Fake reef may help whoopers survive
By ALEX LEARY, Times Staff Writer
CHASSAHOWITZKA -- One of the painful lessons of last winter's whooping crane project was how tidal fluctuations in the remote salt marshes here could fluster the birds.
In early January, one of the few survivors of the history-making flock left a protected pen to roost in a shallow creek. It was a fatal mistake: A bobcat pounced on the hapless crane.
The Chassahowitzka Five, as the remaining cranes came to be known, returned to Wisconsin in the spring, marking the first time in a century whooping cranes had fully migrated in North America.
Now a new batch of whoopers is being trained to follow ultralight aircraft to Florida, with an expected departure of Oct. 7. To solve the bobcat problem, researchers devised a simple, but technically challenging plan.
Using helicopters, about 95 tons of natural shell material was dropped to create a reef intended to keep the cranes from straying from the pen, which will be enlarged to 3 acres from 1 to accommodate 17 birds, roughly twice as many that left Wisconsin last fall.
The reef, built atop an oyster bar, will provide a gradual slope to account for changes in water levels. When the tide is out, the cranes can go to low areas; when it is in, they can move to higher ground.
"You want a whooping crane to roost in water at night because if a bobcat goes to get the crane it will splash the water and alert the crane," said Joyce Kleen, a biologist with the Chassahowitzka National Wildlife Refuge.
The reef also will provide solid footing, making the cranes more secure because they can take off easier than if they were in mud.
As with most things crane, the shell drop was a spectacle.
The material came from a Sarasota company, SMR Aggregates Inc., and was trucked to an open field at a former quarry and divided into heaping piles.
Working in tandem, two helicopters hovered as men wearing hard hats and fire-resistant clothing attached orange vinyl tarps, each loaded with close to 800 pounds of shells, to a claw on the end of a long rope.
Again and again -- there were about 250 trips in all -- the helicopters would veer off toward the salt marshes then hone in on the oyster bar, marked with stakes topped with orange ties.
With a push of a button, one side of the tarp flapped open, spilling its contents into the dark water. The shells disappeared with a loud, white splash.
"We are trying to modify this site to give the cranes a survival edge," refuge manager Jim Kraus said as he watched the drops from the safety of an air boat. "Last year, we had more water out there than anyone imagined."
It took the helicopters five days over the past two weeks to complete the work. Kraus said it would have been exhausting to take the shells by boat. Doing it by helicopter was tough enough given the intense heat and safety considerations.
The project, which cost $20,000, including material to expand the pen, served a dual purpose. Aside from helping the crane project, the job provided valuable helicopter training for staff from five national wildlife refuges: Chassahowitzka, Merritt Island, Lower Suwannee, Loxahatchee, all in Florida, and Savannah Coastal Refuges in Georgia.
Many of the participants work on fire suppression teams at their respective refuges and must complete or update their training, Kraus said.
-- For the latest on the crane project, visit www.operationmigration.org
-- Alex Leary can be reached at (352) 564-3623 or firstname.lastname@example.org.
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