Seabirds’ Ocean-Wide Movements Revealed by GPS Data

Seabirds are among the most endangered groups of animals in the world, facing multiple threats from climate change, fishing, invasive species, and pollution.

But a new study has revealed that many seabirds, especially petrels, are also at risk of encountering plastic pollution in remote areas of the ocean, where they spend most of their lives.

The researchers have identified a vast region of the North Atlantic, spanning nearly 600,000 square kilometers, as a hotspot for seabirds and plastic debris.

They have called for international cooperation to protect this critical habitat and reduce the impact of plastic on seabirds and other marine wildlife.

Seabirds are indicators of ocean health

(Photo : NICOLAS GARCIA/AFP via Getty Images)

Seabirds are birds that breed on land and forage for food at sea, such as albatrosses, gulls, terns, and penguins.

They are considered to be indicators of ocean health, as they reflect the availability and quality of their prey, which are mainly fish and plankton.

Seabirds also play important roles in marine ecosystems, as they transfer nutrients from the ocean to the land, and act as predators and scavengers.

However, seabirds are facing a global decline, with almost half of all seabird species in decline.

According to the International Union for Conservation of Nature (IUCN), 28% of seabird species are threatened with extinction, and 10% are critically endangered.

Some of the main causes of seabird decline are climate change, which affects their breeding and feeding habitats, bycatch, which is the accidental capture of seabirds in fishing gear, and predation by invasive species, such as cats and rats, on their nesting islands.

Another emerging threat to seabirds is plastic pollution, which is increasing in the ocean due to human activities.

Plastic can harm seabirds in various ways, such as entanglement, ingestion, injury, and infection. It can also affect the behavior and physiology of seabirds, such as reducing their stomach capacity, impairing their digestion, and altering their hormone levels.

Plastic ingestion can also have lethal consequences, as it can cause blockages, perforations, and starvation.

Also Read: Ecologists Start to Worry as the Number of Dead Seabirds Dying in Bulk Stacks Up

Petrels are particularly vulnerable to plastic pollution

Petrels are a group of seabirds that belong to the order Procellariiformes, which includes shearwaters, storm petrels, diving petrels, and albatrosses.

They are characterized by their long and narrow wings, tubular nostrils, and ability to fly long distances over the ocean.

Petrels are also known for their remarkable sense of smell, which they use to locate their prey and their mates. They are particularly vulnerable to plastic pollution, as they often mistake plastic items for food or prey.

This bird has a strong attraction to oily substances, such as fish oil, which can be found on some plastic items.

Petrels also have difficulty regurgitating the plastic they ingest, unlike some other seabirds, such as gulls, which can vomit the plastic out.

This means that they can accumulate large amounts of plastic in their stomachs, which can reduce their appetite, weight, and survival.

Moreover, petrels transfer the plastic they ingest to their chicks when they feed them by regurgitation, which can affect their growth and development.

A hotspot for seabirds and plastic in the North Atlantic

In a recent study, a team of researchers from BirdLife International, a conservation nonprofit, and other institutions, tracked the movements of over 7,000 petrels of 77 different species, using satellite tags, GPS devices, and geolocators.

They combined this data with existing maps of marine plastic pollution, which are based on models and observations, to calculate an exposure risk score for each species.

This score indicates the likelihood of a species encountering plastic pollution at sea, based on its distribution, abundance, and behavior.

The researchers found that many petrel species spend a lot of time in areas of the ocean with high concentrations of plastic, especially during the non-breeding season, when they roam widely across the ocean.

They identified a region of the North Atlantic, reaching from the Grand Banks of Newfoundland and Labrador to the Mid-Atlantic Ridge, and from the Azores to the Labrador Basin off Greenland, as a hotspot for seabirds and plastic.

This region accounted for over half of the global plastic exposure risk for petrels and hosted an estimated 2.9 to five million seabirds annually.

The researchers described this region as the highest concentration of seabirds ever documented on the open ocean.

The researchers attributed the high abundance of seabirds and plastic in this region to the presence of oceanographic features, such as cold fronts, eddies, and gyres, which create favorable conditions for both.

These features enhance the productivity and diversity of marine life, by bringing up nutrients and oxygen from the deep ocean and attracting fish and plankton.

They also trap and accumulate plastic debris, by creating circular currents that prevent the plastic from escaping.

The researchers found that the most important feature for seabirds and plastic in this region was the Subtropical Front, which is a boundary between warm and cold water masses that extend across the North Atlantic.

Related article: Plastic Pollution Threatening Seabirds