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Ann Allen, Biology


Most baleen whale species undertake long annual migrations where advanced navigation and
orientation mechanisms are essential. However, despite extensive speculation on the subject, there have been no studies exploring what navigational mechanisms whales utilize while they migrate. Because of the properties of water, vision is limited to tens of meters, while low frequency (LF) sound can travel for tens or even hundreds of kilometers, making it well suited as a distance sense for migrating whales [1]. The vocalizations and hearing capabilities of baleen whales are keyed to LF sound generation and reception [2]. Humpback whales (Megaptera novaeangliae) have the best known vocal behavior of the baleen whales, with LF vocalizations ranging from 20 Hz all the way up to 24 kHz [3]. The hypothesis that I am testing for my thesis research is that humpback whales are utilizing either active or passive acoustic cues to aid in navigation and orientation during their migration.
On both their summer feeding grounds and winter breeding grounds humpback whales producevery loud LF calls that can be heard at distances of at least 13-15 km [4]. Just as odontocetes utilize high frequency echolocation to detect small targets at short ranges, it is reasonable to explore if baleen whales actively use their LF sounds to detect larger targets at greater ranges [5]. In addition to potential active acoustic cues, a significant amount of LF noise is generated in the ocean just by the breaking of shore waves [6]. Specific environments may generate unique combinations of noise that can serve as an identifying sound beacon for a location. With so much oceanic noise present, it bears investigating whether migrating humpback whales are using this plethora of acoustic information to aid in navigation.

Last updated: April 9, 2012