MINNEAPOLIS (WCCO) — Several WCCO viewers have, including Leah from Coon Rapids and Robert from Oak Grove. They wrote to us wanting to know, why are there so many nuts?

The Minnesota Department of Natural Resources says its foresters are reporting more acorns as we wind down the summer. But, foresters say there’s no need to worry – it’s all normal.

According to Mike Reinikainen, a forester with the DNR, the three biggest oak species in Minnesota are masting this year. That’s similar to having a bumper crop.

Oak trees have boom and bust years when it comes to acorns. Masting can happen every two, or five or seven years — it all depends.

Experts don’t know exactly why trees mast in one particular year over another, but the University of Minnesota Extension writes in its blog on acorns that oaks are responding to favorable conditions this spring and summer.

Masting is part of a larger process in nature, says Reinikainen. In a non-masting year, oaks produce just enough acorns for the squirrels and chipmunks and deer to eat. It keeps the animal population in check, but it doesn’t allow for any acorns to grow into baby trees.

But every few years, oaks drop a whole bunch of nuts — way more than the critters could handle. That way, the animals will leave some leftovers to survive and eventually germinate into trees.

And, for anyone who wants the answer to a Good Question from Leah from Coon Rapids: Does a heavy acorn year mean it brutal winter ahead?

No, say foresters from the DNR and University of Minnesota Extension. Acorns can’t predict the future, but they can keep more squirrels full, happy and healthy to make it through the winter.

Heather Brown

Comments (2)
  1. Greg Laden says:

    A somewhat better (more scientifically accurate) way of putting it is this: Masting trees time their production in such a way that the life cycles of their main predators won’t allow them to adapt population size to acorn production on a year to year basis. The squirrels and deer would ideally reproduce a much higher rate during masting years, and eat all the acorns. But it would take three or four years for the deer to quadruple their population, and the mast crop is available for only a few weeks. Squirrels have a fighting chance of using more of the mast since they reproduce faster and will store a lot of acorns, but still not fast enough. There will be more squirrels in the short term, but not enough to eat all the acorns being produced this year.

    Passenger Pigeons, which went extinct in the early 20th century, mainly ate acorns. Presumably they flew from masting site to masting site across North America, in large sky-darkening flocks. But the widespread cutting down of trees from an entirely unregulated and non sustainable lumber industry reduced vast oak forests so much that a follow the mast strategy, even if you have wings, is not viable. (There are other theories for why passenger pigeons went extinct, but that is my preferred one.)

    Masting is like the 7 (or other number) year locust. Same idea. Note that masting or locust years tend to be odd numbers, preferably prime numbers.