Something Wild: Why So Many Acorns?

Oct 10, 2014

We love answering listener's questions and recently we received one that is a common query at both the Audubon and the Forest Society.

Why is it that some years there are tons of acorns and other years hardly any?

The number of acorns a tree produces in a given year has to do with masting. Not mast like on tall ships, but mast as in masticate, or to chew and it refers to the fruit, seeds or nuts that trees produce and are in turn fodder for animals. Especially in New Hampshire, oak mast follows a boom or bust cycle, which means the amount of acorns varies from year to year. Over time, evolution has favored the oak trees that demonstrate this boom or bust cycle.

This keeps seed consumers off balance and that's actually a good thing. If there were the same amount of acorns every year, there would be just enough mice and turkey and deer and others to consume every single acorn. However, by producing very few acorns a couple of years running, they starve the animals and the populations of seed predators crash. Then, the oak has a boom year and there aren't enough animals to eat them all, which allows some of those acorn to become trees. Which means the oaks are calling the shots in the forest.

It goes even further than that. In response to boom years of acorn crops, the numbers of seed predators increases, so the following year there are more mice and squirrels and voles. This in turn leads to an increase in raptors that feed on those small animals. These boom and bust cycles affect humans too. One of the top acorn consumers is the white footed mouse. When there's a boom year and these little mice increase in number, the tick population that feeds on those mice goes up as well. More ticks means more ticks carrying lyme disease, which means an increase in lyme disease in humans. All this from the humble acorn.

And your questions! Keep those questions coming and we'll do our best to feature the answer in a future episode of Something Wild. You can send your questions to: somethingwild@nhpr.org. We'd also love to see your photos too, florae, fauna, anything in nature that catches your eye.