I don’t know if the same is happening in your neighborhood, but the oak trees in my area are just raining acorns this year. Never in my ten years of living under oaks have I seen so many acorns. The plinking and thunking of acorns hitting the roof, bouncing off the grill top, and pelting the patio furniture (and the hapless souls sitting in that furniture) has been ceaseless for the past three weeks – it keeps us up at night!
Acorn boom and bust years are not unusual. In fact, this cyclical pattern of increased acorn production, known as a “mast year,” generally occurs every 3-5 years. These high production years are a boon to native wildlife like chipmunks, squirrels, mice, jays, and grackles. Yes, the grackles have swooped through the neighborhood in flocks, visiting one bountiful tree after another. Their visits are filled with energy and athleticism as they use their interior-keeled beaks to break open shells, while they keep their keen eyes on the neighbors as they run outside in wonder at the acorn hailstorm occurring in their backyards.
It seems scientists have not been able to discern what causes mast years. Some hypothesize it’s a specific weather pattern of temperature and rainfall that benefits acorn production, others wonder if it’s a particular pollinating wind pattern in the spring. Regardless, the ecological strategy seems to be the promise of a new generation of oaks.
Interestingly, my son and I picked up a white oak acorn already sprouting a bright green tap root. I just learned that trees in the white oak family, which are less tannic than those in the red oak family, will sprout right away, increasing the chance of becoming a sapling. Meanwhile, the red oaks, with their bitter-tasting tannins, are more likely left alone by forest foragers and can hope to survive to sprout in the spring. (Additionally, our discovery has sparked our interest in bringing the sprouted acorns inside.)
I also wrote a bit about oaks a few years ago. Here’s a flashback from the November 2015 Nature Net News…
Of the 400+ oak species, Wisconsin is home to seven (or more, depending on which trusted source you cite) native oak species. The most commonly known of these are: white oak, bur oak, northern red oak, and the black oak. When I was young, I was taught that white oak leaves are rounded like a ghost and black oak leaves are pointed like a witch’s hat. Befitting of the season as you shuffle through piles of oak leaves on the ground. Check out the Wisconsin Department of Natural Resources guide to Forest Trees of Wisconsin, or the UW Herbarium list of tree species (scroll down to find Quercus for oaks) for details on each of our native species.
[2021 Update: my hiking companions a few weeks back were having a blast using the app “Seek” by iNaturalist to snap pictures of plants and other species to learn their identity – highly recommended for anyone (like me) who appreciates putting a name to a “face.”]
If a large oak tree can produce thousands of acorns each year, why do we never see acorns at the grocery store? Turns out they are so full of acidic tannins, they’re nearly toxic to humans (and other animals – more on that later). However, because tannins are water soluble, they can be leached from the acorns with a good soaking. For those prepared to put in the work of drying, soaking, and then grinding the acorn nut meats into a flour, a porridge or flatbread can be made. It’s a lot of work – too much to replicate on a large scale – but some hearty foragers and Native American historians are willing to tackle the task to reap the benefits – in the form of healthy fats, minerals and protein – of an acorn meal. Check out this NPR story on eating acorns and see if you’re up for the challenge.
Because of their tannic nature, many livestock animals, including cattle, sheep, goats, and horses cannot eat acorns. One domesticated animal joins the ranks of wildlife animals (such as squirrels, turkeys, deer, and bears) that enjoy a good acorn meal: pigs. In fact, some pasture-raised pigs who are put out to forage under swaying oak branches are considered to be healthier, happier, better for the environment, and to produce a tastier and healthier pork. Find out more – including the lavish per-pound price – from this article on the traditional practice of Acorn-finished Pork.
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