Picoides dorsalis

Baird, 1858

American Three-toed Woodpecker

G5Secure Found in 144 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
Least concernIUCN
Identity
Unique IDELEMENT_GLOBAL.2.106444
Element CodeABNYF07110
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAves
OrderPiciformes
FamilyPicidae
GenusPicoides
Synonyms
Picoides tridactylus dorsalis
Other Common Names
American three-toed woodpecker (EN) Pic à dos rayé (FR) Three-toed Woodpecker (EN)
Concept Reference
American Ornithologists' Union (AOU). 1957. The AOU check-list of North American birds, 5th ed. Port City Press, Inc., Baltimore, MD. 691 pp.
Taxonomic Comments
Formerly considered conspecific with the Old World P. tridactylus (Linnaeus) [Eurasian Three-toed Woodpecker], but separated because of significant differences in mitochondrial DNA sequences (Zink et al. 1995, 2002) and (Winkler and Short 1978, Short 1982) (AOU 2003).
Conservation Status
Rank MethodExpertise without calculation
Review Date2016-04-09
Change Date1996-12-02
Edition Date2002-11-26
Edition AuthorsVan Dam, B., J. D. Soule, and G. Hammerson; revised by S. Cannings
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Number of Occurrences> 300
Rank Reasons
Extensive Holarctic distribution with numerous occurrences, but uncommon in most areas; threatened in some areas by timber harvest, incompatible forestry practices, and probably by fire suppression; more information is needed. Trends unknown, but quite likely downward.
Range Extent Comments
RESIDENT: often locally, in North America from northern Alaska across Canada through northern Saskatchewan to north-central Labrador and Newfoundland, south to western and southern Alaska, southern Oregon, eastern Nevada, central Arizona, southern New Mexico, and the Black Hills of South Dakota; and to central Alberta and Saskatchewan, southern Manitoba, northeastern Minnesota, northern Michigan, central Ontario, northern New England, southern Quebec and Nova Scotia.
Occurrences Comments
Widespread, Holarctic range.
Threat Impact Comments
Threats include incompatible forestry practices and deforestation. This species' association with spatially unpredictable disturbance and its large home range make it sensitive to logging and forest fragmentation, and these activities have undoubtedly resulted in population declines (Hunter 1992, Hagan et al. 1997, Imbeau et al. 1999, Leonard 2001). In many cases, this species is restricted to forests older than planned cutting rotations (Imbeau et al. 1999). In Finland, has declined or disappeared in old-growth tracts less than about 140 square kilometers in area (Vaisanen et al. 1986). In Oregon, the liquidation of old growth lodgepole pine due to its infestation with the mountain pine beetle may reduce or eliminate habitat for this species. In Vermont, clear-cutting threatens the black spruce-balsam fir forest habitat.

Because densities increase following fires, probably detrimentally affected by fire suppression (Spahr et al. 1991).
Ecology & Habitat

Description

PLUMAGE: Adult male has a yellow crown, black forehead that is more or less spotted with dull white, black back and sides that are usually broadly barred with white, secondary feathers that are distinctly spotted with white and quills with white spots (Gabrielson and Lincoln 1959). The adult female is similar to the adult male but without any yellow on the head. The female's forehead and crown is usually spotted or streaked with grayish white but sometimes is completely black. Immatures are similar to adults. Young woodpeckers are naked and blind when hatched (Gabrielson and Lincoln 1959). CALLING BEHAVIOR: make tapping sounds while feeding. In the spring and summer you can hear courtship drumming. The call is a rattle similar to that of the hairy woodpecker (PICOIDES VILLOSUS) (Adams, pers. comm.) although the intervals between taps are longer at the beginning of calling episodes. The voice consists of a squeal resembling that of a small mammal and a short quap or quip (Gabrielson and Lincoln 1959).

NEST: Nesting habitat includes coniferous forests (with spruce, larch, or fir trees), or logged areas and swamps. Cavity nest dug by both sexes and are placed 1.5 to 15 m (5 to 50 feet) high in a stump or other dead or dying trees often near water. The entrance is about 4 centimeters by 5 centimeters (1 3/4 by 2 inches), and the cavity is about 25 to 38 centimeters (10 to 15 inches) deep (Oatman 1985).

