Poison, counter-attack, enemy insertion and the use of overwhelming force all characterize the hidden and sometimes underground world of the acorn. An ebb and flow battle is quietly fought year-round employing a vast array of offensive and defensive maneuvers to an extent we are only beginning to know. It begins with the production of countless legions of acorns across the eastern forest. Just one healthy and mature white oak tree alone may produce more than 20,000 acorns on a good year. But not every year is a good year for acorns. In fact, most years are relatively poor, and in some years there is nearly a complete lack of acorns. It may be that in many years the oak flowers get killed by spring frosts. Or it may be a strategy to keep acorn predators at bay. On years when there aren’t many acorns to eat, the predators don’t do nearly so well and so their populations stabilize or even decline. Then suddenly and almost unpredictably there are years when nearly the entire forest erupts in a bumper crop of acorns – so much so that those who eat acorns are unable to consume the vast quantities to be found. By this use of overwhelming force, the oaks are assured that at least some of their offspring will escape being eaten and live to germinate on the forest floor. This phenomenon of only producing abundant acorn crops from time to time is known as masting.

As for the enemies of acorns, they are numerous and sometimes quite crafty. They range from the obvious like squirrels, turkey and deer, to the tiny acorn weevils, filbert worms and gall wasps. There are 22 species of weevil alone that lay eggs in late summer on the acorn. The larvae then burrow their way into the acorn and consume most of the nut in a matter of weeks. It has been found that in some years insects may eat or damage as many as 80 percent of all acorns before they even fall from the tree and hit the ground. Pick up a handful of acorns this fall and study them closely. It’s almost a sure thing you’ll find at least one that will have a small hole where the weevil chewed his way to freedom after he was finished gorging on the meat. Crack open that acorn and you’ll see why it has no chance of producing a new seedling in the spring.

Even if an acorn survives the onslaught of insects and reaches the ground, it still must dodge numerous squirrels, mice, chipmunks, deer, turkeys, blue jays and nearly 90 more kinds of wildlife that are nut consumers. One way to improve the odds is through the judicious use of a poison known as tannin. Tannins, especially in red oak, are known to cause a bitter taste and can cause adverse reactions in animals that consume them. White oaks don’t contain as many tannins and reportedly taste better, but on the other hand they don’t contain as much energy either.

In a world of eat or be eaten, sometimes an enemy can turn out to be a friend, too. We all know that squirrels scatter nuts and acorns all around their dens in preparation for winter. Many of these they will later eat but others will have been forgotten and end up safely planted in preparation for spring. Less commonly known is that blue jays are perhaps the best acorn distributors of all animals. Blue jays will take acorns much further from the parent tree than squirrels and will frequently bury them in open fields or abandoned pastures where they may later sprout.

One fall day a few years back, I watched a cluster of black oak trees filled with acorns being worked by both squirrels and blue jays at the same time. It appeared to me the jays were plucking acorns from the far tips of the tall crowns where the squirrels were having a bit of difficulty, and the squirrels were taking those more easily reached. Both bird and mammal were certainly intent on taking these nuts prisoner, but unwittingly they are also doing the trees a favor by ensuring some young black oak acorns will escape the confines of deep shadow to be planted where they will thrive. Last year the acorn crop was nearly absent and so squirrels and acorn eaters are probably less abundant this year as a result. In contrast, 2005 was one of those bumper years when the oak trees gain the upper hand in their age old battle against those would consume their future.

For more a somewhat technical but fascinating book on oaks, acorns, and wildlife try Oak Forest Ecosystems. Ecology and Management for Wildlife, edited by William J. MsShea and William M. Healy and published in 2002 by Johns Hopkins University Press. n