Sperm whale codas in the northwestern Gulf of Mexico.

Abstract

Sperm whale (Physeter macrocephalus) coda patterns from the northwestern Gulf of Mexico have been examined. Recordings were collected via a towed passive hydrophone array. Sperm whales are known to produce a characteristic ‘‘hammering’’ click. Codas are rhythmic patterns of clicks [W. A. Watkins and W. E. Schevill, J. Acoust. Soc. Am. 62, 1485–1490 (1977)]. Two types of codas have been proposed: identity codas and general use or shared codas [Watkins et al., Cetology 49, 1–15 (1985)]. Identity codas are patterns that are unique to an individual for at least a few hours, and general use codas are vocalizations that seem to be shared among groups of whales. In the southeast Caribbean, it was found that 50% of the codas analyzed were made up of two patterns; therefore, it was proposed that shared codas may have a function other than individual identity [Moore et al., Mar. Mam. Sci. 9, 1–9 (1993)]. There also appears to be geographical differences in codas’ spacing and composition between the Galapagos and the southeast Caribbean [L. Weilgart and H. Whitehead, Can. J. Zoo. 71, 774–752 (1992)].