The key to controlling this outbreak is to pick up and dispose of as many dead birds as possible, said acting refuge manager Russell Engelke. By late Monday, we had cleaned up the entire lake. We are finding fewer and fewer birds each day, and we will continue to go out and pick up birds until we dont find any more.
Dead birds were initially reported by a volunteer on the refuges Lake Chautauqua on October 2. Refuge personnel collected the birds and sent them to the National Wildlife Health Center, of the U.S. Geological Survey, in Madison, Wisconsin. Early tests ruled out other infectious diseases, and botulism tests are continuing. A wildlife disease specialist from the center is at the refuge to conduct further tests.
We are fairly confident this is a case of avian botulism, said Engelke. The conditions to produce the disease are present here, and the appearance of the birds weve collected seems to point to botulism.
A bacteria (Clostridium botulinum) produces a toxin that when ingested causes avian botulism, type C. This bacteria is commonly found in soils and mud along lakes and rivers. When water levels drop, temperatures rise, and oxygen is no longer present, the bacteria reproduce, generating the toxin. Waterfowl and shorebirds are affected when they ingest toxin while feeding in these areas. The disease can spread quickly when healthy birds feed on maggots on infected carcasses, prompting the extensive efforts to remove dead birds.
Engelke is receiving assistance from the Illinois Department of Natural Resources, which is providing personnel and an airboat, and from personnel at Mark Twain National Wildlife Refuge. Most of the birds collected, about 3,500, are green-winged teal. Other species affected include mallards, pintails, Canada geese, shorebirds, and blue-winged teal. Carcasses are being buried to prevent spread of the disease.
Lake Chautauqua is about 2,000 acres in size, although due to lowered water levels, only about 200 acres is open water. The remainder is moist soil areas and vegetation. Engelke says he is letting as much water as possible onto the lake from a nearby creek in an effort to dilute the toxin and cover exposed mud flats. Personnel in airboats are also hazing the birds to keep them away from the lake.
Engelke says the outbreak has not affected visitation at the refuge. The area around Lake Chautauqua is closed at this time of year for maintenance of levees. Duck hunting, to begin October 18 outside the levees on the Illinois River, will not be affected.
Avian botulism can affect any bird species, although it is most often seen in waterfowl and shorebirds. The disease is not always fatal, but smaller species such as teal are generally at greater risk. Birds die when they lose control of muscles enabling them to fly, breathe, and they can drown when they can no longer hold their heads up. Type C, or avian botulism is rarely a threat to humans, who are more often affected by Type A, B, or E, sometimes found in improperly canned food.
The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 93-million-acre National Wildlife Refuge System which encompasses more than 530 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 66 national fish hatcheries, 64 fishery resource offices and 78 ecological services field stations. The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies. For further information about the programs and activities of the U.S. Fish and Wildlife Service in the Great Lakes-Big Rivers Region, please visit our home page at: http://midwest.fws.gov
