BackgroundAnimals adjust activity budgets as competing demands for limited time and energy shift across life history phases. For far-ranging migrants and especially pelagic seabirds, activity during breeding and migration are generally well studied but the “overwinter” phase of non-breeding has received less attention. Yet this is a critical time for recovery from breeding, plumage replacement and gaining energy stores for return migration and the next breeding attempt. We aimed to identify patterns in daily activity budgets (i.e. time in flight, floating on the water’s surface and active foraging) and associated spatial distributions during overwinter for the laysan Phoebastria immutabilis and black-footed P. nigripes albatrosses using state-space models and generalized additive mixed-effects models (GAMMs). We applied these models to time-series of positional and immersion-state data from small light- and conductivity-based data loggers.ResultsDuring overwinter, both species exhibited a consistent ‘quasi-flightless’ stage beginning c. 30 days after initiating migration and lasting c. 40 days, characterized by frequent long bouts of floating, very little sustained flight, and infrequent active foraging. Minimal daily movements were made within localized areas during this time; individual laysan albatross concentrated into the northwest corner of the Pacific while black-footed albatross spread widely across the North Pacific Ocean basin. Activity gradually shifted toward increased time in flight and active foraging, less time floating, and greater daily travel distances until colony return c. 155 days after initial departure.ConclusionsOur results demonstrate that these species make parallel adjustments to activity budgets at a daily time-scale within the overwinter phase of non-breeding despite different at-sea distributions and phenologies. The ‘quasi-flightless’ stage likely reflects compromised flight from active wing moult while the subsequent increase in activity may occur as priorities shift toward mass gain for breeding. The novel application of a GAMM-based approach used in this study offers the possibility of identifying population-level patterns in shifting activity budgets over extended periods while allowing for individual-level variation in the timing of events. The information gained can also help to elucidate the whereabouts of areas important at different times across life history phases for far-ranging migrants.

Past tracking studies of marine animals have primarily targeted adults, biasing our understanding of at‐sea habitat use toward older life stages. Anthropogenic threats persist throughout the at‐sea ranges of all life stages and it is therefore of interest to population ecologists and managers alike to understand spatiotemporal distributions and possible niche differentiation between age‐classes. In albatrosses, particularly little is known about the juvenile life stage when fledglings depart the colonies and venture to sea with no prior experience or parental guidance. We compared the dispersal of 22 fledgling Black‐footed Albatross Phoebastria nigripes between 2006 and 2008 using satellite telemetry and 16 adults between 2008 and 2009 using geolocaters from Midway Atoll National Wildlife Refuge, Northwest Hawaiian Islands. Following tag deployment, all fledglings spent several days within the calm atoll waters, then travelled northward until reaching 750–900 km from the colony. At this point, fledgling distributions approached the productive North Pacific Transition Zone (NPTZ). Rather than reaching the high chlorophyll a densities on the leading edge of this zone, however, fledglings remained in areas of low productivity in the subtropical gyre. In contrast, adult albatrosses from the same breeding colony did not utilize the NPTZ at this time of year but rather ranged throughout the highly productive northern periphery of the Pacific Ocean Basin among the shelf regions off Japan and the Aleutian Islands. The dichotomy in habitat use between fledglings and adults from Midway Atoll results in complete spatial segregation between age‐classes and suggests ontogenetic niche separation in this species. This research fills a large knowledge gap in at‐sea habitat use during a little known yet critical life stage of albatrosses, and contributes to a more comprehensive understanding of differential mortality pressure between age‐classes and overall conservation status for the vulnerable Black‐footed Albatross.

Marine ecologists and managers need to know the spatial extent of at-sea areas most frequented by the groups of wildlife they study or manage. Defining group-specific ranges and distributions (i.e., space use at the level of species, population, age-class, etc.) can help to identify the source or severity of common or distinct threats among different at-risk groups. In biologging studies, this is accomplished by estimating the space use of a group based on a sample of tracked individuals. A major assumption of these studies is consistency in individual movements among members of a group. The implications of scaling up individual-level tracking data to infer higher-level spatial patterns for groups (i.e., size and extent of areas used, overlap or segregation among groups) is not well documented for wide-ranging pelagic species with high potential for individual variation in space use. We present a case study exploring the effects of sampling (i.e., number and identity of individuals contributing to an analysis) on defining group-specific space use with year-round multi-colony tracking data from two highly vagile species, Laysan (Phoebastria immutabilis) and black-footed (P. nigripes) albatrosses. The results clearly demonstrate that caution is warranted when defining space use for a specific species-colony-period group based on datasets of small, intermediate, or relatively large sample sizes (ranging from n = 3-42 tracked individuals) due to a high degree of individual-level variation in movements. Overall, we provide further support to the recommendation that biologging studies aiming to define higher-level patterns in space use exercise restraint in the scope of inference, particularly when pooled Kernel Density Estimation (KDE) techniques are applied to small datasets for wide-ranging species. Transparent reporting in respect to the potential limitations of the data can in turn better inform both biological interpretations and science-based management decisions.

