The idea seemed too crazy to Rod Simmons, a measured, careful field botanist. Naturalists in Arlington County couldn't find any acorns. None. No hickory nuts, either. Then he went out to look for himself. He came up with nothing. Nothing crunched underfoot. Nothing hit him on the head.Much more discussion at the link, including speculation as to whether this is a result of variations in the weather, or just a random anomaly.
Then calls started coming in about crazy squirrels. Starving, skinny squirrels eating garbage, inhaling bird feed, greedily demolishing pumpkins. Squirrels boldly scampering into the road. And a lot more calls about squirrel roadkill.
But Simmons really got spooked when he was teaching a class on identifying oak and hickory trees late last month. For 2 1/2 miles, Simmons and other naturalists hiked through Northern Virginia oak and hickory forests. They sifted through leaves on the ground, dug in the dirt and peered into the tree canopies. Nothing...
A naturalist in Maryland found no acorns on an Audubon nature walk there. Ditto for Fairfax, Falls Church, Charles County, even as far away as Pennsylvania. There are no acorns falling from the majestic oaks in Arlington National Cemetery.
"Once I started paying attention, I couldn't find any acorns anywhere. Not from white oaks, red oaks or black oaks, and this was supposed to be their big year," said Greg Zell, a naturalist at Long Branch Nature Center in Arlington. "We're talking zero. Not a single acorn. It's really bizarre."
I seem to remember reading somewhere, years ago, that oaks can cycle their acorn production as a survival tactic. If a group of oak trees puts out the same number of acorns each year, the acorn-eater (birds, squirrels, rodents, deer) population will increase to match the food supply. The way for the trees to reproduce successfully is to have a year with a superabundant crop that can't be consumed, or to have a year or two of diminished or absent production to decrease the acorn-eater population.
That's what I assumed was happening this year. But the WaPo article doesn't mention it, and I can't find that theory on a brief Google search.
Addendum: after seeing the reference to "masting" in the comment, I found this excellent link that discusses the phenomenon.