For anyone interested, here are a few articles on botulism from maggots feeding on dead meat...
from here:
http://www.archive.org/stream/avianbotulism00unitrich/avianbotulism00unitrich_djvu.txt
The Botulism Cycle
Favorable environmental conditions occur in the tissues of decaying animal and insect carcasses. The decomposition process uses up all available oxygen in the carcass, creating anaerobic conditions. Bacterial spores ingested during the life of the animal germinate after death. As the bacteria multiply and die, toxin is released.
Outbreaks of avian botulism occur when the toxin is taken in by birds. The die-off may begin as birds feed directly on invertebrate carcasses that contain the toxin, or as a result of feeding on live maggots of flesh-flies and blowflies, Flies lay their eggs on dead vertebrates, and the resulting maggots store botulinal toxin in their bodies as they consume the carcass.
More than 5,000 maggots can be produced by a single bird carcass; consumption of just two to five toxin-bearing maggots is often enough to kill a duck!
from here:
http://www.ncbi.nlm.nih.gov/pubmed/7451318
Type C botulism on a game farm resulted in the death of approximately 320 pheasants in 8 adjacent pens.
Maggots of the genera Calliphora and Wohlfahrtia from 1 dead pheasant were the probable source of toxin for the other birds, and maggot migration before pupation probably resulted in the spread of the disease between pens. Toxin was not isolated from the serum of sick or dead birds, but was isolated from their spleens and livers as well as from maggots.
from here:
http://www.fws.gov/saltonsea/botulism.html
Mode of transmission
Toxin production takes place in decaying animal carcasses. Flies deposit eggs on carcasses, which are fed upon by resulting maggots. These maggots then concentrate the toxin, and the toxic maggots are ingested by birds. These birds then die, leading to the proliferation of more maggots. As the cycle accelerates, major die-offs occur. Fish eating birds, such as pelicans, are believed to get sick when they eat fish that have concentrated the toxin in their intestines. These dying fish become easy prey for the birds that then ingest fatal doses of the toxin.
from here:
http://www.michigan.gov/dnr/0,1607,7-153-10370_12150_12220-26493--,00.html
Type C toxin occurs in carcasses of dead invertebrates, in the flesh of birds dying of botulism, and in maggots feeding on toxic carcasses.
from here:
http://www.avianweb.com/botulism.html
Birds either ingest the toxin directly or may eat invertebrates (e.g. chironomids, fly larvae) containing the toxin. Invertebrates are not affected by the toxin and store it in their body. A cycle develops in a
botulism outbreak when fly larvae (maggots), feed on animal carcasses and ingest toxin. Ducks that consume toxin-laden maggots can develop botulism after eating as few as 3 or 4 maggots.
