While collecting with Frank C. Willard, in southern Arizona, we found the cactus woodpecker fairly common about Tombstone and near Fairbanks on the San Pedro River. Near the former place, one nest was 6½ feet up in a fence post; the cavity was about 10 inches deep and 3¼ inches in diameter at the bottom; another nest was in a cavity 12 inches deep in the dry stalk of a mescal about 5 feet from the ground. In the valley of the San Pedro River, we found a nest about 12 feet from the ground in a willow stub; and another nest was located in a stump of a willow beside a fence; it was only 6 feet up in the solid part of the stub, and so well concealed behind a bunch of sprouts that we had passed it many times without seeing it.
Mr. Willard (1918) says:
“Along the San Pedro River the Cactus Woodpecker (Dryobates s. cactophilus) is the only one nesting at all commonly. In the lines of willows bordering the irrigation ditches and in all the small groups found along the river banks, I had quite a list of pairs whose nests I could count upon finding within certain circumscribed areas. They exhibited individual characteristics. One pair never dug its nest lower than twenty feet from the ground and usually selected a site that overhung the water. Another liked short stubs not over five or six feet tall. Another was partial to fence posts. While these selections were not invariably followed they were so usual that I always began my search by examining all the available sites of that character before looking at others and was usually successful in my first search.”
Eggs.—The cactus woodpecker lays 2 to 6 eggs, usually 4 or 5. These are usually oval or short oval, sometimes elliptical-oval or elliptical-ovate. They are pure white and more or less glossy. The measurements of 18 eggs average 21.48 by 16.18 millimeters; the eggs showing the four extremes measure 23.02 by 16.67, 22.5 by 17.0, and 19.2 by 15.1 millimeters. Bendire (1895) says that incubation lasts for about 13 days and is shared by both sexes.
Plumages.—The young are probably hatched naked (I have not seen any), as is the case with other woodpeckers, but the juvenal plumage is acquired before the young bird leaves the nest. This first plumage is much like that of the adult male, but the sexes are not quite alike. In the young male, the forehead, sides of the occiput, and the nape are uniform black; only the crown is scarlet, more or less dotted with white. The young female is similar to the young male, except that there is usually much less scarlet on the crown, often only a few scarlet tips. In both sexes the back is barred with dull black and grayish white, instead of the clear black and white of the adult; the under parts are “vinaceous-buff,” faintly spotted on the sides and flanks; the plumage is softer and the markings are not so clearly defined as in the adult. Just how long this plumage is worn I have not been able to determine, but July birds show signs of body molt and an increasing amount of the clear black streaks of the adult plumage on the sides and flanks. Probably a plumage that is practically adult is assumed by the first fall at the latest. Adults apparently have a complete annual molt in summer, mainly in August.
Food.—The cactus woodpecker lives mainly on the larvae of wood-boring beetles, which it gleans from the trunks and branches of trees. It also eats the larvae of the coddling moth and other Lepidoptera, ants, caterpillars, and cotton worms. It usually forages at low elevations on small trees, shrubs, and various cacti and is often seen feeding on the ground. Major Bendire (1895) says that this woodpecker, “like several other species, is very fond of the ripe figlike fruit of the giant cactus, and I have met it more than once in Sahuarito Pass, Arizona, eating it on the ground.”
Voice.—Ralph Hoffmann (1927) compares the notes of the cactus woodpecker with those of the downy woodpecker and says that “the common notes are a single high-pitched tschik or a longer rattling call with a slight fall toward the end. It often calls as it flies, and like other woodpeckers drums in spring on dry limbs.” Dawson (1923) refers to the notes as “his plink, plink, and his long rolling chirrup.”
Field marks.—A small woodpecker with the upper parts distinctly and extensively barred with black and white is either one of the races of Dryobates scalaris, commonly called ladderbacks, or Dryobates nuttalli. These two species are very much alike in superficial appearance and might be easily confused; but fortunately their ranges do not overlap, except to a slight extent in some of the mountain passes of southeastern California. Mr. Dawson (1923) says that the cactus woodpecker “is browner above, more strikingly, heavily, and numerously barred, with less of black on sides of head, and red (of adult male) pervading crown as well as nape.”
Winter.—W. E. D. Scott (1886) says that these woodpeckers “are at times gregarious. I particularly noticed this in December, 1885, when I frequently met the species in flocks of from four to a dozen, on the plains at an altitude of 3,000 feet.”