EGGS: lie on beds of chips within the nest and are ovate, pure white, and only moderately glossy (Gabrielson and Lincoln 1959).

Diagnostic Characteristics

Morphologically very similar to the black-backed woodpecker (PICOIDES ARCTICUS) but is smaller. They are sympatric and occur together ecologically. The barred pattern on back distinguishes it from the black-backed.

Habitat

Coniferous forest (primarily spruce), less frequently mixed forest. Optimal habitat includes areas with 42-52 snags per 100 acres, with snags occurring in clumps, measuring 12-16 inches dbh and 20-40 feet tall, and mostly with bark still present (Spahr et al. 1991). Cavity nests placed in dead (occasionally live) tree (commonly conifer or aspen). Sometimes nests in utility poles.

Prefers coniferous forest, primarily spruce and balsam fir in the East. It inhabits areas where dead timber remains after fires or logging. It is found less frequently in mixed forest, and occasionally in willow thickets along streams. Also found in high elevation aspen groves, bogs, and swamps.

In the west, they occur in dense coniferous forests, and are associated with subalpine fir and Engelmann spruce at higher elevations; they occur mainly in lodgepole pine forests or in mixed-conifer forests with a lodgepole component at lower elevations (Short 1982). Seem to prefer disturbed coniferous forests with trees that exhibit thin, flaky bark such as spruce and lodgepole pine.

Ecology

IRRUPTIONS: Periodic irruptions occur, presumably due to a failure of the food supply. Sympatric with Black-backed Woodpecker (PICOIDES ARCTICUS) but irruptions do not coincide possibly due to difference in dependence on live and dead wood insects (Yunick 1985). Less likely to wander in the winter than the black-backed woodpecker. Interspecific competition may be reduced by taking advantage of different foraging heights and having differently sized bills (Peterson 1988).

Forest fire may lead to local increases in woodpecker populations 3-5 years after a fire (Spahr et al. 1991). In the northeastern U.S., territory size of 74 acres and density of 3 pairs per 247 acres (with increases after fire) have been recorded.

