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Home/Species/ Acorn Woodpecker

Melanerpes formicivorus

(Swainson, 1827)

Acorn Woodpecker

G5Secure Found in 158 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
Least concernIUCN
Medium - lowThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.101493
Element CodeABNYF04050
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAves
OrderPiciformes
FamilyPicidae
GenusMelanerpes
Other Common Names
acorn woodpecker (EN) Carpintero Bellotero (ES) Pic glandivore (FR)
Concept Reference
American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Taxonomic Comments
Benitez-Diaz (1993) examined variation in morphometric and plumage coloration characters and identified seven geographic units within the species (two in the U.S.), each of which is diagnosable based on combinations of discrete and continuous character states.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-03-19
Change Date1996-12-02
Edition Date2025-03-19
Edition AuthorsGundy, R. L. (2025)
Threat ImpactMedium - low
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Number of Occurrences> 300
Rank Reasons
This species is widespread in western North America, throughout Central America, and northern South America. The population is stable, but habitat loss is an ongoing threat rangewide.
Range Extent Comments
This species is a widespread resident of western North America, Central America, and northern South America. In North America, it is found west of the Cascades and Sierra Nevada mountain ranges from northwest Oregon south through California to Baja California, México, and from eastern Arizona and western New Mexico south through México. In Central America, it is found in Belize, Guatemala, northern El Salvador, northern Nicaragua, interior Costa Rica, and northern Panamá. In South America, the range is restricted to the Andes of western Colombia (Koenig et al. 2020).
Occurrences Comments
There are hundreds of occurrences throughout the range.
Threat Impact Comments
Habitat loss is the primary threat to this species. Residential development and conversion to agriculture and livestock ranching are the primary threats throughout the range (Koenig et al. 2020).
Ecology & Habitat

Habitat

Oaks, either in unmixed open woodland or mixed with conifers (Subtropical to Temperate, locally also in Tropical zones) (AOU 1983); also semiopen habitats such as farmlands and pasturelands with scattered trees and patches of forest in Colombia (Kattan 1988). Digs and nests in cavity in live or dead trees (usually well decayed tree in Costa Rica; Stiles and Skutch 1989), 3-21 m above ground. Often roosts communally in tree cavities throughout the year (Du Plessis, 1994, Condor 96:631-637).

Ecology

Social; lives in permanently territorial family groups of 2-15 individuals.

May compete with Lewis' woodpecker for food.

Winter food supply (acorns) is a major limiting factor (Hannon et al. 1987).

Reproduction

May produce 2-3 broods annually. Clutch size usually is 4-5. Incubation probably lasts about 14 days. Nests cooperatively in parts of range; this behavior influenced by mast crop. Groups typically contain 1-4 breeding males, 1-2 breeding females, and 0-10 nonbreeding group offspring of past reproductive seasons. May nest as late as September or October.
Terrestrial Habitats
Woodland - HardwoodWoodland - Mixed
Palustrine Habitats
Riparian
Other Nations (1)
United StatesN5
ProvinceRankNative
WashingtonS1Yes
OregonS3Yes
Navajo NationS3Yes
CaliforniaSNRYes
New MexicoS3B,S3NYes
ArizonaS5Yes
TexasS4BYes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentRestricted (11-30%)Serious - moderateHigh (continuing)
1.1 - Housing & urban areasRestricted (11-30%)Serious - moderateHigh (continuing)
2 - Agriculture & aquacultureRestricted (11-30%)Serious - moderateHigh (continuing)
2.3 - Livestock farming & ranchingRestricted (11-30%)Serious - moderateHigh (continuing)

