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  • Some mammalian and avian species alter their vocal communication signals to reduce masking by background noises (including conspecific calls). A preliminary study suggested that Weddell seals (Leptonychotes weddellii) increase the durations of some underwater call types when overlapped by another calling seal. The present study examined the durations and overlapping sequences of Weddell seal calls recorded in Eastern Antarctica. The calling rate, call type (13 major categories), total duration, numbers of elements per call, and overlapping order of 100-200 consecutive calls per recording location were measured. In response to increased conspecific calling rates, the call durations and numbers of elements (within repeated-element call types) did not change or became shorter. Calls that were not overlapped were 3.8 plus or minus 6.1 s long, the first call in a series of overlapped calls was 14.4 plus or minus 15.7 s and subsequent calls in an overlapping series were 6.5 plus or minus 10.3 s. The mean durations of non-overlapped and overlapped calls matched random distributions. Weddell seals do not appear to be adjusting the durations or timing of their calls to purposefully avoid masking each others' calls. The longer a call is, the more likely it is to overlap another call by chance. An implication of this is that Weddell seals may not have the behavioural flexibility to reduce masking by altering the temporal aspects of their calls or calling behaviours as background noises (natural and from shipping) increase.

  • This dataset contains digitized passive acoustic recordings from a hydrophone connected to an autonomous recording device both moored near the sea-floor in the Southern Ocean. Recordings were digitised at a sample rate of 500 Hz and were continuous over the period of operation. The intended purpose of these recordings was to collect baseline data on the acoustic environment (i.e. underwater sound fields). Underwater sounds that were recorded include sounds generated by Antarctic sea ice, marine mammals, and man-made sounds from ships and geo-acoustic surveys. Marine mammal sounds include calls from blue, fin, humpback, and minke whales. The hydrophone was deployed on a mooring on the Kerguelen Plateau.

  • The underwater and in-air recordings were used to derive a technique to classify the call types. The in-air recordings demonstrated that both males and females vocalise and often a single seal will string up to 6 call types together in a variety of orders. No 'Trills' were heard by males or females on the ice. The seals lengthened the duration of multiple-element calls when they were 'interrupted' by another calling seal. This suggests that the seals are listening for the calls of conspecifics while they themselves are calling. A pilot project indicated that almost none of the calls are completely masked by other calling seals. The recordings are being used (in association with recordings obtained in later years) to address other aspects of Weddell seal vocal communication. See the link below for public details on this project.

  • This dataset contains digitized passive acoustic recordings from a hydrophone connected to an autonomous recording device both moored near the sea-floor in the Southern Ocean. Recordings were digitised at a sample rate of 500 Hz and were continuous over the period of operation. The intended purpose of these recordings was to collect baseline data on the acoustic environment (i.e. underwater sound fields). Underwater sounds that were recorded include sounds generated by Antarctic sea ice, marine mammals, and man-made sounds from ships and geo-acoustic surveys. Marine mammal sounds include calls from blue, fin, humpback, and minke whales. The data were collected in 2006 from a hydrophone deployed on a mooring in the Prydz Bay area.

  • The date are of the highest amplitudes across the frequency range of Weddell seal tonal trills (an underwater call made by males). Each column presents the results of a frequency amplitude measure that is relative to the highest amplitude of that trill, independent of the frequency at which that amplitude occurs. This removes the influence of the overall amplitude of the call which is influence of the distance the sea was from the hydrophone when the recording was made. Four trill patterns were identified (A - D) and a number of trills not included in the analyses are classed as type X. The X call types were excluded because the original recording was later found to be overloaded or partly masked by ice noises or the calls of another seal. Analysis details are included in the accompanying manuscript. The accompanying Excel file contain the frequency amplitude measurements of individual trills at two location groups: the Aurora Truning location at the anchorage location of the Aurora Australis near Davis and the other group is a number of breeding groups in the Vestfold Hills. Variable A is the frequency in Hz, Variables B to DH at the Aurora Turning location and B to BY at the Davis locations are data from individual trills. Rows 2 or 3 indicate the four Trill patterns, A, B, C or D, with an X designation for trills that were not included in the analyses due to limited frequency ranges or overloading of the original recordings (that was discovered later in the analyses). ssize or samplesize is the number of trills that were at each frequency bin.

  • This dataset contains digitized passive acoustic recordings from a hydrophone connected to an autonomous recording device both moored near the sea-floor in the Southern Ocean. Recordings were digitised at a sample rate of 500 Hz and were continuous over the period of operation. The intended purpose of these recordings was to collect baseline data on the acoustic environment (i.e. underwater sound fields). Underwater sounds that were recorded include sounds generated by Antarctic sea ice, marine mammals, and man-made sounds from ships and geo-acoustic surveys. Marine mammal sounds include calls from blue, fin, humpback, and minke whales. The hydrophone was deployed on a mooring on the Kerguelen Plateau in 2006.

