I have this big chestnut oak in my back yard that drops about a ton of big, meaty acorns in fall that squirrels relish. However, a brief examination of the tree yesterday revealed very few acorns this year. Without this vital food source, those fluffy-tailed rats might starve. Aw, nuts.
Of course, acorns feed more than just stinking squirrels. Deer, wild turkeys, and other animals depend on them too. But not all acorns are equally palatable. Acorns produced by trees in the white oak family (white oak, swamp white oak, chestnut oak, bur oak, chinquapin oak ) are tasty. Even people can eat them -- Native Americans crushed the nutritious meats to make acorn flour. (Click here to see a demonstration.) However, acorns produced by the red oak family (red oak, scarlet oak, pin oak, willow oak, black oak) contain so much tannin that they're incredibly bitter. People can't eat them and critters prefer not to.
Acorns differ in other ways besides edibility. White oak acorns mature in one year and germinate as soon as they drop to the ground. Red oak acorns mature in two years and don't germinate until they've gone through a winter on the ground (by which time most have been eaten by weevils and other bugs). It's thought that this staggered production keeps predators from gobbling down an entire year's crop in one fell swoop. The trees are hedging their bets.
Why does a tree bear a heavy crop of acorns one year and not the next? Two reasons. First, it takes a lot of energy to ripen a big crop, so basically the oak takes the next year off. Second, bad weather when oaks are blooming can inhibit pollination. No pollination, no acorns.
And no acorns means no squirrels -- or, at least, a lot fewer. Their population directly mirrors the local food supply. Hungry squirrels have fewer babies. Those they have don't live for long.
Does this keep me awake at night? Are you kidding? I'm the Grumpy Gardener! I HATE squirrels! Here's hoping my chestnut oak vacays next year too.