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Roadless Areas (158)
Arizona (24)
AreaForestAcres
Barbershop CanyonCoconino National Forest1,311
BoulderTonto National Forest40,359
Butterfly Roadless AreaCoronado National Forest42,296
Cdo WsaCoronado National Forest1,955
ChiricahuaCoronado National Forest76,876
Coconino RimKaibab National Forest7,213
East Clear CreekCoconino National Forest1,613
GaliuroCoronado National Forest28,333
Happy ValleyCoronado National Forest7,972
Hell HoleApache-Sitgreaves National Forests15,512
HellsgateTonto National Forest6,171
Lower RinconCoronado National Forest3,278
Lower San FranciscoApache-Sitgreaves National Forests59,310
MazatzalTonto National Forest16,942
Middle Dragoon RoadlessCoronado National Forest10,543
Mitchell PeakApache-Sitgreaves National Forests35,398
Oracle RoadlessCoronado National Forest22,365
Painted BluffsApache-Sitgreaves National Forests43,118
PinalenoCoronado National Forest130,920
Pine Mountain Wilderness ContiguousTonto National Forest6,518
Pine Mountain Wilderness ContiguousPrescott National Forest3,129
Sierra Ancha Wilderness ContiguousTonto National Forest7,787
TumacacoriCoronado National Forest44,594
WhetstoneCoronado National Forest20,728
California (104)
AreaForestAcres
AgnewSequoia National Forest9,561
AntimonyLos Padres National Forest40,911
Arroyo SecoAngeles National Forest4,703
Barker ValleyCleveland National Forest11,940
Bear MountainLos Padres National Forest913
Black ButteLos Padres National Forest5,116
Black MountainLos Padres National Forest16,818
Black Mtn.Sequoia National Forest15,102
Bonanza KingShasta-Trinity National Forest16,402
Cahuilla MountainSan Bernardino National Forest6,952
CajonSan Bernardino National Forest7,548
CamuesaLos Padres National Forest8,209
Chalk PeakLos Padres National Forest7,472
ChannellSequoia National Forest45,429
Cherry LakeStanislaus National Forest1,106
ChicoSequoia National Forest39,836
Circle MountainSan Bernardino National Forest6,375
City CreekSan Bernardino National Forest9,997
ColdwaterCleveland National Forest8,402
Cow CreekSix Rivers National Forest1,271
Cow CreekShasta-Trinity National Forest22,627
Crystal CreekSan Bernardino National Forest6,783
Cucamonga AAngeles National Forest1,249
Cucamonga BSan Bernardino National Forest11,933
Cucamonga CSan Bernardino National Forest4,106
Cutca ValleyCleveland National Forest14,530
Deep CreekSan Bernardino National Forest23,869
Devil GulchSierra National Forest30,490
Dexter CanyonInyo National Forest17,053
Domeland Add.Sequoia National Forest3,046
Dry LakesLos Padres National Forest17,043
Eagle PeakCleveland National Forest6,481
Ferguson RidgeSierra National Forest6,104
Fish CanyonAngeles National Forest29,886
Fox MountainLos Padres National Forest52,072
Garcia MountainLos Padres National Forest7,850
Glass MountainInyo National Forest52,867
Granite PeakSan Bernardino National Forest450
Greenhorn CreekSequoia National Forest28,226
Hixon FlatSan Bernardino National Forest8,095
Horse Creek RidgeSan Bernardino National Forest8,969
IshiLassen National Forest21,805
Kings RiverSierra National Forest52,999
La BreaLos Padres National Forest14,031
La PanzaLos Padres National Forest4,954
LaddCleveland National Forest5,300
Little French CShasta-Trinity National Forest11,529
Lpoor CanyonLos Padres National Forest13,762
Machesna MountainLos Padres National Forest12,271
Magic MountainAngeles National Forest15,542
Malduce BuckhornLos Padres National Forest14,177
MatilijaLos Padres National Forest5,218
Mill CreekSequoia National Forest27,643
Mill PeakSan Bernardino National Forest7,884
Mirada PimeLos Padres National Forest13,302
MonoLos Padres National Forest28,141