Reproduction

Nesting occurs in May and June, young can be found in the nest into July (Oatman 1985, Brewer et al. 1991, Adams pers. comm.). In Montana, nest building is observed in June, with the young out of the nest by early August (Davis 1961). One broods per year. Clutch size usually is four. Incubation, by both sexes, lasts 12-14 days. During incubation birds are rather quiet. Male roosts nightly in nest throughout incubation (Ehrlich et al. 1988). Young are tended by both parents, fledge in 22-26 days, remain with adults for at least a month after fledging. Nesting may be somewhat colonial where food is abundant. Pair bond sometimes lasts multiple years. Nesting times are very similar for the three-toed and black-backed woodpeckers.
Terrestrial Habitats
Forest - ConiferForest - MixedWoodland - ConiferWoodland - Mixed
Palustrine Habitats
FORESTED WETLANDRiparian
Other Nations (2)
United StatesN5
ProvinceRankNative
New YorkS2Yes
NevadaS2Yes
MinnesotaSNRB,SNRNYes
AlaskaS5Yes
Navajo NationS3Yes
South DakotaS2Yes
MontanaS4Yes
OregonS3Yes
IdahoS4Yes
ColoradoS3Yes
VermontS1Yes
ArizonaS3Yes
UtahS3Yes
New MexicoS3B,S3NYes
WashingtonS3Yes
WyomingS3Yes
MaineS3Yes
New HampshireS2Yes
MichiganSNRNYes
CanadaN5
ProvinceRankNative
AlbertaS4Yes
British ColumbiaS5Yes
ManitobaS5Yes
Prince Edward IslandS1Yes
LabradorS5Yes
Island of NewfoundlandS3Yes
Nova ScotiaS1Yes
New BrunswickS2Yes
OntarioS4Yes
Yukon TerritoryS5Yes
NunavutSUYes
QuebecS4Yes
Northwest TerritoriesS5Yes
SaskatchewanS4Yes
Roadless Areas (144)
Alaska (10)
AreaForestAcres
Boston BarChugach National Forest53,617
ChichagofTongass National Forest555,858
College FiordChugach National Forest1,130,818
Johnson PassChugach National Forest152,508
Kenai LakeChugach National Forest213,172
Kenai MountainsChugach National Forest306,600
Nellie JuanChugach National Forest713,697
ResurrectionChugach National Forest224,615
Roaded DonutChugach National Forest968
Twenty MileChugach National Forest198,775
Arizona (3)
AreaForestAcres
Big RidgeKaibab National Forest9,087
Black River CanyonApache-Sitgreaves National Forests11,817
Red PointKaibab National Forest7,139
Colorado (8)
AreaForestAcres
Comanche Peak Adjacent AreaArapaho & Roosevelt NFs44,158
Dome PeakRoutt NF35,716
HermosaSan Juan NF148,103
Long ParkRoutt NF42,100
Pole Mountain / Finger MesaRio Grande NF43,863
Red TableWhite River NF39,122
San MiguelSan Juan NF64,263
Storm PeakSan Juan NF57,617
Idaho (4)
AreaForestAcres
PalisadesCaribou-Targhee National Forest122,002
Pioneer MountainsSawtooth National Forest119,563
Pioneer MountainsSalmon-Challis National Forest172,460
SeceshPayette National Forest248,088
Minnesota (1)
AreaForestAcres
Phantom LakeSuperior National Forest6,521
Montana (26)
AreaForestAcres
Allan Mountain (01946)Bitterroot National Forest104,184
Bear - Marshall - Scapegoat - SwanLolo National Forest118,485
Bear - Marshall - Scapegoat - SwanLewis and Clark National Forest344,022
BeartoothGallatin National Forest5,285
Big BaldyLewis and Clark National Forest43,135
Big Snowy Mountains WsaLewis and Clark National Forest88,003
Bmss Ra 1485Flathead National Forest334,275
Cabinet Face East #671Kootenai National Forest50,326
East PioneerBeaverhead-Deerlodge National Forest145,082
Evans GulchLolo National Forest8,059
Freezeout MountainBeaverhead-Deerlodge National Forest97,305
Gallatin FringeGallatin National Forest51,571
Hyalite - Porcupine - Buffalo Horn Wilderness Study AreaGallatin National Forest143,991
Jerico MountainHelena National Forest8,445
Lazyman GulchHelena National Forest11,614
Lolo CreekLolo National Forest14,335
MadisonGallatin National Forest127,859
Marston Face # 172Kootenai National Forest9,098
Mt. BaldyHelena National Forest16,362
Mt. BushnellLolo National Forest41,798
North AbsarokaGallatin National Forest159,075
North AbsarokaCuster National Forest21,063
Scotchman Peaks (MT)Kootenai National Forest53,909
Selway - Bitterroot (01067)Bitterroot National Forest114,953
Silver KingBeaverhead-Deerlodge National Forest64,289
West PioneerBeaverhead-Deerlodge National Forest248,631
New Hampshire (1)
AreaForestAcres
Kinsman MountainWhite Mountain National Forest8,999
