Photo: Rick & Nora Bowers/Vireo

Acorn Woodpecker

Melanerpes formicivorus

A clown-faced western woodpecker with a complicated social structure, living in small colonies. Best known for its habit of hoarding acorns: the birds drill small holes in a dead snag, then harvest acorns in fall and store them in these holes, to be eaten during winter. Such a "granary tree" may be used for generations and may be riddled with up to 50,000 holes. Nesting is a group activity, with several adults (up to 12 or more) taking part in incubating the eggs and feeding the young in a single nest.
Conservation status Still widespread and common. Reliance on specific oak habitats may make it vulnerable to the effects of climate change.
Family Woodpeckers
Habitat Oak woods, groves, mixed forest, oak-pine canyons, foothills. Seldom away from oaks. Most common where several species of oaks occur together (this insures against total failure of local acorn crop, as different oaks respond to different conditions). May be in open oak groves near coast, pine-oak woods in mountains, streamside sycamores next to oak-covered hillsides.
A clown-faced western woodpecker with a complicated social structure, living in small colonies. Best known for its habit of hoarding acorns: the birds drill small holes in a dead snag, then harvest acorns in fall and store them in these holes, to be eaten during winter. Such a "granary tree" may be used for generations and may be riddled with up to 50,000 holes. Nesting is a group activity, with several adults (up to 12 or more) taking part in incubating the eggs and feeding the young in a single nest.
Photo Gallery
Feeding Behavior

Members of group harvest acorns in fall, store them in hole-studded trees, feed on them in following seasons. Insects are gleaned from surface of tree, or caught in swooping, acrobatic flight. Unlike most woodpeckers, rarely or never excavates in wood for insects. May feed on sap, digging pits in bark or visiting those made by sapsuckers.


Eggs

3-7. White. Nests with more eggs (up to 17 recorded) must result from more than one female laying. Incubation mainly by both parents at first, with helpers soon joining in; incubating birds take turns, with rapid turnover, sometimes changing places many times per hour. Incubation period 11-14 days. Young: Are fed by both parents and by helpers, and leave nest at about 30-32 days. 1-2 broods per year, possibly sometimes 3.


Young

Are fed by both parents and by helpers, and leave nest at about 30-32 days. 1-2 broods per year, possibly sometimes 3.

Diet

Omnivorous, eats many acorns and insects. Acorns make up about half of annual diet, and are of major importance during winter. Also feeds on insects, particularly ants. Diet also includes various nuts, fruits, seeds, sometimes eggs of other birds.


Nesting

Breeding group consists of pair, usually assisted by additional birds, generally the pair's earlier offspring or other related individuals. Group may consist of 10+ birds (as many as 16), which defend communal food stores and nesting territory year-round. Nest site is a cavity in tree (almost always dead tree or dead branch of live tree), 5-60' above ground, usually 12-30'. Excavated by both sexes and by helpers.

Illustration © David Allen Sibley.
Learn more about these drawings.

Text © Kenn Kaufman, adapted from
Lives of North American Birds

Migration

Mostly permanent resident throughout range (which extends south to Colombia). Stragglers may appear far from nesting areas at any season. If acorn crops fail, may stage small invasions to lowland valleys in fall and winter.

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Migration

Mostly permanent resident throughout range (which extends south to Colombia). Stragglers may appear far from nesting areas at any season. If acorn crops fail, may stage small invasions to lowland valleys in fall and winter.

  • All Seasons - Common
  • All Seasons - Uncommon
  • Breeding - Common
  • Breeding - Uncommon
  • Winter - Common
  • Winter - Uncommon
  • Migration - Common
  • Migration - Uncommon
Songs and Calls
A loud ja-cob, ja-cob or wake-up, wake-up.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
Learn more about this sound collection.

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