Acorns Low, Lyme Disease High

In a typical autumn season, a mature oak tree will produce about 25 to 30 pounds of acorns. The fall of 2010 was a record year for acorn production, with an astonishing 250 pounds of acorns per tree. This past autumn’s acorn crop was atypical on the opposite end of the spectrum, with oaks producing less than one half-pound each.

“This is the most extreme pair of years that we’ve seen,” said Dr. Richard Ostfeld, a disease ecologist and senior scientist at the Cary Institute of Ecosystem Studies in Millbrook, New York.

Acorns, high in protein, carbohydrates and fat, are a vital food and energy source for deer, bear and wild pigs, as well as white-footed mice, chipmunks and squirrels that, in turn, are prey to hawks, owls, weasels and foxes. Ostfeld says up to 90% of the current high population of rodents could die by next spring due to the lack of acorns and deer may be wandering out closer to roads in search of alternative sources of food. “I would expect that traffic collisions are going to be higher in a year like this year,” he said.

Additionally, the lack of acorns could instigate a public health threat, particularly with residents of the Northeast, who are expected to see a surge in Lyme Disease cases this spring. Five years ago, when a heavy acorn crop followed a sparse acorn crop, black-legged ticks reached a 20-year high. When they emerge in late spring, black-legged ticks, approximately the size of a poppy seed, will no longer be able to feed on a large mouse population.

“We had a boom in acorns, followed by a boom in mice. And now, on the heels of one of the smallest acorn crops we’ve ever seen, the mouse population is crashing,” Ostfeld explained. “This spring, there will be a lot of Borrelia burgdorferi-infected black-legged ticks in our forests looking for a blood meal. And instead of finding a white-footed mouse, they are going to find other mammals—like us.”

According to the Centers for Disease Control and Prevention (CDC), Lyme Disease is on the rise, infecting nearly 30,000 people in 2009. Common symptoms include fatigue, chills, fever, headache, muscle and joint aches and swollen lymph nodes. While many get a “bulls-eye” rash to alert them to the bite, others may have no rash and no recollection of being bitten. Left undiagnosed, Lyme Disease can lead to debilitating conditions such as lowered immune function, chronic fatigue, arthritis, nerve damage and neurological problems. The ticks that transmit Lyme Disease can carry other diseases as well, including babesiosis and ehrlichiosis. The CDC cautions that: “While it is a good idea to take preventive measures against ticks year-round, be extra vigilant in warmer months (April-September) when ticks are most active.”