After Deadly Winter, Whooping Cranes Make Spring Migration North
for National Geographic News
|March 30, 2007|
After a deadly season at their wintering grounds in Florida, more than 60 endangered whooping cranes are making the migration back to their summer home in Wisconsin.
The journey is part of an effort by the Whooping Crane Eastern Partnership, a team of U.S. and Canadian agencies and nonprofits, to create a self-sustaining eastern population of the species.
Many of the birds first learned the route by following ultralight aircraft piloted by conservationists.
(See related story: "Whooping Cranes, Ultralight Planes Take Flight on Annual Migration" [October 5, 2006].)
Operation Migration, an Ontario, Canada-based nonprofit, has used the aircraft to teach nearly 90 birds the way to their wintering grounds.
Last fall 18 birds learned the 1,228-mile (1,976-kilometer) southbound route, which took them from Necedah National Wildlife Refuge in central Wisconsin to Chassahowitzka National Wildlife Refuge on the central Gulf Coast of Florida. (See maps of Wisconsin and Florida.)
But in February all but one of the 18 cranes died when severe storms struck the refuge.
Enthusiasts and scientists alike are closely following the progress of the lone chick that survived, as he prepares to wing his way north.
The ten-month-old crane is still near the Florida refuge, researchers say, but they hope he'll start the journey north in the next few weeks.
It will be the first time the crane makes the trip unaccompanied by an ultralight.
"Each year you're anxious to make sure they get back safely," said Liz Condie, communications director for Operation Migration.
But with only a single surviving crane from last year's new migratory group, there's even more anxiety, she said.
"Everybody is just cheering their little hearts out [for him to make it]," she said.
As of Monday, 29 cranes had completed the trip north, 10 remained in Florida, and the rest were en route.
Along the Suwannee
Most of the whooping cranes that make up the reintroduction program spend the winter in central Florida, while a handful have established territories in South Carolina, Alabama, and Tennessee.
In recent years new winter territories have been established in and around the Suwannee River, where the cranes feast on crayfish, lizards, and insects in swamp prairies and other wetland areas (see an interactive map of the Suwannee River).
Cranes seek out wetlands like those along the Suwannee both as wintering grounds and as migratory stopovers.
In February researchers spotted two whooping cranes in the Okefenokee National Wildlife Refuge, a wetland straddling the Florida-Georgia border where the Suwannee originates.
While thousands of sandhill cranes are known to winter in the swamp's marshes and prairies, a whooping crane had not been seen on the refuge's grounds in more than a century.
"I'm guessing they probably wintered there," said Richard Urbanek, a biologist with the U.S. Fish and Wildlife Service (FWS).
But with only one sighting researchers don't know how long the cranes were in the refuge.
"Unfortunately that's the only observation that we had of them all winter," he said. "We had no opportunity to do another check."
On Wednesday night Urbanek picked up a signal from the radio tag of the female crane in Wisconsin, and he believes the male is there as well.
Next winter researchers will be on the lookout for the two cranes in the Okefenokee.
"There's a tendency, once they winter in an area, to return year after year," added George Constantino, manager of the Okefenokee refuge.
"We're going to be ready for them next year."
"Soap Opera" in Wisconsin
The first cranes to complete the journey north this year arrived in Wisconsin March 12, team members reported.
The early arrivals were two cranes that learned the migration route alongside Operation Migration's ultralights in 2003.
A few days later another key crane arrived. The first whooping crane hatched in the wild in more than a century returned to Wisconsin, accompanied by her parents, which learned the migration route in 2002.
"Now she's done the whole round trip," said Sara Zimorski of the International Crane Foundation, a Wisconsin-based nonprofit that is a member of the Whooping Crane Eastern Partnership.
Intricate social interactions begin to take place once cranes return to Wisconsin, Zimorski explained.
Upon arrival, cranes often split from their traveling companions, stake out new territory, put on mating displays, and find new partners.
"It's a bit like a soap opera at times," Zimorski said.
Cranes can start making nests and incubating eggs in early to mid-April. Those pairs that do lay and hatch an egg will start the journey back south with new chicks this fall.
During the summer a new group of captive-bred cranes will start training to fly with Operation Migration's ultralights in preparation for the autumn trip.
When last year's flock was all but destroyed by the storms, the recovery effort lost a crane group with equal numbers of females and males and high genetic diversity, FWS's Urbanek said.
"They were just about perfect," he said.
The loss makes the coming year all the more important for future of the crane population.
"They can't be replaced," he said. "That's the biggest problem."
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