| 1. |
- Amundin, Mats, 1947-, et al.
(författare)
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An echolocation visualization and interface system for dolphin research
- 2008
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Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966 .- 1520-8524. ; 123:2, s. 1188-1194
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Tidskriftsartikel (refereegranskat)abstract
- The present study describes the development and testing of a tool for dolphin research. This tool was able to visualize the dolphin echolocation signals as well as function as an acoustically operated "touch screen." The system consisted of a matrix of hydrophones attached to a semitransparent screen, which was lowered in front of an underwater acrylic panel in a dolphin pool. When a dolphin aimed its sonar beam at the screen, the hydrophones measured the received sound pressure levels. These hydrophone signals were then transferred to a computer where they were translated into a video image that corresponds to the dynamic sound pressure variations in the sonar beam and the location of the beam axis. There was a continuous projection of the image back onto the hydrophone matrix screen, giving the dolphin an immediate visual feedback to its sonar output. The system offers a whole new experimental methodology in dolphin research and since it is software-based, many different kinds of scientific questions can be addressed. The results were promising and motivate further development of the system and studies of sonar and cognitive abilities of dolphins. © 2008 Acoustical Society of America.
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| 2. |
- Blomqvist, Christer, 1963-, et al.
(författare)
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An acoustic play-fight signal in bottlenose dolphins (Tursiops truncatus) in human care
- 2005
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Ingår i: Aquatic Mammals. - 0167-5427 .- 1996-7292. ; 31:2, s. 187-194
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Fjälling, Arne, 1950-
(författare)
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The conflict between Grey seals (Halichoerus grypus) and the Baltic coastal fisheries : new methods for the assessment and reduction of catch losses and gear damage
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is a problematic interaction going on between grey seals and the small scale coastal fisheries in the Baltic. A large number of seals are by-caught and drowned each year, and the viability of the fishery is threatened by catch losses caused by the seals. Traditional mitigation methods are not sufficient, or have in some cases not been properly evaluated. Available methods of quantifying and analysing the catch losses are also insufficient. This thesis consists of three parts, each studying a different angle of this conflict.In the first part, new models for estimating catch losses are presented. In addition to the commonly used method of counting the number of damaged fish in the nets, the new models also allow for an estimation of the hidden losses. Hidden losses may be fish that are completely removed from nets without leaving any traces, fish that escape through holes in the net torn by the seals, or even fish that are scared away from the fishing gear. Such losses were found to be significant, and hence it is now clear that the traditional models seriously underestimate the total losses. The new models also allow for a deeper analysis of the interaction process. The first presented model compares catches between adjacent days (day-pairs), the second uses nets that are pre-baited before deployment, and the third relies on a detailed inspection and repair of all seal-induced damage to the net meshes.In the second part, some traditional methods of mitigating the conflict are evaluated. A commercially available Acoustic Harassment Device was tested in a field trial. AHDs were deployed at several set-traps for salmonids for three consecutive years. The damage reducing effect was persistent throughout a season, as well as over the full three-year test period, and no “dinner bell” effect was observed. When seal attacks became frequent in the 1980´s, several of the traditional salmon traps were reinforced with newly developed extra strong net materials. These materials dramatically reduced the damage to the nets, and to some degree also the catch losses. However, the losses were still substantial, and the traditional gear was gradually phased out when better solutions emerged.In the third part, new methods of mitigating the conflict are evaluated. A salmon trap was built, using net meshes which were large enough to allow seal-chased fish to escape through, but which would still guide and confine non-stressed fish. The trap was fitted with a fish chamber with a double wall of very taut netting, separating the catch from the surroundings by a fixed distance. Interference by seals was significantly reduced with this construction. Field experiments revealed that seals used their above-water vision to locate and search out buoys of the type that are used in the fisheries. Larger buoys were more readily found than smaller. A set of trials was initiated where certain geographical areas were made unattractive for seals prior to their seasonal arrival to the region, by deploying stationary AHDs. Finally, aquarium experiments demonstrated that underwater vision and hearing were equally important in seals’ detection of fish in a test box. It was also found that there was a “near zone”, within which seals stayed focused on a fish and attempted to catch it by a quick thrust of the head. These studies strongly suggest that new seal-safe fishing gear and mitigation methods should be based on, and would benefit from, an in-depth understanding and analysis of natural seal behaviour.
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| 4. |
- Jildmalm, Ronald, et al.
