Williamson’s Sapsuckers (Sphyrapicus thyroideus) are woodpeckers found in the mature coniferous forests of western North America.
Although they are fairly small, then they are the largest of the four sapsucker species. Initially, the female and male were thought to be two separate species because they look so different! Here is all you need to know about them.
Identification
Williamson’s Sapsuckers have compact, stocky bodies. They are medium-sized woodpeckers, measuring 8.3-9.8 inches long, and have a wingspan of around 17 inches. Their bills are stout and black, their eyes dark, their wings long and broad, and their tails strong and wedge-shaped.
Male
Male Williamson’s Sapsuckers are more boldly colored and generally larger than the females. They are jet black above with bold white patches on the wings. Their chests are black, flanks barred in white and black, and their bellies yellow.
However, their yellow bellies are generally a bit hard to notice if clinging to tree trunks. They have a black head with two white stripes across their face and a small red throat patch. One starts from behind the eye and runs to the nape while the other starts from the base of the bill and runs across the cheek.
Female
Female Williamson’s Sapsuckers are less noticeable and usually smaller than the males. Overall, they are barred in black and white. They have a small black chest patch and a bigger yellow patch on the belly. Their rumps are whitish, their black tails have white bands, and their heads are brownish.
Juvenile Williamson’s Sapsuckers resemble adults but are duller. Male juveniles look like male adults, but they do not have the red throat patch. Female juveniles are paler and browner overall than adult females and do not have the black chest patch.
Vocalizations
Williamson’s Sapsuckers do not sing, but they give various calls that always have a nasal quality to them. Their most common call is a nasal chyaah. It sounds similar to the shrill call of a Red-tailed Hawk. You can also hear a fairly low-pitched soft nasal kr-r-r-r or churrr, descending in pitch. Pairs chatter and give rattling trills during the nesting season.
Other than calls, you can also try to identify them based on their drumming. Their drumming is irregular, starting with a few quick knocks, followed by a combination of pauses and drums, getting slower and quieter towards the end. Both sexes drum, but males drum louder and more often.
Food
Williamson’s Sapsuckers are omnivorous with the specifics of their diet varying based on the season. During the breeding season, they tend to eat more animal matter while during the non-breeding season they eat more plant matter.
The plant part of their diet mainly consists of tree sap but also small fruits and berries such as madrone, juniper, and pinyon pine, and bits of tree tissues, especially cambium and phloem. They drill small neatly spaced holes into tree bark, mainly in conifers, and repeatedly feed on the sap oozing out of them. During the nesting season, one pair maintains 4-6 trees.
The animal part of their diet consists of various insects such as ants, beetles, aphids, flies, moths, and spiders. Their primary foraging technique is gleaning.
They forage for insects in trees, methodically moving along the trunk or a branch. You may also see them looking for them on the ground or flying out to catch flying insects in mid-air. Sometimes insects get stuck in sap, so it is an even easier meal for the bird. Occasionally, they may tear off flakes of bark or drill to reach the larvae or insects.
Nesting and Eggs
Williamson’s Sapsuckers are monogamous and stay together until their young fledge. They sometimes reunite the next year, but not always. Males perform an exaggerated fluttering flight display near the nesting site as a courtship display and pairs bob and swing their heads at each other.
Williamson’s Sapsuckers nest in tree cavities around 5-60 feet above the ground. The pair selects a suitable tree together, often preferring large and old living trees with a fungal infection that softens the heartwood. This is because the softened heartwood makes it easier to excavate, while the living outer layer offers more protection.
They may return to the same tree year after year, excavating a new hole every time. Their nests are often found in aspens, pines, or firs with an entrance hole about 1.6 inches in diameter and the nest itself 3.6 inches in diameter and 10.5 inches deep on average. Males do the excavating and line the bottom of the cavity with wood chips.
One pair has one brood per year with 3-7, mostly 4-5 white eggs in a clutch. Incubation takes 12-14 days. Males incubate at night while females during the day. After the eggs hatch, the young stay in the nest for around 3-4 weeks.
Both parents take care of their offspring, carrying them food and brooding them at night. After leaving the nest, the younglings stay with their parents for some time.