New Mexico (21)
AreaForestAcres
Alamo CanyonSanta Fe National Forest8,639
Aspen MountainGila National Forest23,784
Black CanyonSanta Fe National Forest1,922
Bull - Of - The - WoodsCarson National Forest488
Canada Bonito RNASanta Fe National Forest487
Columbine - Hondo Wilderness Study AreaCarson National Forest43,739
GallinasSanta Fe National Forest13,208
Guaje CanyonSanta Fe National Forest6,104
Holy GhostSanta Fe National Forest2,352
Jacks CreekSanta Fe National Forest740
Juan de Gabaldon GrantSanta Fe National Forest8,023
Latir PeakCarson National Forest3,573
Meadow CreekGila National Forest34,167
NolanGila National Forest13,051
Pacheco CanyonSanta Fe National Forest1,012
PecosCarson National Forest13,436
Pecos WS RiverSanta Fe National Forest5,396
San Pedro ParksSanta Fe National Forest5,824
Thompson PeakSanta Fe National Forest33,001
West Face Sacramento MountainsLincoln National Forest41,176
Wheeler Peak WildernessCarson National Forest2,677
Oregon (12)
AreaForestAcres
BearwallowsDeschutes National Forest7,317
Jaussaud CorralUmatilla National Forest5,535
LakeMt. Hood National Forest1,327
LookingglassUmatilla National Forest4,859
Maiden PeakWillamette National Forest9,627
Maiden PeakDeschutes National Forest26,432
Twin MountainWallowa-Whitman National Forest58,533
Upper Grande RondeWallowa-Whitman National Forest11,723
Waldo - FujiWillamette National Forest15,273
Waldo - LakeWillamette National Forest2,993
Waldo - MoolackWillamette National Forest1,183
Walla Walla RiverUmatilla National Forest34,416
Utah (13)
AreaForestAcres
0419020Ashley National Forest355,684
418040Uinta National Forest1,702
FishhookDixie National Forest12,959
High Uintas (UT)Wasatch-Cache National Forest102,398
Horse Mountain - Mans PeakManti-Lasal National Forest22,159
LakesWasatch-Cache National Forest121,967
Lava BedsDixie National Forest14,944
Lone Peak ContiguousWasatch-Cache National Forest874
Mt. NaomiWasatch-Cache National Forest41,922
Mt. OlympusWasatch-Cache National Forest9,982
Temple PeakWasatch-Cache National Forest24,081
Twin PeaksWasatch-Cache National Forest6,157
White PineWasatch-Cache National Forest1,942
Washington (14)
AreaForestAcres
ChambersGifford Pinchot National Forest2,006
Devils GulchWenatchee National Forest24,419
Goat Rocks AdjWenatchee National Forest6,108
Liberty BellOkanogan National Forest108,495
Meadow CreekUmatilla National Forest4,882
Mt. Baker MaMt Baker-Snoqualmie National Forest24,847
Mt. Baker NorthMt Baker-Snoqualmie National Forest16,873
NaneumWenatchee National Forest4,508
Norse PeakWenatchee National Forest10,169
Pasayten RimOkanogan National Forest17,074
ProfanityColville National Forest28,944
SawtoothOkanogan National Forest122,194
SpanglerUmatilla National Forest5,936
TeanawayWenatchee National Forest72,849
Wyoming (31)
AreaForestAcres
Bruce MountainBighorn National Forest5,417
Canyon CreekShoshone National Forest7,530
Cloud Peak ContiguousBighorn National Forest113,757
Devils CanyonBighorn National Forest37,416
Doyle CreekBighorn National Forest6,542
Encampment River AdditionMedicine Bow-Routt National Forest4,996
French CreekMedicine Bow-Routt National Forest5,928
Grayback RidgeBridger-Teton National Forest295,113
Gros Ventre MountainsBridger-Teton National Forest106,418
Horse Creek MesaBighorn National Forest77,808
Leigh CreekBighorn National Forest19,180
Libby FlatsMedicine Bow-Routt National Forest11,107
Little BighornBighorn National Forest133,949
Little SnakeMedicine Bow-Routt National Forest9,920
Middle ForkMedicine Bow-Routt National Forest13,238
Middle ForkShoshone National Forest51,772
Mosquito Lake - Seven LakesBridger-Teton National Forest51,950
Pacific Creek - Blackrock CreekBridger-Teton National Forest24,658
PalisadesTarghee National Forest1,121
Pass CreekShoshone National Forest6,172
Pennock MountainMedicine Bow-Routt National Forest9,599
Phillips RidgeBridger-Teton National Forest10,108
Rock CreekMedicine Bow-Routt National Forest18,874
Sibley LakeBighorn National Forest10,367
Snowy RangeMedicine Bow-Routt National Forest29,660
Spread Creek - Gros Ventre RiverBridger-Teton National Forest166,097
