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- Blomqvist, Christer, 1963-, et al.
(author)
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An acoustic play-fight signal in bottlenose dolphins (Tursiops truncatus) in human care
- 2005
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In: Aquatic Mammals. - 0167-5427 .- 1996-7292. ; 31:2, s. 187-194
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Journal article (peer-reviewed)abstract
- 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.
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| 2. |
- Blomqvist, Christer, 1963-, et al.
(author)
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An acoustic tag for recording, directional, pulsed ultrasounds aimed at free-swimming Bottlenose dolphins (Tursiops truncatus) by conspecifics
- 2004
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In: Aquatic Mammals. - 0167-5427 .- 1996-7292. ; 30:3, s. 345-356
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Journal article (peer-reviewed)abstract
- We developed an acoustic tag, called MOSART (MObile Submersible Acoustic Recorder of Transients), for recording directional social pulses produced by a bottlenose dolphin (Tursiops truncatus). The tag was attached to the dorsal fin of two dolphins by means of suction cups. Two adult bottlenose dolphins at the Kolmårdens Djurpark, Sweden, were trained to carry the tag comfortably through a desensitising program. The tag included two envelope click-detectors, each with a narrow bandpass filter, centred at 120 and 70 kHz, respectively. The duration of the original pulses and their relative amplitude within the two filter frequency bands was retained. The amplitude differences between the two filter bands reflected changes in the source frequency spectrum and/or the position of the tag hydrophone in the incoming sound beam. The tag recorded "echolocation click trains," "slow and irregular pulses," and "pulse bursts" with varying amounts of energy in both frequency bands. The peak amplitude and duration of clicks in "echolocation click trains" and in "slow and irregular pulses" were logged correctly; however, the tag recorder had more difficulties in handling the complex pulses in the aggressive "pulse bursts," where the duration of the individual pulses could not be determined. Still, the amplitude and the pulse repetition rate could be measured. The possible impact of the tag was investigated by analysing the dolphin's behaviours (12 categories), sounds (3 categories), preferred location in the pool, and respiration intervals. Only four of the behaviours and one preferred location in the pool showed significant differences among pre-tag baselines, tag periods, and post-tag follow-ups, suggesting that the tag had only a minor impact on the dolphin. We describe and discuss the tag and its capacity to record different pulsed sounds.
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