A bird-killing neurotoxin linked to the aquatic weed hydrilla re-appeared this fall at Thurmond Lake, where at least one dead eagle has been recovered in Lincoln County.
Avian vacuolar myelinopathy is believed to be caused by an unusual algae that grows on the dense mats of hydrilla that are popular feeding sites for migrating waterfowl.
“We have been doing some preliminary eagle and waterfowl survey work and have seen fairly high numbers of both,” said Ken Boyd, a conservation biologist with the Army Corps of Engineers.
As winter begins, observers have seen lesser scaup, teal, redheads, canvasback, ruddy ducks, ringnecks and large numbers of coots.
Because coots feed heavily on hydrilla and are often eaten by bald eagles, the small birds play a major role in AVM outbreaks that have killed dozens of eagles at the reservoir since the invasive weed first appeared there in the mid-1990s.
University of Georgia scientists studying the disease visited the lake recently to observe bird activity and test captured birds for AVM.
“We have recovered a number of sick coots during this period, and there are thousands in the area all feeding on hydrilla,” Boyd said. “Unfortunately, with the low lake levels, more hydrilla is exposed and available.”
The first confirmed eagle death this season occurred the day before Thanksgiving. A Georgia Wildlife Resources Division official found the dead bird near Cherokee Boat Ramp.
The possible remains of a second dead eagle, a pile of feathers, were found earlier this month at Bussey Point, where a number of dead or dying eagles have been recovered in past years.
The disorder, which causes fatal lesions in the brains of infected birds, does not affect mammals.
One option under study to control the problem involves introducing grass-eating carp to the reservoir in hopes that the fish would eliminate the hydrilla, which in turn would reduce the likelihood of AVM outbreaks.