Why do oaks drop more acorns some years and not others?

If you have live or walk amongst an oak woodland you know what I’m talking about. Oak trees are the foundation of the landscape here in the foothills, providing food and shelter for squirrels, scrub jays, and acorn woodpeckers that store acorns for food. Turkeys, deer, and even wild pigs eat the acorns off the ground.

Live Oak Acorns

In some years in the foothills,  acorns fall from every oak tree in a deluge. Winter winds cause a shower of these oak seeds, banging against metal barbecues and wheelbarrows with a clatter.

In most of November and December, we’ve been sweeping inches of acorns off the patio.

The winds carry away  leaves but not those inches of acorns.  Watch your step as they are slipperier than banana peels on cement sidewalks.

Acorns collect on patios and decks. They gather in all the flower pots and will sprout in all the flower beds in Spring with their long roots.

Scientists studying oak trees across California find that most years, acorn production is low. This is because producing acorns takes a great expenditure of energy for the trees—energy trees usually spend on growth.

Live oak acorns collect under every oak this year. The wind has blown away the caps.

Every five years or so, oak trees will decide to stop growing and put its effort into producing acorns. And enormous quantities of acorns are created by the oak tree. This is the natural boom and bust cycle of an oak tree.

What is amazing to me is that oak trees all across the whole state of California, synchronize their acorn production booms!  This mysterious synchronization of seed abundance is called a “seed masting” or just mastings.

These seed mastings, amazingly, occur among all kinds of oak trees synchronizing together in one season.  Oak groves from different species 200 miles apart have been found to synchronize their acorn production.

Acorn granary

Acorn from Oracle Oak (Quercus morehus)

Studies suggest that this is a way to flood the ecological food supply. If the oak trees over-produce at the same time, then all of the acorn-loving creatures can eat as much as they want and there will still be some acorns that survive to grow into trees.

Field Mouse with acorn has plenty this winter

This feast and famine has caused wildlife like squirrels, scrub jays, and acorn woodpeckers to store seed as a way to better survive these cycles.

Candle jar with acorns

No one knows for sure why or how these oak trees synchronize their boom cycles. Scientists theorize that the trees are picking up on some kind of climatic condition that signals them to over-produce. It’s a true mystery!

Acorn woodpecker

Acorns’ tannin can affect horses and chickens. If they don’t have an additional food supply they can be affected badly.

Acorns and the weather

While there is some speculation that mast years have a weather connection, scientists say that there is no definitive research in the area.

Can Acorns Predict a Rough Winter?

via Farmer’s Almanac

The following are some “Natural Signs of a Rough Winter” collected over the years. Check them out and let us know if you have witnessed any of these signs or have additional weather wisdom that should be added to the list.

Natural Signs of a Rough Winter:

* Very thick onion skins or corn husks

* Woodpeckers sharing a tree

* Early arrival of crickets on the hearth

* Spiders spinning larger than usual webs

* Lots of acorns

* A small rust/orange band on a wooly worm caterpillar

* Trees are laden with green leaves late in the fall.

* Tree bark is heaviest on the north side of the tree.

* Crickets are in the chimney.

* Hoot owls call late into the fall.

* Raccoons have thick tails and bright bands

* Squirrels gathering nuts early in the year

* Frequent halos/rings around the sun or moon

* Pigs gathering bricks