  • This dataset contains digitized passive acoustic recordings from a hydrophone connected to an autonomous recording device both moored near the sea-floor in the Southern Ocean. Recordings were digitised at a sample rate of 500 Hz and were continuous over the period of operation. The intended purpose of these recordings was to collect baseline data on the acoustic environment (i.e. underwater sound fields). Underwater sounds that were recorded include sounds generated by Antarctic sea ice, marine mammals, and man-made sounds from ships and geo-acoustic surveys. Marine mammal sounds include calls from blue, fin, humpback, and minke whales.

  • Recordings were made of adult male and female Weddell seals on the ice during the breeding seasons of 1990 and 1997. The recordings were made near Davis, Antarctica in the Vestfold Hills. The vocalisations made with both the mouth and nostrils closed were classified into call types. These call types are also produced by the seals when underwater. The call classifications were based on those described by Thomas, J.A. and Kuechle,, V.B. (1982, J. Acoust. Soc. Amer. 72: 1730-1738) and Pahl, B.C., Terhune, J.M. and Burton, H.R. (1997, Aus. J. Zool. 45: 171-187). Nineteen call types were identified. Of these, males made 18 and females made 15. Trills are only made by males and it is likely that a stepped ascending whistle is only made by females. A roar and mew are also potential male-only call types. The data suggest that the Trill vocalisations can be used to indicate the presence of males. This will be useful when recording underwater where the calling seals cannot be observed directly. A description of the types of calls made by Weddell Seals is listed below. SymbolNameDescription OToneConstant-frequency, predominantly sinusoidal call. LGrowlConstant-frequency, broad bandwidth, long call. QWhoopConstant-frequency call with a terminal upsweep. SSqueakBrief call with constant frequency or rising frequency and an irregular waveform. WAWhistle AscendingAscending frequency, sinusoidal waveform. TCTrill Constant-FrequencyNarrow bandwidth trill with a constant-frequency beginning, sinusoidal or frequency-modulated waveform. TTrillNarrow to broad bandwidth, containing a frequency downsweep, greater than 2 seconds. WDWhistle DescendingDescending frequency, sinusoidal waveform (less than 2 seconds). MMewAbruptly descending frequency followed by a long constant-frequency ending. CChugAbruptly descending frequency followed by a brief constant-frequency ending. GGuttural Glug (Grunt)Descending-frequency call that was lower than a Chug and had a brief duration. WAGWhistle Ascending - GruntBrief Ascending Whistle followed by a Guttural Glug (Grunt), the two types alternate in a regular pattern. KKnockAbrupt, brief-duration broadband sound

  • This dataset contains digitized passive acoustic recordings from a hydrophone connected to an autonomous recording device both moored near the sea-floor in the Southern Ocean. Recordings were digitised at a sample rate of 500 Hz and were continuous over the period of operation. The intended purpose of these recordings was to collect baseline data on the acoustic environment (i.e. underwater sound fields). Underwater sounds that were recorded include sounds generated by Antarctic sea ice, marine mammals, and man-made sounds from ships and geo-acoustic surveys. Marine mammal sounds include calls from blue, fin, humpback, and minke whales. The data were collected in 2005 from a hydrophone deployed on a mooring in the Prydz Bay area.

