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Emerging Waterfowl, Raptor Disease Linked to Toxic Algae
COLUMBIA, South Carolina, January 14, 2008 (ENS) – Wildlife biologists and park rangers are monitoring area reservoirs and lakes for signs of a new fatal bird disease that primarily affects waterfowl and raptors.
Biologists are concerned with the emergence of avian vacuolar myelinopathy, AVM, in South Carolina. The disease has been implicated in the death of over 100 eagles and suspected in the death of thousands of American coots in Southeastern reservoirs since it was first documented in Arkansas in 1994.
South Carolina Department of Natural Resources, DNR, Georgia Department of Natural Resources, Southeastern Cooperative Wildlife Disease Study and U.S. Army Corps of Engineers have been collaborating to monitor reservoirs that may support potentially toxic blue green algae, the suspected agent of AVM.
AVM affects the central nervous system of waterfowl and raptors that consume the suspect toxic algae growing on submerged aquatic vegetation in some Southeastern reservoirs.
Research supports the working hypothesis that waterfowl such as American coots feeding on freshwater aquatic plants are susceptible to toxins found in algae growing on the leaves and stems.
Once ingested, toxins damage the birds’ central nervous systems and affected birds become uncoordinated and lose their ability to fly. This makes them vulnerable to raptors, such as eagles, that easily target affected birds. Eagles may then contract the disease from consuming infected prey.
Still, biologists note an 8.5 percent increase in eagle nesting per year since surveys were begun 30 years ago.
In South Carolina, the disease was first observed in 1998 on Lake Thurmond, a 70,000 acre reservoir on Savannah, Broad and Little Rivers bordered by South Carolina and Georgia and managed by the U.S. Army Corps of Engineers.
According to Shirley Willard, a ranger with the Corps of Engineers, 46 eagles have been found dead at Lake Thurmond, and AVM is suspected as the cause of their deaths. The losses translate to the disappearance of six eagle nesting territories, she said.
According to DNR wildlife biologist Tom Murphy, a coordinator of South Carolina’s Midwinter Eagle Survey, “Eagle nesting below Highway 378 in our state has basically been extinguished, and we suspect this is a direct effect of this emerging wildlife disease.”
Only after fresh bird carcasses are submitted for necropsy and microscopic examination to the Southeastern Cooperative Wildlife Disease Study at the University of Georgia, or to other qualified wildlife health laboratories, is AVM implicated in a bird’s death.
Because eagles nest in obscure areas, biologists and rangers alone cannot ensure that all affected birds will be found. Willard says, “The more eyes we have out there helping us to monitor and track this disease, the better.”
The public can help with the research and documentation of the disease if they encounter waterfowl or raptors exhibiting strange behaviors affecting movements or happen upon carcasses while in these areas where characteristics exist that may result in AVM-affected birds – submerged aquatic vegetation, presence of American coots and signs of eagle nests or eagle sightings.
The public is asked to call one of the following to report these types of observations among waterfowl or raptors:
J.Strom Thurmond U.S. Army Corps of Engineers Project Office: 1-800-533-3478
Savannah District U.S. Army Corps of Engineers Project Office: 1-800-944-7207
South Carolina DNR: 843-953-9300Copyright Environment News Service (ENS) 2008. All rights reserved.
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