“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.