  • Metadata record for data from ASAC Project 2184 See the link below for public details on this project. The objectives of this project were: To characterise the mating system of the Weddell seal by: 1) acoustically tracking males under the ice during the breeding season, 2) measuring changes in health and condition of individual males over the breeding season, 3) determining whether vocalisations are used as advertisements of individual quality to attract females, and/or in male-male competition, 4) develop and use a combination of microsatellite loci tests to assign paternity to newborn pups, and then use these results to determine whether the variance in male mating success is related to territory size, tenure and/or individual characteristics. A large number of collected data files are available for download. Many files are in an unknown format, but will open with a standard text editor. See below for summaries of the two seasons of fieldwork. 1997/1998 Season: In November/December 1997, we conducted a pilot study at the Turtle Rock colony (77.727S, 166.85E) in McMurdo Sound. All of the techniques outlined in the proposal were successfully trialled. Acoustic pingers were attached to seven males and five females for a total deployment of 104 seal days and mass and morphometrics obtained for each animal. Preliminary analysis of male movements indicate that males held adjacent yet non-overlapping territories on the southern side of Turtle Rock, along a major ice crack and where the congregation of females was highest. Both the size and shape of the males territories, and the evidence from the vocalisation data show that we captured the dominant males at the site. Both males and females were immobilised using Ketamine/Diazepam with no loss of an animal, nor signs of respiratory depression. Vocalisations were recorded from all territory holding males, and both behavioural and vocal responses of both male and female seals to familiar and unfamiliar calls were observed. We bleach marked all animals to which we attached pingers and these markings were visible on our under-ice video - with which we also recorded behavioural responses to both animals and our under-ice speaker during playback experiments. We conducted a daily census of all animals at Turtle Rock and above-ice movements were recorded. Skin samples were taken from 24/25 males seen at the site and 43/45 mother-pup pairs (One male was only seen on a single occasion at the colony, though sighted elsewhere, and two females disappeared shortly after our arrival at the colony). Significant findings Dominant males hold under-ice territories which are adjacent yet non-overlapping - however territory boundaries change considerably over the course of the breeding season. Males respond to playbacks of their own and others calls as do females. Females towards the end of lactation will visit each males territories. Whether to assess individual males or not is yet to be determined. 1998/1999 Season Between October 29 through December 10 1998, the behaviour of male and female weddell seals at the Turtle Rock colony (77.727S, 166.85E) were monitored both above and below the ice. This season, we switched from the seal sled method of capture and restraint (see K027 report 1997) to the use of a pole net and tripod. Seals were bagged by placing a seal hood over their head and then a 3m pole net (consisting of two, 3m long poles connected by a 2m wide, 2.5cm mesh, net , was placed over them and the poles tied tightly at both ends, leaving them constrained within the netting bag. The pole net was then hoisted under a tripod (built by Antarctica New Zealand) using a chain block suspended from the head of the tripod, and the animal weighed using electronic scales. For attachment of instruments, animals were immobilised with an intra-muscular injection of Ketamine/Diazepam at a dose rate of approximately 2.0mg/100 kg Ketamine, 0.4mg/100 kg Diazepam as was used successfully in 1997. Animals were only immobilised for attachment of instruments with HR electrodes (ie 3 males and 7 females). Animals were not immobilised for removal of instruments with the exception of one female who was particularly active. A small number of untagged animals were tagged in the rear flippers using tags provided by the University of Minnesota Weddell seal program as part of their long-term studies of the McMurdo Sound Weddell seal population. Maximum animal handling time including gluing of instruments and allowing for equilibration of isotopes (see below) was approximately 3 hours/seal. The mass of animals at first and last capture is shown in Table 1 below. Animal Movements - Males: Movements under the ice were monitored using depth modulated acoustic transmitter (Vemco V16P). An array of three hydrophones, each approximately 500m apart, was placed around the colony on the southern side of Turtle Rock.. The position of each animal (x, y, z locations) was automatically logged when it was underwater at intervals of between 15 and 60 sec. The array was powered continuously using 12V dry-fit batteries connected in series. A VHF radio transmitter (Sirtrack) was glued to the dorsal surface of each male using a quick-dry Epoxy (Araldite). Time depth recorders (MkV1) Heart rate loggers, and an Acoustic Heart Transmitter were attached to three males. The VHF transmitter was used to assist in relocating animals that left the study site during the breeding season and to monitor time spent on the ice via a Televilt Scanning receiver mounted atop a Wannagan placed near the SW side of Turtle Rock. The position of males on the surface at the colony was also mapped approximately once every two days. Females: Under ice movements and feeding behaviour of six females was monitored by attachment of acoustic pingers as outlined above. We attached Time depth recorders (MkV1) Heart rate loggers, and an Acoustic Heart Transmitter to each of five of these females, the sixth did not appear to transmit heart-rate. A seventh female was captured but no instruments fitted, as she did not respond to the immobilising agents. Energetics -Body composition of 12 males was determined by