MosesSequoia National Forest22,077
Mt. Shasta BShasta-Trinity National Forest2,809
No NameCleveland National Forest4,897
NordhoffLos Padres National Forest12,031
North Fork Middle Fork American RiverTahoe National Forest11,245
North MountainStanislaus National Forest7,856
Oat Mtn.Sequoia National Forest12,223
Orleans Mtn.Klamath National Forest49,090
Orleans Mtn. BSix Rivers National Forest17,183
PaiuteInyo National Forest58,712
PattisonShasta-Trinity National Forest29,299
Pine CreekCleveland National Forest503
Pleasant ViewAngeles National Forest26,395
Pyramid Peak BSan Bernardino National Forest7,194
QuatalLos Padres National Forest7,253
Raywood Flat BSan Bernardino National Forest11,373
Red MountainAngeles National Forest8,034
RinconSequoia National Forest54,610
Rock Creek WestInyo National Forest3,626
Rouse HillSan Bernardino National Forest13,745
Salt SpringsEldorado National Forest133
San DimasAngeles National Forest7,160
San Gabriel AddAngeles National Forest2,527
San SevaineSan Bernardino National Forest6,866
Santa CruzLos Padres National Forest21,182
Sawmill - BadlandsLos Padres National Forest51,362
Sespe - FrazierLos Padres National Forest106,910
Sespe - FrazierAngeles National Forest4,254
Sheep MountainAngeles National Forest21,098
Sill HillCleveland National Forest5,294
Skeleton GladeMendocino National Forest9,237
Slate Mtn.Sequoia National Forest12,299
Snow MountainMendocino National Forest14,457
South ForkShasta-Trinity National Forest16,786
Strawberry PeakAngeles National Forest7,245
SugarloafSan Bernardino National Forest8,206
Sycamore SpringsSierra National Forest10,015
TequepisLos Padres National Forest9,080
Timbered CraterLassen National Forest4,096
TinemahaInyo National Forest27,060
TrabucoCleveland National Forest23,341
TuleAngeles National Forest9,861
West GirardShasta-Trinity National Forest37,516
WestforkAngeles National Forest4,407
White LedgeLos Padres National Forest18,632
WildhorseCleveland National Forest1,483
WoodpeckerSequoia National Forest11,936
WoolstaffSequoia National Forest41,445
Colorado (1)
AreaForestAcres
HermosaSan Juan NF148,103
Idaho (1)
AreaForestAcres
Bear CreekCaribou-Targhee National Forest118,582
New Mexico (21)
AreaForestAcres
Alamo CanyonSanta Fe National Forest8,639
Apache Kid ContiguousCibola National Forest67,542
Aspen MountainGila National Forest23,784
Candian RiverCibola National Forest7,149
Columbine - Hondo Wilderness Study AreaCarson National Forest43,739
Contiguous To Black & Aldo Leopold WildernessGila National Forest111,883
Contiguous To Gila Wilderness & Primitive AreaGila National Forest79,049
Devils CreekGila National Forest89,916
Ghost TownSanta Fe National Forest219
Grass MountainSanta Fe National Forest3,254
Guaje CanyonSanta Fe National Forest6,104
Hell HoleGila National Forest19,553
Meadow CreekGila National Forest34,167
Pecos WS RiverSanta Fe National Forest5,396
Peloncillo (NM)Coronado National Forest43,339
RendijaSanta Fe National Forest2,176
Ryan HillCibola National Forest34,201
San JoseCibola National Forest16,950
San Pedro ParksSanta Fe National Forest5,824
Sawyers PeakGila National Forest59,743
South Guadalupe MountainsLincoln National Forest20,930
Oregon (4)
AreaForestAcres
Badger CreekMt. Hood National Forest847
ElkhornWillamette National Forest9,380
North KalmiopsisSiskiyou National Forests91,560
South KalmiopsisSiskiyou National Forests104,477
South Dakota (1)
AreaForestAcres
Indian CreekBuffalo Gap National Grassland24,666
Texas (1)
AreaForestAcres
Big CreekNational Forests in Texas1,447
Utah (1)
AreaForestAcres
FishhookDixie National Forest12,959
References (37)
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