July 29, 2014 - Drought conditions have increased the possibility of disease outbreaks in waterfowl, according to the California Department of Fish and Wildlife (CDFW). Clostridium botulinum, the bacterium that causes avian botulism in waterfowl, is common in wetlands throughout California. Toxins from this bacterium affect the central nervous system of waterfowl, ultimately resulting in death.  

Outbreaks of avian botulism typically occur when wetland temperatures are very warm and there is rotting vegetation that bacteria can feed upon, decreasing the oxygen level in the water. Outbreaks can cause substantial localized mortality to waterfowl. Previous outbreaks of avian botulism in California have been responsible for as many as 46,000 waterfowl deaths in a single event. 

Symptoms of avian botulism include:

• Involuntary muscle contractions/convulsions
• Limp wings
• Limp neck
• Paralysis
• Birds propelling themselves through water with their wings

During an outbreak there may also be numerous carcasses of waterfowl in the area. Prompt removal of carcasses often helps to minimize mortality and reduce the spread of disease.

CDFW is asking private landowners to monitor their properties for waterfowl mortality and to please report any possible outbreaks to the CDFW Wildlife Investigations Lab at (916) 358-2790 or online using the Mortality Reporting Form (www.wildlife.ca.gov/Conservation/Laboratories/WildlifeInvestigations/Monitoring/MortalityReport.aspx).