by Andrea Laine, Extension Master Gardener Volunteer

Did you notice an abundance of acorns on the ground this fall? There were so many in one part of my woodland garden that I actually took to raking them aside so I could tend to the soil around my plants. My husband said it was a sign that a lot more squirrels would be born next year. That sounded like an old wives tale to me, but I have since learned it is possible, perhaps even likely.

 

The acorn is the dry fruit of the oak tree and a valuable food resource for wildlife: It is favored by white-tailed deer, raccoons, gray squirrels, chipmunks, wild turkeys, crows, rabbits, opossums, and blue jays, among others.

A mature oak tree stands upwards of 100 feet and can produce a thousand acorns in one season.  Sporadically though, a single oak produces more than 10,000 acorns in a season.This is a scientific phenomenon known as masting. (A mast is any hard fruit such as acorns, beechnuts, or hickory nuts.)

There are hundreds of species of oak. Most fall primarily into two groups: the White Oak and the Red Oak.  The cup of the white oak acorn (left image) is bumpy and bowl shaped, covering less than 1/3 of acorn. The cup of the red oak acorn (right image) is flat and saucer-like, with overlapping scales.

 

 

During masting, a group of trees will form a great amount of acorns to increase the likelihood of a few seedlings reaching maturity. This is the tree’s strategy to increase the odds of some acorns being left alone by birds, mammals and insects long enough to sprout roots and grow into a new tree. Afterall, a plant’s primary purpose is to reproduce.

White oak acorns germinate almost immediately while red oak acorns lie dormant for months. Interestingly, the acorns from red oak trees are higher in fat, protein, calories and fiber  than the white oaks, however, they are less tasty and more difficult for wildlife to digest. So,  they will gobble up acorns from the white oak population first leaving few, if any, in a non-masting year the opportunity to germinate.  Later in winter and spring they will dine on the red oak acorns.

Scientists are unsure what triggers a masting year. But the deer and the squirrels surely know something because when an acorn crop is especially good, wildlife responds by producing more offspring.  Just as my husband predicted.

Sources
Spira, T.P. (2011). Wildflowers & plant communities of the southern Appalachian mountains & Piedmont. Chapel Hill, NC: University of North Carolina Press.

Oak/Acorn Identification Guide:
http://www.gloucesterva.info/Portals/0/mg/documents/HelpDesk/LocalGardening/Trees/oakacorn_id.pdf

http://blog.nwf.org/2013/10/the-wildlife-benefits-of-acorns-and-oaks/

http://www.wsj.com/articles/boom-or-bust-breeding-cycle-that-helps-the-mighty-oak-survive-1478264402

https://plants.ces.ncsu.edu/plants/search/?q=Quercus

Credit for image/caption of single acorns:
http://www.bio.brandeis.edu/fieldbio/Survival/Pages/oak.html

Video of squirrel eating acorns:
https://www.youtube.com/watch?v=CBTULG3xmjE