SPATIAL-DISTRIBUTION, HABITAT UTILIZATION, AND SOCIAL INTERACTIONS OF HUMPBACK WHALES, MEGAPTERA-NOVAEANGLIAE, OFF HAWAII, DETERMINED USING ACOUSTIC AND VISUAL TECHNIQUES

Acoustic and visual methods were used to track and observe humpback whales off the island of Hawaii. Sixty-two singing whales were located acoustically in water depths from 10 to 305 fathoms (mean 126 fathoms; 1 fathom = 1.828 m). This indicates that singers are not confined within the 100-fathom contour, although nearshore waters had a higher density of singers. The separation distance between singers (mean 5.1 km) was found to be significantly greater than that between nonsinging singletons (mean 2.1 km), supporting the hypothesis that song functions to maintain spacing between singers. The mean speed of singers determined from visual data was 1.79 km/h and from acoustic data 1.6 km/h. Some singers actively swam while singing. Other singers continued singing while affiliating with or being joined by other whales. The correlation between breaching and the cessation of singing suggests that the sounds of aerial behavior can convey information to other whales. These observations suggest the need to expand the traditional interpretations of the behavior of singing humpback whales obtained from visual observations alone.