Lesson learned from whooping cranes' flightBy ALEX LEARY, Times Staff Writer
© St. Petersburg Times
published February 17, 2002
CHASSAHOWITZKA -- In the early morning of Nov. 28, 2001, Deke Clark swooped low over a field in Suwannee County and then opened the throttle of his ultralight aircraft as a flock of whooping cranes on the ground burst into flight.
The maneuver, called an air pickup, was executed perfectly, but as Clark began to climb, his radio began to crackle. Joe Duff, trailing in another craft, was worried.
One of the cranes held its neck in a U-shaped position, unlike the others which were straight and sleek. "We better turn around," Duff said.
With the nervous migration team looking on, a veterinarian examined the crane, a usually dominant male called No. 5.
Did the bird have food stuck in its throat? Perhaps it was a screw or other foreign object. X-rays showed no obstruction, however.
Weeks later, researchers have concluded that No. 5 injured itself by getting its long beak stuck in a band used for identification.
The revelation is one of many made along the 50-day, 1,227-mile journey from Wisconsin to Chassahowitzka National Wildlife Refuge.
Last week, nearly 40 members of the Whooping Crane Eastern Partnership, an umbrella group of federal, state and nonprofit organizations, gathered in Crystal River to discuss those lessons with the hope of improving a repeat migration this fall.
Four more human-led trips are scheduled, using new birds each year. Once in Florida, it is up to the birds to return north in the spring.
"Every year, I say I can't believe these guys will go back on their own, and every year they do," said Bill Lishman, whose work with geese and sandhill cranes paved the way for the whooping crane recovery project.
The ID bands were designed to fit higher on the cranes' long legs but these were placed closer to the foot, making them loose. Tighter bands have been placed on the five cranes spending the winter in Chassahowitzka.
Seven cranes made the trip to Florida but two were killed by bobcats. Though a pen with an electric fence is provided, the cranes are encouraged to explore their surroundings.
Still, researchers want them to roost inside the pen. Cranes in the wild roost in water because it protects them from predators. The splashing noise of a bobcat, for example, would tip them off to trouble.
"These birds don't have street smarts yet," said John Christian, a U.S. Fish and Wildlife Service official who is coordinating the whooping crane project. "They don't know what alleys to go down, so to speak."
Crane No. 10 was trying to do the right thing. It found a roost outside the pen but the creek was narrow and within easy striking distance of a bobcat. It was last seen alive on Jan. 10.
Scientists monitoring the cranes' daily progress are now using brood calls to lure the cranes into the pen at night.
One of the reasons they may have been leaving to roost elsewhere is fluctuating water levels caused by changing tides. If the water is too shallow they lose a defense mechanism; too deep and their feathers get wet.
To compensate, the pen will be enlarged to encompass an area with deeper water. A plan was devised to build an underwater platform that would shift with the tide, so the water level remained constant. Now researchers are considering creating a graduated island with crushed oyster shells.
The most basic but most challenging change for the upcoming experiment is using more cranes. Eighteen hatchery-raised chicks will be delivered to Necedah National Wildlife Refuge in Wisconsin; last year, 10 were used.
The new chicks will begin hatching in April and begin training immediately. They could depart for Florida in September, several weeks ahead of last year. Poor weather in the north caused numerous delays so an earlier takeoff is eagerly anticipated by the pilots.
More birds means more ultralights are needed and Operation Migration, the Canadian team that provides the pilots, will add three new craft to its fleet.
The team will also use a second temporary pen along the migration. Previously, the birds after landing had to be led to a hiding spot while workers erected the pen. This was time consuming and problematic because cranes prefer open areas, not woods.
Considering all the crew went through, getting birds to Citrus County was a major accomplishment, Christian said.
"We feel pretty good about what happened. We encountered some bumps because it's complicated and no one has done it before."
-- Alex Leary can be reached at (352) 564-3623 or firstname.lastname@example.org.
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