New research suggests that a rise in tick-borne diseases could be linked to a shortage of mouse predators like foxes and martens.

When left to take care of itself, Mother Nature does a pretty good job of figuring stuff out … until the human part of the equation comes along and messes things up, that is. Habitat destruction and nudging harmonious ecosystems out of whack come to mind – and both of those could be contributing to a rise in tick-borne diseases.

A new study looking at the relationship between ticks, mice, and mouse predators – especially red foxes and martens – suggests that “the rise in tick-borne disease may be tied to a dearth of traditional mouse predators, whose presence might otherwise send mice scurrying into their burrows,” writes Amy Harmon in The New York Times. When first hatched, larval ticks rely on mice and other small mammals for their blood meals. Fewer predators like foxes means more freedom for the mammalian food trucks to be out and about, which leads to a veritable feast for ticks.

For the study, titled “Cascading effects of predator activity on tick-borne disease risk,” lead researcher Tim R. Hofmeester positioned cameras in 20 plots throughout the Dutch countryside to measure the activity of foxes and stone martens, both major predators of mice. Some of the cameras were in areas in which foxes were protected, other cameras were in places in which foxes were heavily hunted.

After two years of painstaking work – trapping mice, counting ticks, testing the ticks, and dragging a blanket on the ground to capture additional ticks – Hofmeester had some rather conclusive-seeming data. “In the plots where predator activity was higher, he found only 10 to 20 percent as many newly hatched ticks on the mice. Thus, there would be fewer ticks to pass along pathogens to next generation of mice,” writes Harmon.

Curiously, areas of higher predator activity didn't correlate to a decrease in the numbers of mice themselves, just a lower rates of infected ticks. Hofmeester suggests that the predators' activity curtailed the roaming of the small mammals, which was enough to make an impact.

“This is the first paper to empirically show that predators are good for your health with respect to tick-borne pathogens,” Dr. Taal Levi, an ecologist at Oregon State University, told The Times. “We’ve had the theory but this kind of field work is really hard and takes years.”

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