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From the abstract of the referenced paper: Satellite telemetry data are a key source of animal distribution information for marine ecosystem management and conservation activities. We used two decades of telemetry data from the East Antarctic sector of the Southern Ocean. Habitat utilization models for the spring/summer period were developed for six highly abundant, wide-ranging meso- and top-predator species: Adelie, Pygoscelis adeliae and emperor, Aptenodytes forsteri penguins, light-mantled albatross, Phoebetria palpebrata, Antarctic fur seals, Arctocephalus gazella, southern elephant seals, Mirounga leonina, and Weddell seals, Leptonychotes weddellii. The regional predictions from these models were combined to identify areas utilized by multiple species, and therefore likely to be of particular ecological significance. These areas were distributed across the longitudinal breadth of the East Antarctic sector, and were characterized by proximity to breeding colonies, both on the Antarctic continent and on subantarctic islands to the north, and by sea-ice dynamics, particularly locations of winter polynyas. These areas of important habitat were also congruent with many of the areas reported to be showing the strongest regional trends in sea ice seasonality. The results emphasize the importance of on-shore and sea-ice processes to Antarctic marine ecosystems. Our study provides ocean-basin-scale predictions of predator habitat utilization, an assessment of contemporary habitat use against which future changes can be assessed, and is of direct relevance to current conservation planning and spatial management efforts. The data files provided here comprise the model predictions of the preferred habitat for each of the six species listed above, as well as the overlap results obtained by combining these six sets of results. See the paper for methods used to generate the model predictions and to combine the individual species results. File names for individual species are of the form results_SPP_TYPE.asc, where SPP is one of "afs" (Antarctic fur seal), "ap" (Adelie penguin), "ep" (emperor penguin), "lma" (light-mantled albatross), "ses" (southern elephant seal), or "ws" (Weddell seal. TYPE is either "mean" (mean estimate of habitat preference) or "iqr" (inter-quartile range of uncertainty in the estimate; see paper for details). Data values for individual species results are percentiles of the study area, so that values of 90% or higher are pixels corresponding to the most important 10% of habitat for that species, values of 80% or greater are the top 20% of habitat, and so on. The overlap results files are named overlay_results_mean.asc and overlay_results_iqr.asc. Values in these files represent the average of the top four individual species results in a given pixel (see paper for details).
Database Description The files represent the 41 different Weddell seal (Leptonychotes weddellii) call types identified at either Mawson, Davis, and/or Casey. They were collected between 60 degrees 49' E and 110o 40' E in longitude, and between 66 degrees 12' S and 68 degrees 34' S in latitude. Each call type name includes two elements. The first is a three-digit number starting at 301 to identify the call type. The second is a one to three-letter code referring to the call category that each type falls into. The 13 different possible call categories are: 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 (from: Pahl, B.C., Terhune, J.M. and Burton, H.R. 1997). The 41 call types were divided into two sections, the first 33 (301-O to 333-K) being common call types and the last 8 (334-Q to 341-WD) being rare call types. In each call type folder, one to five different samples of each call type are provided. They are identified by a small case letter added at the end of the call type name. Each sample includes both a .WAV audio sample and a .JPG image of the call type spectrogram showing call shape, i.e., changes in call frequency (vertical) over time (horizontal). These call types were used to identify: (a) unique call types or call categories, (b) differences in call type or call category usage (the frequency of occurrence of each call type or category), and (c) differences in call features (number of elements, start frequency, frequency shift and first element duration) among the three stations. The download file also includes a spreadsheet of data and a text file explaining how to interpret the data. Analysis of this dataset is ongoing.
