Abstract:
The U.S. Navy maintains a network of listening arrays for detection of submarines. For several years, some of the sounds from these arrays have been made available to scientists for study of cetacean movements and vocalizations. Here the vocal behavior of blue (Balaenoptera musculus) and finback (B. physalus) whales are analyzed. These species produce long sequences of calls, lasting hours to days, that exhibit several types variation across areas of the North Atlantic and Pacific. Finback produce two commonly heard general types of calls, with other types present less frequently. Finbacks in different geographic areas exhibit variations in frequency, in intercall timing, in the mixture of call types, in patterns of calls and silences, and in other ways. Blue whales, unlike finbacks, show distinctly different vocalizations in the Atlantic and Pacific; but like finbacks, both Atlantic and Pacific whales have two principal call types, with different mixtures of the types in different areas. Differences in timing and frequency are heard in distinct areas, with certain patterns heard only in one or a few areas. [Work supported by ONR.]