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Woodpeckers are such an interesting group of birds. Just the thought of them spending the day hammering away against hard trees makes my head hurt, and these birds do it every day, for their whole lives.
American three-toed woodpeckers, with their sleek black side profile, look like they were sprinkled with white powder on their sides and back, and the males look like their head was dusted with pollen.
They are a quintessential woodpecker, leaning back with a powerful blow, filling their ecological niche as beetle control agents. As a trained biologist, I’m fascinated by how natural selection has shaped their morphology, their function, their interaction with other species – let’s dive into learning about this spruce forest specialist.
Bottom Line Upfront
American three-toed woodpeckers are a black-and-white boreal bird, chiseling away on spruce trees and eating beetle larvae. It is one of only two North American species with three toes, which allows it to lean farther back and deliver a more powerful blow to the tree trunk.
Despite this cool adaptation, there is still more to learn about this quiet bird, whose cavities create nesting sites for other animals, and who are important in controlling beetle outbreaks.
Taxonomy
The American three-toed woodpecker (P. dorsalis) is a separate species from the Eurasian three-toed woodpecker (Picoides tridactylus), though they were considered the same species until about 30 years ago and are sister taxa (their closest relative).
Their ranges do not overlap – as their names suggest, the American three-toed woodpecker is only found in North America, while the Eurasian three-toed woodpecker is found from northern Europe to Asia and Japan.
The only other species in this genus is the black-backed woodpecker (P. arcticus), which has a similar range to the three-toed woodpecker in North America.
There are three subspecies of American three-toed woodpeckers: in the Rocky Mountains, with a very pale back, P. d. dorsalis; Great Lakes eastward, with a very dark back, P. d. bacatus; and western Canada, Alaska, and south into the US, with variable back coloration, P. d. fasciatus.
These subspecies also differ in size, with larger individuals in the southern part of their range, and the northeastern birds the smallest. However, a genetic study showed no differences in populations.
How to Identify an American Three-toed Woodpecker
American three-toed woodpeckers are a medium-sized woodpecker, about 21-23 cm long, and they weigh on average 55 g (44.8-67.9 g).
The back of an American three-toed woodpecker is barred, as are its flanks. Its wings are partially spotted (the primaries and secondaries have some white spots), similar to black-backed woodpeckers, but much less than downy or hairy woodpeckers.
American three-toed woodpeckers have a white belly and throat, and a white mustache from the beak to the back of the neck.
They have a second narrow white stripe extending from the back of the eye and curving down towards the side of the neck; this second stripe is absent (though there is a small white stripe or spot) in black-backed woodpeckers.
Males have yellow crowns, while females do not; juveniles have a small yellow patch as well. Males are slightly (8-13%) heavier than females.
The most similar species are the hairy, downy, and black-backed woodpeckers. If you can see their back, it’s the easiest way to tell them apart:
| Back pattern | Flank pattern | Wing pattern | Head | |
| Hairy woodpecker | White stripe | White | Partially spotted | Two white stripes |
| Downy woodpecker | White stripe | White | Partially spotted | Two white stripes |
| Three-toed woodpecker | Barred | Barred | Minimally spotted | Two white stripes |
| Black-backed woodpecker | Black | Barred | Minimally spotted | One white stripe |
You can also look at how many toes it has. As their name suggests, they have three toes, as do the Eurasian species and the black-backed woodpecker.
Other woodpeckers (including the downy and hairy) have four toes, with two facing forward and two facing backward. It is thought that three toes allow American black-backed woodpeckers to lean farther back and therefore impart a more powerful blow at the tree bark.
Where Does an American Three-toed Woodpecker Live: Habitat
This species prefers coniferous forests, especially spruce trees, ranging across most of Canada, Alaska, and parts of the western United States. This is the most northern breeding woodpecker in North America.
They rely heavily on disturbed forests, which include burned areas, areas damaged by beetle outbreaks, and also areas where wind or floods have killed trees.
These dead trees and snags are what they require for food and nesting. They will follow beetle outbreaks and during these times, appear outside their normal range, a phenomenon termed ‘irruptions’.
American Three-toed Woodpecker Diet and Feeding
Their main prey are bark beetle larvae. They also follow spruce beetle (Dendroctonous rufipennis) outbreaks, and forage preferentially on larger dead snags but will also forage on live trees.
They use their beaks to flake or scale bark off trees, chipping sideways to remove bark and find the insects underneath, in contrast to black-backed woodpeckers which excavate into trees more frequently.
Primary insects eaten are spruce beetle, mountain pine beetle, and other wood-boring or bark beetle larvae (in families Buprestidae, Pythidae, Cleridae, and Scolytidae), in addition to consuming ant larvae, moth pupae, and spiders. They will also lick sap, especially in the spring, and do this more often than black-backed woodpeckers.
There are no obvious sex-related foraging differences in American three-toed woodpeckers.
American Three-toed Woodpecker Breeding
Both sexes call and drum frequently during breeding. Fast drumming (average 13.8 beats/sec) is used in territorial displays, while slow drumming (average 11.4 beats/sec) is used between pairs, and may be involved in breeding.
