Humpback Whales (Megaptera novaeangliae) Feeding Along Migration Routes and Within Breeding Grounds-A Review

Humpback whales traditionally fast during migration and on breeding grounds, relying on reserved energy within blubber to sustain them. However, occurrences of feeding along migration routes and within breeding grounds have been documented for several populations, suggesting an intrinsic ability to adapt to changing conditions and prey variability. This systematic quantitative literature review yielded 77 publications, demonstrating that humpback whales feed outside their polar and sub-polar feeding grounds globally. We identified that the feeding documented within this review could generally be attributed to either opportunistic/supplementary feeding, or the identification of new or expansion of current feeding grounds. Key findings included substantial feeding behaviour in productive regions with high prey availability, including off eastern Australia, South Africa, and along the coasts of North and South America. Ontogenetic drivers may also encourage younger whales to forego migration to breeding grounds and remain along migratory routes during winter to exploit seasonally available prey. The definition of this feeding behaviour lacks specificity and may lead to underrepresentation in the literature, underscoring the need to investigate its prevalence and contribution to the behavioural budgets of these populations. Our study improves current understanding of the scope of feeding away from polar and sub-polar regions and encourages future work to further understand the drivers of the behaviour.