During the winter and spring of 2002, underwater calling rates were measured near mid-day on an opportunistic basis at 7 breeding sites and, at two breeding sites, over 24 hour periods once a month. The data were analysed with respect to reproductive season (early ice formation, prebreeding, pupping and mating) and if the recordings were made when it was dark or twilight/light. Taken from the abstract of the paper referenced below: Underwater vocalisation monitoring and surveys, both on ice and underwater, were used to determine if Weddell seals (Leptonychotes weddellii) near Mawson Station, Antarctica, remain under the fast ice during winter within close range of breeding sites. Daytime and nighttime underwater calling rates were examined at seven breeding sites during austral winter and spring to identify seasonal and diel patterns. Seals rarely hauled out at any of the sites during winter, although all cohorts (adult males, females, and juveniles) were observed underwater and surfacing at breathing holes throughout winter (June-September) and spring (October-December). Seal vocalisations were recorded during each sampling session throughout the study (n=102 daytime at seven sites collectively, and n=5 24-h samples at each of two sites). Mean daytime calling rate was low in mid-winter (July) (mean = 18.9 plus or minus 7.1 calls per minute) but increased monthly, reaching a peak during the breeding season (November) (mean = 62.6 plus or minus 15.7 calls per minute). Mean nighttime calling rate was high throughout the winter and early spring (July-October) with mean nocturnal calling rate in July (mean = 61.8 plus or minus 35.1 calls per minute) nearly equal to mean daytime calling rate in November (during 24-h daylight). Reduced vocal behaviour during winter daylight periods may result from animals utilising the limited daylight hours for nonvocal activities, possibly feeding. The following study sites were among those used in this project (provided by Phil Rouget): - Forbes site (identified as Site 6 in the paper) is located at Forbes Glacier (approx. 0.5 km to the west of the glacier tongue and approximately 200 meters offshore of the mainland). (67 degrees 35.256 minutes S, 62 degrees 16.756 minutes E) - Kista site is located in the middle of Kista Strait (site 7 in the Marine Mammal Science paper). (67 degrees, minutes 33.840 S, 62 degrees 47.402, minutes E) - SPA site was our site located just west of the western boundary of the SPA which itself is located west of Mawson and east of Forbes Glacier. (Site 2 in Marine Mammal Science paper). (67 degrees 35.179 S, 62 degrees 25.425 minutes E) - McDonald Islands (or Rocks) was the site located North/NorthWest of Kista Strait, as it is named so on the Framens Mtn. Nautical Chart. From memory, it was approximately 12 km north/north west of Mawson Station. (This was site 5 in the Marine Mammal Science paper). (67 degrees 29.414 minutes S, 62 degrees 41.011 minutes E) - Stewart Rocks (also named Sewart Rocks on an alternative map) is located due north of Mawson Station, also by about 12 km. (East of McDonald site, and North East of Kista). This was site 4 in the Marine Mammal Science paper. (67 degrees 29.933 minutes S, 62 degrees 51.765 minutes E) - Anderson Rocks is an extensive group of rocky islets west of Auster Island (approximately 6-7 km offshore). This was site 3 in the Marine Mammal Science paper. (67 degrees 26.445 minutes S, 63 degrees 25.414 minutes E) - SEAL MO was located just north of Macey Hut by about 2 km. This was site 1 in the Marine Mammal Science paper. (67 degrees 23.399 minutes S, 63 degrees 47.977 minutes E) - Aside from SEAL MO and SPA, the names from all these sites are indicated in the Framnes Mountain Chart. An image showing the locations of the fields sites is also part of the download file. The fields in this dataset are: Site Period Day Calling rate photoperiod Sun time
Adult Weddell seals (Leptonychotes weddellii) exhibit site fidelity to where they first breed but juveniles, and perhaps transient adult males, may disperse from their natal location. If there is mixing between adjacent breeding groups, we would expect that common vocalisations would exhibit clinal patterns. Underwater Trill vocalisations of male Weddell seals at Mawson, Davis, Casey, McMurdo Sound, Neumayer and Drescher Inlet separated by ca. 500 to greater than 9,000 km, were examined for evidence of clinal variation. Trills are only emitted by males and have a known territorial defence function. Trills from Davis and Mawson, ca. 630 km apart, were distinct from each other and exhibited the greatest number of unique frequency contour patterns. The acoustic features (duration, waveform, frequency contour) of Trills from Neumayer and Drescher Inlet, ca. 500 km apart, were more distinct from each other than they were from the other four locations. General Discriminant Analysis and Classification Tree Analysis correctly classified 65.8 and 76.9% of the Trills to the correct location. The classification errors assigned more locations to sites greater than 630 km away than to nearest neighbours. Weddell seal Trills exhibit geographic variation but there is no evidence of a clinal pattern. This suggests that males remain close to single breeding areas throughout their lifetime. This work was completed as part of ASAC project 1132 and 2122 (ASAC_1132, ASAC_2122).
