Botulism Likely Kills Waterfowl Near American Falls

About 1,100 dead waterfowl have been recovered from the American Falls area since Thursday, September 17. Officials suspect the deaths were caused by botulism, a paralytic illness caused by a nerve toxin produced by the bacterium, Clostridium botulinum. Samples from dead birds are being submitted to a national diagnostic laboratory to confirm the disease. Affected birds include mallards, blue-winged teals, green-winged teals, pintails, coots, ruddy ducks, and widgeons, as well as some gulls and white-faced ibis, though all waterfowl and shore bird species are susceptible. Botulism in waterfowl is generally not considered harmful to humans, unless raw tainted meat is eaten. Proper cooking destroys the toxin and eliminates human health concerns. With youth waterfowl season beginning September 26, the Idaho Department of Fish and Game is advising waterfowl hunters to refrain from hunting in the vicinity of the upper end of American Falls Reservoir. Hunters should never harvest waterfowl that look or act sick, nor should hunters or the general public pick up dead or dying birds. Typical symptoms for botulism poisoning in waterfowl include difficulty flying, paddling and holding up their heads. Botulism deaths in waterfowl have been making headlines this year because of various factors. In southeast Idaho, 2009 started off as a great water year, with record rainfalls in early summer. That led to the shallow flooding of mudflats and wetland areas. These shallow waters are characterized by higher temperatures and low oxygen levels, perfect conditions for the botulism bacteria to thrive. As waterfowl and shorebirds feed on the vegetation and small invertebrates, they consume the bacteria that produce the botulism toxin. The result for infected birds is paralysis and death. But the botulism cycle does not stop there. Botulism concentrates in the tissues of those animals linked to each other through the food chain, including the maggots of flies that feed on carrion. Waterfowl and shore birds eat insects and can ingest botulism by eating the maggots living on tainted carcasses. Furthermore, contaminated carcasses present a botulism risk to a variety of scavengers, including foxes, coyotes, bald eagles, ravens, and even domestic cats and dogs. Bird dogs can contract botulism through the act of retrieving sick or dead birds. So hunters are cautioned to maintain control of their dogs when hunting close to this botulism outbreak. Though nothing can be done about the background presence of botulism in the natural environment, intensive efforts are being made to recover the dead birds to reduce additional deaths and to limit the potential for spreading botulism through the food chain. Fish and Game has been coordinating the recovery effort with the U.S. Fish and Wildlife Service and the Shoshone-Bannock Tribes. "At this point, we need to hope for some cold nighttime temperatures to knock down the bacteria and kill the maggots," says Mark Gamblin, regional supervisor for the southeast region of the Idaho Department of Fish and Game. "In the meantime, we ask people to leave dead or dying ducks and other waterfowl alone. Please do not bring these animals into the office. If you have concerns or questions about this issue or what you are seeing in the field, please call Fish and Game." The southeast regional office of the Idaho Department of Fish and Game is at 1345 Barton Road in Pocatello and can be contacted at 208-232-4703.