Whooping cranes leave Coastal Bend for Canada

Jun 19, 2012 | Corpus Christi Caller-Times by David Sikes | Related Press

CORPUS CHRISTI — The last remaining flock of wild whooping cranes has returned to Canada following another difficult drought season in the Coastal Bend.
U.S. Fish and Wildlife Service officials estimated that roughly 245 endangered whoopers left the Aransas National Wildlife Refuge and surrounding marshes by mid-April. Another dozen or so cranes spent winter in north or central Texas, and in Kansas, Nebraska and other states.
It’s unclear how many birds survived the 2,500-mile migration to the Wood Buffalo National Park in Canada’s Northwest Territories, where the iconic, 5-foot, white birds nest and rear their chicks. The Canadian Wildlife Service conducts a nesting count each summer.
The wild whooping population has grown from its low point of 15 birds in 1941 to an estimated 283 birds counted on the refuge during winter 2010-11. An estimated 278 of those birds survived that season. Two years earlier, 23 birds died during the 2008-09 season, presumably of lack of nourishment caused by a major Texas drought.
A lawsuit involving those deaths was filed last year against the Texas Commission on Environmental Quality by The Aransas Project, a nonprofit group of local governments, advocacy groups and tourism-dependent businesses in the Coastal Bend. It claims the state mismanaged water in the Guadalupe River watershed, contributing to the record die-off. A verdict from U.S. District Judge Janis Graham Jack is expected this summer.
The refuge’s population estimate of 245 birds represents a change in how the whoopers are counted. The new technique is called distance sampling, which involves three days of airplane surveys using a grid system.
This method is not designed to produce an exact count, but rather a rough tally or percentage of the population.
Former USFWS Whooping Crane Coordinator Tom Stehn, who retired in October, said the new method is accurate to within about 15 percent. Stehn said the previous method, which he used for the past 29 years, also involved flyovers but on a much tighter grid with the flexibility to conduct more thorough searches off the grid.
Stehn believes the 15 percent error range is unacceptable when dealing with a population size of fewer than 300 birds. He said proper flock management should include closer scrutiny to detect population fluctuations far less than what is produced by distance sampling.
“I’m really frustrated and disappointed with the changes in the census the refuge has made,” Stehn said. “It’s simply not accurate enough when you’re dealing with such a small population of endangered birds.”

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