Acorns have been bombing my home’s roof and deck and pinging the roof of the metal shed in the backyard heavily since late summer. The quantity of acorns seems to vary from year to year. This year might be what is known as a “mast year.”
I had to look up what a mast year means. The fruits, nuts, berries, and buds produced by trees and bushes are called “mast.” Things like walnuts, pecans, hickory nuts, hard seeds, and acorns are called hard masts, and berries and fruits, and buds are soft mast. A mast year is a year when the amount of that mast is unusually high in number,
Since my first association with the word “mast” is with a sailing ship, I had to check the etymology of this botanical usage. It comes from Middle English and earlier Old English mete similar to mæst in Old High German where it meant food. If you think of an acorn as food (many animals and some humans do) then inside that shell is the meat.
Can we predict these cycles of acorn plenty? Do we know why they occur? There are theories but it is still mostly a mystery.
These mast years seem to occur in irregular cycles of two to five years. An abundance of acorns is often said to be a nature sign of a bad winter. The folk belief is that squirrels, chipmunks, mice and other animals somehow know that they need to stock up for a bad winter and that nature somehow knows to increase the supply chain of acorns. But there’s no real science behind that folk wisdom and weather lore. that they need to stock up. The Farmers’ Almanac – which has lots of folklore around weather – seems to indicate that if acorn numbers mean a bad winter then almost every year is a bad winter.
But I continue and observe and write about signs of the seasons in nature and keep a nature calendar.
Squirrels, mice, chipmunks and deer feed on the acorns in my neighborhood. When the trees produce smaller crops for a few consecutive years, they are in effect keeping the populations of these animals in check. But during a mast year, the trees produce more food than the animals can possibly eat.
This abundance causes a boom in the populations of smaller mammals. It also guarantees that some acorns will survive and grow into new trees. Producing nuts slightly stunts the tree’s growth, but as it happens in cycles the tree gets a chance for growth in the non-mast years. Living things generally live to reproduce.
Chipmunks hibernate in cold weather and so in Paradelle, they spend most of the winter sleeping in their dens. I read that one chipmunk can gather up to 165 acorns in a day. But those cute little Disneyesque critters don’t just eat acorns. Along with seeds and fungi, they will eat grain, fruit, nuts, insects, and worms. I was surprised to find that though they don’t hunt for bird eggs and even nestling birds and baby mice, they will eat them when they find them. They also love to dig in my outdoor potted plants, so cute as Chip and dale might be, they are also pests around here.
In 2020, the chipmunk population locally was insanely large. This year I barely saw any – until the acorns started to fall in late August and now they are all over my backyard and deck. Where were they all spring and summer?
In reading the novel The Overstory by Richard Powers and some other research as a follow-up. I learned a lot about trees. For example, most people probably believe that trees compete with each other for sunlight, water, and nutrients. That isn’t true. In fact, in most settings, they communicate and cooperate.
With acorns, temperature and moisture are probably factors in these cycles, and now it is theorized that oaks might be sending chemical signals to coordinate their production. In my part of the country (Northeast) last winter and spring were generally mild winter and so white and red oak trees are able to produce more of them when they start creating seeds in the spring. A harsh winter or cold spring or freeze can mean little acorn production, or sometimes none at all.
There are still mysteries in all this. How trees communicate with each other is still being explored. We can’t predict when any one species will have a mast year.
but we do better understand what causes it. The weather certainly has a part to play. To produce a healthy crop, the trees need the right combination of temperature and rainfall in the spring.
Phenology is the study of the timing of natural events in relation to the weather. This is the scientific version of weather lore and the studies continue.
SIDEBAR: Can humans safely eat acorns? Yes, they can be used in a variety of ways. They can be eaten whole, ground up into acorn meal or flour, or made into mush to have their oil extracted. Once you’ve safely leached the tannins from your raw acorns, you can roast them for 15 to 20 minutes and sprinkle them with salt for a snack. I haven’t tried eating yet, but maybe this is a good year for it.
FURTHER READING ON TREES
The Overstory: A Novel
The Hidden Life of Trees: What They Feel, How They Communicate
The Heartbeat of Trees: Embracing Our Ancient Bond with Forests and Nature