According to the National Wildlife Health Center,
http://www.nwhc.usgs.gov/disease_information/avian_botulism/index.jsp, avian botulism is a paralytic disease caused by a toxin produced by the bacterium, Clostridium botulinum. The toxin affects the birds' nervous systems, leaving them unable to use their wings and legs, neck muscles (as in the photo above) and other muscles. Although we only saw a few dozen crippled or dead cormorants, avian bacteria can strike thousands of waterfowl at once.
Botulism comes in several strains. Type C affects birds, mostly waterfowl, shorebirds, colonial waterbirds, and other species. Humans, dogs, and cats are resistant to this strain. Only a few cases are reported from people and their pets. We have to worry about Types A, B, and, perhaps E. A and B are contracted from eating improperly preserved canned products. Type E is from poorly cooked fish, and affects gulls, loons, and other birds. Thorough cooking destroys all types of botulism, according to the National Wildlife Health Center.
John and I immediately reported this mini-outbreak to the Minnesota Department of Natural Resources. Outbreaks can be controlled by collecting and destroying carcasses and, if dealt with promptly, through intervention by wildlife rescue organizations.