Teton Corridor TrailheadsBridger-Teton National Forest286
Walker PrairieBighorn National Forest62,434
West Slope TetonsTarghee National Forest47,448
West Slope WindsBridger-Teton National Forest143,252
Wilderness Study AreaTarghee National Forest51,961
References (47)
  1. American Ornithologists' Union (AOU). 1957. The AOU check-list of North American birds, 5th ed. Port City Press, Inc., Baltimore, MD. 691 pp.
  2. American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
  3. 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 <i>The Auk</i>]. Also available online: http://www.aou.org/.
  4. American Ornithologists' Union (AOU). Banks, R.C., C. Cicero, J. L. Dunn, A. W. Kratter, P. C. Rasmussen, J. V. Remsen, Jr., J. A. Rising, and D. F. Stotz. 2003. Forty-fourth supplement to the American Ornithologists' Union Check-list of North American Birds. The Auk 120(3):923-931.
  5. Belson, M. S. 1998. Red-headed Woodpecker (<i>Melanerpes erythrocephalus</i>) use of habitat at Wekiwa Springs State Park, Florida. M.Sc. thesis, Univ. of Cnetral Florida, Orlando.
  6. Bent, A.C. 1939d. Life histories of North American woodpeckers, U.S. Nat'l. Mus. Bull. 174. Washington, D.C.
  7. Bock, C.E., and J.H. Bock. 1974. On the geographical ecology and evolution of the three-toed woodpeckers, PICOIDES TRIDACTYLUS and P. ARCTICUS. American Midland Naturalist 92(2):397-405.
  8. Brewer, R., G.A. McPeek, and R.J. Adams, Jr. 1991. The Atlas of Breeding Birds of Michigan. Michigan State University Press, East Lansing, Michigan. xvii + 594 pp.
  9. Cramp, S., editor. 1985. Handbook of the birds of Europe, the Middle East, and North Africa. The birds of the western Palearctic. Vol. 4, terns to woodpeckers. Oxford University Press, Oxford, England.
  10. Crockett, A. B. 1975. Ecology and behavior of the Williamson's Sapsucker in Colorado. Ph.D. dissertation, University of Colorado, Boulder.
  11. Davis, C. V. 1961. A distributional study of the birds of Montana. Ph.D. dissertation. Oregon State University, Corvallis. 462 pp.
  12. Dixon, R. D. 1995a. Density, nest-site and roost-site characteristics, home-range, habitat-use, and behavior of white-headed woodpeckers. Deschutes and Winema National Forests, Oregon. Oregon Dept. of Fish and Wildlife Nongame Report 93-3-01.
  13. Dixon, R. D. 1995b. Ecology of White-headed woodpeckers in the central Oregon Cascades. M. Sc. thesis, University of Idaho, Moscow, ID.
  14. Dixon, R. D., and V. A. Saab. 2000. Black-backed Woodpecker (<i>Picoides arcticus</i>). No. 509 IN A. Poole and F. Gill, editors. The birds of North America. The Birds of North America, Inc., Philadelphia, PA. 20pp.
  15. Edwards, H. H., and G. D. Schnell. 2000. Gila Woodpecker (<i>Melanerpes uropygialis</i>). No. 532 IN A. Poole and F. Gill, editors, The birds of North America. The Birds of North America, Inc., Philadelphia, PA. 16pp.
  16. Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birder's handbook: a field guide to the natural history of North American birds. Simon and Shuster, Inc., New York. xxx + 785 pp.
  17. Gabrielson, I. N. and F. C. Lincoln. 1959. The Birds of Alaska. Stackpole, Harrisburg, Pennsylvania, and Wildlife Management Institute, Washington, D.C.
  18. Goggans, R., R. D. Dixon and L. C. Seminara. 1988. Habitat use by Three-toed and Black-backed woodpeckers, Deschutes National Forest, Oregon. Oregon Department of Fish and Wildlife - Nongame Wildlife Program Report 87-3-02. 43pp.
  19. Hagan, J. M. III, P. S. McKinley, A. L. Meehan, and S. L. Grove. 1997. Diversity and abundance of landbirds in a northeastern industrial forest. Journal of Wildlife Management 61:718-735.
  20. Harrison, C. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins, Cleveland, Ohio.
  21. Harrison, H. H. 1979. A field guide to western birds' nests. Houghton Mifflin Company, Boston. 279 pp.
  22. Hunter, M. L., Jr. 1992. Natural fire regimes as spatial models for managing boreal forests. Biological Conservation 65:115-120.
  23. Husak, M. S. 1997. Seasonal variation in territorial behavior of the Golden-fronted Woodpecker. M.Sc. thesis, Angelo State University, San Angelo, Texas.
