise (shallow water) was maintained out to approximately 3 km by using a Lombard response. In high wind noise (over 105 dB re 1 μPa; 12–15 knots), the vocal communication space was significantly reduced, though the increased use of surface-generated sounds likely aided in maintaining this space. In vessel-dominated noise, communication space was significantly reduced in levels exceeding 110 dB re 1 μPa (vessel within approximately 2 km), with no evidence that the signaler switched to using surface-generated sounds. These models can be updated as more information on humpback auditory capabilities becomes available.