Current Situation
Williamson’s Sapsuckers range throughout western North America and Mexico, although they are less common in Canada. They breed in the mountainous regions of western North America and fly south to the southwestern United States and Mexico for the winter. Some populations are resident. Females tend to migrate further south than males.
Williamson’s Sapsuckers typically inhabit mature coniferous or mixed forests, particularly those dominated by species such as spruce, fir, and pine. They are often found in montane and subalpine regions.
During the breeding season, they nest in fairly open woodlands. Migrating or wintering individuals can be found in a wider array of woodland habitats, including oak scrub, riparian corridors, and pine-oak woodlands. They generally stay at higher altitudes and near conifers but may move to lowlands in winter.
Williamson’s Sapsucker is listed as a species of least concern on the IUCN Red List. Population declines are mostly local and tied to the loss of mature forests. You are unlikely to find this species in extensively logged areas.
Facts About Williamson’s Sapsuckers
- Early reports indicated that Williamson’s Sapsuckers drill sap wells in conifers and sometimes aspen trees. However, over the last century, observers have noted that they only create sap wells in conifers. It’s possible that the early accounts were actually describing Williamson’s Sapsuckers pilfering sap from wells created by Red-naped Sapsuckers.
- The different appearances of male and female Williamson’s Sapsuckers led Cassin to believe that the two were separate species. Ornithologists realized that they were the same species in 1873 when a pair was found and observed in Colorado.
- The ranges Williamson’s, Red-naped, and Red-breasted Sapsuckers overlap extensively, they hybridize and were once thought to be the same species. However, their preferred habitat type differs slightly.
- Williamson’s Sapsuckers often take hour-long naps while still clinging to the tree. They also sunbathe by spreading their wings out.
Similar Species
Several woodpecker and sapsucker species share similarities in appearance with Williamson’s Sapsucker, specifically the male of the species. Here are three of the most similar ones and how to tell them apart.
Black-backed Woodpecker
Male. Photograph © Glenn Bartley
Black-backed Woodpeckers are resident throughout northern and parts of western North America. Adults are black above, have barred flanks, grayish underside, a stripe across their face, and a small white mark behind their eye. Males have a yellow crown patch.
They may look very similar from afar but if you get a closer look, it should be fairly easy to tell them apart.
Williamson’s has two white face stripes, a yellow belly, and a large white wing patch, whereas Black-backed Woodpecker has one stripe on the face, a white throat, and small white spots on the wing. Male Williamson’s has a small red throat patch whereas male Black-backed has a yellow crown.
Red-naped Sapsucker
Red-naped Sapsucker ranges throughout western North America and northern Mexico. Adults are black above with white markings on the back, a red crest, two white stripes on their face, and a white patch on the wings.
They are whitish below and have barred flanks and a black chest patch. Males have a red nape and throat whereas females have a white throat with a red border and either a red or a white nape.
Males of the species can be distinguished by their backs and nape. Red-naped has a red crown, nape, and throat and white markings on its back whereas Williamson’s has only a small red patch on its throat and uniformly black back. Juvenile Red-napes resemble female Williamson’s Sapsuckers, but the former has two face stripes while the latter has a uniformly brownish head.
Red-breasted Sapsucker
Red-breasted Sapsuckers range along the western coast of North America. Adults are black above with white markings on the back, a barred underside, and a deep red head, throat, and chest.
Juveniles are dark overall with a slightly paler underside and some red on the head. Male Williamson’s is similar to the juvenile Red-breasted Sapsucker, but the latter is darker overall, does not have white face markings, and does not have a yellow belly.
Frequently Asked Questions
Who are Williamson’s Sapsuckers named after?
Williamson’s Sapsuckers are named after Robert Stockton Williamson, an army colonel and topographical engineer who conducted surveys throughout the western United States during the mid-19th century.
Do Williamson’s Sapsuckers migrate?
Williamson’s Sapsuckers are short- to medium-distance migrants.
What kinds of habitats do Williamson’s Sapsuckers prefer?
Williamson’s Sapsuckers prefer mature mountainous woodland habitats with conifers.
What do Williamson’s Sapsuckers eat?
Williamson’s Sapsuckers eat insects, tree sap, and small berries and fruits.
Are Williamson’s Sapsuckers similar to other sapsuckers?
Williamson’s Sapsuckers are fairly similar to other sapsuckers, but still easily distinguishable if you know what to look for.
