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Acorn Woodpecker | Melanerpes formicivorus

Eikelspecht | Carpintero bellotero

The Acorn Woodpecker lives in tight-knit, resident groups that together store thousands of acorns in a single tree, each in its own bill-drilled hole — a granary tree that can remain in use for generations.

Acorn Woodpecker (Melanerpes formicivorus) — Photo: Becky Matsubara — CC BY 2.0 · Wikimedia Commons

Voice

Very vocal: a repeated, harsh waka-waka-waka, often called by several birds at once.

Listen: CallXC110258

Recording: Jonathon Jongsma — CC BY-SA 3.0 · McClellan Ranch Preserve, Santa Clara, California, United States · xeno-canto

Identification

A clownish face with white eyes, a black back, a white forehead and throat, and a red crown that in the female is separated from the forehead by a black band. White on the wings and rump stands out in flight.

Confusion species

The striking face pattern makes confusion with other woodpeckers unlikely; only the head of the Golden-fronted and Gila Woodpeckers, both lacking the white eye and black-and-white face pattern, superficially resembles it.

Habitat

Oak woodland and mixed oak-pine forest, from savanna-like open oak country to denser forest in the mountains.

Where the bird is most often found, arranged by the USNVC — the vegetation classification of the United States and Canada — and CMECS for sea and coast.

Range and movements

Resident from south-western Oregon through all of California and the south-western United States, south through Mexico and Central America to Colombia.

Resident
Breeding (summer)
Winter
Passage
dark = core range, pale = thinly spread

The map is a density field, not a drawn range boundary: it is built from the records themselves and therefore does not follow state or national borders. Both the seasonal colour and the depth of colour come, cell by cell, from the records of GBIF (2006–2026), counted per 0,7° cell and divided by all bird records in that same cell, so that the density of birdwatchers does not count. Every cell is counted separately for June–July, December–January and the migration months, and takes the colour of the season that wins there; a cell is only called summer or winter where the other season is nearly empty. Country outlines: Natural Earth (public domain).

Where and when to look

Look for 'granary trees' with hundreds to thousands of small holes, each holding an acorn — often the same dead tree or pole used by one family group for years.

Conservation

Not threatened; the species depends heavily on old oaks with enough space for storage, and loss of oak woodland is a local risk for its cooperatively breeding groups.

Scientific name

Melanerpes formicivorus | (Swainson, 1827)

Originally described by Swainson in 1827 as Picus formicivorus; since moved to Melanerpes, author and year stand in parentheses. Formicivorus is Latin for 'ant-eating', though the diet consists mostly of acorns and insects.