Waterfowl spring migration in the United States. Avian botulism outbreaks can kill millions of birds in a single season. USFWS
Late summer and fall are prime time for die-offs of ducks, geese, and other wild water birds due to the toxin that causes botulism. This year is no different in the northern hemisphere, with small outbreaks reported in Colorado and North Carolina in the United States, and France and possibly the UK in Europe.
Since waterfowl die-offs due to botulism were first reported little more than a century ago in western North America, the disease has spread to over 28 countries today, many only since the 1970s. Periodic outbreaks leave hundreds of thousands to millions of birds dead.
Avian botulism appeared and accelerated in lockstep with the exponential growth in the human population, and in particular the latter’s altering of wetland ecosystems. But just how to explain this association is not easy. Unprecedented environmental changes over the past two decades have witnessed not an increase in, but rather an absence of mass avian botulism die-offs. While our understanding has improved, we are nevertheless little closer to predicting and controlling these outbreaks today than we were a century ago.