Botulism Outbreak Kills More Than 16,000 Birds

About 16,000 to 18,000 dead waterfowl and shorebirds have been recovered from the American Falls area since Thursday, September 17. Officials from the Idaho Department of Fish and Game have confirmed that the deaths were caused by botulism, a paralytic illness brought on by a nerve toxin produced by the bacterium, Clostridium botulinum. "This loss of nearly 18,000 water birds is a substantial number to lose in a single incident but does not cause concern on a population level," Jeff Gould, head of Fish and Game's wildlife bureau. "We have been through this before, and undoubtedly will see this again in the future when similar natural conditions arise." Affected birds have included mallards, blue-winged teal, green-winged teals, pintails, coots, ruddy ducks, American wigeons, white-fronted and Canada geese, as well as some gulls, avocets, least sandpiper, white-faced ibis, and at least six river otters. All waterfowl shorebirds and carnivores 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. Still, with youth waterfowl season beginning September 26, Fish and Game is advising waterfowl hunters as an extra precaution to refrain from hunting in the upper end of American Falls Reservoir where the botulism outbreak has been most concentrated. Hunters should not harvest waterfowl that look or act sick, nor should hunters or the general public pick up dead or dying birds. Bird dogs can contract botulism through the act of retrieving sick or dead birds. Typical symptoms for botulism poisoning in waterfowl include difficulty flying, paddling and holding up their heads. Though nothing can be done about the background presence of botulism in the natural environment, efforts are still 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. "Hopefully the worst is over, and we will be able to pull back from our recovery efforts as we find fewer and fewer dead birds," said Jennifer Jackson, regional conservation educator for Fish and Game's Southeast Region. "However, we will continue with field inspections and associated recovery efforts as long as necessary." 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 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. For more information about this botulism outbreak, please contact the Fish and Game office in Pocatello at 208-232-4703.