Electronic tracking tags have revolutionized our understanding of broad-scale movements and habitat use of highly mobile marine animals, but a large gap in our knowledge still remains for a wide range of small species. Here, we report the extraordinary transequatorial postbreeding migrations of a small seabird, the sooty shearwater, obtained with miniature archival tags that log data for estimating position, dive depth, and ambient temperature. Tracks (262 ؎ 23 days) reveal that shearwaters fly across the entire Pacific Ocean in a figure-eight pattern while traveling 64,037 ؎ 9,779 km roundtrip, the longest animal migration ever recorded electronically. Each shearwater made a prolonged stopover in one of three discrete regions off Japan, Alaska, or California before returning to New Zealand through a relatively narrow corridor in the central Pacific Ocean. Transit rates as high as 910 ؎ 186 km⅐day ؊1 were recorded, and shearwaters accessed prey resources in both the Northern and Southern Hemisphere's most productive waters from the surface to 68.2 m depth. Our results indicate that sooty shearwaters integrate oceanic resources throughout the Pacific Basin on a yearly scale. Sooty shearwater populations today are declining, and because they operate on a global scale, they may serve as an important indicator of climate change and ocean health.avian migration ͉ diving behavior ͉ habitat use ͉ sooty shearwater ͉ tracking

The rockhopper penguin (Eudyptes chrysocome) is a conspicuous apex marine predator that has experienced marked population declines throughout most of its circumpolar breeding distribution. The cause(s) for the declines remain elusive, but the relatively large spatio-temporal scale over which population decreases have occurred implies that ecosystem-scale, at-sea factors are likely to be involved. We employ stable isotope analyses of carbon ( 13 C/ 12 C, expressed as d 13 C) and nitrogen ( 15 N/ 14 N, d 15 N) in timeseries of rockhopper penguin feather samples, dating back to 1861, in order to reconstruct the species' ecological history. Specifically, we examine whether rockhopper penguin population decline has been associated with a shift towards lower primary productivity in the ecosystem in which they feed, or with a shift to a diet of lower trophic status and lower quality, and we use long-term temperature records to evaluate whether shifts in isotope ratios are associated with annual variations in sea surface temperature. Having controlled temporally for the Suess Effect and for increases in CO 2 concentrations in seawater, we found that overall, d 13 C signatures decreased significantly over time in rockhopper penguins from seven breeding sites, supporting the hypothesis that decreases in primary productivity, and hence, carrying capacity, for which d 13 C signature is a proxy, have been associated with the decline of penguin populations. There was some evidence of a long-term decline in d 15 N at some sites, and strong evidence that d 15 N signatures were negatively related to sea surface temperatures across sites, indicative of a shift in diet to prey of lower trophic status over time and in warm years. However, a siteby-site analysis revealed divergent isotopic trends among sites: five of seven sites exhibited significant temporal or temperature-related trends in isotope signatures. This study highlights the utility of stable isotope analyses when applied over relatively long timescales to apex predators.

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Species distribution models (SDMs) are increasingly applied in conservation management to predict suitable habitat for poorly known populations. High predictive performance of SDMs is evident in validations performed within the model calibration area (interpolation), but few studies have assessed SDM transferability to novel areas (extrapolation), particularly across large spatial scales or pelagic ecosystems. We performed rigorous SDM validation tests on distribution data from three populations of a long-ranging marine predator, the grey petrel Procellaria cinerea, to assess model transferability across the Southern Hemisphere (25-65°S). Oceanographic data were combined with tracks of grey petrels from two remote sub-Antarctic islands (Antipodes and Kerguelen) using boosted regression trees to generate three SDMs: one for each island population, and a combined model. The predictive performance of these models was assessed using withheld tracking data from within the model calibration areas (interpolation), and from a third population, Marion Island (extrapolation). Predictive performance was assessed using k-fold cross validation and point biserial correlation. The two population-specific SDMs included the same predictor variables and suggested birds responded to the same broad-scale oceanographic influences. However, all model validation tests, including of the combined model, determined strong interpolation but weak extrapolation capabilities. These results indicate that habitat use reflects both its availability and bird preferences, such that the realized distribution patterns differ for each population. The spatial predictions by the three SDMs were compared with tracking data and fishing effort to demonstrate the conservation pitfalls of extrapolating SDMs outside calibration regions. This exercise revealed that SDM predictions would have led to an underestimate of overlap with fishing effort and potentially misinformed bycatch mitigation efforts. Although SDMs can elucidate potential distribution patterns relative to large-scale climatic and oceanographic conditions, knowledge of local habitat availability and preferences is necessary to understand and successfully predict region-specific realized distribution patterns.

