Identify Williamson’s Woodpecker

Many types of wildlife will relish the sweet taste of tree sap when it is readily available. Various woodpeckers occasionally bore into the bark to access the sap. But North America’s four species of suckers are unique in their degree of specialization on this resource, regularly drilling rows of “sap pits” into trees, then returning to sip the gooey treat that oozes out of them.

Three of the suckers—yellow-bellied, red-naped, and rufous-breasted—are common and widespread, found collectively from coast to coast. They are very close relatives, differing primarily in the amount of red on the head, and they were once grouped together as one species. But the fourth, Williamson’s Woodpecker, is very distinctive. A specialty of the western mountains, it is rare and elusive, a prize for bird watchers.

Williamson’s Woodpecker breeding range extends from southern British Columbia to the mountains of southern California, northern Lower Baja, northern Arizona and central New Mexico . It winters in the southern part of this range and well south to Mexico. In all seasons, it is mainly found in the mountains, but a few appear at low altitudes during migration and in winter. Wandering migrants have appeared east of Louisiana and the Great Lakes, and one has already been found on Long Island, New York.

So while the species is extremely rare east of the Great Plains, birdwatchers around the world have reason to keep an eye out for it.

Even in its normal range, Williamson’s Woodpecker can be difficult to find. Woodpeckers in general are often quiet and inconspicuous, but Williamson’s is also very rare everywhere. It is more specialized in its habitat than other woodpeckers. Where its breeding range overlaps that of the Red-naped Woodpecker and Red-breasted Woodpecker, these two can be found in coniferous, mixed, or hardwood forests, including pure stands of aspen or poplar. That of Williamson, on the other hand, is very strongly related to conifers such as pine, fir, larch and Douglas fir. It is also more specialized in its diet. Other woodpeckers are known to burrow sap wells into hundreds of species of trees and woody vines, but Williamson’s woodpeckers almost always tap pines or other conifers.

Among North American woodpeckers, Williamson’s Woodpecker is unique in its degree of sexual dimorphism (the difference in appearance between the sexes). In most woodpeckers, males and females differ only in the amount of red or yellow on the head. Male and female Williamsons are so different that one would assume they belong to different species (in fact, this has happened; see box below).

Fortunately, these birds aren’t hard to identify once you find them. The predominantly black male with bold accents of white, yellow and red is unlike any other species. The female, more enigmatically patterned in brown, could be mistaken for a few other things, but the images in this column should provide enough information to make her recognizable.

Williamson’s Woodpecker, adult male. June in Weber County, Utah. Photo by Brian E. Small

Williamson’s Woodpecker, adult male. Nothing really resembles the male Williamson’s Woodpecker. Even other woodpeckers with a lot of black in the plumage, such as black-backed woodpeckers or acorn woodpeckers, are easily distinguished by a glance at the face pattern or the wing pattern. Although it looks striking in photos, the overall dark appearance of this bird helps make it inconspicuous in the shady coniferous forest where it lives. Furthermore, juvenile Williamson’s Woodpeckers look very similar to adults of the same sex. Juvenile males have white throat centers instead of red, but otherwise look almost identical to adult males. Similarly, juvenile females resemble adult females, but without the black patch in the center of the breast.

Yellow-bellied Woodpecker, juvenile. October in Kern County, California. Photo by Brian E. Small

Yellow-bellied Woodpecker, juvenile. In three of the four woodpecker species (including Williamson’s woodpecker), juveniles have essentially completed their moult and assume their plumage in the first winter to early fall, before leaving the breeding grounds. However, young Yellow-bellied Woodpeckers complete their moult much later, migrating south while mostly still in juvenile plumage. These young birds could be mistaken for the female Williamson’s Woodpecker, as they are very brown overall, with buff-brown flakes on the back and some brown barring on the sides. However, even young yellow-bellied juveniles show some pattern of white stripes on their faces. And at any age, they show a large white vertical band on the wing; the female Williamson is the only one not to bear this mark.

Williamson’s woodpecker, adult female. June in Larimer County, Colorado. Photo by Brian E. Small

Williamson’s woodpecker, adult female. With its muted colors and extremely irregular marking pattern, it is probably the best camouflaged woodpecker in North America. Although Williamson’s Woodpecker places its nests in the pale-barked trunks of trembling aspen trees, such as this one, it feeds almost entirely on the dark trunks of pines, firs, larches and other conifers, where the female motif blends into the landscape. particularly well. As shown in the photo from the previous broadcast, the adult female has a yellow belly center and a black chest patch (an early name for the species was “Black-breasted Woodpecker”), but these markings are usually difficult to have. , leaving the bird with some obvious field marks.

Gila Woodpecker, adult female. April in Pima County, Arizona. Photo by Brian E. Small

Gila Woodpecker, adult female. The woodpeckers are not closely related to the zebra-backed woodpeckers of the genus Melanerpes, such as the red-bellied, golden-fronted, and Gila woodpeckers, but the color pattern of the female Williamson may suggest these birds. Williamson’s Woodpeckers sometimes appear in the southwestern lowlands in fall or winter, and females can be confused with the female Gila’s Woodpecker, which has no red on its head. Further east, they could be confused with juvenile Red-bellied or Golden-fronted Woodpeckers, whose heads initially lack most of the color. These Melanerpes woodpeckers are sharper in black and white on the back and do not have heavy bars on the sides. They are also much more active and noisy than Silent and Stealthy Woodpeckers.