Over a 7-day period beginning 8 August 2011, a large number of wild birds of several species were found dead or with neurologic clinical signs along the shore of Crostolo stream, in the Emilia Romagna region, Italy. Twenty-eight Mallards (Anas platyrhynchos), two Hooded Crows (Corvus corone cornix), and three coypus (Myocastor coypus) were found moribund on the Crostolo stream bank, collected, and sent to Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Reggio Emilia Section. The cause of mortality was determined to be Clostridium botulinum type C toxin. The toxin was identified by a mouse bioassay for botulinum toxins and confirmed in bird sera and blowfly larvae (Lucilia caesar) collected from the stomachs of birds.