Avian Botulism Rears Its Ugly Head Again

Hooded Mergansers

A newspaper story crossed my desk this week that brought tears to my eyes. Avian botulism has once again returned to my community. I first heard of this disease back in 2008 when I attended a workshop on how to become a beach ranger. For a 4 year period ending in 2006, more than 52,000 Great Lakes birds were killed by botulism. The disease had appeared to run its course so when I read about the finding of dead birds along the Lake Michigan shoreline, it brought me back to images of dead birds strewed across the sand.

Botulism spores can lie dormant on land and in the water. The spores become active when environmental conditions such as warmer water and air temperatures, soil and aquatic substrate rich with large amounts of decaying plant materials and anoxic (oxygen deprived) conditions occur at the same time. Considering the hot, dry summer we experienced here in northern Michigan, it should have been no surprise that an outbreak would occur.

The sad theme in this story is the impact that active botulism has on the entire food chain. Botulism spores are consumed by fish and mussels that inhabit the warmer, oxygen-deprived water environments. As primary nourishment for waterfowl, the disease-laden fish transfer the botulism spores to the birds that will eventually kill the animal. The reality that most waterfowl carcasses are typically found on shorelines creates a scenario where the dead diseased birds become easy food sources for other birds and animals. The bacteria that had originated in the water can now impact land based wildlife and domestic pets.

Some of my favorite waterfowl are affected by this disease. The loon with its distinctive black and white markings and its mournful song is one such bird. Many of my favorite travel destinations are selected simply because they are home to loon populations. I love to awake to the song of loons filling the air and having the chance to see them floating across the water in search of food.

The same could be said of the merganser, another bird impacted by botulism. Several winters ago, I spotted a pair of hooded merganser that had taken up residence in the protected waters of the Boardman River. Their unique coloration and head ornaments distinguished them from the families of mallards that inhabited the same area. Throughout the winter, I returned to that spot at the river to watch them swim and chase each other through the current.

There is very little that can be done once an outbreak occurs. How does one vaccinate a body of water as big as Lake Michigan? Or live-trap and treat infected waterfowl? The only possible solution is to look at the mitigating factors that cause the dormant bacteria to germinate. As our summers get hotter and drier and the winters lose their blustery punch, it seems likely that there will be more outbreaks of botulism. It is time for all of us to do what we can to address the ever increasing impact we have on our climate. The loons and the mergansers will thank us.