Of the 289 whooping cranes brought to central Florida since 1993 under the guidance of the U.S. Fish and Wildlife Service only 31 have survived and just nine chicks have hatched in the wild. After meetings last month in which models were presented that pegged the birds’ chances of surviving at less than 50/50, the recovery team made the decision to halt the reintroduction.
The case highlights the dramatic effort to save whoopers, as scientists call whooping cranes, perhaps America’s most famous endangered bird. The entire North American continent is home to just 536 whoopers, 131 of which are in captivity.
The effort to save the whooping crane from extinction has been committed, creative and sometimes comical. (Courtesy of USGS)
“Whooping cranes are very water dependent and basically their nesting areas got drained, their migration areas got drained and they lost a lot of habitat,” said Tom Stehn, whooping crane coordinator for the U.S. Fish and Wildlife Service.
By 1941 the North American whooping crane population had been reduced to 16 individuals. Since then there have been several considerable efforts to reestablish wild populations. A program in the mid-1970s to transfer whooping crane eggs to sandhill crane nests in Idaho was deemed a failure by the late 1980s. Another project of the same era tried to establish a population in Colorado but power line mortality clipped the program short. The most prominent project began in 2001 when the group Operation Migration started leading young whooping cranes from Wisconsin to Florida. The birds fly behind an ultralight steered by someone in a crane costume to encourage future migration success independent of humans. As of 2007, there were more than 50 whooping cranes migrating on their own between Wisconsin and Florida. (See “Breakout” by Phil McKenna in Audubon November/December 2007).
Carlyn is wearing a poncho-like body costume and a hood which covers her face. The camouflage netting on the hood allows her to see, but disguises her face from the chick. The puppet head she's holding will be the "parent" to the chick. (Courtesy of Carlyn Williamson, USGS Patuxent Wildlife Research Center)
The one wild flock in the United States is in Aransas National Wildlife Refuge, on the Texas coast, where Stehn is stationed. There are 266 birds here; they summer in Woods Buffalo National Park, Alberta. The dwindling central Florida flock represents the continent’s third flock, and one that was intended to be non-migratory.
Central Florida has never had a non-migratory population of whoopers, likely one reason for the reintroduced birds’ low survival rate, says Stehn. The decision to place the flock here was based on the region’s large population of sandhill cranes, whose numbers are stable—in reintroductions related species can help influence survival skills, say researchers. At the time of reintroduction in the early 1990s a site in Louisiana was also considered but abandoned because it was deemed too close to the Texas flock and the risk of intermingling too high.
The 31 whoopers left will still be studied and success of the population isn’t ruled out, said Stehn, just at this point it’s unlikely.
“The question,” said Stehn, “is nationwide can we maintain enough wild habitat to support the reintroduction of whooping cranes? The last big block that the recovery team is looking at is in Louisiana. We have a graduate student there right now.”