ABOUT AVIAN BOTULISM
Botulism--or more precisely the spores of the bacterium Chlostridium botulinum--occurs naturally in wetlands, both in vegetation and in animals. However, it needs an anaerobic environment (such as an animal carcass) to germinate and produce the botulinum toxin that is responsible for the shorebird deaths. Invertebrates are unaffected by the toxin, so they effectively concentrate it. Eating as few as 2-4 toxic maggots is enough to kill waterfowl (and presumably shorebirds). It essentially becomes a self-perpetuating cycle, because more death means more botulism. An influx of sewage into the lake, as happens after storms, could potentially increase the occurrence of botulism by decreasing the amount of oxygen available in the water and thus killing fish, giving the bacterial spores habitat to germinate. It also thrives in high temperatures like we have been having, which is why late summer and early fall is the worst time of year for botulism.
WHAT TO LOOK FOR
Botulism causes paralysis in birds. The main things to be on the lookout for are birds that can't walk, can't open their eyes, and/or can't hold their heads up. The type that is likely at issue here is Type C botulism, which severely affects shorebirds and waterfowl, but not people and only very rarely dogs.
WHAT TO DO
So what can we do? Disposal of carcasses is the easiest, most effective way to combat botulism outbreaks. Even though this is a very minor outbreak (botulism outbreaks have killed millions of birds at a time), burying dead fish quickly will come close to eliminating botulism on our beaches. I'm a bit of two minds on this because dead fish are also an important food source, but this time of year, when hot weather and peak shorebird migration meet, it is probably best to bury dead fish, at least at Montrose. We don't want shorebirds' lives threatened in the very limited safe habitat they have on the Chicago lakefront. And what if an endangered species like a Piping Plover were to show up?