American Three-toed Woodpecker Life History

Habitat

Habitat Forests

American Three-toed Woodpeckers inhabit coniferous forest, both the boreal forest (mostly spruce and fir) and mountain forests, especially in the Rocky Mountains. They are most numerous in mature and old-growth forests that have been damaged in some way, such as by wind storms, floods, or fire. Disturbed areas such as this often have large numbers of snags and dead and dying trees, ideal for woodpecker feeding and breeding because they are infested by insects and provide abundant places to nest. Boggy areas with dying trees also provide good habitat. In the eastern part of the range, the species frequents forests with black spruce, American larch, and balsam fir, while across the boreal forest these species plus jack pine, quaking aspen, and white spruce constitute the preferred habitat. In the Northwest and Rocky Mountains, Three-toed inhabits forests with Engelmann spruce, lodgepole pine, western white pine, ponderosa pine, western hemlock, subalpine fir, western larch, western red cedar, paper birch, balsam poplar, quaking aspen, and Douglas-fir, depending on where insect populations are high. The species is very scarce or absent in logged areas.

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Food

Food Insects

American Three-toed Woodpeckers eat mostly beetle larvae, chiefly those of bark beetles (family Scolytidae), especially mountain pine beetle and spruce beetle. They also feed on larvae of wood-boring beetles of the family Cerambycidae, beetles in several other families (Buprestidae, Pythidae, Cleridae), ant larvae, moth pupae, and spiders. Three-toed Woodpeckers tend to forage mostly on trunks or snags of small trees by flaking or scaling off the bark, usually on dead or dying trees. When this woodpecker occurs alongside the larger Black-backed, it may forage higher on the tree than its larger relative. Like Black-backed, Three-toed spends fairly long periods in a single tree, removing bark by pecking and striking sideways until chunks of bark fall to the ground. This species sometimes digs into the hard wood of the tree for prey such as wood-boring beetles, or gleans insects from the bark. In some areas, Three-toed Woodpeckers dig small sapwells in trees and drink the sap that flows, much as sapsuckers do.

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Nesting

Nest Placement

Nest Cavity

Nests are usually constructed fairly low in trunks of small dead coniferous trees (living trees are sometimes used).

Nest Description

Both male and female excavate the nest cavity and line the bottom with wood chips. The male does more excavation early in the process, with the female doing more work as the hole nears completion. The cavity entrance averages about 1.6 inches in diameter and often has a bevel in the bottom edge. The finished cavity averages about 4 inches across and 11 inches deep.

Nesting Facts
Clutch Size:3-7 eggs
Egg Length:0.9-1.0 in (2.41-2.53 cm)
Egg Width:0.7-0.7 in (1.74-1.77 cm)
Incubation Period:12-14 days
Egg Description:

White, rather round.

Condition at Hatching:

Naked and helpless.

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Behavior

Behavior Bark Forager

American Three-toed Woodpeckers forage alone during most of the year, coming together in pairs during the breeding season, when pairs spend time in the same tree and call more frequently than at other times of year. Pairs may remain together for multiple consecutive nesting seasons. When another Three-toed Woodpecker enters a breeding territory, both male and female may react by raising the crest, spreading the wings and tail, swaying the head, and pointing the bill. In places where prey is abundant, such as young burned areas, pairs of Three-toed Woodpeckers may nest quite near one another. Both sexes excavate the nest cavity, incubate the eggs, and feed the young. American Three-toed Woodpecker is subordinate to the larger Black-backed Woodpecker; when the two come into contact, the smaller Three-toed typically flies away quickly, sometimes chased by the Black-backed.

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Conservation

Conservation Low Concern

According to the North American Breeding Bird Survey, populations of American Three-toed Woodpecker increased between 1966 and 2015, though this estimate is complicated by the species’ range, which mostly lies north of the limits of the survey. Partners in Flight estimates a global breeding population of 1.6 million and rates the species an 8 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. American Three-toed Woodpeckers eat bark beetles and are sensitive to the pesticides used to kill them during outbreaks. Forest fragmentation and timber harvest on short cycles reduce availability of habitat and may cause population declines, as this species favors mostly mature habitats. Wildfire creates habitat for this and many other bird species, so fire suppression, mechanical thinning, and salvage logging (removing burned trees after a forest fire) also reduce numbers of the species.

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Credits

Leonard Jr., David L. (2001). American Three-toed Woodpecker (Picoides dorsalis), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

Tremblay, J. A., D. L. Leonard Jr. and L. Imbeau. (2018). American Three-toed Woodpecker (Picoides dorsalis), version 2.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.

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