Successful conservation of threatened species is often hindered by a lack of long-term data required to identify the vital rates contributing to population decline and the extrinsic factors influencing those rates. Museum collections can provide a valuable resource for reconstructing the historic demography and diet of otherwise elusive species. Here, we used age ratios (the relative number of hatch-year to after-hatch-year individuals) to examine the hypothesis that population declines in a threatened seabird, the marbled murrelet Brachyramphus marmoratus, are due to declines in reproductive success over the past 150 yr. We also used stable-nitrogen isotopes to examine the hypothesis that variation in reproductive success over this period is related to the quality of food received by young in the nest. Age ratios from at-sea surveys conducted from 1994 to 2001 were significantly lower than museum collection age ratios for the period 1860 to 1950. Stable-nitrogen isotope values indicated that the trophic feeding level of marbled murrelet nestlings declined significantly (-2.6 ‰) from 1854 to 2008. Our results suggest that the reproductive success of marbeled murrelets breeding in the Salish Sea has declined over the past 150 yr and that declines in nestling diet quality may be partly responsible. Overall, our results support the idea that managers should consider the quality of both nesting and marine foraging habitat as they attempt to improve reproductive success and population growth rate in this threatened species.KEY WORDS: Marbled murrelet · Stable isotopes · Age ratios · Diet reconstruction · Museum specimens · Brachyramphus marmoratus · Salish Sea Resale or republication not permitted without written consent of the publisher Contribution to the Theme Section 'Forensic methods in conservation research' OPEN PEN ACCESS CCESS

1. Habitat loss and degradation are contributing to severe declines in many North American bird species. For American woodcock Scolopax minor ('woodcock'), loss of preferred young forest habitat matrices are generally attributed as the primary drivers of range-wide population declines in eastern North America, but regional patterns in abundance or habitat availability have not been assessed in Nova Scotia, the northeastern-most portion of the range. 2. Our objectives were to (a) identify regions of similar trends over the past five decades, (b) evaluate spatiotemporal relationships in the effect of habitat availability on abundance across the province and (c) provide recommendations for woodcock management priorities in Nova Scotia to target local population declines. 3. Using 50 years of standardised surveys and habitat measures, we investigated woodcock population trends and local habitat availability by applying a novel spatiallyexplicit model with Integrated Nested Laplace Approximation. 4. Province-level declines were primarily driven by losses of breeding woodcock in the north and south of the province, while the central region experienced growth. The proportion of area around a survey route comprised of clear-cut, harvested forest was the most important habitat feature of nine potential explanatory variables to affect abundance, where higher levels of clear-cut area predicted higher abundance, particularly in the last 15 years (increase from two to 10 birds on average as the amount of clear-cut area increased from zero to 28%). 5. Historically, habitat for species requiring open areas and regenerating forests would be established through periodic natural disturbance. Today, it is impractical for these processes to occur unimpeded, thus commercial timber harvests and proactive habitat management are necessary to ensure habitat availability. For woodcock in Nova Scotia, partnering with both the local forest products industry and wider national and international habitat management initiatives to provide habitat in the southern and northern regions of the province could be key to improving the population status both locally This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Opportunist gulls use anthropogenic food subsidies, which can bolster populations, but negatively influence sensitive local ecosystems and areas of human settlement. In the eastern Gulf of Maine, Canada, breeding herring gulls Larus argentatus have access to resources from aquaculture, fisheries and mink farms, but the relative influence of industry on local gull populations is unknown. Our objectives were to 1) assess use of natural and anthropogenic habitats by herring gulls from multiple colonies, 2) evaluate variation among colonies in use of distinct resource types within these habitats and 3) highlight areas of high gull:industry interaction. Using GPS devices on 39 gulls from four colonies, we identified visitation behaviour (slow, localized movements) and assigned visits to nine resource types. To evaluate the spatial distribution of visits, we created a use intensity index, reflecting both fidelity (i.e. repeated visits) and time spent in specific areas. All four anthropogenic resource types were heavily used (56 ± 11% of visiting time across colonies), notably, fish plants and mink farms. Despite large distances among three colonies, birds overlapped at particular distant, inland mink farms. In contrast, birds from close colonies overlapped in visitation to specific nearby resources (e.g. fish plants and human settlement), and otherwise diverged in distribution and use of offshore and coastal areas. Birds from three colonies also made frequent, long visits to uninhabited islands. Industry is clearly influencing the behaviour of breeding gulls in the eastern Gulf of Maine, Canada, where birds are travelling great distances or spending large proportions of time interacting with anthropogenic resources, while otherwise paying lengthy visits to nearby coastal islands. Studies have shown that concentrations of gulls can have harmful direct and indirect ecological and societal impacts. Our findings have implications for the management and regulation of industry to mitigate detrimental effects on local ecosystems and humans.

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