On April 6, 1902, I saw about a dozen Williamson Sapsuckers near the summit of the mountains at an altitude of about 9,000 feet. Though not at all in a compact flock they seemed to keep rather close together, and when one flew any distance away, the others soon followed. The bulk of them were females, and but one or two males were seen, one of which was, with great difficulty secured, for they were very wild. On April 9 several more were seen and a female secured at this same place; and a male was taken a mile or two from this place, at an altitude of nearly 10,000 feet. These were the last I saw in the spring, though they do occur later as I have a female that was taken in the Huachucas by H. Kimball on April 20, 1895.
Nesting.—The nesting habits of this woodpecker do not seem to differ materially from those of the species elsewhere. Bendire (1895) quotes W. G. Smith, as follows: “Williamson’s Sapsucker is a common summer resident in Estes Park, Colorado, where it nests mostly in dead pines, often within a few feet of the ground, and again as high as 70 feet up. Full sets of fresh eggs are usually found here during the first week in June. The male appears to me to do most of the incubating, and hereabouts it is most often found at altitudes between 7,000 and 8,000 feet, but I have also taken it at much higher ones, where it nests somewhat later.”
Mr. Skinner says in his notes: “On June 14, 1914, I discovered the nest of a pair of Williamson sapsuckers in the gulch beside the trail to Snow Pass at the beginning of the last ascent. The nest was in an aspen trunk about 6 inches in diameter. The opening to the nest was 1½ inches in diameter and located 5 feet above ground. On June 30, 1915, the nest was in the same tree, but 2 feet above the 1914 nest and in a fresh opening.”
Eggs.—The eggs of Natalie’s sapsucker do not differ materially from those of the other race of the species. The measurements of 51 eggs average 23.60 by 17.41 millimeters; the eggs showing the four extremes measure 26.2 by 17.9, 24.2 by 19.4, 21.5 by 17.0, and 22.0 by 16.0 millimeters.
Young.—Mr. Skinner says in his notes that the young “seem to arrive irregularly between June 10 and July 1. I have seen young Williamson’s sapsuckers hunting by themselves before August 10. In the nest recorded above there were five young on June 14, 1914, and both parents were kept constantly busy bringing food, and frequently came so fast that one parent had to wait for the other to leave the nest. In feeding the young the adults disappeared completely into the nest cavity and came out head first. In 1915 there were five more young on June 30 and they were still there on July 10. When I visited them on June 30, the male was in the nest, and it required about five raps on the tree trunk to dislodge him, although he came to the opening and looked out at each rap.”
Food.—The feeding habits of Natalie’s sapsucker are apparently similar to those of the species elsewhere, but Mr. Skinner tells me he has “seen it drumming on firs for insects, picking insects from a crotch of a lodgepole pine and catching spruce-budworm moths from fir foliage.”
Behavior.—The feeding and other habits of Natalie’s sapsucker seems to be similar to those of the other subspecies, but Bendire (1895) quotes the following notes from Denis Gale, about its behavior around the nest, which are worth repeating here:
A marked peculiarity I have noted with Sphyrapicus thyroideus is that the male takes a lookout station upon some suitable tree, where, at the approach of any possible danger, he gives the alarm by striking a short dry limb with his bill, by which a peculiar vibrating sound is given out, which the female, not very distant, fully understands, and is at once on the alert. If either excavating, guarding, or covering her eggs, she will immediately look out of her burrow, and, should the intruder’s path lie in the direction of her nest, she will silently slip away and alight in a tree some distance off, but in view of both her nest and the intruder. The first or second blow of a hatchet upon the tree trunk in which the nest is excavated will mark her movement again by a short flight, so managed as not to increase the distance—in fact oftener coming nearer. When satisfied that her treasures have been discovered, she utters a peculiar, low, grating sound, not unlike the purring of a cat. The male then comes to the fore and braving the danger, is very courageous, and, should the eggs be far advanced in incubation, he will even enter the nest when you are almost within reach of it. When the latter are rifled, he is always the first to go in and discover the fact, often passing in and out several times in a surprised sort of manner.