A comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continent

• Main Author: Rasehlomi, Tshikana Phillip
• Other Authors: Rouault, Mathieu
• Format: Master Thesis
• Language: English
• Published: University of Cape Town 2015
• Subjects: Ocean and Atmosphere Science; Antarctic; Indian; The Antarctic; Antarc*; Marion Island
• Online Access: http://hdl.handle.net/11427/20005; https://open.uct.ac.za/bitstream/11427/20005/1/thesis_sci_2015_rasehlomi_tshikana_phillip__.pdf

Two sympatric Phoebetria albatrosses, P. fusca and palpebrata breeding at Marion Island in the South Indian Ocean were studied. Adult individuals were tracked between 2008 and 2011. The study examined the foraging distribution of the two species in relation to environmental parameters such as sea surface temperature. Interaction with mesoscale features expressed by sea surface temperatures, was tested with statistical models. Tracked P. fusca demonstrated positive association with sea surface temperatures in the Southern Indian Ocean, in particular during incubating and chick-provisioning periods, by travelling shorter distances to the interfaces of mesocale features created as a result of the Agulhas Return Current located << 500 km to the north of breeding islands. During nest construction, tracked P. fusca travelled greater distances in search of food possibly because they had no chick to return to at the colonies. Contrastingly, tracked P. palpebrata did not demonstrate any positive association with sea surface temperatures. During incubating and chick-provisioning periods, tracked P. palpebrata travelled shorter distances to foraging grounds located to the south of breeding islands possibly to maximise returns to chicks while minimising efforts. During nest construction, tracked P. palpebrata travelled to distant foraging grounds to the south of the Antarctic Polar Front in areas of low mesoscale variability suggesting that greater distances can be achieved when they have no chick to feed at the colonies. Individuals of both tracked species foraged within close proximity during energy-demanding periods indicating their ability to employ an efficient foraging strategy that ensures minimal effort whilst maximising returns. Generalised Linear Models with the response variable being species and explanatory variables comprised of sea surface temperatures, annual breeding stages, distance traversed and activity, were conducted to examine the effect of environmental factors on seabird foraging distribution. ...