Eurasian Three-toed Woodpecker Picoides tridactylus Scientific name definitions

Three-toed Woodpecker (Picoides tridactylus)

20–24 cm (Eurasia), 21–23 cm (North America); male 65–74 g, female 54–66 g (tridactylus), 46–76 g (other Old World races), male 50–64·5 g, female 47–59 g (fasciatus). Male has long nasal tufts mixed black and white, black forehead mottled whitish, brass-yellow or pale lemon-yellow central forecrown usually with some black and white feather bases showing through; glossy black crown sides, hindcrown and band down central hindneck, crown usually with some white streaks; white supercilium  from rear of eye broadening backwards, extending as band down rear neck side to meet white of mantle; glossy black from in front of and just below eye, through ear-coverts and down neck side, bordered by broad white cheekband; deep black malar stripe  , obscured by white tips near bill, extending back to broad area of black on neck side that continues irregularly down to upper breast side; white chin and throat; white central mantle, innermost scapulars, back and rump, a few dull black spots or bars at margins, dull brownish-black mantle side, remaining scapulars and uppertail-coverts; dull brownish-black wings, outer ­coverts occasionally with white dots, flight-feathers with variably sized white spots largest on inner webs, including those of tertials, forming prominent barred pattern; uppertail black, tips of outer 3 feather pairs with increasing amount of black-barred white; white below, faintly tinged cream-buff in fresh plumage, breast side streaked black, flanks and undertail-coverts variably barred; longish bill straight, chisel-tipped, very broad across nostrils, slaty-grey, darker tip, paler base of lower mandible; iris deep red or brown-red; legs slate-grey, only 3 toes. Female has forehead and crown black with variable amount of white spots and streaks. Juvenile duller, browner, than adult, with white of back less extensive and sometimes barred, underparts duller and buffer with heavier but diffuse markings, eyes paler, male with dull yellow forecrown patch smaller than on adult, patch probably reduced or sometimes absent on female. Races differ mostly in amount of white in plumage, E ones also on average slightly larger and longer-billed: crissoleucus has plumage more fluffy than nominate, more white on head, back and flight-feathers, less black in outer tail, very few or no markings below; albidior is even whiter, with pure white outer tail and underparts, much white in wings, including spots on coverts; <em>alpinus</em> is darker overall, with white of back narrower and barred or spotted black, dark underside pale-barred with narrow central white band, outer tail more broadly barred black, juvenile mostly dark above and below with pale restricted to throat, spots on mantle and mottling on underparts; <em>dorsalis</em>  is smaller than previous races, has narrower postocular stripe, all-white outer tail feathers (as in E Asian albidior and crissoleucus); <em>fasciatus</em>  is still smaller, with shorter bill, back with numerous thin black bars, sides strongly barred; bacatus is smallest of all, has less white on head (forehead sometimes all black, supercilium much reduced or absent), back almost wholly black with just few white spots, female crown often all black.

Editor's Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.

Three-toed Woodpecker (Picoides tridactylus)

Closely related to P. funebris and P. arcticus; possibly sister to former (1 Weibel, A.C. and Moore, W.S. (2002). Molecular phylogeny of a cosmopolitan group of woodpeckers (genus Picoides) based on COI and cyt b mitochondrial gene sequences. Mol. Phyl. & Evol.. 22(1): 65–75. Close ). In recent decades North American subspecies commonly treated as forming a separate species (P. dorsalis) on basis of genetic evidence (2 Johnsen, A., Rindal, E., Ericson, P.G.P., Zuccon, D., Kerr, K.C.R., Stoeckle, M.Y. and Lifjeld, J.T. (2010). DNA barcoding of Scandinavian birds reveals divergent lineages in trans-Atlantic species. J. Orn. 151(3): 565–578. Close ), but morphological differences involve merely narrower postocular stripe (1) and smaller size (according to published measurements, no more than 1); all-white outer tail feathers shared by East Asian races albidior and crissoleucus, and notion of less white in forecrown not supported by specimen evidence. Distinctive form funebris, however, here allowed species status, as it differs from P. tridactylus in its all-blackish underparts, with white flecking, from breast to vent (plus black feet, blackish lower mandible and greatly reduced white barring on tail) vs white chin to mid-belly with bold blackish streaks on breast sides and flank-bars (plus greyish feet, pale horn lower mandible and boldly white-barred tail) (4); chin and throat plus pale lines on face tawny-whitish vs white (1); all-black crown (apart from frons) vs dense white streaking on female (2). Currently accepted races designated according to coloration, but variation is clinal, birds becoming darker and larger from N to S; comprehensive revision based on genetic and biogeographical grounds required. Birds from Sakhalin, described as race sakhalinensis, appear indistinguishable from nominate; named races tianschanicus (Tien Shan), kurodai (Korea) and inouyei (EC Hokkaido) barely differ from European alpinus, thus regarded as better merged with that taxon. Seven subspecies recognized.

Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Three-toed Woodpecker (Picoides tridactylus)

Mature boreal  and montane mixed conifer forests. Spruce (Picea) and fir (Abies) forest typical habitat in N Europe ; in E European natural forest, territories are in wettest parts of ash–alder (Fraxinus–Alnus), coniferous and oak–hornbeam (Quercus–Carpinus) stands; primarily in taiga of larch (Larix) in Siberia. Nearctic populations occupy similar habitats, with general preference for spruce, and in W of range found also in forests with fir or lodgepole pine (Pinus contorta); has bred in old stands dominated by Douglas fir (Pseudotsuga) in SW Canada (W British Columbia), and often in swampy areas in E North America. Forest with a good proportion of insect-infested dead trees and fallen timber, and often dense and shady, are favoured, and a preference for burned forest also is evident. Outside breeding season, also in more open areas or brush, and in Nearctic not uncommonly in urban areas during irruptions. Will concentrate locally in windfall areas, also takes advantage of forest areas damaged by insect plagues or pollution. Mainly lowlands at higher latitudes; from 650 m and to over 1900 m in European Alps; in North America, occurs at 1300–2700 m, locally to 3350 m, in W and at 360–1250 m in E.

