Although storing food for the winter is not unheard of among birds, the
acorn woodpecker's practice of carefully drilling holes in trees and
stuffing them with hundreds of acorns is rather unusual. This industrious
hoarder is undoubtedly one of the most fascinating birds because of its
intricate feeding system and occasionally spectacular social behavior.
One of the 239 species of woodpeckers that make up the family Picidae is
the acorn woodpecker. From the Oregon and California coasts all the way down
to Mexico and Colombia, it may be found. These birds are more frequent in
urban and suburban settings, but they prefer western oak and pine-oak woods
at higher elevations. They are grouped in families of up to 12 people, so
chances are if you encounter one, you'll discover others shortly. The family
units share a common nesting area and occupy a certain territory. Typically,
dead trees with sizable cavities are used for their nests. Acorn woodpecker
activities therefore take place in and around their tree and the area that
their family occupies.
When there are several breeding females in a family group, all of the
ladies deposit their eggs in one nest, which causes weird things to happen.
Before each breeding female begins to lay eggs simultaneously, the family of
an acorn woodpecker starts consuming any eggs it discovers in its nest. This
is to guarantee that not just the oldest eggs have a chance to survive,
claims Bill Schutt, professor of biology at LIU Post and research associate
at the American Museum of Natural History. "It seems to reason that the
eldest hatchling would have the greatest chance of surviving. The birds will
continue to consume each other's eggs until they both lay their eggs on the
same day, which may take weeks, in an effort to eradicate this
advantage."
They will remain with their family for a few years after they reach
adulthood to assist with the new babies. They will eventually go to the air
to search for a new family. They typically replace an adult who just passed
away. As soon as fall is almost around the corner, acorn woodpeckers start
hoarding acorns for the colder winter months. The entire family spends a lot
of time gathering and stockpiling acorns. They create a type of tree known
as a "granary tree," which they use to store the harvested seeds in tiny
holes. Any tree will suffice, provided it has thick bark, although
woodpeckers that dwell in suburban settings are also quite content to drill
holes in wooden poles and store their acorns there.
It's a significant operation that involves careful preparation to drill
those holes. The acorns may fall out of their position if the holes are too
large, or worse still, other birds may take the stored items. It's dangerous
to leave the hole too small since the acorn can crack or lose its quality.
To select the best fit for the supplied acorn, the bird first gently presses
the acorn into each hole in turn. Once the acorn is in position, it moves on
to install another one, and so forth. But the task doesn't end there. The
family members must constantly care to the granary trees and be on the alert
for prospective acorn thieves like squirrels or even other woodpeckers in
order to protect their store. As a result, one of the group's members is
always watching after their tree.
Thousands of acorns are typically stored in a typical granary tree. Every
square inch of the tree, which may be covered in holes from the bottom to
the top, is used by the woodpeckers. 50.000 holes were ever documented on a
granary tree, which was the labor of several generations of woodpeckers. Due
to their high fat content, acorns are ideal for the winter, proving that
their evolutionary plan has paid off. The woodpecker is the only bird that
hoards food on such a large scale, yet this behavior does help the bird
survive cold periods without having to fly to warmer climes.
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