When faced with plagues of deer mice and outbreaks of deadly hantavirus, checking in with the weatherman probably isn’t on most people’s minds. But new science shows that maybe it should be.
Scientists report in the Journal of Animal Ecology that they have been able for the first time to quantify the link between weather events, like El Niño, and booms in potentially hazardous deer mouse populations. Best take this news seriously. We’re in the middle of an El Niño season.
Their findings may help public health officials develop better hantavirus prevention strategies as well as enable scientists to predict how climate change could affect the severity and locations of deer mouse outbreaks.
The Sin Nombre hantavirus is an illness not worth wishing on your worst enemy. It’s a zoonotic disease, meaning it can be transferred from animal to human. The first recognized U.S. outbreak occurred in 1993 in the Four Corners region, and on average, 20 to 40 cases are reported each year, according the U.S. Centers for Disease Control. Unlucky victims can look forward to flu-like symptoms and respiratory and heart failure, and survivors face recurring symptoms for the rest of their lives. The disease is transferred by deer mouse droppings, urine and the animal itself.
Biologist Angela D. Luis with Pennsylvania State University, Richard J. Douglass at the University of Montana and colleagues combined capture-release, climate and vegetation data with computer models to find out if deer mouse population and disease presence were influenced by weather. 15 years and more than 4,700 mice later, Luis and her colleagues found the connection.
At first glance, it sounds like more rain means more food, more mice and more hantavirus, as rainy years create better food crops for the cute but pesky disease carriers. But the relationship is not so straightforward. The “more rain equals more everything else” scenario is partially influenced by season. Luis found that higher temperatures and rain in the summer through early winter months bode well for mouse populations, but not so well during the spring.
This could be particularly key for the Southwest, as during El Niño years, this region typically experiences significantly more rainfall. The study isn’t perfect, factors like predation, migration, and competition could also be affecting deer mouse outbreaks, but the weather connection appears to be strong.
Right now Luis and her colleagues are expanding their study. So far they’ve looked at habitat in Montana only. They are looking at more types of environments throughout the state, including sagebrush and pine forests, which will help determine whether their model could be applied to multiple regions.