By Linda Felaco
Tick populations have been soaring this year thanks to the
unusually mild winter that allowed more of them to survive. Plus tick
populations follow a multiyear cycle in which a drought causes oak trees to
produce more acorns, which swells populations of small rodents, which spread
tick larvae. So the drought conditions of two years ago are also giving us
more ticks this year. A
study earlier this year also showed a correlation between increased incidence
of Lyme disease and the decline of red foxes, which are very effective at
reducing the population of small rodents.
Not only are there more ticks, but last week, researchers at the
Centers for Disease Control and Prevention announced the discovery of a
brand-new tick-borne pathogen, one of several that have been discovered
recently.
Why the sudden emergence of new tick-borne diseases?
So
much for Michael Chambers’s thesis about the “irreversibility” of land
conversions. But of course anyone who’s ever planted a garden and then
neglected to weed it knows how “irreversible” it is.
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| The edge effect. (Credit: Nicholas, Wikimedia Commons) |
But as the farms reverted to forest, they were now
interspersed with dense human settlements, creating what is called “edge habitat.” The animals
that survive best in these edge habitats then came to predominate. And those
animals just happen to be the ones that best spread ticks, namely deer and
mice. Dense populations of deer—whose only natural predator other than humans,
namely wolves, are long gone from these parts—and mice have made fertile
breeding grounds for ticks and the pathogens that tag along for a ride.
So what’s the solution to the tick problem? Obviously, no
one wants to reintroduce wolves to keep the deer population in check. Barring
that, land conversions do a good job of getting rid of ticks. Ticks don’t live
in the nice suburban lawns of subdivisions; they live in leaf litter on the
forest floor.
But shh, don’t tell Ruth Platner I said that …