Keyword

EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > ANIMALS/VERTEBRATES > MAMMALS > CARNIVORES > SEALS/SEA LIONS/WALRUSES

126 record(s)
 
Type of resources
Topics
Keywords
Contact for the resource
Provided by
From 1 - 10 / 126
  • 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.

  • Results from a February 2007 survey of the Vestfold Hills coastline and offshore islands for used and disused southern elephant seal wallows. The data here are point locations of the wallows, not the extents or boundaries of the wallows. The table below gives the coordinates (decimal degrees) for the elephant seal wallows found, their unofficial names and the wallow status as used or disused at the time of survey. Data were used in the 2018 Vestfold Hills/Davis Station Helicopter map: Wallow name Latitude Longitude Status Hawker Island -68.637360 77.840040 Used Hawker Island -68.634950 77.841310 Used Hawker Island -68.632180 77.841560 Used Mule Island -68.647860 77.825900 Unused Mule Island -68.646650 77.823920 Unused Zappert Point -68.505100 78.081020 Unused Old Wallow -68.598345 77.937185 Used Davis beach -68.577926 77.967032 Used Heidemann Bay -68.592067 77.945325 Used North of station -68.571916 77.971011 Used

  • This is a digital version of the grid reference map used to plot all sightings of Weddell seals in the Vestfold Hills. The point of origin is the same as the original map and each grid cell is numbered with the same numbering scheme. This can be used to plot any data using the same numbering scheme by joining (ArcInfo) or linking (ArcView) records to this coverage's polygon attribute table (pat) through the item GRIDREF. The original map was a 1:100 000 map of the Vestfolds, provided by Harry Burton, with a grid drawn over it. The grid references were given as either six or four figure values on which field scientists are to plot their data. This map has the following Antarctic Division drawing reference number: M/75/05A Some research with John Cox revealed that this grid was drawn up over a map digitised from another map with the following specifications: Scale 1: 100 000 Date: 1958 (reprinted 1972) Projection: Polyconic Published by: Division of National Mapping, Canberra Reference number: NMP/58/084 Data are referenced to a 'grid' of 1 minute spacing in x axis and 30 second spacing in y axis. The point of origin is apparently 68 20 S 77 48 E. There are 45 rows and 47 columns. The 'grid reference' is in fact in geographic coordinates (but using arbitrary units) so the projection of the original map became irrelevant. The procedure adopted to create a new digital grid was as follows: (Carried out in Arc/Info) 1. Generate a coverage using the original 'grid references'. 2. Tics were also generated using the corners of the 'grid reference' system. 3. A new coverage was created with tics at the same locations but given the true latitude/longitude vales. 4. The original coverage was then transformed to the new coverage based on the new tic values. 5. The new coverage was then projected from geographic coordinates to UTM metres. The data locations were then viewed in Arc/Info using a coverage of the coastline supplied by the Mapping Officer, Antarctic Division. This had previously been determined to be in the UTM projection. An offset was clearly visible between the data locations and the coastline. In order to determine whether the offset was more or less uniform, ten locations were plotted from the original data onto the original map using the 'grid'. Finally a manual corrected was made by moving all the data locations by a uniform distance of 508 metres north and 68 metres west. Information from John van den Hoff, February 2019: The grid cells were originally labelled from 1 to 47 along the x axis and 1 to 45 along the y axis. The four digit values in the GRIDREF field of the attribute table are the x value followed by the y value. To avoid confusion between x and y values, the grid was later revised so that the y values were prefixed with a ‘1’ so for example 01 became 101. The GRIDREF_X and GRIDREF_Y fields have the x and y values of the revised grid. This needs to be kept in mind when data is sourced from field books. The map shows the revised grid.

  • Southern elephant seals are among the deepest diving of all marine mammals. This study examined physiological and behavioural mechanisms used by the seals to conserve energy while diving and estimated metabolic rate. Data were collected on Time Depth Recorders (TDRs), and stored in hexadecimal format. Hexadecimal files can be read using 'Instrument Helper', a free download from Wildlife Computers (see the provided URL).