measuring total body water using hydrogen isotope dilution on two separate occasions. At first capture, a blood sample (5ml) was drawn directly into Vacutainer collection tubes from the femoral vein at the base of the rear flippers using a 1 * inch, 18g needle and each animal was then injected with 5ml tritiated water (HTO) (specific activity 1 mCi per ml). The animal was then weighed as outlined above. Unless further instrument attachment was to occur, the animal was then released in order to allow the HTO to equilibrate with the body water pool (approximately three hours), and later recaptured for a second blood sample to be taken. Recapture and sampling usually took less than 10min. The blood samples were allowed to settle in the warmth of the Apple in the field and the serum fraction separated. Aliquots of serum were then held frozen for later analysis in Australia at the University of Tasmania. This procedure was repeated later in the season, and the changes in mass and TBW will be used to estimate energy expenditure (Reilly and Fedak 1991). Mass changes are shown in Table 1. Seal Tag Name Mass1 (kg) Mass2 (kg) Mass loss Seal Days Rate of mass lost/day Purple 37 #1 Dudley 413.5 354.5 59 24 2.46 Purple 547 #2 Shed 369.5 319.5 50 20 2.50 Pink 928 #3 385.5 338.5 47 22 2.14 Red CT 283/965 #4 352.5 304.5 48 22 2.18 White 423 #5 King C 455 428.5 26.5 22 1.20 Pink 981 #6 Whiteboy 370.5 331.5 39 17 2.29 Y1339 #7 405.5 384.5 21 15 1.40 Pink CT 549 #8 Joe 362 325.5 36.5 15 2.43 Y1299 #9 Markboy 314.5 280.5 34 16 2.13 Orange CT 842 #10 344.5 293.5 51 14 3.64 Purple 808 #11 337.5 . . Red 347 #12 313.5 . . 2) Function of Vocalisations Method: Hydrophones were used to obtain several recordings of five major call types from 8 of our captured males (pinger frequency allowed us to distinguish between individuals occupying the array). Following the 1999 field season, a correlational analysis will be used to determine if information on male characteristics (assessed using our physiological measures of their health or "quality") are revealed by vocalisations of the males we sampled over the three field seasons. Our current total sample size for this component of the research stands at 13 (1997 and 1998). It has become increasingly clear that the Long Trill calls, produced exclusively by males, may play important role in attracting females and challenging rivals. Two playback experiments were conducted to examine the function(s) of this important vocalisation, and other call types used by males. In the first experiment (initiated in 1997), the responses of 8 monitored males and a single female to the playback of each major call type and a control sound (walrus calls) were examined according to a systematic experimental schedule. For both males and females, we were able to record changes in position relative to the underwater speaker (using data from the pinger array), vocal behaviour (using a DAT recorder and a pair of hydrophones), activities near the playback speaker (using three underwater video cameras), swimming speed and heart rate of specific animals. Our current total sample size for this component of the research stands at 13 males and 2 females (1997 and 1998). The second experiment (also initiated in 1997) examined male-male competition and inter-sexual call function more directly. Our pilot study showed that males actively overlap the Long Trill songs of rivals with their own Trills, in a manner that is similar to territorial songbirds. We conducted "interactive" playback experiments to examine the consequences of overlapping the Long Trill calls of rivals. Five consecutive Long Trill calls of specific resident males (identified using a "real time" field spectrograph) were either (1) completely overlapped, (2) partially overlapped or (3) preceded by the recorded Long Trill calls of an unfamiliar male. A MiniDisc player was used to broadcast these calls to different resident males according to a systematic schedule. Underwater video cameras, the pinger array and hydrophones were then used to record the changes in patterns of under-ice movements and the vocal responses of 4 males and 5 females. Our current total sample size for this component of the research now stands at 7 males and 8 females (1997 and 1998). We also obtained continuous sound and video samples of male and female Weddell seals occurring along the main ice crack at Turtle Rock using a timelapse VCR connected to fixed video cameras and a hydrophone. 3) Paternity analysis: collection of samples Method The mating success of males at Turtle Rock will be determined by laboratory analysis of skin samples (6 mm diameter). These were collected from the edge of the interdigital webbing of the hind flipper using a leather punch, from all males, females and pups in 1997 and 1998, with further collections planned for 1999 and 2000. Samples were stored in eppendorf tubes filled with 100% ethanol. Sample degradation is minimal using this technique. Analysis has still to be conducted. This season we trialled a new technique for sampling using a small biopsy punch on the end of a pole but this technique proved unsatisfactory as biopsy heads became blunt after only 2-3 animals had been sampled. However, the clipping technique proved so successful that an experienced clipper could remove samples with such discretion that at times the animal being sampled did not wake. Significant findings Some of the results from the first year of this study were presented at the SCAR conference in Christchurch last August, and the abstract published in the NZ Natural Sciences series. Harcourt, R.G., Hindell, M.A. and Waas, J.R. 1998. Under-ice movements and territory use in free-ranging Weddell seals during the breeding season. New Zealand Natural Sciences 23: 72-73 One of the most interesting findings relates to the interpretation of three dimensional dive profiles. One paper on three dimensional dive profiles in free-ranging Weddell seals is nearing completion. Other planned papers include measurement of heart-rate during diving, female foraging behaviour, communication and territorial behaviour, as well as the major reproduction papers.