| Summary: | Humpback whales (Megaptera novaeangliae) are a widely distributed baleen whale species, well known for their diverse acoustic behavior. On high-latitude foraging grounds, humpback whales produce a suite of non-song vocalizations (“calls”) in concert with foraging and social behavior. In this dissertation I investigated the role of calls in the acoustic ecology of humpback whales in Southeast Alaska and the potential impacts of vessel noise on humpback whale calling behavior in this region. By comparing the earliest known acoustic recordings of humpback whales in Southeast Alaska (1970’s) with recordings collected in the 1990’s, 2000’s, and 2010’s, I determined that of the sixteen known humpback whale call types produced in Southeast Alaska, twelve were stable over a 36-year time period; eight call types were present in all four decades and every call type was present in at least three decades. I conclude that repertoire stability at this temporal scale is indicative of multi-generational persistence and confirms that acoustic communication in humpback whales is best described as a coupled system of communication that contains some highly stable call elements in strong contrast to ever-changing song. I further looked for evidence of shared call types between two allopatric humpback whale populations while on their northern hemisphere foraging grounds in order to test the hypothesis that some calls are fixed within the humpback whale acoustic repertoire. Despite being geographically and genetically discrete populations, humpback whales in Southeast Alaska (North Pacific Ocean) share at least five call types – known as droplets, growls, teepees, swops, and whups – with humpback whales in Massachusetts Bay (North Atlantic Ocean). This study is the first to identify commonly produced call types shared by allopatric populations and provides additional evidence that some call types may be innate within the humpback whale repertoire. One call type, the “feeding call” was noticeably absent from the North Atlantic ...
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