Analysis of Hyperoodon ampullatus (Northern Bottlenose Whale) Vocalisations P. White 1 , R. Prieto 2 , S. Magalhães 2 , M.A. Silva 2 , A.Williams 3 1 ISVR, University of Southampton, UK 2 Dept. Oceanography and Fisheries, University of the Azores, Portugal 3 Biscay Dolphin Research Programme, UK Introduction References [1] Hooker, S.K., and Whitehead. H., “Click characteristics of northern bottlenose whales (Hyperoodon ampullatus)” Marine Mammal Science, 18, 69-80, 2002. [2] Winn, H.E., Perkins, P.J. and Winn, L., “Sounds and behaviour of the bottlenose whale”, 7 th Annual Conf. on Biological Sonar and Diving Mammals, Stanford Research Institute, 53-59, 1970. [3] Silva, M.A. et al, “Occurrence and distribution of cetaceans in the waters around the Azores (Portugal), Summer and Autumn 1999- 2000”, Aquatic Mammals, 29(1), 77-83, 2003. Results Fig. 2 shows a sample period recorded whilst the animals were on the surface. The data has a high Signal to Noise Ratio. There is an unusual subjective quality to the sound, which contains a mixture of clicks and creaks. Click Interval Histograms: Dived Mean: 0.15s Median: 0.06s Click Interval Series: Click Detections : Surfaced Mean: 0.3s Median: 0.15s Discussion Acoustic data from northern bottlenose whale recordings were made and analysed. The bandwidth of the system did not allow meaningful frequency analysis to be performed. Analysis of the click intervals revealed a lower mean click interval (higher click rate) in the dived case than when the animals were on the surface, this is the opposite to the observation made in [1]. When at the surface and when dived the vocalisations contained consistently spaced click pairs. The separation between these pairs varied slowly with time. This consistency may constitute a useful feature for recognising calls from this species. Method Hyperoodon sighting Figure 1: Site of encounter During a cetacean survey conducted off the Azores during 1999-2000 [3], acoustic data were collected from a group bottlenose whales (Hyperoodon ampullatus). On the morning of 7/8/00, a group of 9 bottlenose whales, including a calf, was detected 17 miles west of Faial, see Fig. 1. Survey effort was halted and the boat stay with the whales for approximately 1hr 40m. During most of the encounter the animals were socialising, but at the end they started a deep dive. The sighting conditions were very good (Beaufort scale 1) and no other cetaceans were detected in the vicinity during the encounter. The previous sighting (also H. ampullatus) was made 1hr 16m prior to this encounter and the subsequent sighting (unidentified species) 1hr 18m later. During this encounter recordings were made with the animals both on the surface and dived. Equipment Array: Magrec HP/30ST stereo towed array with HP25ST monitoring box. Hydrophones: 2×Benthos AQ4. DAT recorder: TASCAM DA-P1 Bandwidth: 200Hz-15kHz Figure 2: Data example upper trace- Time series lower plot- Spectrogram Comparatively little is known of the vocalisations of northern bottlenose whales (Hyperoodon ampullatus) [1,2]. Most recently Hooker and Whitehead [1] provide a report of vocalisations recorded in “the Gully” off Nova Scotia, detailing click rates and frequency content of the clicks.