During the winter and spring of 2000 and 2002, underwater calls of Weddell seals were recorded near Mawson. The goal was to determine if some call types were only given during the spring breeding season. The calls were classified into 10 broad types and the proportional usage of each was determined from May to December. All call types were present throughout the study period and during periods of darkness and light and at high, medium or low calling rates. Taken from the abstract of the referenced paper: Proportional underwater call type usage by Weddell seals (Leptonychotes weddellii (Lesson, 1826)) near Mawson, Antarctica, investigated the hypothesis that certain call types function specifically in breeding behaviour. Recordings were collected at various sites in 2000 and 2002 from June to December. Twenty-four hour recordings were collected in 2002 at two sites. One hundred consecutive calls from each of 248 recordings were classified into one of ten common call types. Time to 100 calls provided the calling rate. The study period was divided into four periods representing initial sea-ice formation, pre-pupping, pupping, and mating. Calling rate and light-dark differences were also examined. No presence-absence differences were observed for any of the call types with season. The largest difference between nonbreeding and breeding situations was an increase from 32.2% to 38.1% for descending whistles (F[3,244] = 4.483, p = 0.004). Trills gradually increased from 1.8% to 7.3% toward the mating period (F[3,244] = 30.932, p less than 0.001). The proportion of trills, chugs, descending whistles, and other call types also varied with calling rate and light-dark conditions. Some pre-reproductive behaviours may occur in winter, but no call types of Weddell seals function solely in the breeding season.
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 comprises the actual video footage and audio recordings made during a number of experiments made as part of ASAC project 1148 (ASAC_1148). The primary objective was to measure the responses of Antarctic wildlife to various human disturbance stimuli. An excel spreadsheet of a catalogue of the video and audio tapes is available for download from the url given below. The video and audio tapes themselves are stored at the Australian Antarctic Division. For descriptions of (and access to) processed data see the metadata records with the following titles: Measuring the effects of human activity on Weddell Seals (Leptonychotes weddellii) Effects of helicopter operations on emperor penguin chicks Effects of helicopters on Southern Antarctic Fulmars Effects of helicopters on Antarctic wildlife Effects of human activity on Gentoo penguins on Macquarie Island Effects of human activity on King penguins on Macquarie Island Effects of human activity on Royal penguins on Macquarie Island Behavioural responses of Weddell seals to human activity. A copy of the full dataset of video and audio files, as well as another Excel spreadsheet catalogue is available for download from the provided URL. These data were digitised in 2021, and the excel spreadsheet created from the available files.
The number of people travelling to Antarctica is growing, with much of the recent increase in visitor numbers attributable to an expansion in commercial tourism (Enzenbacher 1992; 1994). Most visitors to the region seek direct interactions with the wildlife and so visit breeding groups of seals and seabirds (Stonehouse 1965; Muller-Schwarze 1984). Invariably, this involves travelling to breeding sites by helicopter, inflatable motorised boat (e.g. zodiac) or over-snow vehicle, then making relatively close approaches on foot to photograph and observe the animals. At present, there is information to suggest that visitation can have a negative effect on some Antarctic wildlife, causing changes to behaviour, physiology and breeding success (Culik et al. 1989; Woehler et al. 1994, Giese 1996; Giese 1998, Giese and Riddle 1999). However, the responses of Weddell seals (Leptonychotes weddellii) to human activity have never been systematically examined. As a result, any guidelines to control human activity around these animals are based either on opportunistic observations of seal response, and/or assumptions as to the level of disturbance seals are experiencing. Therefore, the primary objective of the research is to measure the responses of Weddell seals to various human disturbance stimuli. In so doing, the research aims to make quality information available for the development of a comprehensive and scientifically based set of guidelines for managing interactions between people and Antarctic seals. The research will adopt an experimental approach, whereby seals are experimentally exposed to particular types and intensities of human activity while their responses are objectively quantified. As far as possible, experiments are designed to replicate actual disturbances that Weddell seals are presently exposed to in Antarctica. As such, the responses of cow/pup pairs to approaches by pedestrians, over-snow vehicles and helicopters will be examined. In particular, experiments will investigate how approach distance (or altitude), approach speed, time of day, weather conditions and the time of the breeding season, influence the responses of Weddell Seals to these disturbance stimuli. Disturbance responses will be quantified by measuring the behaviour and heart rate of individual