Biz Bell bands a Black Petrel on Great Barrier Island

The ACAP-listed and globally Vulnerable Black Petrel Procellaria parkinsoni is a New Zealand endemic that breeds on Great and Little Barrier Islands at the edge of North Island’s Hauraki Gulf.  The breeding colony on the upper slopes of Mount Hobson/Hirakimata on the former island has been studied for many years by the New Zealand-based ecological consultancy Wildlife Management International, with burrows marked and monitored every breeding season.  Adults and chicks close to fledging are banded for identification but fewer fledglings than might be expected have been returning to the study colony to prospect for burrows as young adults and commence breeding.

An illustrated article recently published online by RZN News describes the 29-year study and considers what might be happening to the birds in their first few years at sea.  The article states “… on average, more than 70 percent of petrel parents monitored by the survey successfully fledge a chick each year.  But of the thousands of chicks that have been banded over the decades, only about 10 percent of them have ever been found again.  What happens to the rest is still largely a mystery”.

Black Petrel at sea off North Cape, New Zealand, photograph by Kirk Zufelt

In the article, the Managing Director of Wildlife Management International Elizabeth ‘Biz’ Bell is quoted as saying "We've banded over 5500 chicks over the 29 years and we've had less than 500 return.  Is that because we can't search this entire, massive island and they're somewhere else?  Are they dying at sea?  Are they dying on migration?  Are they dying in fishing boats? Are they dying from pollution events, climate change?  It's one of our biggest gaps of knowledge.”

Black Petrels are known to be caught on long lines.  Adoption and implementation of ACAP-approved best-practice mitigation measures by fisheries throughout the species’ at-sea range is required to reduce the numbers of fledglings assumed to being drowned on hooks.

With thanks to Susan Waugh for information.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 26 February 2025

Graphical abstract from the publication

Yasmina Rodríguez (Instituto de Investigação em Ciências do Mar, Universidade dos Açores, Horta, Portugal) and colleagues have published open access in the journal Marine Environmental Research on plastic ingestion by Cory/s Shearwaters Calonectris borealis.  They show that breeding birds “clear out” >80% of their ingested plastics by regurgitating them to their chicks.

The paper’s abstract follows:

“Plastic ingestion has been extensively studied in seabirds.  However, knowledge gaps remain in understanding how plastic loads behave over time and their residence inside Procellariforms.  This study investigated the temporal dynamics of ingested plastics by adult Cory's shearwaters (Calonectris borealis) during the breeding season to shed light on plastic retention times.  We analysed the plastic content in the stomachs of 96 adults collected from 2015 to 2022 in the Azores archipelago (NE Atlantic) across distinct nesting periods: pre-laying, incubation, and chick-rearing. Our results revealed a general decrease in plastic loads over the breeding season, resulting in a marked reduction in the number of plastics before the winter pelagic phase. We found that plastic contents in breeders are mainly influenced by the intergenerational transfer of this contaminant to the offspring, indicating that progenitors highly reduce the concentrations of plastics from the stomachs (>80%) during the chick-rearing period. Understanding temporal patterns and retention time of plastic litter in seabirds is crucial for using them as indicators, with our results supporting fledglings of the studied species as the preferable age for fulfilling such a role in the breeding areas. Cory's shearwater breeders may contain plastics from their far-away wintering foraging grounds at the beginning of the breeding season, which would reflect plastics ingested in their transoceanic migrations or wintering regions beyond their breeding colonies. Moreover, they reset their plastic loads when nesting leading to underestimations if they are used as sentinels of plastic contamination during or after chick-rearing”.

Reference:

Rodríguez, Y., Rodríguez, A., Pereira, J.M. & Pham, C.K. 2025.  Plastics reset in an adult Procellariform seabird species during the breeding season.  Marine Environmental Research 204. 106939.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 25 February 2025

The six marine flyways identified across four ocean basins from analysis of tracking data for 48 pelagic seabird species breeding at the 64 colonies indicated by the black squares

Joanne Moreton (BirdLife International, Cambridge, UK) and many colleagues have published open access in the journal Global Ecology and Biogeography on identifying marine flyways by tracking pelagic seabirds.

The paper’s abstract follows:

“Aim

To identify the broad-scale oceanic migration routes (‘marine flyways’) used by multiple pelagic, long-distance migratory seabirds based on a global compilation of tracking data.

Location

Global.

Time Period

1989–2023.

Major Taxa Studied

Seabirds (Families: Phaethontidae, Hydrobatidae, Diomedeidae, Procellariidae, Laridae and Stercorariidae).

Methods

We collated a comprehensive global tracking dataset that included the migratory routes of 48 pelagic and long-distance migrating seabird species across the Atlantic, Indian, Pacific and Southern Oceans. We grouped individuals that followed similar routes, independent of species or timings of migration, using a dynamic time warping clustering approach. We visualised the routes of each cluster using a line density analysis and used knowledge of seabird spatial ecology to combine the clusters to identify the broad-scale flyways followed by most pelagic migratory seabirds tracked to-date at an ocean-basin scale.

Results

Six marine flyways were identified across the world's oceans: the Atlantic Ocean Flyway, North Indian Ocean Flyway, East Indian Ocean Flyway, West Pacific Ocean Flyway, Pacific Ocean Flyway and Southern Ocean Flyway. Generally, the flyways were used bidirectionally, and individuals either followed sections of a flyway, a complete flyway, or their movements linked two or more flyways. Transhemispheric figure-of-eight routes in the Atlantic and Pacific oceans, and a circumnavigation flyway in the Southern Ocean correspond with major wind-driven ocean currents.

Main Conclusions

The marine flyways identified demonstrate that pelagic seabirds have similar and repeatable migration routes across ocean-basin scales. Our study highlights the need to account for connectivity in seabird conservation and provides a framework for international cooperation.”

Reference:

Moreton, J.A, et al. 2025.  Global marine flyways identified for long‐distance migrating seabirds from tracking data.  Global Ecology and Biogeography 34(2). e70004.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 24 February 2025

A Manx Shearwater off the coast of Brazil, photograph by Dimas Gianuca

Katrina Siddiqi-Davies (Department of Biology, University of Oxford, UK) and colleagues have published open access in the journal Scientific Reports on migrating Manx Shearwaters Puffinus puffinus

The paper’s abstract follows:

“Long-distance migrants must optimise their timing of breeding to capitalise on resources at both breeding and over-wintering sites. In species with protracted breeding seasons, departing earlier on migration might be advantageous, but is constrained by the ongoing breeding attempt. Here we investigated how breeding timing affects migratory strategies in the Manx shearwater (Puffinus puffinus), a trans-hemispheric migratory seabird with large temporal variation in the onset of breeding. Using a geolocator tracking dataset, we found that that later-laying shearwaters had shorter overall breeding periods, yet still departed later for autumn migration. Earlier laying birds had increased migratory duration, stopped with greater frequency and at sites of higher chlorophyll concentration. Meanwhile, later departing birds flew more at night during migratory stints, and night flight generally increased with moon illumination, which could reflect moonlight providing the light conditions required for visually guided flight. Accordingly, birds that experienced higher levels of moon illumination whilst migrating had shorter migration durations. Here we provide an example of migratory behaviour being adjustable with breeding timing, allowing birds to both complete breeding and capitalise on resource availability at the wintering site.”

Reference:

Siddiqi-Davies, K., Wynn, J., Padget, O. et al. 2024.  Night flight facilitates late breeding catch-up in a long-distance migratory seabird.  Scientific Reports 14. 31792.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 21 February 202