  24. Hutto, R.L. 1995b. Composition of bird communities following stand-replacement fires in northern Rocky Mountain (U.S.A.) conifer forests. Conservation Biology 9:1041-1058.
  25. Imbeau, L, J. L. Savard, and R. Gagnon. 1999. Comparing bird assemblages in successional black spruce stands originatng from fire and logging. Canadian Journal of Zoology 77:1850-1860.
  26. Ingold, D.J. 1991. Nest-site fidelity in Red-headed and Red-bellied Woodpeckers. Wilson Bulletin 103(1):118.
  27. Lawrence, L. deK. 1967. A comparative life-history study of four species of woodpeckers. Ornithological Monographs No. 5. 156 pages.
  28. Leonard, D. L., Jr. 2001. Three-toed Woodpecker (<i>Picoides tridactylus</i>). <i>In</i> The Birds of North America, No. 588 (A. Poole and F. Gill, editors). The Birds of North America, Inc., Philadelphia, PA. 24pp.
  29. Lisi, G. 1988. A field study of Black-backed Woodpeckers in Vermont. Vermont Fish and Wildlife Department, Nongame and Endangered Species Program, Technical Report 3.
  30. Miller, A. H., and C. E. Bock. 1972. Natural history of the Nuttall Woodpecker at the Hastings Reservation. Condor 74:284-294.
  31. Moskovits, D. 1978. Winter territorial and foraging behavior of Red-headed Woodpecker in Florida. Wilson Bulletin 90:521-535.
  32. Murphy, E. C., and W. A. Lehnhausen. 1998. Density and foraging ecology of woodpeckers following a stand-replacement fire. Journal of Wildlife Management 62:1359-1372.
  33. National Geographic Society (NGS). 1983. Field guide to the birds of North America. National Geographic Society, Washington, DC.
  34. Oatman, G.F. 1985. Three-toed Woodpecker, PICOIDES TRIDACTYLUS. Pages 162-163 in S.B. Laughlin and D.P. Kibbe, editors. The atlas of breeding birds of Vermont. University Press of New England, Hanover, NH.
  35. Peterson, J.M.C. 1988. Three-toed Woodpecker, PICOIDES TRIDACTYLUS. Pages 236-237 in R.F. Andrle and J.R. Carroll, editors. The atlas of breeding birds in New York State. Cornell University Press, Ithaca, NY.
  36. Price, J., S. Droege, and A. Price. 1995. The summer atlas of North American birds. Academic Press, New York. x + 364 pp.
  37. Ruge, K. 1997. Three-toed Woodpecker. Pages 458-459 <i>in</i> the EBCC atlas of European breeding birds: their diestribution and abundance (E. J. M. Hagemeijer and M. J. Blair, editors.) T. and A. D. Poyser, London.
  38. Sauer, J. R., J. E. Hines, and J. Fallon. 2001. The North American Breeding Bird Survey, Results and Analysis 1966 - 2000. Version 2001.2, USGS Patuxent Wildlife Research Center, Laurel, MD.
  39. Short, L. L. 1982. Woodpeckers of the World. Museum of Natural History [Greenville, Delaware], Monograph Series xviii + 676 pp.
  40. Spahr, R., L. Armstrong, D. Atwood, and M. Rath. 1991. Threatened, endangered, and sensitive species of the Intermountain Region. U.S. Forest Service, Ogden, Utah.
  41. Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.
  42. Thomas, J. W., R. G. Anderson, C. Maser, and E. L. Bull. 1979. Snags. Pages 60-77 in J. W. Thomas (editor). Wildlife Habitats in Managed Forests: the Blue Mountains of Oregon and Washington. U.S.D.A. Handbook 553.
  43. Vaisanen, R. A., O. Jarvinen, and P. Rauhala. 1986. How are extensive, human-caused habitat alterations expressed on the scale of local bird populations in boreal forests? Ornis Scand. 17:282-292.
  44. Venables, A., and M. W. Collopy. 1989. Seasonal foraging and habitat requirements of Red-headed Woodpeckers in north-central Florida. Florida Game Fresh Water Fish Comm. Nongame Wildlife Program Final Report Project no. GFC-84-006.
  45. Williams, J. B., and G. O. Batzli. 1979. Competition among bark-foraging birds in central Illinois: experimental evidence. Condor 81:122-132.
  46. Yunick, R.P. 1985. A review of recent irruptions of the Black-backed Woodpecker and Three-toed Woodpecker in eastern North America. Journal of Field Ornithology 56(2):138-152.
  47. Zink, R. M., S. Rohwer, A. V. Andreev, and D. L. Dittman. 1995. Trans-Beringia comparisons of mitochondrial DNA differentiation in birds. Condor 97:639-649.