First Description of Atlantic Humpback Dolphin Sousa teuszii Whistles, Recorded Off Angola

The Atlantic humpback dolphin Sousa teuszii is endemic to the west coast of Africa and is poorly studied. During January 2008, 2.7 hr of acoustic recordings were made during 11 S. teuszii encounters in the Namibe province of Angola. Echolocation click trains were audible in most recordings. A total of 298 individual dolphin whistles were recorded, of which 86 were of sufficient signal to noise ratio for the measurement of 10 fundamental frequency variables. Sousa teuszii whistles occurred in the 2.5 to 23.4 kHz fundamental frequency range and were relatively simple in structure, with 85% having a single inflection point. The fundamental frequency was relatively low, with mean minimum and maximum frequencies of 4.8 and 8.2 kHz respectively. Harmonics occurred in 92% of whistles, sometimes extending beyond the 44 kHz recording range. The most frequently recorded contour categories were convex and concave, and very few whistles exhibited complex modulation. The whistles produced by S. teuszii are broadly comparable with those published for the Indo-Pacific humpback dolphin S. chinensis. Future studies should consider context-specific use of whistle types, and should include comparisons with S. teuszii groups in other geographic locations to ensure the full species’ whistle repertoire is adequately characterised