The food, of this woodpecker is varied, nearly everything being grist that comes to his mill. He pecks around decayed and dying trees as well as green ones, and presumably get the insects usually found and eaten by such birds. The giant cactus is pecked into very frequently, and I believe some of the pulp is eaten. The small punctures made are not enlarged, and in some cases quite an area is bitten into. The fruit of the giant cactus is eaten as long as it lasts, and the berries of the Lycium are also freely eaten. The Gila woodpecker frequents corn fields, and pecks through the husks into the ears of corn. The birds may peck in at first to get a worm, but it is a case similar to the discovery of roast pig as portrayed by Lamb. They alight on the ground and feed upon table scraps thrown to chickens, three of them being regular morning visitors, star boarders, to a pen of chickens I fed. They are very fond of peaches and pears, and volubly resent being driven from a tree of the fruit. They peck holes in ripening pomegranates and then the green fruit beetle helps finish the fruit They relish grapes, both white and colored, and will spear one with their bill and carry it to a convenient crevice where it may be eaten at leisure. On bird tables I have tried them with various articles of food and found very little that they rejected. They would not eat cantaloupe at all but were regular watermelon fiends, eating it three times a day and calling for more. They did not care for oranges, and I had no success in trying to teach them to eat ripe pickled olives. I tried the olive diet on them because two Mocking-birds in our yard learned to eat this fruit. Meat, raw and cooked, was eaten, and they ate suet greedily. Their favorite cut of beef was the T-bone steak and we always left some meat on the bone for them. They picked it clean, and if a new supply was slow in coming the softer parts of the bone were devoured. * * * Mr. Frank Pinkley, custodian of the Casa Grande Ruins told me of a pair of these woodpeckers that stayed around his home and became quite tame, coming into the shed to drink from a can of water. He said they got into the habit of sucking the eggs in the chicken house, or at least pecking into them and eating of the contents. * * *
The Indians store corn in the ear on the flat tops of their houses and sheds, * * * and each home has one or more of woodpecker retainers or pensioners hanging about most of the time. This corn provides an abundant and sure source of food, and the birds make the most of it. I have never seen any indication of food-storage on the part of the Gila woodpecker, as with the California Woodpecker, for they live in a claw-to-beak fashion. They peck at a kernel until it comes off the cob, when it is carried to a post or tree and placed firmly in a crack. Here it is pecked to pieces and eaten. They seem never to swallow a kernel whole but always break it up.
W. L. Dawson (1923) says that this woodpecker indulges in “a systematic search for birds’ eggs, especially those of the Lucy warbler, yellow warbler, and Arizona Least Vireo. In case of the first-named, the eggs are devoured in spite of the most emphatic protests of the tiny parents; but eggs of Cardinal, Cooper Tanager and Towhee must be obtained by stealth.”
A. H. Anderson (1934) writes:
In the Tucson, Arizona, area a gall-insect (Pachypsylla venusta) frequently attacks the leaves of the hackberry tree (Celtis reticulata). The galls form on the leaf petiole, becoming from a quarter to half an inch in diameter. During the winter the outer shell hardens like a nut.
I have often seen the Gila woodpeckers tear the galls loose from the twigs and, flying to a fence post, proceed to chisel out the contents. The hard gall is wedged into a crack on the post and then opened by repeated hammering. Around the base of one fence post I counted nearly 300 empty shells. Sometimes cracks in nearby trees are used. At one time five of these woodpeckers were seen in a single tree, all of them feeding on the galls.
Behavior.—The Gila woodpecker is not only the most abundant woodpecker, in fact one of the most abundant birds, in the region it inhabits, but it is more conspicuous, noisier, and more active than any of its neighbors. It is always much in evidence, always protesting the intrusion of a stranger, and shows the greatest concern when its nest is approached, especially if it has young. It is a close sitter and will often remain in the nest hole to peck viciously at an investigating hand; while the nest is being robbed, it flits nervously about, scolding vociferously with all the vile epithets it can muster. As to its behavior with other species, Mr. Gilman (1915) writes:
This woodpecker has not the best disposition in the world, for he is very quarrelsome and intolerant. He fights his own kin and all the neighbors that he dares. He, or she, is a great bluffer however and when “called”, frequently side-steps, subsides, or backs out entirely. I saw one approach a Bendire Thrasher that was eating, and suddenly pounce on him. He had the thrasher down and I was thinking of offering my friendly services as a board of arbitration, when the under bird crawled from beneath and soon gave the woodpecker the thrashing of his career. Several times I have seen the woodpeckers start to attack Bendire and Palmer thrashers, but they were always bluffed or beaten at the game. With the Bronzed Cowbirds it is a drawn battle, sometimes one and then the other backing down. Most other birds, such as Cardinals, Abert Towhees, Dwarf Cowbirds and Cactus Wrens do not attempt to assert their rights, but always take a rear seat. But when it is woodpecker versus woodpecker it seems not to be a case of “Thrice armed is he who hath his quarrel just”, but rather, “Four times he who gets his blow in fust”.
I had two bird tables about twenty feet apart, and frequently one woodpecker might be peacefully assimilating watermelon, when another one would come hurrying up and make a dive at him, causing a retreat to the other table. Frequently the new-comer would then follow and drive him from the second table. He seemingly would rather fight than eat if another was eating at the same time. One day I saw him, or her, I forget which, hanging to the edge of the table busily eating steak, when another one perched on the table and made a vicious stab at him. He dodged backward clear under the table, though retaining his hold, and then bobbed up again, just like the Punch and Judy show. The attack was renewed, and the dodging as well, but this time he did not “come back”. Another day one of them was at work on a piece of melon when one of his fellows came and perched on the end of the table. The diner made a pass at the new comer, and seizing him by the feathers of the neck held him suspended over the end of the table for a few seconds.
Voice.—Major Bendire (1895) says: “Its ordinary call note, sounding like ‘dchürr, dchürr,’ can be heard in all directions in the spring; when flying from one point to another it usually utters a sharp, shrill ‘huit’ two or three times, resembling the common call note of the Phainopepla, and which may readily be mistaken for it. It is also more or less addicted to drumming on the dead tops of cottonwood, sycamore, and mesquite trees.”