Life histories of North American woodpeckers

by Arthur Cleveland Bent

SPHYRAPICUS THYROIDEUS THYROIDEUS (Cassin)

WILLIAMSON’S SAPSUCKER

HABITS

Williamson’s sapsucker is not only one of our most unique woodpeckers in its striking coloration, but it has an interesting history. Owing to the radical difference in appearance between the two sexes, they were for some time regarded as two distinct species. The female was the first to be described by John Cassin (1852, p. 349), based on a specimen collected by John G. Bell in Eldorado County, Calif. Under the name black-breasted woodpecker (Melanerpes thyroideus), Cassin describes and figures (1854) the adult female as the male of the species and says of the female: “Similar to the male, but with the colors more obscure, and the black of the breast of less extent and not so deep in shade,” which is a very fair description of the immature female. The male was discovered and described and figured by Dr. Newberry (1857, p. 89, pl. 34) under the name Picus williamsonii, based on a specimen collected by him on August 23, 1855, on the shores of Klamath Lake, Oreg. Baird, Cassin, and Lawrence (1860) give a very good description of an adult male, as the male of the species, but say “female with the chin white instead of red,” which, of course, is the immature male. Thus we have the adult of each sex regarded as the male of a species, and the young bird of each sex regarded as the female of a species. With careless, or improper, sexing of specimens, such an error might easily occur, but it is remarkable that it remained so long undiscovered. Baird, Cassin, and Lawrence (1860) describe the male as Sphyrapicus williamsonii Baird, Williamson’s woodpecker, and the female as Sphyrapicus thyroideus Baird, brown-headed woodpecker. J. G. Cooper (1870), in the Geological Survey of California, edited by Baird, follows the same error but calls the female the round-headed woodpecker. Even Baird, Brewer, and Ridgway, in their history of North American Birds, had not discovered the error, for they use substantially the same nomenclature.

It remained for Henry W. Henshaw (1875) to discover the true relationship of the two supposed species and clear up the previous misunderstanding. He writes: “While near Fort Garland, I obtained abundant proof of the specific identity of the two birds in question; williamsonii being the male of thyroideus. Though led to suspect this, from finding the two birds in suspicious proximity, it was some time before I could procure a pair actually mated. A nest was at length discovered, excavated in the trunk of a live aspen, and both the parent birds were secured as they flew from the hole, having just entered with food for the newly hatched young.”

Mr. Ridgway (1877) comments on the discovery as follows:

A suspicion that the two might eventually prove to be different plumages of one species several times arose in our mind during the course of our field-work, the chief occasion for which was the very suggestive circumstance that both were invariably found in the same woods, and had identical manners and notes, while they also agreed strictly in all the details of form and proportions, as well as in the bright gamboge-yellow color of the belly. Our theory that thyroideus was perhaps the young, and williamsoni the adult, proved erroneous, however; and it never occurred to us that the differences might be sexual, an oversight caused chiefly by the circumstance of our having seen in collections many specimens of thyroideus with a red streak on the throat and marked as males, while the type specimen of williamsoni had a white streak on the throat and was said to be a female. We were thus entirely misled by the erroneous identification of the sex in these specimens. We gave the matter up, however, only after shooting a very young specimen of what was undoubtedly williamsoni, and another of thyroideus, both of which very closely resembled the adults of the same forms, a circumstance which at once convinced us that the differences could not depend on age; so we finally concluded that the two must be distinct.

All observers seem to agree that this woodpecker is confined to the higher elevations in the mountains among the pines, in sharp contrast to the haunts of the red-breasted sapsucker at lower levels among the deciduous trees.

Joseph Grinnell (1908), referring to the San Bernardino Mountains, in southern California, says: “This Williamson sapsucker appeared to be restricted to the Canadian zone and upper edge of Transition. We found it only among the tamarack pines on the slopes and ridges of San Gorgonio peak, and among the silver firs, tamarack and yellow pines around Bluff lake. In the former locality the species was common for a woodpecker, especially around Dry Lake, 9,000 feet altitude, where several nests were found.”

Courtship.—Charles W. Michael (1935) noted the mating behavior of a male Williamson’s sapsucker, which had just left a fresh nest-hole, as follows: