Researchers from the University of Cambridge, the University of Liverpool, Island Conservation and Oikonos are using GPS to track and uncover the movements of the Stejneger’s and Juan Fernandez Petrels.

The Juan Fernández Islands are located in the southwest Pacific Ocean, almost 500 miles west of Chile. For centuries they were thought to be the inspiration behind Daniel Defoe’s famous novel Robinson Crusoe, based on the Scottish pirate Alejandro Selkirk who spent four years marooned there in the early 18^th century. Although this link is not so clear-cut, the names of the two largest islands, Robinson Crusoe and Alejandro Selkirk, are living reminders of the islands’ seafaring past.

In recent decades, the archipelago has gained international attention for its ecological significance – due to their distinct climate and remoteness, the islands host unique and fauna found nowhere else on Earth. Per square kilometre, they are 61 times richer in endemic plant species and 13 times greater in endemic bird species richness than the Galápagos Islands. In recognition of its rich marine life, in 2017 the Chilean Government committed to creating a new marine reserve around the archipelago, the largest in the Americas at 485,000 km².

Despite the islands’ isolation, many species are under threat, both on land and at sea. Introduced and invasive plants and mammals such as cattle, cats, goats, mice, rabbits and rats, have damaged native ecosystems through grazing, habitat alteration and destruction, and predation. Through predation and competition for nesting burrows, non-native mammals directly threaten two endemic seabird species the Stejneger’s Petrel (Pterodroma longirostris) and Juan Fernandez Petrel (P. externa). Both species are listed as Vulnerable by the International Union for the Conservation of Nature (IUCN).

Like the seafarers of old, these two seabirds spend most of their lives at sea. Yet, very little is known about where they go, including feeding areas and the marine threats they face. Like other related species, they may cover thousands of miles in search for food. Both species are thought to feed in the South Pacific Gyre and anecdotal evidence suggests they migrate to and feed in the North Pacific Gyre, the location of the now infamous Great Pacific Garbage Patch. The birds feed by picking fish and squid off the sea surface and so are likely to be at risk of ingesting plastics. While the effects on populations are not clear, eating large quantities of plastic provides little room for food, and so may lead to starvation.

Our new project, funded by the National Geographic Society (NGS) Explorer Scheme plans to use tracking technology to uncover their migration and feeding habits. The research team, led by Michael Brooke from the University of Cambridge in the UK, includes seabird researchers and conservation scientists from the University of Liverpool in the UK and the NGOs Oikonos and Island Conservation, based in the USA and Chile.

In December 2019, NGS Explorer Michael will lead an 8-week research expedition to Isla Alejandro Selkirk, to track the movement patterns of both petrel species. Lightweight GPS devices (weighing 9 g) will be attached to breeding Juan Fernández petrels providing precise information on foraging movements and behaviors.

Michael willl also deploy miniature geolocators (weighing 1 g) on both Juan Fernández and Stejneger’s Petrels which will record their year-round movements, including trans-equatorial migrations to the North Pacific Ocean. In two years, the team will return to the southeast Pacific to retrieve the loggers and see where the birds spend the years.

We hope that with this project we can uncover the mysteries of these seabirds. This information will enable us to monitor the extent to which they are exposed to plastic pollution, and whether their feeding areas are protected by the new marine reserve. Ultimately, we hope our work can advise marine conservation policy to protect these birds, and also highlight the role of seabirds as flagship species for conservation at ocean-basin scales.

Featured photo: Endemic Stejneger’s Petrel. Credit: Island Conservation