Acorn Woodpecker Granaries

Acorn Woodpeckers, Costa Rica

At this time of year when the acorns are dropping, California’s acorn woodpeckers are busy. They store their nuts in a most unique way.

 

A medium-sized woodpecker, Melanerpes formicivorus uses its bill to pick up acorns, one at a time, then flies each nut to a designated storage facility, called a granary. Usually granaries are dead oak trees, but sometimes they are man-made wooden structures, like a telephone pole or fence post.

 

Acorn Woodpeckers at a granary, Belize

 

Fencepost granary. Photo by Giles Clark. Courtesy atlastobscura.com

 

Last month I had the pleasure of taking my morning walks through a state park, and was enchanted by the large population of acorn woodpeckers. As I walked down the lane, I spotted the characteristic dip of the woodpecker flight pattern, and heard their delightfully raucous voices.

 

Calif. State Park, lane with numerous acorn woodpeckers

Such an attractive bird, with their bright red-capped heads and flashy red, white, and black markings. Every day I saw at least 20 acorn woodpeckers.

 

Here in California we see granaries often. From a distance it looks like a dead tree; but when you get close you see the tree trunk is filled with holes. Upon closer examination, each hole has an acorn stuffed into it.

 

The social structure of acorn woodpeckers is extensive and complicated, with cooperative breeding and large family groups. Not only do they tend their nests together, they also build their granary together.

 

There’s an ancient phrase that’s goes something like…a granary wasn’t built in a day. Each granary is a culmination of years of acorn gathering. A granary can be pocked with thousands of acorns and perfected over a decade.

 

Male acorn woodpecker at granary. Photo by Johnath, courtesy atlasobscura.com

 

Photo by David Litman, courtesy atlastobscura.com

The woodpeckers actually work all year long on their granaries, but this time of year is especially exciting when the acorns have become harvestable.

 

Building the granary is only half of the work; maintenance and protection are also important.

 

To keep other birds and squirrels from stealing the precious nuts, each acorn is tightly fitted into a hole. The woodpecker has a sharp bill and excavates the hole, then pounds the acorn in with no extra space, making it difficult to be removed.

 

Over time, however, the old, dry acorns tend to shrink. When this happens, the woodpeckers remove the loose acorn and find (or create) a smaller and more suitable hole.

 

Acorn woodpeckers also eat insects, other nuts, lizards, seeds, grass, and more.

 

Acorn Woodpecker Wikipedia

 

This bird species, dependent on oak trees, lives primarily in the western and southern parts of the U.S., as well as Mexico and Central America. We are lucky to see them all over California. See range map below.

 

Excellent short video of acorn woodpeckers at a granary:  Click here.

 

With their clown-like look, colorful markings, cheerful laughter, and productive activities, this bird will bring a smile to your face even before you see their masterpiece.

 

Written by Jet Eliot

Photos by Athena Alexander, unless otherwise specified.

 

Acorn Woodpecker Range Map. Courtesy allaboutbirds.com