(författare)
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Food Preferences and Nutrient Composition in Captive White-handed Gibbons, Hylobates lar
- 2008
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Ingår i: International journal of primatology. - : Springer Science and Business Media LLC. - 0164-0291 .- 1573-8604. ; 29:6, s. 1535-1547
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to assess spontaneous food preferences in captive white-handed gibbons and to analyze whether they correlate with nutrient composition. Via a 2-alternative choice test, we repeatedly presented 3 male Hylobates lar with all possible binary combinations of 10 types of food that are part of their diet in captivity and found the following rank order of preference: grape > banana = fig > apple > pear > honeydew melon > carrot > tomato > cucumber > avocado. Correlational analyses revealed a highly significant positive correlation between the food preference ranking and the total carbohydrate, fructose, and glucose contents of the foods (p < 0.01, respectively). With the exception of the trace mineral selenium (p < 0.05), there was no other significant correlation with any other macro- or micronutrient. In addition, the food preferences were stable across the day because rankings obtained from tests performed at 0900, 1200, and 1500 h, respectively, did not differ significantly (p > 0.05). Our results suggest that captive white-handed gibbons are not opportunistic, but selective feeders with regard to maximizing net gain of energy because only the content of carbohydrates, but not the contents of total energy, proteins, or lipids significantly correlate with the displayed food preferences. Further, the results suggest that captive Hylobates lar, in contrast to their free-ranging conspecifics, do not display marked changes in their food selection across the day.
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| 5. |
- Laska, Matthias, 1960-, et al.
(författare)
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Successful acquisition of an olfactory discrimination paradigm by South African fur seals, Arctocephalus pusillus
- 2008
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Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 93:4-5, s. 1033-1038
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Tidskriftsartikel (refereegranskat)abstract
- The present study demonstrates that South African fur seals, Arctocephalus pusillus, can successfully be trained to discriminate between objects on the basis of odor cues. Using a task based on a food-rewarded two-choice discrimination of simultaneously presented odor stimuli the animals acquired the basic operant conditioning paradigm within 480 to 880 stimulus contacts. Moreover, the fur seals could readily transfer to new S+ and S- stimuli, were capable of distinguishing between fish- and non-fish odors as well as between two fish odors, and were able to remember the reward value of previously learned odor stimuli even after 2- and 15-week breaks. The precision and consistency of the fur seals' performance in tests of discrimination ability and memory demonstrate the suitability of this paradigm for assessing olfactory function in this pinniped. An across-species comparison of several measures of olfactory learning capabilities such as speed of initial task acquisition and ability to master transfer tasks shows that A. pusillus is similar in performance to non-human primates, but inferior to rodents such as mice and rats. The results support the assumption that fur seals may use olfactory cues for social communication and food selection and that the sense of smell may play an hitherto underestimated role in the control of their behavior. © 2008 Elsevier Inc. All rights reserved.
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| 6. |
- Mello, I., et al.
(författare)
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Reactions of three bottlenose dolphin dams with calves to other members of the group in connection with nursing
- 2005
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Ingår i: Zoo Biology. - : Wiley. - 0733-3188 .- 1098-2361. ; 24:6, s. 543-555
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Tidskriftsartikel (refereegranskat)abstract
- The suckling behavior of three bottlenose dolphin (Tursiops truncatus) mother-calf pairs at the Kolmården Wild Animal Park, Sweden, was followed from birth until the calves were 1 year old, with emphasis on the behavior of the mothers toward other dolphins present in pool. The results show that 80.44% of the sucklings occurred when the dams were not accompanied by another member of the group. This preference declined, as the calf grew older, for all three dams. Three factors influenced this company preference in relation to nursing and contributed to the total variance in a detectable way: the month post partum, company preference, and the mother's ID, i.e., which mother was involved. The time between the category "dam leaves company" and the beginning of nursing increased over the months for all three dams. These results indicate that another dolphin is not automatically an asset to a dam with a newborn, and that, in human care, ample space and limited number of pool mates must be provided to allow the dam the necessary privacy in connection with nursing. © 2005 Wiley-Liss, Inc.
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| 7. |
- Nachtigal, Paul E., et al.
(författare)
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Polar bear Ursus maritimus hearing measured with auditory evoked potentials
- 2007
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 210, s. 1116-1122
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Tidskriftsartikel (refereegranskat)abstract
- While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in half-octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2–22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bear's environment to operate with caution.
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| 8. |
- Starkhammar, Josefin, et al.
