An Agate Original
Common Terns are agile fliers. Photo by Carrol Henderson 
There isn’t much to a tern nest, but parents defend their young fearlessly. Photo courtesy Fred Strand 
A fluffy tern chick emerges. Photo courtesy Fred Strand 
About 40,000 Ring-billed Gulls nest on Interstate Island. Photo courtesy Fred Strand 
Outline of planned island expansion. Photo courtesy SEH Inc. 
April: Workers place sand to raise flooded portions of Interstate Island, April, 2020. Photo courtesy JB Brennan 
Fred Strand and NRRI researcher Annie Bracey monitor terns. Photo courtesy MN DNR 
Gini Breidenbach spreads gravel. Nesting area is elevated; fence posts are not yet in place. Photo courtesy MN Land Trust 
Raised nesting area in center, scattered driftwood for habitat, and sinuous gravel wind vanes to reduce wind erosion. Photo courtesy SEH Inc.
Thousands of cars zip between Duluth and Superior every day, crossing the St. Louis River on the busy Blatnik Bridge. Far below sits a flat, five-acre island poised in mid-channel between a massive coal dock on the Wisconsin side and Duluth’s wastewater treatment plant. In the summer, if you look down from the bridge, you may catch a glimpse of someone on the island, hard to see amid the chaos of thousands of white birds and their nests–most of them Ring-billed Gulls (Larus delawarensis) and a few Common Terns (Sterna hirundo). Fred Strand has spent his summers here for about fifty years, keeping an eye on those few terns. And this past summer, if you looked closely, you may have noticed a surprising change in the island.
Working among the birds—counting and banding—is neither easy nor particularly pleasant. Strand and his colleagues wear hard hats to protect their skulls from sharp beaks. “Earlier in my career, we used to wear baseball caps, and the terns can strike hard enough that they’ll draw blood from your head through the baseball cap,” Strand says. “The backs of your ears often get pecked, because the hard hat doesn’t cover them. And when you use binoculars, your little pinkies stand up, and they’ll peck those. They’re very precise. They make their living catching small fish, so they’ve got to be very precise.”
Beaks aren’t the only danger. Workers often come away covered in bird poop and half-digested fish. And the chicks frequently regurgitate their food. “The young grow very rapidly, they eat a lot, and many times the fish is bigger than they can completely swallow at one time, so regurgitation is probably a way for them to avoid getting bogged down with the tail of a fish that hasn’t been fully digested sticking partway out of their mouth.”
Last year Strand shared the island with Gini Breidenbach, the restoration program manager for the St. Louis River with the Minnesota Land Trust. “It’s different from anyplace you’ve ever been,” she says. “With 40,000 gulls, you have to watch every step: there are nests everywhere, eggs everywhere, chicks everywhere. It’s extremely loud, so you wish you had hearing protection, and you have to yell to talk to people.” It’s not just the birds cluttering things up; it’s the stuff they bring to the island with them: cigarette lighters, toys, disposable gloves, tooth flossers, hair ties.
“The whole island is fairly odiferous,” adds Strand. “We don’t take a picnic lunch when we go out there.”
Why are these people subjecting themselves to such conditions? They’re trying to make the island a safer place for terns. This tiny island in the middle of an industrial harbor is one of only two places in all of Lake Superior where common terns nest and raise their young.
As their name suggests, common terns are abundant in some parts of the world, including the eastern seaboard of North America. But in the western Great Lakes region, these social birds are barely hanging on. “If we want to keep them in this part of the world, we have to do the work to provide nesting and young-rearing habitat for them,” Strand says.
They have never been numerous in the upper Midwest, and in recent years they have only been found nesting on a few large lakes in Minnesota and Wisconsin (Leech Lake, Lake of the Woods, Mille Lacs Lake, Green Bay, and the Winnegabo chain). In Lake Superior, Duluth’s Interstate Island and a human-built structure at the end of an old ore dock in Ashland, Wisconsin are the only places these birds gather to nest. “If we lose one or both of these places in western Lake Superior, they will be extirpated from the entire basin,” says Strand.
The terns must share Interstate Island with ring-billed gulls, which are bigger and are happy to eat tern eggs and chicks. Using a standard wildlife management strategy, workers installed parallel rows of fenceposts, four feet apart, with string attached to the tops. The bigger and clumsier gulls tend to avoid this area, giving the terns a measure of peace to raise their families.
In addition to the string overhead, the tern nesting area is surrounded with a fence, to keep the young chicks from wandering too far from their parents and making themselves vulnerable to the gulls. Another fence is designed to form a buffer between the two species. Strand has a federal permit to destroy the nests of any gulls that try to occupy the safe zone.
