A Tale of Two Islands:
Whitetails, Warblers, and Woods at Sleeping Bear Dunes
By Marcia Goodrich, Media Relations Manager
The 2001 crew of
students on North and South Manitou Islands (pictured below, left to
right) are: Audra Bassett, MTU Erica Richards,
LSSU Lisa Baker, MTU This
is the forest primeval. The murmuring pines and the hemlocks, --Henry
Wadsworth Longfellow, prologue to Evangeline
For the great pines and hemlocks
of Longfellow's day have largely disappeared from Michigan's northwoods.
Cleared by farmers and clearcut by loggers, by the first half of the twentieth
century only a few remnant tracts of the old forest remained. In fact,
there's some question as to what the forests of the Great Lakes were really
like three hundred years ago, before European colonizers settled the Midwest.
The National Park Service is
the only federal agency with a mandate to restore some small segment of
America's forests to their presettlement majesty. Working with Assistant
Professor David Flaspohler (SFWP), the park service is taking advantage
of a natural laboratory at Sleeping Bear Dunes National Lakeshore to help
fulfill this mandate to determine what, exactly, constitutes a forest
primeval.
However, they aren't yet focussing
on rolling back the effects of timber harvesting and agriculture. Instead,
researchers are beginning a four-year project to determine the effect
a superabundant native species, whitetail deer, is having on forest ecology.
And they are doing it by studying birds.
"Whitetails
are native, but throughout much of Michigan they're at much higher density
than at any other time in history," said Flaspohler, an avian ecologist.
"That has consequences for the forest structure and for animal species
that use the forest."
Nowhere are these consequences
more stark than on Lake Michigan's North Manitou Island in Sleeping Bear
Dunes National Lakeshore. In 1926, people introduced deer to the island
to create a private game park and then fed them, with disastrous results.
"The population exploded,
crashed, exploded, and crashed again," Flaspohler said. "The
consequences for the forest were that the deer were eating everything
within reach, even alewives after they ran out of plants."
Why birds? Mainly because they're
diverse and use many features of the forest. And--no small matter--they
are easier to spot than, say, salamanders, Flaspohler says. "If you
can hear their song, you know they're there."
They're also easier to catch.
Using mist nets, Flaspohler and a team of graduate students are banding
birds, primarily long-distance, migratory songbirds, and comparing populations
of various species on both islands. The researchers will also compare
the forest structures on the two islands to determine how they may be
influencing bird communities.
After examining the biological
diversity and the current forest conditions on both islands, the researchers
will determine the likelihood of the islands and their forests returning
to their original, presettlement condition.
Thus, while neither North nor
South Manitou island is in anything approaching a primeval state, this
study may reveal clues about the nature of America's first forests and
what it might take to bring them back. Old growth has essentially disappeared
downstate, and only a few good stands, such as the Estivant Pines, still
remain in the Upper Midwest. Should they be destroyed, by fire or human
activity, a precious resource could be gone forever.
"The park service's goal
is to preserve the area's natural history," Flaspohler said. "If
that memory is lost, if those few places are lost, then no one will even
know what they missed."
(Photos courtesy
of
Dr. David Flaspohler)
Mark Fogg, MTU
Applied Ecology
PHD candidate, advised by Flaspohler
Applied Ecology
Bearded with moss, and in garments green, indistinct in the twilight,
Stand like Druids of eld, with voices sad and prophetic . . .
It's been a long, long time since the forest primeval was reflected in
the waters of the Great Lakes. And if the trees did indeed murmur with
voices prophetic, they may have been foretelling their own sad end.
After
the park service acquired the island, it introduced a hunt that brought
the whitetail population down to sustainable levels. But the deer have
left their mark. Decades of heavy browsing had left North Island "like
a parkland," Flaspohler says, with tall-trunked trees looming over
a leafy forest floor. Brush, tree seedlings, and herbaceous plants were
few and far between. Now, almost twenty years after reducing the deer
population through hunting, the forest appears to be recovering. Yet,
no one knows how profoundly it has been affected. Just a few miles away,
South Manitou Island has been virtually deer-free for as long as anybody
can remember. So researchers are using South Island as a control, comparing
its ecology with that of North Island to see how deer have made a difference.
And the first creatures they are studying are birds.
"Often,
people don't realize that many birds nest on or near the ground and not
in trees," he said. About half a dozen species nest on the ground
or in the understory, including the ovenbird, the hermit thrush, the veery,
and the black-throated blue warbler. With deer eating their nesting and
foraging habitat, researchers suspect that populations of these songbirds
may differ on the two islands, "but we'll have to wait and see,"
Flaspohler said.