The maggots which hatch out eat through the contaminated flesh and concentrate the botulism toxin in their own bodies. When the maggots drop off, other birds eat them. At this point, the toxin is so concentrated that a single maggot can kill a bird. Then the cycle repeats, and there is a massive outbreak. This outbreak is temperature dependent.
Warmer temperatures increase the spread of the disease.
Management practices include picking up dead birds and incinerating them, spreading lime at the water s edge to limit the number of bugs, and providing grain as alternative protein source. These are all costly measures. Avian Cholera this is apparently caused by a virus and is similar to a cold in humans, except that it can kill a bird within 8 hours. Cholera is thought to be carried mostly by white geese, who may already have the latent virus in their blood stream when they arrive in California from Baffin Island. Then, when they arrive in the warmer climate, the virus becomes active and the goose becomes congested and suffers from a thick nasal discharge.