| Summary: | Pacific populations of humpback whales (Megaptera novaeangliae) perform yearly migrations to the cold waters of the Gulf of Alaska to feed on fish and krill. Some of these whales form small social groups and cooperate to forage for fish using a technique called bubble-net feeding, whereby the whales work together to create a net of bubbles around a school of fish, and use loud modulated vocalizations to confuse and stun their prey. Once the school is packed tightly together, the whales move upwards through the school with their mouths open to engulf the fish (known as lunge feeding). This complex behavior requires reliable cooperation and coordination within the group, which is most likely accomplished through vocal communication. In addition to the loud modulated vocalizations (known as food calls), humpback whales have a large repertoire of complex vocalizations, such as burps, growls, trills, squeaks, etc. that they use for communication. They also produce percussive sounds (e.g. breaches, pectoral flipper slaps, tail slaps), which may also be used for communication. Not all feeding events lead to successful completion of lunge feeding by the group. As this behavior requires significant coordination, we hypothesized that successful feeding events would include social signals most likely used to coordinate the group’s activity, and that these signals would be missing from unsuccessful feeding events. Using vocal recordings collected from humpback whales performing bubble-net feeding in the Gulf of Alaska in 2004 and 2007, we compared sequences of food calls which resulted in successful lunge feeding with sequences that did not. We expected successful sequences to have social calls just before or after to coordinate the events. We expected unsuccessful events to lack social calls; they may also be marked at the end by percussive sounds out of frustration over failed hunts.
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