Their drum fades towards the end. Their usual call is a sharp pik or nasal klimp and is higher than a black-backed woodpecker call.
There are many displays involved in both interspecific (with other species, like black-backed woodpeckers) and intraspecific (with the same species) interactions, including crest raising, spreading wings and/or tails, pointing the bill, and swinging the head side-to-side.
Pairs may remain together for two years; there are no data indicating longer pair bonds.
American Three-toed Woodpecker Nesting
Nest building occurs from March-June. Both sexes excavate the nest cavity, which has an opening of 1.6 inches in diameter. They usually use a dead conifer tree but have been known to sometimes use live trees or telephone poles. Nests are generally not reused in subsequent years.
American Three-toed Woodpecker Eggs
American three-toed woodpeckers lay 3-7 white, ovate eggs; the average number is 4. Incubation lasts 12-14 days and is performed by both sexes, as is feeding the chicks. Time to fledge is around 24 days, and fledglings may stay near adults for a few weeks afterward.
American Three-toed Woodpecker Population
American three-toed woodpeckers are non-migratory, and juveniles may make up most of the individuals seen outside their normal range in the winter.
Their range includes most of the northern parts of Quebec, Ontario, Manitoba, Saskatchewan, and Alberta; most of Labrador, Alaska, and British Columbia; and parts of Washington, Oregon, Idaho, Montana, Wyoming, Utah, and Colarado.
Their range barely enters South Dakota and Nevada, and they are scarce in Arizona, New Mexico, Newfoundland, New Brunswick, Prince Edward Island, and Nova Scotia. These woodpeckers have been recorded breeding in both Michigan and Minnesota as well.
There are many small, disjunct areas inhabited by this species, which makes these populations more vulnerable to habitat changes or stochastic events that may reduce breeding success.
Their population is estimated at 1.6 million individuals. As human-caused habitat interventions intensify, such as using pesticides to kill beetles, fire suppression, salvage logging, and mature forest logging, the population of this species will likely decline as well.
In any one area, these woodpeckers can increase in abundance when conditions are favorable, but overall they are at low densities.
Is the American Three-toed Woodpecker Endangered?
They are classified as Least Concern, though the most recent assessment (in 2016) combined the Eurasian and American species into one (Picoides tridactylus) and data are lacking in some areas.
This species is generally at low abundance and combined with its northern distribution, more research into its ecology and good population census data is sorely needed.
American Three-toed Woodpecker Habits
The range of American three-toed woodpeckers overlaps to a large extent with black-backed woodpeckers, and both use the same types of habitat. However, on a local scale, they are not often found together. The American three-toed woodpecker is subordinate to black-backed woodpeckers and will move away if challenged.
These birds have several different types of calls, including a rattle, twitter, chirp, and squeak. In general, they are described as more silent than other woodpeckers, which contributes to the difficulty in detecting them and conducting a population census.
This is reflected in their foraging strategy, where they concentrate on one area of bark for long periods, frequently pausing and remaining quiet.
American Three-toed Woodpecker Predators
Northern goshawks have been known to predate American three-toed woodpeckers, and other hawks or falcons likely do the same. Chicks are vulnerable in the nest to back bears, squirrels, and martens.
American Three-toed Woodpecker Lifespan
This species has been recorded to live 6 years in the wild, though a recent (2020) sighting found a color-banded individual that was 11 years old.
FAQs
Answer: Yes! Bark beetles damage timber, and these woodpeckers are specialists in consuming them. One study estimated they can consume several thousand larvae – each day!
Answer: That’s a great evolutionary question, and we can’t say for sure how it happened – whether it was a mutation for a sudden loss of a toe or a gradual selection for shorter toes – but either way, it happened a long time ago (before the three-toed woodpecker species diverged from each other) and has let them become more powerful at chiseling and hammering.
Answer: No they don’t, and this has been researched to help better protect human heads from impacts. Surprisingly, it was initially thought a woodpecker’s skull served as a shock absorber to protect their brain, but recent research suggests that their small brain size is the critical factor.
Conclusion
If you’re wondering whether these woodpeckers are around, have a look at the bark on dead trees – since they fling off pieces of bark while foraging, a sign of their presence is a trunk with a patchwork of dark bark and lighter inner wood showing.
However, you’d need to be in the right habitat, which is typically not urban landscapes, nor deciduous forests – instead, head north to the spruce trees.
For a species with a fairly large range, so much of their biology is still only known from a handful of studies, and the scientist in me wants to go out and learn even more after seeing how little is currently known about their demography, dispersal, wintering ecology, and the impacts of humans.
References
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- Biewener, A. A. (2022). Physiology: Woodpecker skulls are not shock absorbers. Current Biology, 32(14), R767-R769.
- Dufort, M. J. (2016). An augmented supermatrix phylogeny of the avian family Picidae reveals uncertainty deep in the family tree. Molecular Phylogenetics and Evolution, 94, 313-326.
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