The Hutton's shearwater Puffinus huttoni is an endangered seabird endemic to Kaikōura, New Zealand, but the spatial and temporal aspects of its at‐sea foraging behavior are not well known. To identify foraging areas and estimate trip durations, we deployed Global Positioning Systems (GPS) devices and Time‐Depth Recorders (TDR) on 26 adult Hutton's shearwaters during the chick‐rearing period in 2017 and 2018. We found Hutton's shearwaters traveled much further from their breeding grounds at Kaikōura than previously considered, with most individuals foraging in coastal and oceanic areas 125–365 km south and near Banks Peninsula. Trip durations varied from 1 to 15 days (mean = 5 days), and total track lengths varied from 264 to 2,157 km (mean = 1092.9 km). Although some diving occurred in near‐shore waters near the breeding colony, most foraging was concentrated in four regions south of Kaikōura. Dive durations averaged 23.2 s (range 8.1 to 71.3 s) and dive depths averaged 7.1 m (range 1.5 to 30 m). Foraging locations had higher chlorophyll a levels and shallower water depths than nonforaging locations. Birds did not feed at night, but tended to raft in areas with deeper water than foraging locations. Mapping the spatial and temporal distribution of Hutton's shearwaters at sea will be fundamental to their conservation, as it can reveal potential areas of overlap with fisheries and other industrial users of the marine environment.

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.

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Stable isotope analysis of feathers can provide an indirect method to investigate the diet and foraging locations of birds during the time the feathers were growing. We used the isotopic composition of experimentally-induced feathers to investigate the foraging locations of the Hutton's shearwater (Puffinus huttoni), an endangered seabird that is a breeding endemic to the Kaikōura region of New Zealand. The isotopic composition of feathers was first compared with potential prey items collected from the near-shore marine environment near the breeding colony. By applying trophic fractionation factors (2-4 ‰ increase in δ 15 N for every 1 ‰ increase in δ 13 C) and comparing the isotopic composition of the induced tail feathers and sampled prey items, we found that feather isotopic compositions were not consistent with a diet based on feeding locally. Both the δ 13 C and δ 15 N from zooplankton and fish collected within 8 km of Kaikōura were significantly different than the isotopic composition of induced feathers and were outside of the range expected for consumed local prey items. Instead, we found the isotopic composition of Hutton's shearwater feathers was more consistent with feeding on potential prey items in the seas north-east and around Banks Peninsula, an area c. 100 km south of the breeding colony and where they had been tracked previously. Stable isotope analysis can provide insight into the foraging behaviour of birds at sea and demonstrates the importance of isotopic research in pinpointing foraging locations in seabirds with large geographic ranges.