Acorn Woodpeckers at Work

Wildlife Safari: Sept 20, 2011 -- I drew these drawings a month ago, but life has been busy. I wanted to add the color before posting them.

Fall has come. Grasses are golden, oak leaves are dulling, ash is turning yellow. Coolness in the morning air. Its not a great acorn year, at least not where I’m parked; yet there are enough to keep a family of acorn woodpeckers busy storing their winter food supply.

Watching the colony of acorn woodpeckers is a treat! They are such busy, talkative birds. Their antics remind me of a covey of clowns at work. I think there are only four birds using this granary at ‘mid-canyon’ at Wildlife Safari. At least I’ve only seen four on the granary tree at once. Some years the colony is twice this size. Acorn woodpeckers are unusual in that the family group stays together throughout the year and more than just the biological parents care for the nestlings.

Now that the acorn crop is ripening the woodpeckers are busy harvesting hundreds, if not thousands of acorns. One after another each bird flies off to one of the nearby oaks and wrenches an acorn free. They then fly back to the granary tree, in this case an old oak snag. A good granary tree is used until it falls apart, so hundreds of holes have already been drilled. When the bird first returns to the tree the pointy end faces down the bird’s throat – the way it grew on the tree. But that isn’t the correct position for storing. The bird then has three choices. Most are taken to a fairly level branch, the ‘anvil,’ and turned around. Once positioned correctly the woodpecker searches out the right sized hole. Choosing the correct hole is a trial and error process. One is too tight, one is too loose. When the right fit is found he taps it in, always pointed end first. Later, as the acorns dry out, there will have to do a little rearranging – don’t want these acorns easily stolen by the local scrub jays and squirrels.

A few of the acorns still have their caps on. These seem just a little greener. A handy cavity was serving as a holding well for the capped ones. The wood was so old and cracked we could see quite a bunch had already been dropped in.

Sometimes the woodpecker chooses to hull the acorn as soon as it flies in. The shell falls to the ground and the two halves break apart. One at a time he wedges each half into a crack in the wood. I even observed one of the woodpeckers breaking the acorn half into smaller pieces and wedging those into a small crack.

We’ll be watching the granary to see if they succeed in filling all the available holes. One a good year there will still be a few acorns in storage in March. Last year was a poor year. By late December most of the acorn were gone. Fortunately the woodpecker forage for other foods too.

It is easy to tell the sexes apart. The male forehead goes from white to red, whereas the female has a band of black between the white and the red.
Note: Only the first set of drawings was drawn from life. We spent two wonderful mornings photographing the colony … and I ended up with plenty of reference photos to draw from.