Type C botulism losses at Horicon National Wildlife Refuge, 1978

Avian botulism was responsible for the death of over 6,000 waterfowl at Horicon National Wildlife Refuge in Wisconsin in 1978. The outbreak occurred in early fall on a flooded 250 hectare fallow agricultural area on the northeast end of the refuge. The species most severely affected was the green-winged teal (Anas carolinensis), which made up almost 45% of the total birds found. Carcass pick-up, mouse toxicity tests, and antitoxin injections of waterfowl are discussed.