He sounded his harsh call several times. Seemingly in answer to his call the female appeared. This was the first we had seen of the female. The female examined the nest hole, flew up on a branch and uttered a series of low notes. The male joined her, alighting a foot away and uttering a series of low chuckling notes. While giving these notes he strutted along the limb with wing-tips and tail jerking rapidly. As he approached his mate she crouched low on the limb and the mating act was accomplished. The act lasted several seconds before the birds separated to perch side by side on a limb. After a minute or so the female flew off through the woods and the male went into the nest hole. In about five minutes the female came to the nest hole and again uttered her soft coaxing notes. The male came out of the hole and both birds flew to a limb where again the mating act was consummated. The male returned to the nest. In our two-hour watch the female only went to the nest hole to call the mate out.
Nesting.—Dr. Grinnell (1908) says of its nesting in the San Bernardino Mountains:
Tamarack pines were selected as nest trees, usually old ones with the core dead and rotten but with a live shell on the outside. In one found June 22, 1905, there were four holes drilled one above the other about eighteen inches apart, and one of these holes contained three small young and two infertile eggs. * * * Later on in the same day another nest was found similarly located containing four half-fledged young. A nest with half-grown young was found in the same locality, June 14, 1906; and on June 26 of the same year a nest twenty feet up in a half-dead tamarack held five two-thirds-grown young and one rotten egg. So that a full set of eggs probably varies from four to six in number. On June 18, 1907, a nest with small young was located ten feet up in an exceptionally large nearly dead tamarack pine. This was one of the lowest of a series of forty-seven well-formed holes of similar external appearance, which penetrated this one tree trunk on all sides up to an estimated height of thirty-five feet.
W. L. Dawson (1923) writes: “One soon comes to recognize the rigid requirements of the Williamson Sapsucker in the matter of nesting sites. Given a pine which is beginning to die at the top, usually in a fairly sheltered situation, and a pair of birds will adopt it for a permanent home. They will occupy it from year to year, or perhaps the year around, nesting twice in a season; and a long occupation is evinced by a trunk riddled with holes at all levels. One such ‘family tree,’ closely examined, had 38 holes, apparently complete and fit for habitation or incubation. At the time of our visit, on June 19th, the male was industriously drilling a new excavation at a height of 45 feet.”
Major Bendire (1895) says:
I obtained my first set of eggs of this species on June 3, 1883, about 9 miles north of Fort Klamath, in the open pine forest on the road to Crater Lake. It consisted of five eggs, slightly incubated. The nesting site was excavated in a partly decayed pine whose entire top for some 20 feet was dead; the height of the excavation from the ground was about 50 feet. The man climbing the tree reported it to be about 8 inches deep and about 5 inches wide at the bottom, and freshly made. A second set, of six fresh eggs, was taken June 12 of the same year, about 12 miles north of the Post, at a still higher altitude than the first one. It came also out of a pine about 40 feet from the ground. A third nest, found a week later, near the same place, contained five young, just hatched. This nest was in a dead aspen, about 20 feet from the ground. Only one brood is raised, and, like the other two species, it is only a summer resident in the vicinity of Fort Klamath.
Other observers have found nests in lodgepole pines, red firs, and larches at various heights from 5 to 60 feet above ground but always in conifer associations.
Eggs.—Bendire (1895) says: “The number of eggs laid to a set varies from three to seven, sets of five or six being most often found. These, like all woodpecker’s eggs, are pure china-white in color; the shell is close grained, rather thin, and only slightly glossy. In shape they vary from ovate to elongate ovate, and a few approach an ovate pyriform, a shape apparently not found in the eggs of other species of this genus.” The measurements of 30 eggs average 23.54 by 17.23 millimeters; the eggs showing the four extremes measure 25.91 by 17.27, 24.1 by 18.3, and 20.1 by 15.4 millimeters.
Young.—Both parents assist in the duties of incubation, but the length of time required for this function does not seem to be definitely known; both sexes also help in feeding the young. Dr. J. C. Merrill (1888) says, of two nests that he watched for some time: “The males brought food about twice as often as did the females, and frequently removed the excrement of the young on leaving the nest, alighting on the nearest tree for a moment to drop it and to clean their bills; I did not see either of the females remove any excreta. About four feet above one of the holes was another occupied by a pair of pigmy nuthatches, but neither species paid any attention to the other when they happened to arrive with food at the same time.”
Dr. Grinnell (1908) writes: “We usually located the nests by watching the movements of the parent birds, which flew from their foraging places, often far distant, direct to the nest tree. The young uttered a whinnying chorus of cries when fed, and the adults, though generally very quiet, had a not loud explosive cry, more like the distant squall of a red-tailed hawk. The bill and throat of an adult male, shot as it was approaching a nest, was crammed with large wood ants, not the kind, however, that are common at lower altitudes and smell so foully.”