Migratory and captive flocks of whooping cranes had a good year in terms of production, according to the annual Whooping Crane Recovery Activities report issued last Wednesday by the U.S. Fish and Wildlife Service (FWS).
“The Aransas-Wood Buffalo population (AWBP) of whooping cranes rebounded from 263 in the spring of 2010 to 279 in the spring, 2011,” FWS whooping crane coordinator Tom Stehn wrote in the report, which documents crane recovery projects in North America from October, 2010 to August, 2011. “With approximately 37 chicks fledged from a record 75 nests in August 2011, the flock size should reach record levels of around 300 this fall.”
Stehn told The Journal that optimal nesting conditions in Wood Buffalo National Park have been responsible for the flock’s ability to maintain a steady four per cent growth rate each year since the 1940s.
“It just means the flock has received enough protection that the birds are able to slowly grow in numbers,” he said.
But Stehn could not say the same for the eastern migratory flock moving from Florida to Wisconsin. Composed of birds raised in captivity then reintroduced to the wild, the flock has seen zero reproduction recently.
“The habitat just isn’t right,” said Stehn, naming wetland loss as a major issue alongside the challenges of trying to reintroduce 90 birds from captivity. He also mentioned that swarms of black flies seem to be bothering the birds – compelling evidence that the flock needs to be relocated further east, which biologists are starting to do this fall.
Fortunately for the eastern flock, reproduction rates for captive birds were promising this year, allowing 18 chicks raised in captivity to be added to the Wisconsin-Florida flock and another 17 to a brand new non-migratory group that was started in February, 2011 in Louisiana where cranes nested in the 1930s.
“The Louisiana reintroduction is the first time we’ve put cranes back into their historical range,” said Stehn. “The question is, is the habitat there now? There have been a lot of changes.”
Only seven of the ten birds released there in February have survived. But, said Stehn, reintroduction projects can take 30 years to yield successful results.
“You can’t just give up after two or three years,” he said.
Final numbers for the cranes, including juveniles expected to be reintroduced this fall, are estimated at 278 for the AWBP and 115 for the Wisconsin-Florida flock, with 20 non-migratory birds in Florida and 24 in Louisiana. In addition to the 162 cranes in captivity, the total whooping crane population is approximately 599.