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 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.