Three-toed Woodpecker (Picoides tridactylus)

Mountain populations (Alps, Tien Shan, Altai, Rocky Mts) largely resident, but often shift to lower altitudes or move short distances after breeding. N Eurasian populations perform eruptive migrations at long intervals. In Scandinavia, most juveniles move out of nesting area and appear far outside breeding areas; Siberian populations (crissoleucus) regularly migrate greater distances. In North America, E populations make periodic eruptive migrations, and occasionally appear S of breeding range in winter, with casual records also S to Nebraska, S Wisconsin and Pennsylvania; movements less marked than those of P. arcticus.

Three-toed Woodpecker (Picoides tridactylus)

Larvae and pupae of beetles living beneath bark form bulk of diet, and also important as nestling food; other insect larvae (hymenopterans, lepidopterans) and imagines also taken, also spiders. Insects prone to occur in heavy infestations, e.g. Polygraphus and Ips, particularly frequent items; in North America, this woodpecker is an important predator of spruce bark beetle (Dendroctonus obesus). Apart from sap , vegetable matter (e.g. berries, spruce seeds) taken only occasionally; sap taken more commonly by Old World populations, less so by Nearctic ones. Forages singly; local concentrations in areas of food abundance, especially in areas of insect plagues. Prefers trunks of dead trees and stubs, foraging mostly at heights of 1–3 m, occasionally on ground (rarely so in Nearctic). On average, males forage slightly lower than females, mainly on trunks, and prefer large trees; females forage  slightly higher up and have a greater niche breadth, also using relatively thin trees and branches, and more frequently live trees (in summer). Both sexes forage lower in winter. Pecking, hammering and, especially, stripping-off of bark are predominant foraging techniques; gleaning and probing less common. In Eurasia, conspicuous sap wells drilled into a wide range of tree species, mainly conifers, locally lime (Tilia), trees becoming covered with sap holes from base of trunk up into crown; this habit seems to be particularly common in subalpine zone. Nearctic races only occasionally drill sap wells.

Three-toed Woodpecker (Picoides tridactylus)

Single “kip”  , in series when alarmed; short, rattling “kri-kri-kri-kri-kri”; also emits repeated “wutsch” notes in agonistic situations. Both sexes drum , rolls slightly accelerating at very end, duration typically c. 1·3 seconds.

Three-toed Woodpecker (Picoides tridactylus)

Laying from mid-May ( up to 2 weeks earlier in S Europe) to end Jun, occasionally early Jul. Courtship from second half of Mar; flutter-aerial display, bill-pointing, head-swinging with crest erect. Nest-hole excavated  2–10 m up in dead tree , or in dead section of live tree with heart-rot, spruce and other conifers preferred but some non-coniferous species (Populus, Betula, Alnus) also used, hole  diameter averages 4·7 cm and cavity depth 30·5 cm in Europe, in North America diameter 3·8–4·5 cm, depth c. 24–30 cm; usually a new nest made each year. Clutch 3 or 4 eggs in Alps, 3–6 (rarely 7) with mean 4·1 in Scandinavia, and 3–5 eggs (usually 4) in North America; both sexes share all nest duties ; incubation period 11–14 days, nestling period 22–26 days; fledglings accompanied by parents for up to c. 1 month (at least in North America, brood apparently divided between parents). Average young produced per nest 1·7 in Switzerland, dormice (Eliomys) possibly significant nest predators; in USA, success (pairs producing at least one young) 79·2% in Montana and Idaho. First breeding probably at 1 year. Longevity in wild at least 6 years.

Three-toed Woodpecker (Picoides tridactylus)

Not globally threatened (Least Concern). Generally uncommon, and rather scarce in many parts of range, but perhaps locally more numerous. Can become common in some places during bark-beetle outbreaks. Estimated W European population in 1990s c. 51,370–65,340 pairs, with further 10,000–100,000 pairs in European part of Russia, combined total probably c. 90,000 pairs; largest known concentrations in Finland (15,000–20,000) and Belarus (9000–14,000), with 10,000–25,000 in Scandinavia. Densities vary depending on habitat quality; in Finland, 10 pairs/km² in partially burned old-growth forest but 0·03–1·2 pairs in other habitats; lower densities in S European mountains, e.g. 1 pair/42–200 ha (mean 108 ha) in Switzerland, and all pairs requiring home range of at least 100 ha. Has expanded since 1980s in C Europe, but declines also noted in some areas (e.g. Czech Republic); evidence of reduction in numbers in N Europe. No meaningful data on Asian populations; has become rare in N Japan (Hokkaido). In North America ccurs in low densities, highest in burned or otherwise disturbed forest: c. 1 bird/4·05 ha in burned coniferous forest in SE Montana; in a Colorado conifer forest, 0·25 individuals/ha before burn but 1·2/ha two years after fire. Across its enormous range this species is susceptible to habitat loss, forest degradation and fragmentation. Owing to its relatively small population sizes, its dependence on snags, and its preferences for burnt forest and for large stands of old-growth conifers (which are vulnerable to commercial cutting), its survival in managed forests is not guaranteed. Modern intensive forestry methods, including clear-cutting, fire suppression, removal of dead trees and pesticide use, are detrimental to this woodpecker and have led to local declines.