At least eight bald eagles died at Thurmond Lake during the winter and early spring because of an algae-borne neurotoxin linked to the invasive weed hydrilla.
The birds, some of which were recovered by wildlife authorities, succumbed to avian vacuolar myelinopathy, caused by algae that grow on mats of hydrilla that are popular feeding sites for small aquatic birds called coots.
Because coots are eaten by bald eagles, the small birds play a major role in AVM outbreaks, which create fatal lesions in the brains of infected birds.
Ken Boyd, a conservation biologist with the Army Corps of Engineers, said low water levels and unseasonably warm temperatures may have hastened the growth of hydrilla and made existing mats of the invasive weed more accessible to feeding birds.
The eight eagle deaths confirmed at the reservoir this season are down slightly from the previous season, when 11 eagles died.
Eagle mortality at Thurmond Lake is the focus of research by wildlife agencies and by University of Georgia scientists.
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.
Although eagle deaths at the reservoir continue to recur, Georgia’s Department of Natural Resources reported last week that eagle populations across the state continue to expand.
Aerial surveys in January and March documented 158 occupied nesting territories, 116 successful nests and 190 young eagles fledged. All three totals are up from last year’s 142 nesting territories, 111 successful nests and 175 eaglets.
Reach Rob Pavey at (706) 868-1222, ext. 119,