Immobilisation data of juvenile and adult male and female Weddell seals at Drescher Inlet from expeditions DRE1990 and DRE1992

Fourten Weddell seals (Leptonychotes weddellii) and two crabeater seals (Lobodon carcinophaga) were immobilised at Drescher Inlet (Riiser Larsen Ice Shelf), eastern Weddell Sea coast, between January and February 1990 using a combination of ketamine, xylazine, and diazepam. Eleven Weddell seals were drugged once, and two and one were drugged two and three times each, coming to a total of 18 immobilisation procedures. Another 16 seals were immobilised between January and February 1992. Ten seals were drugged once, and three and two were drugged two and three times each, coming to a total of 25 immobilisation procedures. Narcoses were terminated with yohimbine. Data as given by doi:10.1594/PANGAEA.438920 were selected for publication. Data sets doi:10.1594/PANGAEA.438921 and doi:10.1594/PANGAEA.438926 followed the same methods and dose regimes.

At surface behaviour of adult male southern elephant seals from King George Island from expedition JUB2000

Adult male southern elephant seals instrumented in 2000 on King George Island (n = 13), travelled both to the north (doi:10.1594/PANGAEA.231580, doi:10.1594/PANGAEA.231585) and to the east (doi:10.1594/PANGAEA.231571, doi:10.1594/PANGAEA.231579, doi:10.1594/PANGAEA.261708, doi:10.1594/PANGAEA.261709, doi:10.1594/PANGAEA.261710, doi:10.1594/PANGAEA.261711) of the Antarctic Peninsula. Five males (doi:10.1594/PANGAEA.231571, doi:10.1594/PANGAEA.231579, doi:10.1594/PANGAEA.231580, doi:10.1594/PANGAEA.261710, doi:10.1594/PANGAEA.231585) remained within 500 km of the island and focusing movements in the Bransfield Strait and around the Antarctic Peninsula. Sea-surface temperatures encountered by these animals showed little variation and they seemed to move about irrespective of sea ice cover, but frequented areas of shallow bathymetry. Three males (doi:10.1594/PANGAEA.261708, doi:10.1594/PANGAEA.261709, doi:10.1594/PANGAEA.261711) moved as far as 75°S to the east of the peninsula, into the Weddell Sea, with maximum distances of more than 1500 km from King George Island. They travelled into the Weddell Sea along the western continental shelf break until they reached the region of the Filchner Trough outflow. Here the bathymetry consists of canyons and ridges which support the intensive mixing between the warm saline waters of the Weddell Gyre and the very cold outflow waters with Ice Shelf water ingredients at the Antarctic Slope Front. Another five data sets were shorter then 40 days, and excluded from analyses (doi:10.1594/PANGAEA.231568, doi:10.1594/PANGAEA.231576, doi:10.1594/PANGAEA.231572, doi:10.1594/PANGAEA.231577, doi:10.1594/PANGAEA.264710). A computer animation was developed to visualize the animal movements in relation to the extent and concentration of sea ice (doi:10.1594/PANGAEA.509404). The need for re-instrumentation of adult males from King George Island is highlighted to investigate whether males continue to travel to similar areas and to obtain higher resolution data.

Dive depth and dive duration data of subadult and adult, male and female southern elephant seals from Marion Island between 2004 and 2008 with links to datasets

Although numerous studies have addressed the migration and dive behaviour of southern elephant seals (Mirounga leonina), questions remain about their habitat use in the marine environment. We report on the vertical use of the water column in the species and the potential lifetime implications for southern elephant seals from Marion Island. Long-term mark-resight data were used to complement vertical habitat use for 35 known individuals tagged with satellite-relay data loggers, resulting in cumulative depth use extrapolated for each individual over its estimated lifespan. Seals spent on average 77.59% of their lives diving at sea, 7.06% at the sea surface, and 15.35% hauled out on land. Some segregation was observed in maximum dive depths and depth use between male and female animals-males evidently being physiologically more capable of exploiting increased depths. Females and males spent 86.98 and 80.89% of their lives at sea, respectively. While at sea, all animals spent more time between 300 and 400 m depth, than any other depth category. Males and females spent comparable percentages of their lifetimes below 100 m depth (males: 65.54%; females: 68.92%), though males spent 8.98% of their lives at depths in excess of 700 m, compared to females' 1.84% at such depths. Adult males often performed benthic dives in excess of 2,000 m, including the deepest known recorded dive of any air-breathing vertebrate (>2,133 m). Our results provide a close approximation of vertical habitat use by southern elephant seals, extrapolated over their lifespans, and we discuss some physiological and developmental implications of their variable depth use.

Dive depth and dive duration data of subadult and adult, male and female southern elephant seals from Marion Island between 2004 and 2008 with links to datasets

Sexual segregation in habitat use occurs in a number of animal species, including southern elephant seals, where differences in migration localities and dive behaviour between sexes have been recorded. Due to the extreme sexual size dimorphism exhibited by southern elephant seals, it is unclear whether observed differences in dive behaviour are due to increased physiological capacity of males, compared to females, or differences in activity budgets and foraging behaviour. Here we use a mixed-effects modelling approach to investigate the effects of sex, size, age and individual variation on a number of dive parameters measured on southern elephant seals from Marion Island. Although individual variation accounted for substantial portions of total model variance for many response variables, differences in maximum and targeted dive depths were always influenced by sex, and only partly by body length. Conversely, dive durations were always influenced by body length, while sex was not identified as a significant influence. These results support hypotheses that physiological capability associated with body size is a limiting factor on dive durations. However, differences in vertical depth use appear to be the result of differences in forage selection between sexes, rather than a by-product of the size dimorphism displayed by this species. This provides further support for resource partitioning and possible avoidance of inter-sexual competition in southern elephant seals.

Dive depth frequency of 23 adult male southern elephant seals (Mirounga leonina) from Marion Island and King George Island

Access to different environments may lead to inter-population behavioural changes within a species that allow populations to exploit their immediate environments. Elephant seals from Marion Island (MI) and King George Island (KGI) (Isla 25 de Mayo) forage in different oceanic environments and evidently employ different foraging strategies. This study elucidates some of the factors influencing the diving behaviour of male southern elephant seals from these populations tracked between 1999 and 2002. Mixed-effects models were used to determine the influence of bathymetry, population of origin, body length (as a proxy for size) and individual variation on the diving behaviour of adult male elephant seals from the two populations. Males from KGI and MI showed differences in all dive parameters. MI males dived deeper and longer (median: 652.0 m and 34.00 min) than KGI males (median: 359.1 m and 25.50 min). KGI males appeared to forage both benthically and pelagically while MI males in this study rarely reached depths close to the seafloor and appeared to forage pelagically. Model outputs indicate that males from the two populations showed substantial differences in their dive depths, even when foraging in areas of similar water depth. Whereas dive depths were not significantly influenced by the size of the animals, size played a significant role in dive durations, though this was also influenced by the population that elephant seals originated from. This study provides some support for inter-population differences in dive behaviour of male southern elephant seals.