Return customers: foraging site fidelity and the effect of environmental variability in wide-ranging Antarctic fur seals

• Published in: PLOS ONE
• Main Authors: Arthur, B, Hindell, M, Bester, M, Trathan, P, Jonsen, I, Staniland, I, Oosthuizen, WC, Wege, M, Lea, M-A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science 2015
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarctic; Antarc*; Antarctic Fur Seals
• Online Access: https://doi.org/10.1371/journal.pone.0120888; http://www.ncbi.nlm.nih.gov/pubmed/25807082; http://ecite.utas.edu.au/99614

Strategies employed by wide-ranging foraging animals involve consideration of habitatquality and predictability and should maximise net energy gain. Fidelity to foraging sites iscommon in areas of high resource availability or where predictable changes in resourceavailability occur. However, if resource availability is heterogeneous or unpredictable, as itoften is in marine environments, then habitat familiarity may also present ecological benefitsto individuals. We examined the winter foraging distribution of female Antarctic fur seals, Arctocephalus gazelle , over four years to assess the degree of foraging site fidelity at twoscales; within and between years. On average, between-year fidelity was strong, with mostindividuals utilising more than half of their annual foraging home range over multiple years.However, fidelity was a bimodal strategy among individuals, with five out of eight animals recordingbetween-year overlap values of greater than 50%, while three animals recorded valuesof less than 5%. High long-term variance in sea surface temperature, a potential proxyfor elevated long-term productivity and prey availability, typified areas of overlap. Withinyearforaging site fidelity was weak, indicating that successive trips over the winter targetdifferent geographic areas. We suggest that over a season, changes in prey availability arepredictable enough for individuals to shift foraging area in response, with limited associatedenergetic costs. Conversely, over multiple years, the availability of prey resources is lessspatially and temporally predictable, increasing the potential costs of shifting foraging areaand favouring long-term site fidelity. In a dynamic and patchy environment, multi-year foragingsite fidelity may confer a long-term energetic advantage to the individual. Such behavioursthat operate at the individual level have evolutionary and ecological implications andare potential drivers of niche specialization and modifiers of intra-specific competition.