Humans responsible for the St. Louis River are in the middle of a huge project to recover its natural health and beauty after years of contamination and industrial misuse. In 1987, the estuary, where the river flows into the harbor and then into Lake Superior, was named an “Area of Concern” under the Great Lakes Water Quality Agreement. Since then, the federal government and the states of Minnesota and Wisconsin have been investing millions of dollars in various restoration projects.
Melissa Sjolund is the coordinator for these projects at the Minnesota DNR. She explains that historic dredging and filling for shipping ruined a lot of habitat that the common tern and other birds once used. In the 1930s some of the dredged materials were dumped at one spot in the river, forming Interstate Island, which straddles the invisible boundary between Minnesota and Wisconsin. Later, some of that material was hauled away from the island to expand the docks of the Duluth Seaway Port Authority. Terns used that waterfront land for their nests until it was built up with a warehouse and a vast paved storage space. They had also been nesting on Barker’s Island in Superior, until it was developed into a hotel and marina. “Because of our actions and alterations, we’ve basically confined the birds to this one little place in the river,” Sjolund observes. “Bird experts had recommended protecting and improving the island as very critical, the only thing we could do to help terns recover in the estuary.”
The island was named a state Wildlife Management Area in 1989, and workers cleared vegetation and placed decoys to attract terns and other birds. That effort was successful, and since 1990, all the terns in the region have been building their nests here, according to Fred Strand.
The goal is to maintain a stable tern population, and to achieve that, the birds need to produce between 0.8 and 1.1 fledglings per nest per year, but in records he’s kept since the 1970s, the main thing Strand has observed is huge variability. Some years, the weather is bad or a predator destroys all the eggs and productivity is zero. One notable year, as many as 300 chicks survived from 180 nests. “Personally, I don’t like to see a bust year, but in years when reproduction is great, I feel much better about it,” he says.
Lake Superior’s notorious water level fluctuations have flooded the island in recent years, wiping out about half of it. Clearly, saving the terns required rebuilding the island.
Sjolund was part of a team that studied historic information, old photos, water level records, and population numbers, and came up with a good size for the gulls and terns: 5.5 acres.
In the spring of 2020, contractors began loading gravel onto the island. They had to stop during the weeks of tern nesting and rearing, and begin the work again in the fall.
Workers spread the gravel across the island in a liquid slurry. As it dried, they pushed the material into berms at the outer edges of the island, which served as barriers to contain the next load. They brought enough gravel to raise the central tern nesting area by four feet, to account for future high water and wave action. Sjolund says they were careful to minimize mud flow into the river.
The island is also federally designated as stopover habitat for Piping Plover. Sjolund says that required a gently sloped beach along the shoreline, as opposed to stone riprap. Another project under the Great Lakes Restoration Initiative aims to improve habitat for Piping Plover on Wisconsin Point.
Altogether the project cost $1.6 million. For Gini Breidenbach and Melissa Sjolund, it’s a great accomplishment. “This is a special species of bird that lives here and only in one other place in the Lake Superior watershed,” says Breidenbach. “The bird migrates thousands of miles to South America every year and then comes back to this little island in our harbor. I feel the impact will be important for this species, and I’m hoping we’ll see some really good results in our monitoring over the years following this restoration.”
Sjolund agrees: “We should see quick results; it won’t take years and years.” She says researchers from the Natural Resources Research Institute have documented 16 other bird species using the island. “For migrating birds, having stopover habitat is really important,” she says.
Fred Strand calls common terns a “high-maintenance species.” They need more than someone nailing a birdhouse to a fencepost and forgetting about it. “If we didn’t do gull management, there wouldn’t be a suitable place for terns to nest in the estuary,” he says. He feels it’s his responsibility, and ours as a society. “If we want them, we’ve got to do the work to keep them.”
About the Common Tern
With its signature black cap, orange-red beak (often tipped in black), and sharply-pointed white wings, the Common Tern makes a striking figure against the sky. While it has a large world-wide distribution, in recent decades this long-distance migrant and colonial nester has consistently nested at only four sites in Minnesota, where it is classified as a Threatened Species.
Common terns belong to the gull family. Agile hunters, they hover with rapid wingbeats and make shallow dives to capture small fish near the water surface. They nest on the ground, laying 2-3 eggs in a depression shaped by their body and often lined with grasses. Both adults are fierce defenders of their eggs and young. The average age of adult nesting terns is 8-10 years old, which is remarkable considering that “Minnesota’s” terns make annual treks to wintering grounds as far away as Peru.
Find more in Minnesota’s Breeding Bird Atlas.
Learn more about St. Louis River restoration projects
St. Louis River Area of Concern Storymap
