Aquatic Mammals a publication of the European Association for Aquatic Mammals Vol. 31, No. 2 2005
For information about journal subscriptions and manuscript submissions, please contact Dr. Jeanette Thomas Editor, Aquatic Mammals [EMAIL PROTECTED] Email is the preferred method of communication. Wiggins, S.M.*, E.M. Oleson, M.A. McDonald, and J.A. Hildebrand. 2005. Blue whale (Balaenoptera musculus) diel call patterns offshore of southern California. Aquatic Mammals 31(2):161-168. *Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0205, USA Diel and seasonal calling patterns for blue whales (Balaenoptera musculus) were observed in coastal waters off southern California using seafloor-mounted autonomous acoustic recording packages (ARPs). Automated call counting from spectrogram cross-correlation showed peak seasonal calling in late summer/early fall. When call counts were organized by daily time intervals, calling peaks were observed during twilight periods, just after sunset and before sunrise. Nighttime calling was grater than daytime calling, but also showed a minimum between the dusk and dawn calling peaks. These peaks correlate with the vertical migration times of krill, the blue whales' primary prey. One hypothesis to explain these diel variations is that blue whale calling and foraging may be mutually exclusive activities. Fewer calls are produced during the day while prey are aggregated at depth and foraging is efficient. More calls are produced during the twilight time periods when prey are vertically migrating and at night when prey are dispersed near the sea surface and foraging is less efficient. Mello, I.*, and M. Amundin. 2005. Whistle production pre- and post-partum in bottlenose dolphins (Tursiops truncatus) in human care. Aquatic Mammals 31(2):169-175. *Kolmården Djurpark, Research and Education Centre, Kolmarden, Sweden The bottlenose dolphin (Tursiops truncatus) has a highly variable acoustic repertoire of whistles, clicks, and pulse burst sounds. Whistles are used to express individuality (signature whistle) and emotional state, and to initiate and maintain contact within a group. This study investigated the whistle production type pre- and post-partum of three female bottlenose dolphins and their calves at the Kolmården Djurpark, Sweden. Gestation lasts approximately 12 months, and with the approach of delivery, the behaviour of the female changed in several ways. Observations of the behaviour and sound production were done for up to seven months prior to birth and for up to the first 22 months of the calves' lives. The results showed that whistle production increased significantly for all three females in the seven months pre-partum, with an accelerating increase in the days prior to birth. The whistles, therefore, might be used as an indicator that delivery is imminent. After birth, the mother-calf pair whistled more often when separated (66%) than when together (34%), and significantly more often when the calf returned to its mother than when she retrieved the calf. Blomqvist, C.*, I. Mello, and M. Amundin. 2005. An acoustic play-fight signal in bottlenose dolphins (Tursiops truncatus) in human care. Aquatic Mammals 31(2):187-194. *Department of Research and Education, Kolmårdens Djurpark, Kolmården, Sweden Play-fighting is common in many mammals, especially among juveniles and subadults, providing a safe opportunity to practice behaviours important in adult life. To prevent escalation into a potentially dangerous real fight, play-fighting often is accompanied by acoustic and/or visual appeasement behaviours. We studied aggressive and play-fight behaviours in bottlenose dolphins (Tursiops truncatus) at the Kolmården Djurpark. The results showed that play-fighting subadult dolphins emitted a characteristic sound, which was never observed in aggressive interactions. This was a short pulse burst followed by an FM-whistle. By plotting pulse repetition rate (PRR) vs. duration of the bursts, two main clusters were found. The bottom cluster had a mean PRR of 59 pulses per second (pps), and a mean duration of 154 msec. The top cluster had a mean PRR of 502 pps and a mean duration of 149 msec. These play-fight clusters were compared separately to corresponding adult aggressive pulse burst clusters. Taking both PRR and duration into consideration, no significant difference was found between the top clusters, or between the bottom clusters, in the two age groups. The trailing whistles were divided into five different frequency contour categories. These did not resemble the signature whistles of any of the play-fighting dolphins. The average start and end frequencies were 13.0 kHz and 10.1 kHz, respectively, and the maximum and minimum frequencies were 13.7 kHz and 7.0 kHz, respectively. The mean duration was 410 msec. Based on the fact that this sound occurred only in play-fights, we propose that it helps prevent a play-fight from escalating into a real fight and, hence, is analogous to the "laugh" and "chuckle" seen in apes. Morisaka, T.*, M. Shinohara, and M. Taki. 2005. Underwater sounds produced by neonatal bottlenose dolphins (Tursiops truncatus): I. Acoustic characteristics. Aquatic Mammals 31(2):248-257. *Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake, Sakyo, Kyoto, 606-8502, Japan Bottlenose dolphins (Tursiops truncatus) communicate using various acoustic signals, including whistles and pulsed sounds. Many studies have been conducted on dolphin whistle development over a long span, but little research has been done on sounds produced by neonatal dolphins just after birth. For this reason, we studied the acoustic characteristics of underwater sounds produced by two neonatal dolphins. Both whistles and burst-pulses were identified as neonatal sounds at 1.5 h after birth. Whistles became longer by the hour. Whistle durations were highly correlated with respiration intervals. The neonate randomly produced various types of whistles, but no dominant whistles were documented. There were significant differences between neonates in the proportion of whistles to burst-pulses used, and also in the acoustic characteristics of their whistles. Acoustic characteristics that are unique to each individual neonate might help a mother dolphin to recognize her neonate. Morisaka, T.*, M. Shinohara, and M. Taki. 2005. Underwater sounds produced by neonatal bottlenose dolphins (Tursiops truncatus): II. Potential function. Aquatic Mammals 31(2):248-257. *Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake, Sakyo, Kyoto, 606-8502, Japan Neonatal bottlenose dolphins (Tursiops truncatus) produce many sounds just after birth, including whistles and pulsed sounds. Herein, we report the possible function of the sounds produced by two captive-born, neonatal bottlenose dolphin as revealed by behavioural observations. Typical sucking sounds were observed during 71 to 81% of all suckling bouts. Since the neonates produced more sounds at the beginning of the suckling sequence than expected, it appeared that they might use the sounds as care-solicitation signals or begging signals. These sounds contained a higher proportion of whistles than sounds in other contexts, which implied that the proportions of sound types, especially whistles, were important for neonatal dolphins and their mothers to initiate the nursing sequence.
