http://www.siftingsherald.com/articles/2007/01/29/news/news1.txt
Three bald eagles found dead at DeGray this winter
By Dolores Harrington
Published: Monday, January 29, 2007 1:52 PM CST
...Three bald eagles have died at DeGray Lake this winter, according to Johnny Cantrell, wildlife biologist with the U.S. Army Corps of Engineers at DeGray.
"We picked up three (eagles)," Cantrell said. "The first one was in real good shape and we sent it to Madison (Wis.). The other two were too decomposed, and we sent them to the repository."
The birds' deaths raised concern about another outbreak of avian vacuolar myelinopathy (AVM) at the lake where 29 bald eagles died during the winter of 1994-95. Die-offs continued for several years after that, and eagles also died at Lake Ouachita during that period.
After years of investigation by task forces made of state, government and private agencies, the cause of those deaths was finally attributed to a previously unknown toxin which causes AVM.
AVM is characterized by lesions, found by necropsy, in the brains of the affected birds. The condition has also been found in coots and ducks. Affected eagles, found before they died, exhibited symptoms such as disorientation, staggering and the lack of ability to fly.
The toxin comes from a blue-green alga that grows on hydrilla, a water plant that grows abundantly at DeGray. Coots that winter at the lake feed on the plants, and coots are the food of choice for the wintering eagles. Eating affected coots apparently leads to infection of the eagles.
The last known eagle deaths attributed to AVM at DeGray were during the winter of 1997-98. There have been eagle deaths at the lake since then - one was found in June 2000 and another in 2004. Those carcasses were too decomposed to determine the cause of death.
This winter, the first dead eagle was found in early December. "We found it on Dec. 10, and I shipped it (to the lab) on Dec. 11," Cantrell said. "We have had a preliminary report back."
The lab suggested that the eagle had died from electrocution, but Cantrell discounts that analysis. "There wasn't a power line within miles of where it was found." He is still waiting for a full report, and said the lab has assured them it will be sent soon.
The two decomposed carcasses were found sometime later than Dec. 10, but it is speculated that the three birds all died around the same time. That's another reason Cantrell doubts the electrocution finding.
In November, the Corps pulled blue-green algae samples and sent them to South Carolina to be tested, and "the disease center ranked it highest for toxicity than any other location in the country," he said. That was based on the amount of the algae sample - not that it was more toxic.
Cantrell does not necessarily think the eagles died of AVM, but the fact that there were three dead birds is cause for concern. "They could have ingested lead," he said. If the birds fed on ducks that had been shot with lead ammunition, it would be a case for investigation by law enforcement. The use of lead in shells is illegal.
No dead coots have been found at the lake this winter, Cantrell said. The lake was low in November and the weather mild, recent heavy rains and colder temperatures have changed conditions. "The vegetation is farther underwater than where the coots feed," he said, "and the colder weather may have stopped the algae from blooming."
The annual survey of eagles at DeGray earlier this month found far fewer birds than longer "than I can remember," he said. "We did two counts. The first day was clear and sunny. We had three boats out and saw seven eagles. There was rain and fog the next day, and we saw seven. We had more in November and December.
"The milder weather we had earlier may have kept the eagles farther north," Cantrell said, and that may have been a blessing...
Three bald eagles found dead at DeGray this winter
By Dolores Harrington
Published: Monday, January 29, 2007 1:52 PM CST
...Three bald eagles have died at DeGray Lake this winter, according to Johnny Cantrell, wildlife biologist with the U.S. Army Corps of Engineers at DeGray.
"We picked up three (eagles)," Cantrell said. "The first one was in real good shape and we sent it to Madison (Wis.). The other two were too decomposed, and we sent them to the repository."
The birds' deaths raised concern about another outbreak of avian vacuolar myelinopathy (AVM) at the lake where 29 bald eagles died during the winter of 1994-95. Die-offs continued for several years after that, and eagles also died at Lake Ouachita during that period.
After years of investigation by task forces made of state, government and private agencies, the cause of those deaths was finally attributed to a previously unknown toxin which causes AVM.
AVM is characterized by lesions, found by necropsy, in the brains of the affected birds. The condition has also been found in coots and ducks. Affected eagles, found before they died, exhibited symptoms such as disorientation, staggering and the lack of ability to fly.
The toxin comes from a blue-green alga that grows on hydrilla, a water plant that grows abundantly at DeGray. Coots that winter at the lake feed on the plants, and coots are the food of choice for the wintering eagles. Eating affected coots apparently leads to infection of the eagles.
The last known eagle deaths attributed to AVM at DeGray were during the winter of 1997-98. There have been eagle deaths at the lake since then - one was found in June 2000 and another in 2004. Those carcasses were too decomposed to determine the cause of death.
This winter, the first dead eagle was found in early December. "We found it on Dec. 10, and I shipped it (to the lab) on Dec. 11," Cantrell said. "We have had a preliminary report back."
The lab suggested that the eagle had died from electrocution, but Cantrell discounts that analysis. "There wasn't a power line within miles of where it was found." He is still waiting for a full report, and said the lab has assured them it will be sent soon.
The two decomposed carcasses were found sometime later than Dec. 10, but it is speculated that the three birds all died around the same time. That's another reason Cantrell doubts the electrocution finding.
In November, the Corps pulled blue-green algae samples and sent them to South Carolina to be tested, and "the disease center ranked it highest for toxicity than any other location in the country," he said. That was based on the amount of the algae sample - not that it was more toxic.
Cantrell does not necessarily think the eagles died of AVM, but the fact that there were three dead birds is cause for concern. "They could have ingested lead," he said. If the birds fed on ducks that had been shot with lead ammunition, it would be a case for investigation by law enforcement. The use of lead in shells is illegal.
No dead coots have been found at the lake this winter, Cantrell said. The lake was low in November and the weather mild, recent heavy rains and colder temperatures have changed conditions. "The vegetation is farther underwater than where the coots feed," he said, "and the colder weather may have stopped the algae from blooming."
The annual survey of eagles at DeGray earlier this month found far fewer birds than longer "than I can remember," he said. "We did two counts. The first day was clear and sunny. We had three boats out and saw seven eagles. There was rain and fog the next day, and we saw seven. We had more in November and December.
"The milder weather we had earlier may have kept the eagles farther north," Cantrell said, and that may have been a blessing...