seals and the haul-out behaviour of entire groups of animals. Experiments will also be conducted to quantify the sound generated by vehicle operations in Antarctica to help determine whether anthropogenic noise effects vocal communication among Weddell seal, as indicated by changes in their calling rates. Also see the metadata record entitled: Behavioural responses of Weddell seals to human activity. At this stage most of the analysis is in progress and therefore it is not possible to provide complete data sets. These will be submitted upon the completion of the work. The attached word document summarises the experiments that have been completed during the three field seasons to date (up to the end of the 2002/2003 season), which included, the experiment type, location and sample size. The two excel data sheets 'Experimental recording details' provide information on the video recordings that were made during the 2001/2002 and the 2002/2003 summers. These details state the experimental procedure, the details of the experimental, the time, date etc. They include Hi8 video camera recordings of Weddell seal behaviour and DAT recordings of vocalisations. Biological data collected during the 2002/2003 summer include: Collected 10 sample of blood (up to 50 ml each) Collected 6 samples of urine Collected 11 samples of fur Collected 9 samples of blubber Collected 6 samples of faecal swabs (from the ice or thermometer) Conducted a post mortem on a recently deceased seal and collected organ and tissue samples. These samples are being analysed by investigators in ASAC 1144. When results are available they will documented in either ASAC 1148 or 1144. The fields in this dataset are: Date Time Tape Number Counter Number Camera Number Cow ID New ID Event Respiration Rate Heart Rate Where Approached Position of Pup Distance of Closest Pair Distance of Tide Crack Location Wind Direction Cloud Cover Temperature Wind Speed Conductivity Salinity pH Further data has been added to the archive for up to the end of the 2006. These include data files, plus scanned field notes taken during the project. Finally, video tapes relating to the project have also been stored in the Australian Antarctic Division's multimedia library.
Many vocalisations produced by Weddell seals (Leptonychotes weddellii) are made up of repeated individual distinct sounds (elements). Patterning of multiple element calls was examined during the breeding season at Casey and Davis, Antarctica. Element and interval durations were measured from 405 calls all greater than 3 elements in length. The duration of the calls (22 plus or minus 16.6s) did not seem to vary with an increasing number of elements (F4.404 = 1.83, p = 0.122) because element and interval durations decreased as the number of elements within a call increased. Underwater vocalisations showed seven distinct timing patterns of increasing, decreasing, or constant element and interval durations throughout the calls. One call type occurred with six rhythm patterns, although the majority exhibited only two rhythms. Some call types also displayed steady frequency changes as they progressed. Weddell seal multiple element calls are rhythmically repeated and thus the durations of the elements and intervals within a call occur in a regular manner. Rhythmical repetition used during vocal communication likely enhances the probability of a call being detected and has important implications for the extent to which the seals can successfully transmit information over long distances and during times of high level background noise. See other metadata records and datasets associated with ASAC project 2122 (ASAC_2122) for further information. The fields in this dataset are: Tape/Site/File Filename Call Type Total Number of Elements Attribute Frequency Time Casey Davis
Possible communication between territorial male Weddell seals (Leptonychotes weddellii) under the ice with females on the ice was investigated. In-air and underwater recordings of underwater calls were made at three locations near Davis, Antarctica. Most underwater calls were not detectable in air, often because of wind noise. In-air call amplitudes of detectable calls ranged from 32-74 dB re. 20 microPa at 86 Hz down to 4-38 dB re. 20 microPa at 3.6 kHz. Most of these would be audible to humans. Only 26 of 582 amplitude measurements (from 230 calls) ranged from 5 dB to a maximum of 15 dB above the minimum harbour-seal (Phoca vitulina) in-air detection threshold. Seals on the ice could likely hear a few very loud underwater calls but only if the caller was nearby and there were no wind noises. The low detectability of underwater calls in air likely precludes effective communication between underwater seals and those on the ice. See other metadata records and datasets associated with ASAC project 2122 (ASAC_2122) for further information. The fields in this dataset are: Column A: G = grunt, T = trill, CT = constant freq. trill, O = tone, C = chug, AW = ascending whistle, DW = descending whistle, L = growl, R - roar Column B: frequency (Hz) Column C: underwater call level NOTE dB re 20 uPa Column D: in-air call level dB re 20 uPa Column E: in-air background noise level at this frequency dB re 20 uPa Column F: water - air difference dB Column G: location, 1-3, see paper for code Column H: seal in-air threshold dB re 20 uPa Column I: human in-air threshold dB re 20 uPa Column J: seal in-air threshold at this frequency dB re 20 uPa