The official website of the Elkhorn Slough Foundation and Elkhorn Slough National Estuarine Research Reserve
Elkhorn Slough Birds: Acorn woodpecker

Scientific Name:
Melanerpes formicivorus

Picidae (Woodpeckers)

Found at the Slough:
Oak, pine and riparian woodland habitats

Season(s) seen:
Common year round

Did you know...
Woodpeckers have the longest tongues of all birds.

The Acorn Woodpecker is a medium-sized, clown-faced woodpecker with a black back, white belly, red crown, and white eyes. Males have red head with white foreheads, while females have a black patch separating the red from the white.

Here at the Slough the Acorn Woodpecker can often be found tending to their granary trees. These acorn granaries are usually made in dead tree trunks or trees with thick bark such as the Reserve's Monterey Pines. These birds are very social and will work together in large colonies to tend and defend their stash.

You can see these birds in action at the Elkhorn Slough National Estuarine Research Reserve along the South Marsh Loop Trail.

They eat a variety of foods including nectar from trees, insects, flowers, a variety flying bugs, and acorns of course.

Woodpeckers have many specialized adaptations. Their tail has stiff feathers, so that it can be used to help stabilize them while perched on trees. They have the longest tongues amongst birds. These protractile (like in chameleons) tongues, are sticky and covered by spiky hairs at the tip for piercing insects like a skewer. Their heads are specially-adapted to withstand the high impact of banging on wood all day. The beak of the woodpecker grows continuously as it wears down. Their bills can hit a tree with a speeds exceeding 1,000 times the force of gravity, this is about 100 times higher than the acceleration experienced by an astronaut during the launch of a spaceship. The brain of a woodpecker can withstand the shock of all this due to its skull's large cranial surface (which distributes the shock evenly) and stiff neck muscles which do not allow the twist of its neck.

The Acorn Woodpecker currently has the status of "Least Concern" on the IUCN Red List.


Acorn Woodpecker with acorn Acorn woodpeckers with their granary tree Granary tree at Elkhorn Slough Reserve

Some woodpecker fun: Download the printout here.

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This site is maintained by the Elkhorn Slough Foundation in partnership with the Elkhorn Slough National Estuarine Research Reserve