Biologists at the Klamath Basin National Wildlife Refuge Complex in Oregon are currently combating an outbreak of avian botulism affecting a wide range of migratory species including stilts, pintails and wigeons.

Botulism occurs in populations of birds on lakes and water systems that have been stressed by drought resulting in the concentration of birds, lowered water levels and exposure of rotting vegetation.  Birds that ingest botulinum toxin are themselves responsible for perpetuation of outbreaks since other birds feed on maggots on rotting carcasses that contain lethal quantities of toxin.  Volunteers are gathering dead birds for safe disposal. Mildly affected birds showing paresis are been transported to rehabilitation centers to receive supportive care.

Outbreaks of avian botulism occur frequently along the Mississippi and Pacific Flyways following disturbances in water level in habitats as a result of drought or inappropriate management of water systems.