Pectoral herding: an innovative tactic for humpback whale foraging

Area of Science:

• Marine Biology
• Animal Behavior
• Ecology

Background:

• Humpback whales (Megaptera novaeangliae) possess unusually long pectorals, aiding navigation and maneuverability.
• Previous hypotheses suggested pectorals might be used for prey manipulation, but direct evidence was lacking.

Purpose of the Study:

• To document and describe the novel foraging behavior of 'pectoral herding' in humpback whales.
• To explore the specific mechanisms and conditions promoting this innovative feeding strategy.

Main Methods:

• Analysis of aerial videos and photographic sequences of humpback whale feeding events.
• Observation of foraging behavior near salmon hatchery release sites in Southeast Alaska (2016-2018).

Main Results:

• Humpback whales utilize pectorals to create secondary boundaries, condensing prey after initial corralment with bubble-nets.
• Pectorals are used to form physical barriers, guide prey with water motion, and reflect light to alter prey movement.
• Three distinct methods of pectoral herding were identified: physical barriers, water motion guidance, and light reflection.

Conclusions:

• Pectoral herding represents an innovative foraging behavior in humpback whales, enhancing prey capture efficiency.
• Behavioral plasticity in foraging strategies may help whales adapt to changing environments and prey availability.
• Further research is needed to determine the prevalence of pectoral herding across the humpback whale population and the factors influencing its use.