Distribution and abundance of birds and mammals in the Southern Indian ocean, larsemann hills and princess astrid coast East Antarctica

Abstract

The spatial distribution and abundance of sea birds, penguins and pack ice seals along the Southern Ocean, Ingrid Christensen and Princess Astrid Coast during 29th Indian Scientific Expedition to Antarctica was carried out between November 2009 and March 2010. A total of 34 species of birds with an encounter rate of 9.82/ nautical miles2 were recorded. High species turnover of sea birds was observed between 40° and 50° S longitude. Six aerial sorties were flown along the Ingrid Christensen and Princess Astrid Coast to count penguins and seals along the coast, totalling a length of approx. 1200 km. Adelie and Emperor penguins were recorded with encounter rate of 0.63 ± 0.20 (#/nm ±SE) and 3.81 ± 1.68 (#/nm ±SE) respectively at Ingrid Christensen casts. At Princess Astrid Coast more number of Adelie penguins (1.22 ± 0.12/nm ±SE) was recorded when compared to Emperor penguin (0.60 ± 0.2/nm ±SE). In the present survey, a total of 3601 hauled-out seals were counted from six aerial sorties totalling a length of approx. 1200 km, with each sortie lasting about two hours. Weddell seal Leptonychotes weddellii was the most commonly sighted species in both the areas surveyed (98.2%), and had an encounter rate of 2.9 seals/km. The other species encountered during the survey were crab-eater seal Lobodon carcinophagus (1.7%) and leopard seal Hydrurga leptonyx (0.03%). Group size of hauled-out weddell seals varied considerably and ranged from solitary to maximum of 42 individuals. The median group size of weddell seals hauled-out along the Ingrid Christenson coast was found to be significantly different between the December 2009 and January 2010 survey. Further, along this Coast weddell seals were found hauled-out mainly close to the ice shelf and their spatial distribution appeared to be influenced by the extent of sea ice in the area.