from vicki davis – 07/16/2005
http://sfgate.com/cgi-bin/article.cgi?file=/n/a/2005/07/12/national/a181120D69.DTL
Officials Probing Pelican Deaths in N.D.
By JAMES MacPHERSON, Associated Press Writer
Tuesday, July 12, 2005
(07-12) 18:11 PDT Bismarck, N.D. (AP) —
The Fish and Wildlife Service is investigating the deaths of thousands of young white pelicans at the Chase Lake National Wildlife Refuge in central North Dakota, a year after thousands of adult birds abruptly left the refuge.
At least 8,000 white pelican chicks may have died over the past two months, spokesman Ken Torkelson said.
"The difference is, last year the adults left first," Torkelson said. "This year, the young have died and the adults have no reason to stick around."
Severe storms or a disease outbreak may have caused the mass die-off at the rookery, said Marsha Sovada, a biologist at the U.S. Geological Survey’s Northern Prairie Wildlife Research Center in Jamestown.
"Because of weather and some apparent disease or disturbance of some sort, we’ve seen a reduction of birds," Sovada said.
The Fish and Wildlife Service said an inspection of the refuge last week indicated only about 500 chicks left from a nesting period that could have produced as many as 9,000 of them. The check also showed all but about 2,000 adults had left, from a population estimated at 18,850 in late May.
Officials had hoped the refuge would return to normal after nearly 30,000 adult pelicans took off last year, leaving their young behind. A check in late May indicated the pelicans were back, but officials still could not pinpoint what caused last year’s exodus.
Now, they have another mystery to solve.
The white pelican, one of the largest birds in North America, breeds only once a year, and males and females take turns caring for their young. The birds have a wingspan of nearly 10 feet and live about 25 years.
The white pelican colony at the 4,385-acre Chase Lake National Wildlife Refuge north of Medina has been the largest in North America, peaking at 35,466 birds in 2000.
The pelicans normally stay at the Chase Lake refuge through September, raising their young and feasting on crawfish, small fish and foot-long salamanders from small ponds known as prairie potholes.
Samples have been sent to the National Wildlife Health Center in Madison, Wis., to try to find out what killed the young birds at Chase Lake.
Torkelson said that will take some time.
"They have to rule out a lot of diseases before they can pin down the correct one," he said.
The chicks that remain at the refuge are more than a month old, still being cared for by adults, Torkelson said.
"Typically, two hatch but only one survives," Torkelson said. "There won’t be any repeat now."
The chicks remaining at the refuge appear to be healthy, Sovada said.
Biologists have attached backpack-like electronic tracking equipment to eight pelicans at Chase Lake to monitor their movements when they leave the colony. Two other pelicans were to be fitted with the equipment.
Sovada said the pelicans fitted with tracking equipment are foraging in the area, but have not returned to the rookery at Chase Lake.
Sovada said large die-offs of pelican chicks have been reported this week at Medicine Lake National Wildlife Refuge in northeast Montana and at Waubay National Wildlife Refuge in northeast South Dakota.
"I don’t believe they are experiencing an exodus, but they are seeing significant deaths of pelican chicks," Sovada said. "It could have no relation to what’s happening at Chase Lake."
She said the West Nile virus likely is to blame for the chick deaths in Montana and South Dakota.
Pelican nesting colonies in Montana, South Dakota and Minnesota also have had high chick mortality rates in the past three years, Torkelson said.
He believes some of the pelicans will be back next year at Chase Lake, but perhaps not in great numbers.
"I’d be surprised if zero came back and I’d be surprised if 30,000 came back," Torkelson said. "I think it will be somewhere in between."