  • Public summary for project 2128: The aim of this study is to relate the foraging behaviour of Antarctic fur seals breeding on the Kerguelen Plateau at Iles Kerguelen and Heard Island, to the distribution of prey species at sea. Specifically this project seeks to examine the relationship between predators and prey, and how their locations at sea vary according to the position of major productive zones, such as the Antarctic Polar Frontal Zone. This project will provide important data on the relationship between predators and their prey and the developing commercial fisheries in the region. These data are central to improved conservation and management of marine resources on the Kerguelen Plateau. Variations made to the work plan The original comparative aspects of the program planned for the 1999/00 season, where fur seals from Iles Kerguelen and Heard Island were to be satellite tracked simultaneously could not be undertaken because of original 1999/00 field season to Heard Island was re-scheduled to 2000/01. Fortunately the project collaborator Dr Christophe Guinet (French CEBC-CNRS) agreed to extend the work program at Iles Kerguelen another season, and the comparative and integrated fur seal-prey-fisheries study over the Kerguelen Plateau was undertaken the following season (2000/01). Details of this study are presented in ASAC project 1251 (CI - Goldsworthy)and 1085 (CI-Robertson). Significant findings: The distribution of the foraging activity of Antarctic fur seal females was investigated at Cap Noir (49 degrees 07 S, 70 degrees 45E), Kerguelen Island in February 1998. Eleven females were fitted with a satellite transmitter and Time Depth recorder. The two sets of data were combined to locate spatially the diving activity of the seals. The fish component of the fur seal diet was determined by the occurrence of otolotihs found in 55 scats collected during the study period at the breeding colony. Oceanographic parameters were obtained simultaneously through direct sampling and satellite imagery. The mesopelagic fish community was sampled on 20 stations along four transects where epipelagic trawls were conducted at night at 50 meters of depth. We then investigated, using geographic information systems, the relationship between the spatial distribution of the diving activity of the fur seals and oceanographic factors that included sea surface temperature, surface chlorophyll concentration, prey distribution and bathymetry obtained at the same spatio-temporal scale as the spatial distribution of the diving activity of our study animals. An inverse relationship was found between the main fish species preyed by fur seal and those sampled in trawl nets. However, the diving activity of Antarctic fur seal females was found to be significantly related to oceanographic conditions, fish-prey distribution and to the distance from the colony but these relationships changed with the spatial scale investigated. A probabilistic model of the Kerguelen Plateau was developed that predicted where females should concentrate their foraging activity according to the oceanographic conditions of the year, and the locations of their breeding colonies. Maternal allocation in growth of the pup was measured in Antarctic fur seals (Arctocephalus gazella) at Iles Kerguelen during the 1997 austral summer. Absolute mass gain of pups following a maternal foraging trip was independent of the sex of the pup but was positively related to the foraging trip duration and to maternal length. However, daily mass gain, i.e. the absolute mass gain of the pup divided by the foraging trip duration, decreased with increasing foraging trip duration but increased with maternal length. While fasting, the daily mass loss of the pup was related to the sex of the pup and initial body mass, with both heavier pups and female pups losing more mass per day than lighter pups and male pups. The mass specific rate of mass loss was significantly higher in female pups than in male pups. Over the study period, the mean growth rate was zero with no difference between female and male pups. The growth rate in mass of the pup was positively related to maternal length but not maternal condition, negatively related to the foraging trip duration of the mother and the initial mass of the pup. This indicated that during the study period heavier pups grew more slowly due to their higher rate of daily mass loss during periods of fasting . Interestingly, for a given maternal length, the mean mass of the pup during the study period was higher for male than for female pups, despite the same rate of daily mass gain. Such differences are likely to result from sex differences in the mass specific rate of mass loss. As female pups lose a greater proportion of their mass per day, a zero growth rate i.e. mass gain only compensates for mass loss, is reached at a lower mass in female pups compared to male pups. Our results indicate that there are no differences in maternal allocation according to the sex of the pup but suggest that both sexes follow a different growth strategy. Results are in line with the objectives of the project. animal_id (identifier of the individual animal) location_class (the Argos location class quality, 0-3) latitude (decimal degrees) longitude (decimal degrees) observation_date (the date of observation, in ISO8601 format yyyy-mm-ddTHH:MM:SSZ. This information is also separated into the year, month, day, etc components) observation_date_year (the year of the observation date) observation_date_month (the month of the observation date) observation_date_day (the day of the observation date) observation_date_hour (the hour of the observation date) observation_date_minute (the minute of the observation date) observation_date_time_zone (the time zone of the observation date) deployment_longitude (location that the tracker was deployed, decimal longitude) deployment_latitude (location that the tracker was deployed, decimal latitude) trip (the identifier of the trip made by this animal) at_sea (whether this point was at sea (1) or on land (0)) complete (was this trip complete - i.e. did the animal return to the colony) scientific_name (scientific name of the tracked animal)

