A Mysterious Fungus Is Killing Rattlesnakes | National Geographic

They're a unique little species. They live in wetlands primarily, which is not what you typically think of when you think of rattlesnakes. The real stronghold for Eastern massasaugas is here in Michigan. This species was recently listed under the US Endangered Species Act as federally threatened, and that protects them from a lot of the activities that are affecting them. But it doesn't protect them from something like snake fungal disease.

So, snake fungal disease is an emerging fungal pathogen. It's found to infect about 30 some odd species of snakes in the United States. A lot of these snake species, particularly massasauga rattlesnakes, are already suffering from the effects of multiple stressors. Habitat loss, these snakes were persecuted at one point directly, and snake fungal disease, we know, is relatively new to these populations. It's just an additional stressor on top of the things that these snakes are already experiencing.

Even if this disease occurs at a relatively low prevalence, maybe 5 to 10%, that could be an additional 5 to 10% of mortality that's added on top of what's already occurring. Those are the kinds of things that can drive these populations to extinction. It seems to be an increasing phenomenon that emerging infectious diseases have been impacting wildlife species across different taxa, such as bat white-nose syndrome, amphibian chytrid fungus, and now also snake fungal disease.

These pathogens are so complex and much more complicated than we first assumed. We still have so many questions that have been unanswered, even though some of these species are common, because we don't have a long-term data set before there was ever a reason to be concerned. It makes it very difficult for us to predict what will happen in the future.

Still not rattling? Yep, touching once.

Yeah, so for the last seven or so years, we have been collecting mark-recapture data on this population of Eastern massasauga rattlesnakes. The idea is to establish a population that we can study over the long term, so we can try and understand the changes in demography and the population dynamics. We are lucky enough here to have been studying this population before we detected the disease, which will allow us to understand the impact on the population over time.

We can lose individuals, right? And we know that we lose individuals occasionally. But from a conservation standpoint, it's really important to understand what's the impact of populations. What we really need to do is to sample in the environment, figure out where it's distributed, and then try and understand how it's spreading both locally and across the country. Ultimately, hopefully not across the globe.

Hopefully, we can apply some of what we learned and slow or control the spread before declines in snakes really become commonplace. To be able to respond more quickly is of the essence. Right now, we have that advantage with snake fungal disease. I really hope to get more people aware that we have rattlesnakes in Michigan and that they are important. They provide a valuable ecosystem service, control mammal populations, and mammals carry ticks. You know, they deserve to be here. They provide a service, and they're just a beautiful species.