good tern deserves another
Man-made island in Chequamegon
Bay provides safe habitat for declining bird population
The Daily Press
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
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
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
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
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,
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
"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.