  • This log contains notes and observations of Leopard seals at Mawson, collected between 1979 and 1987. The hard copy of the log has been archived by the Australian Antarctic Division library.

  • This is a scanned copy of the vertebrate ecologists report from Macquarie Island, 1985, written by Mark Hindell. The report includes: The diet of the four penguin species breeding on Macquarie Island (Royal, Rockhopper, King and Gentoo). Aspects of the morphology of the four penguin species The past and present status of the southern elephant seal on Macquarie and Heard Islands

  • To quantify the post-breeding movements of adult female Antarctic females (Arctocephalus gazella) we tracked females using Biotrack GLS (geolocation) data loggers. Females were captured towards the end of the lactation period (March/April) and the GLS tag, affixed to a Dalton flipper tag, was deployed in the trailing edge of the left or right foreflipper. Tags were generally retrieved just prior to or after giving birth the following season. Data files were extracted from the tags using BASTrak software. .lig - light data .tem - temperature data .act - activity data Metadata for each individual include: Site, year, GLS ID, sex, age, deployment site, lat and long of deployment site, flipper tag number, deployment and retrieval times (GMT).

  • This dataset represents Weddell Seal haulout and pupping sites in the Vestfold Hills, Antarctica. The data were sourced from a dataset compiled by Samantha Lake and described by the metadata record 'Distribution of Weddell seals pupping at the Vestfold Hills'. She used a reporting grid described by the metadata record 'Weddell seal reporting grid of the Vestfold Hills, Antarctica' to show observations made over 24 years (pupping areas) and 28 years (non-breeding areas). The map Samantha produced of pupping areas is linked to the metadata record 'Distribution of Weddell seals pupping at the Vestfold Hills'. Polygons were generated by copying relevant grid rectangles from a digital version of the reporting grid, referring to the maps produced by Samantha; the grid rectangles used were those in which there had been greater than 20 observations (pupping), 17 observations (non-breeding). The data was used in an A3 map of the Vestfold Hills published by the Australian Antarctic Data Centre in October 2001 and which is available from a Related URL below. The data are included in the data available for download from a Related URL below. The data conform to the SCAR Feature Catalogue which includes data quality information. See a Related URL below. Data described by this metadata record has Dataset_id = 155. Each feature has a Qinfo number which, when entered at the 'Search datasets & quality' tab, provides data quality information for the feature.

  • To quantify the dietary preferences and trophic level consumption of post-breeding adult female Antarctic fur seals (Arctocephalus gazella), we analysed the carbon:nitrogen composition of whiskers and blood samples from the females. Females were captured towards the end of the lactation period (March/April) and whiskers and a blood sample were collected at this time. Females were generally recaptured just prior to or after giving birth the following season and a further whisker and blood sample were collected at this time. Metadata for each individual include: Site, GLS ID, year, flipper tag number, season, sampling date, tissue type, whisker segment number, cumulative length along whisker of the segment, d15N, d13C, percentage N, percentage C and CN ratio.