Evidence of stereotyped underwater vocalizations of male Atlantic walruses (Odobenus rosmarus rosmarus)

Adult male Atlantic walruses (Odobenus rosmarus rosmarus) vocalize extensively underwater during the breeding season. The individual calls are composed of one or more short repetitious pulses which may vary individually in the number, pattern, and rate at which they are given. Individual male walruses give repeated stereotyped vocalization cycles totalling several hundred pulses each for up to several hours at a time, both while the whole body is submerged and between breaths with the head submerged while at the surface. We analyzed the vocalization cycles of a sample of different walruses, and sound spectrograms of particular calls from within those cycles, to test the hypothesis that the stereotyped vocalizations of individuals are unique and recognizable. In our sample, the pulse patterns of particular calls given by individual walruses in a series of vocalization cycles were nearly identical but were consistently different from the same call given by other animals. One call, the diving vocalization of...