Thousands of Birds Dead After Suspected Avian Botulism Outbreak; What Waterfowl Hunters Should Know

After a recent suspected avian botulism outbreak killed thousands of birds in northern Utah, the Utah Division of Wildlife Resources is providing some safety reminders for waterfowl hunters this fall.
DWR biologists first discovered dead and sick birds in mid-September in the Willard Spur and Harold Crane waterfowl management areas. Many birds have been collected and submitted for disease testing. The birds tested negative for highly pathogenic avian influenza. (Cases of highly pathogenic avian influenza have decreased in Utah this year.) While final test results are still pending, biologists suspect the birds died of avian botulism.
Avian botulism is a paralytic, often fatal, disease of birds that results from the ingestion of a toxin produced by a bacteria, Clostridium botulinum. The toxin is produced under certain environmental conditions in the summer and fall when there are low oxygen levels and warm water temperatures. Botulism mainly occurs in stagnant pools where there is no water flowing, and sick and dead birds are most often found along the shoreline.
Waterfowl, gulls and shorebirds are the bird species most often affected by avian botulism. Signs of avian botulism include the inability for a bird to hold its head up and a bird flapping its wings, but not having the strength to take off.
Avian botulism occurs almost yearly in Utah — typically between July and September — particularly during periods when the weather is really hot and after periods of rainfall. Those conditions often create stagnant pools of water that hold and grow the anaerobic bacteria that causes avian botulism. Read more