(författare)
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Acoustic Touch Screen for Dolphins, First application of ELVIS - an Echo-Location Visualization and Interface System
- 2007
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Ingår i: 4th International Conference on Bio-Acoustics 2007. - 1478-6095. - 9781604238082 ; 29:part 3, s. 63-68
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Konferensbidrag (refereegranskat)abstract
- Dolphin sonar has been extensively studied over several decades, and much of its basic characteristics are well known (Au 1993). However, most of these studies have been based on an experimental setup where the dolphin has been trained to be voluntarily fixed, so its directional sonar beam could be recorded with fixed hydrophones. Although this allows for very exact measurements, it most likely has prevented the full dynamic potential of the dolphin’s sonar to be revealed. Also the dolphin’s response to scientific questions, e.g. in target detection threshold or discrimination trials, mostly has been a “go/no go” response or pressing a yes/no paddle. This traditional experimental methodology to measure the response makes rather coarse indications of choice. It is difficult to refine and will be unpractical with a multi-choice paradigm. Therefore a new EchoLocation Visualisation and Interface System (ELVIS) has been developed at Lund University in cooperation with Kolmården Wild Animal Park, and is presently being used in dolphin food preference investigations at the Kolmården Dolphinarium. ELVIS basically consists of a matrix of 16 hydrophones attached to a semi transparent screen lowered into the water of the pool where the dolphins swim freely. The hydrophones hit by a sonar pulse generate electric signals in relation to the received sound pressure level. After subsequent amplification these signals are transferred to a computer. The signal analysis is performed by custom designed LabVIEW software that constitutes the core of the interactive features of the interface system. The software can for example in real time create a round colour spot on the computer screen, corresponding to the maximum intensity in the sound beam. The recorded sound intensity can be coded into colour and/or light intensity. The resulting image on the computer screen is continuously projected back onto the hydrophone matrix screen, hence giving the dolphin an immediate visual feedback to its sonar output. Since only 16 hydrophones were used, the exact location of the maximum sound intensity point was derived through interpolation between the hydrophones in the matrix. This made the spatial resolution of the sound beam recordings quite sufficient for the present study. However, future systems will certainly rely on increased hydrophone matrix size. This system offers a whole new experimental methodology in dolphin research since it can function as an acoustic “touch screen” for the dolphins. It is highly adaptable to different studies since the core of the interface features is software based.In cognitive studies with primates, e.g. the chimpanzee, a computerized symbol interface, based on a finger operated touch screen, has been successfully used (Rumbaugh et al. 1975). Even with birds, like chickens and doves, this approach has been used (Cheng & Spetch, 1995). So far, however, it has not been attempted with dolphins, partly due to the inherent problems in using electronics in salt water. However, the ELVIS screen is based on acoustic detection and activation, using hydrophones, which is well suited for underwater use. The software used in the present experiment designate active areas on the screen, indicated by white symbols, e.g. a filled circle or a filled square. When the dolphin aims its sonar beam axis at this symbol, it flashes to indicate a “hit” and a bridging stimulus (a 400 ms, 10 kHz sinus tone) is played. In this study each of four such symbols represented a different fish (herring, mackerel, capelin and squid). When the dolphin “clicked” on one of them, it was rewarded by the fish represented by it. Thereby the dolphin could choose what kind of fish it preferred. Hence, for the first time the dolphins could execute and run a computer program using their sonar beam like we use a mouse cursor. The size and trig level of these “buttons” or active areas of the screen can easily be altered so that, as the dolphin’s skills in handling the program increased, the more accurate hits and more distinct sound pressure levels of the dolphin’s sound beam could be required.Three bottlenose dolphins (Tursiops truncatus) were trained to perform the task of pointing their sonar beam selectively on the symbols shown on the ELVIS screen. They quickly learned this task and were highly motivated to explore it.
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| 9. |
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| 10. |
- Starkhammar, Josefin, et al.
(författare)
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Editorial: 47-channel burst-mode recording hydrophone system enabling measurements of the dynamic echolocation behavior of free-swimming dolphins
- 2009
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Ingår i: Journal of the Acoustical Society of America. - : A I P Publishing LLC. - 0001-4966 .- 1520-8524. ; 126:3, s. 959-962
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Detailed echolocation behavior studies on free-swimming dolphins require a measurement system that incorporates multiple hydrophones (often andgt; 16). However, the high data flow rate of previous systems has limited their usefulness since only minute long recordings have been manageable. To address this problem, this report describes a 47-channel burst-mode recording hydrophone system that enables highly resolved full beamwidth measurements on multiple free-swimming dolphins during prolonged recording periods. The system facilitates a wide range of biosonar studies since it eliminates the need to restrict the movement of animals in order to study the fine details of their sonar beams.
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