The relationship between behavioral activity and underwater vocalizations of the white whale, Delphinapterus leucas

Abstract

The underwater vocalizations of white whales, Delphinapterus leucas, summering at Cunningham Inlet, N.W.T. (74°05′ N, 93°45′ W), were recorded from mid-July to mid-August 1983. Vocalizations were classified into one of eight major whistle contour types, one of four pulsed call categories including click series and three types of pulsed tones, and noisy vocalizations. To determine the relationship between vocalizations and behavioral activities, a total of sixty-three 2-min samples were recorded when whales were resting, swimming in a directive manner, socially interactive, and alarmed. Differences in the total number of whistles, pulsed tones (including noisy vocalizations), and click series emitted per whale/min during each behavioral activity were examined. The number of whistles emitted did not differ with changes in behavioral activity (χ2 = 5.42, df = 3, p = 0.143); however, the number of click series (χ2 = 31.85, df = 3, p = 0.0001) and the total number of pulsed tones emitted (χ2 = 7.33, df = 3, p = 0.062) did show distinct trends. More specific analyses considering each of the major whistle contour types, the three types of pulsed tones, and noisy vocalizations were also completed. The rate at which one type of whistle, two types of pulsed tones, and the noisy vocalizations were emitted was influenced by changes in behavioral activity. These results reveal a general association between white whale behavioral activity and the types of vocalizations emitted.