Biologists at the Klamath Basin National Wildlife Refuge Complex are currently combating an outbreak of avian botulism affecting a wide range of migratory and domestic species. Birds affected in the Tule Lake National Wildlife Refuge include dowitchers, stilts, pintails and wigeons.

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

Outbreaks of avian botulism occur frequently along the Mississippi, Pacific and Central Flyways associated with disturbances in water level as a result of drought or imprudent management of water systems.