The identification of geographic areas where the densities of animals are highest across their annual cycles is a crucial step in conservation planning. In marine environments, however, it can be particularly difficult to map the distribution of species, and the methods used are usually biased towards adults, neglecting the distribution of other life‐history stages even though they can represent a substantial proportion of the total population. Here we develop a methodological framework for estimating population‐level density distributions of seabirds, integrating tracking data across the main life‐history stages (adult breeders and non‐breeders, juveniles and immatures). We incorporate demographic information (adult and juvenile/immature survival, breeding frequency and success, age at first breeding) and phenological data (average timing of breeding and migration) to weight distribution maps according to the proportion of the population represented by each life‐history stage. We demonstrate the utility of this framework by applying it to 22 species of albatrosses and petrels that are of conservation concern due to interactions with fisheries. Because juveniles, immatures and non‐breeding adults account for 47%–81% of all individuals of the populations analysed, ignoring the distributions of birds in these stages leads to biased estimates of overlap with threats, and may misdirect management and conservation efforts. Population‐level distribution maps using only adult distributions underestimated exposure to longline fishing effort by 18%–42%, compared with overlap scores based on data from all life‐history stages. Synthesis and applications. Our framework synthesizes and improves on previous approaches to estimate seabird densities at sea, is applicable for data‐poor situations, and provides a standard and repeatable method that can be easily updated as new tracking and demographic data become available. We provide scripts in the R language and a Shiny app to facilitate future applications of our approach. We recommend that where sufficient tracking data are available, this framework be used to assess overlap of seabirds with at‐sea threats such as overharvesting, fisheries bycatch, shipping, offshore industry and pollutants. Based on such an analysis, conservation interventions could be directed towards areas where they have the greatest impact on populations.

Pelagic seabirds are highly mobile, reducing the likelihood of allopatric speciation where disruption of gene flow between populations is caused by physically insurmountable, extrinsic barriers. Spatial segregation during the non-breeding season appears to provide an intrinsic barrier to gene flow among seabird populations that otherwise occupy nearby or overlapping regions during breeding, but how this is achieved remains unclear. Here we show that the two genetically distinct populations of Cook's petrel (Pterodroma cookii) exhibit transequatorial separation of non-breeding ranges at contemporary (ca. 2-3 yrs) and historical (ca. 100 yrs) time scales. Segregation during the non-breeding season per se appears as an unlikely barrier to gene flow. Instead we provide evidence that habitat specialization during the non-breeding season is associated with breeding asynchrony which, in conjunction with philopatry, restricts gene flow. Habitat specialization during breeding and non-breeding likely promotes evolutionary divergence between these two populations via local adaptation.

Breeding sooty shearwaters Puffinus griseus cycle between long (11 to 14 d) and short (1 to 2 d) foraging bouts at sea, but no information exists on bird behavior during these trips. We tested the hypothesis that shearwaters use these long trips to travel to distant Antarctic waters compared to remaining in local waters. Patterns of habitat use of 28 breeding sooty shearwaters were studied using 6 g archival data loggers that recorded location, environmental temperature, and diving behavior. Dive activity was compared to remotely-sensed environmental data to characterize the habitats visited by shearwaters on long and short trips. Sooty shearwaters traveled predominantly (70% of all long trips) to cold oceanic waters along the Polar Front (mean ± SD, 1970 ± 930 km from colony) on long trips or remained within warmer neritic waters of the New Zealand shelf (515 ± 248 km from colony) on short trips. Diving depths (mean depth 15.9 ± 10.8 m, max depth 69.9 m, n = 2007 dives) were not significantly different between excursion types. Activity patterns suggest that shearwaters commuted between distant foraging grounds (e.g. Polar Front) and the breeding colony and that more than 95% of diving activity occurred during daylight hours. Although shearwaters traveled primarily to Antarctic waters on long trips, occasional trips around New Zealand waters were observed; all but 2 birds were from the northern-most study colony. Oceanic habitats in Antarctic waters were substantially different from neritic habitats around New Zealand, indicating that shearwaters experience dramatically different environmental conditions associated with each excursion type. The ability of sooty shearwaters to use 2 vastly different habitats provides greater flexibility for maximizing resource acquisition during breeding and reduces competition near the colony.

Petrels are highly mobile seabirds that face many threats and whose conservation is frequently hampered by a lack of understanding of their biology at sea. We used a combination of data from burrow monitoring and geolocationimmersion loggers to study the intra-and inter-seasonal distribution and behaviour of the endangered Chatham Petrel (Pterodroma axillaris), breeding on Rangatira Island, New Zealand. Breeding extended from November to June with a prelaying exodus of 35 days; an incubation period of 46 days, with up to five incubation shifts; and a chick-rearing period of 87 days, including a desertion period of 10 days. When breeding, Chatham Petrels foraged between the Subtropical Convergence and Subantarctic Fronts, moving 2000-3000 km to the south-east of the Chatham Islands, during the pre-laying exodus and incubation period, but restricting foraging to the south of the Chatham Islands, around the Bollons Seamount, during chick-rearing. Between April and June birds migrated east and north to core non-breeding distributions~1000 km from the coast of Peru and Chile. Birds spent a greater proportion of time resting and nocturnally active during the nonbreeding period than when breeding, when birds where active during darkness and daylight. These data contribute to the conservation management of the Chatham Petrel and to conservation initiatives to identity marine protected areas for endangered seabirds on the high seas beyond national jurisdictions.