With over 600 species of oak trees on our planet, this venerable tree surrounds many of us. This time of year we watch the seasonal changes, but every season is a joy with oak trees.
Oak trees live only in the Northern Hemisphere. They belong to the genus Quercus, meaning “fine tree” in Latin.
More info: Oak Wikipedia
Here in Northern California, the oaks have endured the summer drought with stoic strength. They stretch their mighty roots deep into the earth for moisture when the rest of the landscape is parched.
We have approximately 20 species in California, the Bay Area has eight or nine. See penultimate photo. Oak woodlands cover approximately 8.8 million acres of California (Bay Nature, Spr. 2022).
Everywhere I go in this great state, I am always studying the oak trees, trying to determine which species I am fortunate to have the pleasure of meeting.
I look closely at the bark and leaves, the shape of the tree, take note of the location.
Acorns are also helpful identifying tools, if there are any on the tree. Phone apps for identifying species help, too.
But identifying an oak species can be tricky, I have found, because they hybridize. So I try not to get too involved with identification studies…I am not presenting a dissertation, it’s simply a walk among friends.
More important than identification is taking note of the grand queen I am in the presence of, and what she has to offer.
An early springtime stroll through oak woodlands reveals lichen-covered and leafless oaks, and winter rains still saturating the hillsides.
Later in spring the lupine wildflowers emerge and the trees are budding.
Winter brings a bouquet of moss and lichen to every tree; many are draped with lace lichen, the State Lichen.
This brown creeper, below, was busy hunting insects nestled in the lichen and moss.
Oaks are magnets for all sorts of wildlife.
This week I had the pleasure of a great horned owl serenade in the oaks out back…a calm duet in the middle of the night.
Autumn is a great time for watching creatures pluck the acorns and whisk them off to their special hiding places in preparation for inclement days.
Acorn woodpeckers, named for their expert reign over oak trees, can often be seen snatching the acorns, squawking loudly, calling waka-waka-waka. They robustly tug and remove the nut and fly off in a flurry of black and white to deposit it.
A granary is a designated place acorn woodpeckers have chosen for storing their precious acorn supply. Usually a granary is a dead tree (not necessarily an oak), but the birds also use utility poles, fence posts, wooden buildings. As colonial birds, they rely on each other to protect their wares.
Over the years they have created these holes for storing acorns.
You can see (below) the holes that are stuffed with tan-colored acorns.
Over time a granary acorn will dry out and get smaller, so the acorn woodpeckers relocate it to a different hole where it fits more snugly and safely.
Every species of woodpecker visits the oak trees, not just acorn woodpeckers.
And both our jay species do, too. Western scrub-jay and Steller’s jay. When the acorns are ready, the jays doggedly gather acorns all day long.
Equally as fun is witnessing the jays months later retrieving the buried acorns from the ground or shrubbery.
Nuthatches get their name from jamming large nuts and acorns into tree bark, then whacking them with their sharp bill to “hatch” out the seed of the nut.
Squirrels of course take to the nuts. We expect this of tree squirrels, but even so-called ground squirrels scramble about in the leaves at acorn time. Apparently the ground squirrels throw caution to the wind, scurrying about in the oak tree instead of on the ground. More than once I have witnessed the ground squirrel falter and fall out of the tree, plop on the ground. They don’t seem to be hurt and in fact go right back up the trunk.
Here you can see a trio of acorns (lower right) that the ground squirrel is precariously heading toward.
Long ago acorns were prized by human indigenous populations too. There is, however, a lot of work to preparing an acorn for human consumption, due to the nut’s tannins.
More info: Acorn Wikipedia
After the acorn celebration is over, in a few months the deciduous oaks will be leafless, giving us a clean view of the gnarly limbs and multiple trunks.
They close down and rest for a season of cold days and nights.
When spring arrives, the tree produces catkins, its flowers. In the black oak (Quercus kelloggii), photo below, you can see hanging filaments dotted with tiny red balls–those are the catkins.
The leaves start out red.
As the season progresses, the leaves get bigger and turn from red to lime green. Then as the California sunshine intensifies, the lime green leaves turn darker green and get tougher, leathery.
Our old black oak tree was very entertaining every spring when birds arrived to pluck juicy caterpillars rolled up in the new leaves. It was great for the tree too, removing pests.
With each new season the oaks change and we are reminded by this lovely being how wise and wonderful life on earth can be.
Written by Jet Eliot.
Photos by Athena Alexander.
Great reference guide for oaks: The Sibley Guide to Trees (2009) by David A. Sibley