lack of use of the Polar Front zone directly south of New Zealand, and the overlap of their foraging ranges with those of conspecifics such as short-tailed shearwaters [2]. Many studies have shown that oceanic winds can influence the flight of seabirds during foraging trips [e.g. 17,18,19,20,21]. The weather systems and wind patterns south of New Zealand and Australia generally comprise polar easterlies near the Antarctic continent, and westerly winds around and to the south of the Subantarctic and Polar Fronts (,50–55uS). North of the Subantarctic Front, alternating low- and high-pressure systems result in variable winds [22]. It seems likely that oceanic winds should have an effect on the foraging strategies of these birds, and plausible that a spatially bimodal foraging pattern might be due in part to wind considerations. The study of wide-ranging marine predators such as these is a challenging field. Electronic tagging technologies typically play an vital role in such studies [23], but greatest insight can potentially be obtained by combining tag data with other information such as ship-based observations of predators and prey, hydrodynamic model data, and ocean parameters [11,23,24,25]. Here, we integrate tracking data from sooty and short-tailed shearwaters, a long-term data set of at-sea observations of seabirds, pelagic trawl data, records of near-surface zooplankton, and remotely- sensed ocean surface wind data to provide a synoptic view of the foraging behaviour of these seabirds. Our aims were to determine the extent to which oceanic winds influenced foraging behaviour, the overlap in foraging habitat between species and populations, and to examine the relationships between foraging and potential prey distributions and oceanographic features. Methods Ethics statement All protocols employed in the sooty shearwater tracking study were approved by the University of California at Santa Cruz Institutional Animal Care and Use Committees, the Wellington Conservancies of the Department of Conservation, New Zealand, and the Kia Mau Te T¯ıt¯ı Mo Ake To¯nu Atu (Keep the T¯ıt¯ı Forever) research programme. The South Australian short-tailed shearwater study was approved by the Department of Primary Industries and Resources of South Australia (ethics number 16/03), and the Department of Environment and Heritage (permit number A24684). The Tasmanian short-tailed shearwater study was approved by the University of Tasmania Ethics Committee (A0008138) and the Nature Conservation Branch of Tasmanian Parks and Wildlife Service (permit FA 05151). The SO-CPR survey, shipboard surveys of seabirds, and pelagic trawls were approved by the Australian Antarctic Science Advisory Committee (AAS Projects 472, 2208, and 2070), with AMLR Act permits 96/1 (trawls) and 05-10_047 (SO-CPR). Data collection – sooty shearwater foraging trips Tagging was conducted on breeding adult birds on Whenua Hou (Codfish Island), New Zealand (167u399E 46u469S) and Mana Island, New Zealand (174u509E 41u069S). Details are given by Shaffer et al. [13]. The tags used were Lotek LTD 2400 archival data loggers (Lotek Wireless, St. John’s, Newfoundland). These tags yielded one location fix per day, and also recorded light intensity, temperature, and pressure at a user-programmable sampling rate. The pressure data were used to infer diving activity, and the temperature data to refine position estimates by matching against sea surface temperature data [13,26]. Eight birds were tagged for a single foraging trip with tags set to record at either 24 or 32 seconds (referred to as fast sampling rate tags). This sampling Shearwater Foraging rate was chosen to provide reasonably fine-scale information on diving activity. A subsequent deployment of 19 birds was made using a slower sampling rate (432 seconds), designed to record behaviour throughout the remainder of breeding and the six month migration that followed [1]. The slower sampling rate reduces the amount of data collected each day, and so allows for longer times between recovery and download of tags. Data collection – short-tailed shearwater foraging trips Tagging was conducted on breeding adult birds in two separate studies: one from two South Australian offshore islands (Althorpe Island, 136u529E 35u229S, and St Peter Island, 133u359E 32u179S) and the other from an offshore Tasmanian island (Wedge Island, 140u409E 43u089S). Details of the South Australian studies are given in [27]. Briefly, these birds were tagged with KiwiSat 202 satellite transmitters (Sirtrack Ltd, North Havelock, New Zealand), with a transmission interval of 60s. In this study we use data from long foraging trips, comprising a single long trip from each of 11 individual birds, spread over three breeding seasons (Feb/Mar 2005, n = 4; Feb 2006, n = 1; Feb/Mar 2007 n = 6). Due to transmitter loss and battery failure, none of these 11 trips was completely recorded. However, all but one trip were recorded to at least 50uS, and three trips were recorded to south of 60uS [27]. Thus, these records give a reasonable indication of the outward leg of long foraging trips by these birds. The Tasmanian birds were tagged with light-based geolocation tags (Lotek LTD 2400 and BAS Mk3, British Antarctic Survey). Long foraging trip data from February and March of 2006 (n = 2 birds, 5 trips total) and 2008 (n = 2 birds, 5 trips total) were used here. Data collection – at-sea observations of shearwaters The at-sea observations were taken from data collected by the Australian Antarctic programme over the 1980/81 to 2005/06 austral summer seasons [28,29]. The details of the methodologies used to collect observations and physical oceanographic and environmental data are described elsewhere [30,31]. Briefly, observations of the numbers and behaviours of all species of seabirds present within a 300m forward quadrant of the ship were recorded continuously while the vessel was underway during daylight hours. Ship-followers were excluded from all analyses, following the BIOMASS Working Party on Bird Ecology protocols [32]. Ship-followers typically associate with the vessel for extended periods, either following the vessel at the stern or circling the vessel, or both. Neither sooty nor short-tailed shearwaters are generally regarded as ship-followers, typically flying in straight lines and only detouring around the vessel if required to avoid collision. Data collection – fish, squid, and zooplankton distributions Mesopelagic fish and squid distributions in the Polar Front region around 140uE were obtained from an Australian voyage conducted during September 1996. Fish and squid sampling was undertaken using an International Young Gadoid Pelagic Trawl with a multiple-opening pelagic net (MIDOC). Four depth strata were sampled at each station, at nominal depths of 0–250m, 250– 500m, 500–750m, and 750–1000m [33]. 37 trawls were made from 5–20 September, on a northward transect from approxi- mately 140uE, 60uS to 146uE, 46uS (Figure 1). Near-surface zooplankton data were obtained from the Southern Ocean Continuous Plankton Recorder (SO-CPR) survey [34]. In this survey, the CPR instrument is towed at a constant PLoS ONE | www.plosone.org 2 June 2010 | Volume 5 | Issue 6 | e10960