Shearwater Foraging in the Southern Ocean: The Roles of Prey Availability and Winds Ben Raymond1*, Scott A. Shaffer2, Serguei Sokolov3, Eric J. Woehler4, Daniel P. Costa5, Luke Einoder1, Mark Hindell4, Graham Hosie1, Matt Pinkerton 6 , Paul M. Sagar7, Darren Scott8, Adam Smith9, David R. Thompson 6 , Caitlin Vertigan 4 , Henri Weimerskirch10 1 Australian Antarctic Division, Kingston, Tasmania, Australia, 2 Department of Biological Sciences, San Jose State University, San Jose, California, United States of America, 3 CSIRO Wealth from Oceans National Research Flagship, CSIRO Marine Research and Antarctic Climate and Ecosystems Cooperative Research Centre, Hobart, Tasmania, Australia, 4 School of Zoology, University of Tasmania, Hobart, Tasmania, Australia, 5 Ecology and Evolutionary Biology, University of California, Santa Cruz, California, United States of America, 6 National Institute of Water and Atmospheric Research Ltd., Taihoro Nukurangi, Kilbirnie, Wellington, New Zealand, 7 National Institute of Water and Atmospheric Research Ltd., Taihoro Nukurangi, Christchurch, New Zealand, 8 Department of Zoology, University of Otago, Dunedin, New Zealand, 9 Institute of Information and Mathematical Sciences, Massey University, Albany, Auckland, New Zealand, 10 Centre d’Etudes Biologiques de Chize´, Centre National de la Recherche Scientifique, Villiers en Bois, France Abstract Background: Sooty (Puffinus griseus) and short-tailed (P. tenuirostris) shearwaters are abundant seabirds that range widely across global oceans. Understanding the foraging ecology of these species in the Southern Ocean is important for monitoring and ecosystem conservation and management. Methodology/Principal Findings: Tracking data from sooty and short-tailed shearwaters from three regions of New Zealand and Australia were combined with at-sea observations of shearwaters in the Southern Ocean, physical oceanography, near- surface copepod distributions, pelagic trawl data, and synoptic near-surface winds. Shearwaters from all three regions foraged in the Polar Front zone, and showed particular overlap in the region around 140uE. Short-tailed shearwaters from South Australia also foraged in Antarctic waters south of the Polar Front. The spatial distribution of shearwater foraging effort in the Polar Front zone was matched by patterns in large-scale upwelling, primary production, and abundances of copepods and myctophid fish. Oceanic winds were found to be broad determinants of foraging distribution, and of the flight paths taken by the birds on long foraging trips to Antarctic waters. Conclusions/Significance: The shearwaters displayed foraging site fidelity and overlap of foraging habitat between species and populations that may enhance their utility as indicators of Southern Ocean ecosystems. The results highlight the importance of upwellings due to interactions of the Antarctic Circumpolar Current with large-scale bottom topography, and the corresponding localised increases in the productivity of the Polar Front ecosystem. Citation: Raymond B, Shaffer SA, Sokolov S, Woehler EJ, Costa DP, et al. (2010) Shearwater Foraging in the Southern Ocean: The Roles of Prey Availability and Winds. PLoS ONE 5(6): e10960. doi:10.1371/journal.pone.0010960 Editor: Yan Ropert-Coudert, Institut Pluridisciplinaire Hubert Curien, France Received March 15, 2010; Accepted May 13, 2010; Published June 4, 2010 Copyright: 2010 Raymond et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was conducted as part of the Census of Antarctic Marine Life (CAML) and Tagging of Pacific Pelagics (TOPP) projects, and was supported in part by the Alfred P. Sloan, Gordon and Betty Moore, and David and Lucile Packard Foundations, and the Australian Antarctic Program (Projects 472, 681, 2208, and 3227). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: ben.raymond@aad.gov.au Introduction Sooty (Puffinus griseus) and short-tailed shearwaters (P. tenuirostris) are abundant seabirds that range widely across global oceans [1], breeding principally in New Zealand, south-eastern Australia, and southern South America [2,3]. They are of cultural and economic importance for Ma¯ori and Tasmanian aboriginal societies [4,5], important as predators within their marine ecosystems, and as engineers within their island ecosystems due to their burrowing and deposition of biological material [6,7,8]. Understanding the foraging ecology of these birds is important for continued monitoring of their populations [9], conservation and manage- ment of their island ecosystems [10], and facilitating their use as indicators of Southern Ocean prey stocks [9,11]. Breeding adult sooty and short-tailed shearwaters forage locally to the colony in order to provision their chicks at a maximal rate, but periodically undertake long foraging trips to Antarctic waters [12,13,14,15]. During long trips the adults forage to replenish their own body mass as well as to provision their chicks [12]. This pattern has also been reported for other species [e.g. 16]. New Zealand sooty shearwaters make long foraging trips in a spatially bimodal pattern, utilising foraging grounds around the Polar Front, to the south-east and south-west of New Zealand [1,13]. The foraging patterns of these birds were recently examined in relation to bathymetry, sea surface temperature, primary produc- tivity, and surface wind speeds [13]. However, questions remain regarding the foraging behaviour of these shearwaters in the high latitude regions of the Southern Ocean, including their apparent PLoS ONE | www.plosone.org 1 June 2010 | Volume 5 | Issue 6 | e10960