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One good tern deserves another
Man-made island in Chequamegon Bay provides safe habitat for declining bird population
Rick Olivo
The Daily Press
Posted 09/30/2002

They are supremely graceful in flight, their small, delicate, mostly white and gray bodies with a jaunty black cap hovering above the water, wings fluttering in a ballet of aerial grace, suddenly darting head first into the water to emerge seconds later with a small fish in their long pointed bills.

The Common Tern is one of the most spectacular of the many shorebirds to be found along the coastline of Chequamegon Bay, an elegant, agile presence, sailing through the sky with effortless precision.

The name "Common Tern" is a misnomer, says Department of Natural Resources wildlife manager Fred Strand.

"It probably stems from their cosmopolitan distribution along the east coast of North America, where they have always been abundant," he said one sunny September day recently.

Strand was outward bound in a small boat, headed towards a tiny manmade island in Chequamegon Bay used by the terns as a nesting ground.

In the Great Lakes, Common Tern numbers have never been high, and in recent decades, they have declined dramatically, he said, rounding the Soo Line Ore Dock. Now, there are less than 300 breeding pairs along all of Lake Superior.

Strand's goal was the outer end of the remains of the old Chicago Northwestern Ore Dock. The timber structure which once shipped out millions of tons of Gogebic Range iron ore to the steel mills of Chicago and Pittsburgh has been gone for decades. Only the pilings that once supported the immense structure remain in place, barely breaking the lake's surface.

All gone, that is, except for a tiny island at the very end of the former dock.

Of the thousands of miles of shoreline on all of Lake Superior, the ruins of the departed oredock are one of only two spots where the endangered terns nest, lay eggs and rear their young.

The spot was far from ideal. Terns prefer sandy, isolated locations with sparse vegetation where they can rear their young in relative peace and safety. The old dock was heavily vegetated, making it a poor choice for nesting. It was also privately owned and the potential of development for industrial or recreational use was not inconceivable.

In 1986 the dock, acquired by the city of Ashland and renamed "Ashland Tern Island," was the scene of a cooperative venture between area sportsmen and bird lovers, the Wisconsin Department of Natural Resources and the Wisconsin Coastal Management Program.

Coastal Management provided the funds for restoration of the island, DNR provided the expertise and local volunteers provided the muscle to build a new timber-sided rock and concrete rubble-filled crib. It was then capped with sand, a veritable Tern Hilton.

And none too soon, either. Terns immediately made cup-like nests on the island. Within two days of completion of the project, a new egg appeared in one of the nests.

In recent years, up to 75 pairs of terns have nested at the site.

However, all was not well. Predation by great horned owls and mink has been a continuing problem, but more seriously, less than two decades after the island was rebuilt, the northwest facing wall - made of recycled railroad timbers - collapsed into the bay. The future of the colony site might have been threatened as wave action washed out a substantial chunk of the 50 foot by 50 foot island.

However, action taken this year by the DNR to reconstruct Tern Island should ensure that the birds have protected nesting grounds into the conceivable future. With $70,000 in grant funding from the Environmental Protection Agency, the DNR has hired Nelson Construction of La Pointe, specialists in marine construction, to build a new Tern Island, just inshore from the crumbling existing island.

"The new island will be 30 by 96 feet," said Strand. "In terms of square footage, it will be slightly larger than the old island."

The new island will be built atop the same submerged pilings that once supported the old oredock. Protected by the cold waters of the bay, the pilings remain in excellent shape, Strand said.

In fact, the pilings provide the framework for the new steel and oak plank walls of the island. Thick steel tubes were driven over the top of pilings, like a sleeve, with square steel tubing welded to them, forming the framework of the structure. To this frame, stout oak planks are attached. When complete, rock and rubble fill, some from the old island, will fill the structure, which will then be capped with sand.

"We've got about five feet on the outside of the structure that will fill with rock riprap to protect it from waves and ice," Strand said.

The last two feet of the old island above water will be left in place to provide a further buttress against the power of the lake.

One unusual feature is a two foot metal flashing shield that will run completely around the island. The purpose of this band of metal is to thwart predators who used to climb the old island in search of an easy meal.

"In the last several years we have had a problem with mink predation. They swim out and climb up and eat the eggs or chicks. This way, if it works as it's supposed to, the mink won't be able to climb up to the top of the island," Strand said. "We like mink, but we don't need them to come out here and have a buffet."

Great horned owls have been a problem in the past, but haven't been much of an issue in the last eight years or so. One species that might be thought of as a threat to the terns is the ringed-bill gull, an opportunist abundant in Chequamegon Bay that will eat just about anything. However, Strand said ring-bills do not appear to be more than an occasional predator. He said at the other concentration of terns, in the Duluth-Superior harbor, they are important as competitors for nesting sites, but otherwise are not a significant problem.

Strand said he believed the activities of man in reducing habitat, both in nesting and in wintering areas, were largely to blame for the downturn in numbers.

"We've got some records from not so many decades ago where they were up to about 400 pairs, but in the last two decades, they have been down to 200 pairs in Duluth-Superior."

The numbers have remained static in Ashland as well, despite the effort in 1987 to construct a second tern island at the Bayfront power plant.

"The island looks like suitable tern habitat to our human eyes, but the terns have ignored it," Strand said. In Duluth-Superior, terns nest in only two of six sites the Wisconsin and Minnesota Departments of Natural Resources have built.

"'If you build it they will come' does not necessarily hold true for wildlife choosing breeding sites," Strand observed.

Given this, providing an ideal breeding site in a spot terns are known to prefer is all the more important.

"We are at least hanging on to what we have," Strand said.

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