Checking Shorebirds for Microplastics at Alaska’s Unique Migration Stopover

On the vast mud flats of Alaska’s Copper River Delta, scientists catch Sandpipers and take faecal samples to reveal how much plastic they have unwittingly eaten on their challenging journey northwards.

Spring is a critical time on Alaska’s Copper River Delta. Millions of hungry shorebirds land to rest and forage after flying for thousands of miles from their overwintering grounds in South America. Sandpipers and other shorebirds take a well-earned break in these enormous landscapes of tidal mudflats fringed by snowy mountains – before resuming the journey to their breeding grounds further north.

Unfortunately for the hungry birds, even this alluring wilderness may be less pristine than it first appears. Microplastics – tiny pieces less than five millimetres long – might be finding their way into the birds’ stomachs. But with little known about the effects or the extent of the problem, researchers at the Prince William Sound Science Center are determined to carefully investigate the birds’ diets.

We spoke to the Center’s Senior Research Scientist Dr. Mary Anne Bishop about her team’s project.

Alaska’s Copper River Delta 2
Photo: Prince William Sound Science Center

Microplastics in the remote wilderness

Each year, approximately 11 million tonnes of plastic enter the world’s seas. “Plastics are a major pollutant in the ocean,” says Mary Anne. “Some birds and marine animals like sea turtles get tangled in some of the bigger pieces.”

However, much of it breaks down in different ways into smaller pieces. Microplastics such as this are either microfibres or tiny pieces of hard plastic.

“We're trying to find out if the shorebirds ingest tiny pieces of plastic on the delta’s mudflats, because microplastics tend to accumulate in coastal areas,” says Mary Anne. “They tend to be found more on a coastline than where a bird might be migrating inland.”

“Is this wilderness pristine? Or are plastics here like everywhere else? That’s what we’re trying to find out with this project.”

“The Copper River Delta is the major spring migratory shorebird stopover site on the Pacific Flyway.”

– Dr. Mary Anne Bishop, Senior Research Scientist, Prince William Sound Science Center

A special location on the migration route

This is an ideal place to sample birds. “We get many shorebirds coming through here,” says Mary Anne. “The Copper River Delta is the major spring migratory shorebird stopover site on the Pacific Flyway.”

At about 100 kilometres across, the delta is a national forest and an undeveloped wilderness like few others. This makes it a special habitat for shorebirds like the Western Sandpiper.

“If you're a shorebird coming up that West Coast, you suddenly see this enormous mudflat and it’s like a bonanza. It’s an enormous mudflat. It’s so impressive – it’s just spectacular,” enthuses Mary Anne.

The Western Sandpiper

The Western Sandpiper is the most numerous Sandpiper on the West Coast, and most of them stop on the Copper River Delta here to rest and eat. They have come from as far south as Mexico and Peru, with their last major stopover before the delta at Gray’s Harbor Washington, some 1,300 miles (approximately 2,200 km) distant.

“The main thing they come here for is to rest and eat,” says Mary Anne. “There are worms, small crustaceans, and fly larvae. But one of the main things that they eat is Macoma balthica, a small clam that occurs in high densities here,” she says.

“So, because these birds are foraging on the mudflat, we're going to be sampling both the sediments and faecal samples from the birds.”

“People love it, and we usually let them release birds once they are banded.”

– Mary Anne Bishop, Senior Research Scientist

Mist netting to catch the birds

To get samples, the team from the Prince William Sound Science Center sets up long nets along the shore. These are so fine the birds can’t see them very easily.

“The birds are flying up and down the mudflats on the rising and falling tides,” explains Mary Anne, “so that’s when we go out with a team of people who help extract them from the net.”

The Science Center banding team puts the birds in cardboard boxes that have been lined with aluminium foil, to catch their droppings. Then they take the birds out, measure them, and tag them with a ring on their leg so they can be individually identified.

It’s not always as easy as it sounds, however. “It can be hard if the wind’s blowing, or if there aren’t a lot of birds around,” says Mary Anne. “Sometimes, we'll try to herd them into the nets, and they'll still go around the side or they'll fly over the net. So it can be tricky!”

For this project, the team are going to be sampling about 30 birds, and shipping the faecal samples off to a lab in Canada that's doing the analysis.

Engaging the public

“People love it, and we usually let them release birds once they are banded. People love birds, especially when they get to see them up close. And this really gives them that opportunity,” says Mary Anne.

The Prince William Sound Science Center also publishes an annual newspaper about the local natural history called Delta Sound Connections, which will contain an article about the project. They also make posters to display at the Copper River Delta Shorebird Festival, which explains the shorebird microplastic project.

These activities – as well as the sampling itself – is funded by Hurtigruten Foundation with NOK 50,000 (approx. €4,340).

“The funding gets us a skilled workforce for the mist netting we’re doing, as well as the posters and the article,” explains Mary-Anne. “If you want to do fieldwork, you need money to pay for that time.”

“The idea here is to get some preliminary data to get things going, and then to apply for more funding in future,” she concludes.

The Canadian connection

Mary Anne’s work on the Copper River Delta is one important part of a large-scale, international effort led by the Canadian government department, Environment and Climate Change Canada. Combined with the results of similar projects, the work of Mary Anne and the Prince William Sound Science Center will contribute to investigating and understanding shorebirds and microplastics all along their migration route, from Mexico to the Yukon Kuskokwim Delta in western Alaska.

Where can I learn more?

You can read more and follow the scientists’ progress on the Prince William Sound Science Center website.

If you would like to learn more about travelling to Alaska, see Hurtigruten Expeditions’ cruises to Alaska