The male Williamson's Sapsucker is a silken black woodpecker with a cherry-red throat, a rich yellow belly, and sharp white wing patches. Unlike most woodpecker species, the female looks totally different (and was originally thought to be a different species entirely). It looks almost like a diminutive flicker, with a mousy brown head, banded back, and small patches of black and yellow on the belly. This fairly common sapsucker of western mountains drills rings of holes in coniferous trees, then feeds on the tree’s sap.
Look for Williamson’s Sapsuckers in mature mountain forests with large coniferous trees. Listen for the unusual, raptorlike call of the species and for its drumming, which is less erratic than Red-naped and Red-breasted Sapsuckers.
Sapsuckers get their name from their habit of drilling rows of shallow holes in tree bark. The birds come back to these holes to lick the sap that flows from these holes and to eat insects that have become caught in the sticky residue.
Early ornithologists in the West reported seeing Williamson’s Sapsuckers at sapwells in aspen trees; however, in the past 100 years, observers have seen their sapwells only in conifers, never in deciduous trees. The early reports might have been of Williamson’s stealing sap from wells made by Red-naped Sapsuckers.
The three western sapsucker species—Williamson’s, Red-naped, and Red-breasted—overlap extensively in range. Where two species occur together, they appear to choose slightly different habitats. In Colorado, Williamson's nests more in open ponderosa pine forest, whereas Red-naped tends to nest more in deciduous or mixed forests.
Male and female Williamson’s Sapsuckers look so different that it wasn’t until 1873 that ornithologists realized they were the same species. Naturalist Henry Henshaw located a pair at their nest in Colorado and published his observations, thus putting an end to the confusion.