Species Profile
Williamson's Sapsucker
Sphyrapicus thyroideus
Williamson's Sapsucker
Quick Facts
Conservation
LCLeast ConcernLifespan
5–7 years
Length
21–25 cm
Weight
44–66 g
Wingspan
43–46 cm
Migration
Short-distance migrant
Also known as: Williamson's Woodpecker
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Appearance
Williamson's Sapsuckers exhibit striking sexual dimorphism. Males are predominantly black with a yellow belly, white wing patch, and red throat. Their back features a distinctive white rump and central white stripe.
Males and females are so unalike that they were originally thought to be two different species. Females share the yellow belly patch, although theirs is much smaller in size. A small black patch marks the upper breast, but otherwise, their plumage is mottled with white and brownish-black barring, apart from a solid white rump and a brown head with faint lighter streaks.
Both sexes have black bills and legs, with males showing more contrast in their plumage compared to the cryptic coloration of females. Juveniles of both sexes resemble adults, although their markings are duller and less clearly defined.
Identification & Characteristics
Male Colors
- Primary
- Black
- Secondary
- Red
- Beak
- Black
- Legs
- Black
Female Colors
- Primary
- Brown
- Secondary
- Buff
- Beak
- Black
- Legs
- Black
Female Markings
Barred body, brown head, white rump
Attributes
Understanding Attributes
Rated 0–100 based on research and observation. A score of 50 is average across all bird species. These attributes are relative and don't necessarily indicate superiority.
Habitat & Distribution
Williamson's Sapsuckers inhabit montane conifer forests across western North America, from British Columbia to northern Mexico. They show a preference for mature stands of pine, fir, and aspen.
During the breeding season, they are found at higher elevations in the Rocky Mountains and the Sierra Nevada. In winter, some populations move to lower elevations or slightly southward but remain within forested areas.
Distribution
Diet
Williamson's Sapsuckers primarily feed on tree sap, which they obtain by drilling rows of small holes in conifers. The inner moist bark layer of a tree trunk, known as phloem, is also important in their diet.
Ants, aphids, and beetles are also eaten, picked off the surface of the bark of a tree, or extracted, coated in sap, from the wells they have drilled.
In winter, fruits and seeds become more important, with berries and juniper, pine, and madrone among the most popular foods.
Behaviour
Williamson's Sapsuckers are known for their systematic sap-feeding behavior, drilling neat rows of holes in conifer trees. They defend these sap wells aggressively from other birds.
During courtship, males perform slow, floating display flights to attract females.
Calls & Sounds
Williamson's Sapsuckers have a relatively quiet call, a sharp 'chuck' or 'kyik'. Their drumming is distinctive, starting slow and accelerating to a rapid roll. During territorial disputes, they may produce a harsh, chattering series of notes.
They also use drumming to communicate, with a series of rapid taps, followed by three or four rhythmic, slower beats.
Nesting & Breeding
Breeding occurs from late April to July. Males initiate courtship with aerial displays and drumming to attract females. Pairs form monogamous bonds for the breeding season.
Nests are excavated in dead or diseased trees, typically at heights of 5-18 meters. Inside the chamber, a shallow layer of wood chippings is used as a lining, with no additional material added. The female lays 4-6 white eggs.
Both parents incubate the eggs for about 12-14 days. Nestlings fledge after 25-29 days, with parents continuing to feed them for several weeks post-fledging.
Conservation
While currently listed as Least Concern, Williamson's Sapsuckers face threats from habitat loss due to logging and climate change.
Conservation efforts focus on protecting mature conifer forests and maintaining snags for nesting sites.
Birdwatching Tips
- Look for their distinctive sap wells on conifer trees
- Listen for their sharp 'chuck' call or rapid drumming
- Observe tree trunks carefully, as their plumage blends well with bark
- In the US, focus on montane conifer forests of the western states
Did You Know?
- Williamson's Sapsucker was named after Lieutenant Robert Stockton Williamson, who led a Pacific Railroad Survey expedition.
- They are the most sexually dimorphic of all North American woodpeckers.
- Their sap wells are used by other species, including hummingbirds and insects.
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