For the Birds Radio Program: Whooping Cranes II
Last time I talked about the history of Whooping Cranes in the United States. After hunting the species became prohibited and their wintering grounds in Aransas National Wildlife Refuge started being protected, the species grew from an entire population of 15 in 1941 to between 60 and 70 wild individuals in the 1970s. By then, there were several dozen additional birds being used in captive breeding studies, most at the International Crane in Baraboo, Wisconsin, and the Patuxent Wildlife Research Center in Maryland.
Scientists also conducted an experiment placing Whooping Crane eggs in the nests of Sandhill Cranes, and although the Sandhill Cranes did a fine job of raising their adopted babies, the experiment failed because the Whooping Cranes had imprinted on their foster parents. At this point, ornithologists seemed stymied about how to proceed next. But then a man and his daughter trained some Canada Geese to migrate following an ultralight airplane, inspiring the movie Fly Away Home, and inspiring a new plan for establishing another wild Whooping Crane flock. The US Fish and Wildlife Service studied places where this flock would have their best chances, and settled on the Necedah National Wildlife Refuge in Wisconsin for a breeding ground and the Chassahowitzka National Wildlife Refuge in Florida for a wintering ground.
The first step was to make sure Florida’s degraded habitat was still appropriate for cranes. So biologists introduced 90 captive-reared whoopers to the area near Kissimmee, Florida. These birds are just now reaching reproductive age. They’ve had several nest failures, but last year one pair did raise one baby successfully. These birds live in Florida year-round. Some individuals died, and others have been moving around to various places throughout the state. Only time will tell if this introduction has been a success.
Meanwhile, scientists at the Whooping Crane Eastern Partnership, a group that includes researchers at Patuxent and the International Crane Foundation, started working on stage two, to see whether it was possible to train cranes to follow an ultralight airplane.
Canada Geese are strong fliers, capable of flapping for many miles. Cranes normally don’t flap that much on migration, riding thermals and gliding for the most part. But ultralights can’t fly that way, so scientists needed to first establish that cranes were physically capable of covering long distances behind a plane. And even if they were strong enough, how could they induce the birds to follow a plane without the birds losing their wildness, and becoming imprinted on the pilot or the plane itself?
Whooping Cranes were far too rare to experiment on without at least some assurances that the project would work. So the first birds scientists used in the study were Sandhill Cranes. From the time the birds were in brand new eggs in the incubator, the recorded sounds of ultralight motors were played so the birds would be familiar and comfortable with the sound. When the babies hatched, they never saw a human being–at least not a human who wasn’t covered with a billowing sheet, using a sophisticated crane-head puppet to feed the little ones and care for them. The Sandhill Cranes thrived. As they became strong walkers, an ultralight pilot wearing the white billowing costume with a covered face mask started taxiing the plane in circles around their pen, reaching inside the fence with the crane puppet to feed them. As the birds grew and became ready to fly, they flew for minutes at a time behind the ultralight.
That fall, they made their migration. Most flights were 40-60 miles, so it took well over a month for them to cover the distance from Wisconsin to Florida. They survived the winter, and next spring, all on their own, no ultralight to guide them back, they turned up back in the Necedah Wildlife Refuge.
They were less wild than the researchers wanted–they had made a few mistakes as far as allowing the birds to see and hear humans here and there, but overall, it looked promising. So last year, scientists started trying the same thing with Whooping Cranes.
Tomorrow I’ll tell you how that experiment is working out.