Abstract

Collective migration occurs throughout the animal kingdom, and demands both the interpretation of navigational cues and the perception of other individuals within the group. Navigational cues orient individuals towards a destination, while communication between individuals can enhance navigation through a reduction in orientation error. We develop a mathematical model of collective navigation that synthesises navigational cues and perception of other individuals. Crucially, this approach incorporates uncertainty inherent to cue interpretation and perception in the decision making process, which can arise due to noisy environments. We apply our framework to the migration of baleen whales, which are renowned for acoustic communication. Under pristine conditions, they can plausibly communicate and detect signals over hundreds of kilometres. However, ocean noise has been considerably inflated by human activities. Here we investigate the extent to which ambient noise levels inhibit whale migration. Rising ambient noise levels are assumed to impinge on navigation through three mechanisms: (i) a diminished communication space; (ii) reduced quality of information from external sound cues and; (iii) at high levels, triggering noise avoidance responses. Comparing navigation between pristine and current ocean soundscapes, we observe reduced efficiency of navigation, ranging from mild (increased journey time) to extreme (failure to navigate). Interestingly, the three mechanisms induce qualitatively different impacts on migration behaviour. We explore the extent to which migration may be altered under various future shipping and construction scenarios. Co-author: Prof. Kevin Painter