M. P. Skinner says in his notes: “In many of their ways, motions, and mannerisms these birds strongly resemble the red-headed woodpeckers of Eastern United States. Often they are very quiet and remain motionless in one position for many minutes at a time. They are as apt to perch crosswise as lengthwise of a horizontal, or nearly horizontal, limb. At times, they hop along a limb, or the cross-arm of an electric pole, while their bodies are turned a little sideways. Although one exhibited the usual woodpecker habit of nervously jumping down backward, and swaying from side to side, so as to be seen first on one side of his dead stub and then on the other, he was really noticeably quiet and motionless most of the time. One was seen in the Yosemite Valley on the under side of a cottonwood twig, clinging there with his back down.”
Bendire (1895), on the other hand, says: “It is one of the most restless Woodpeckers I know of, and never appears to be at a loss for amusement or work of some kind, and no other bird belonging to this family could possibly be more industrious.” This was my impression of it, as well as the opinion of others.
Henry W. Henshaw (1921) evidently considered this woodpecker playful, for he writes: “In searching for the motives underlying the storing habit of the California Woodpecker we should not lose sight of the fact that the several acts in the process, the boring of the holes, the search for the acorns, the carrying them to the holes and the fitting them in, bear no semblance to work in the ordinary sense of the term, but is play. I have seen the birds storing acorns many times, and always when thus engaged they fill the air with their joyous cries and constantly play tag with each other as they fly back and forth. When thus engaged they might not inaptly be likened to a group of children at play.”
California woodpeckers are well known to be sociable birds and to live more or less in communities or loose colonies, where food conditions are favorable. But a most remarkable story of apparently communal nesting is told by Frank A. Leach (1925). On February 2, 1922, he discovered these woodpeckers excavating a nest in a wooden trolley pole at Diablo, Calif. He estimated that they must have started work on this hole about the middle of January and thinks that it was some time near the latter part of April before it was finished. On March 1, he “saw two go in one after the other. Both appeared to be working on the inside. Two other birds on the pole showed interest in the work by remaining there and taking an occasional peep into the hole.” On April 3, there were “from four to six woodpeckers about the place all day. On one occasion saw three go into the hole. Heard digging while they were inside.” On April 17, he saw “three birds go into the cavity and soon after heard two of them working. Four other birds were on the pole, one looking into the hole.”
The above extracts from his notes, made at frequent intervals and often for several days in succession, would seem to indicate that at least two, and possibly three, pairs of woodpeckers assisted in the excavation of that nest, but evidently their work was not very efficient, as the time involved was unusually long. The same cooperative behavior continued during incubation of the eggs and the feeding of the young, several different birds working in relays; and this continued during the rearing of three broods of young that season. He says that “in the case of the second brood, on eight different occasions I saw three different old birds feed the young ones in the nest, and at one time I witnessed a fourth one delivering food to them.”
Referring to the third brood, he says:
In the large oak tree standing so near the trolley pole that some of its outer branches nearly reached the pole, there were almost always from six to eight mature woodpeckers, all of which seemed to be interested in the welfare of the nestlings in the pole. I repeatedly saw three of them feed the youngsters, and on two occasions noted four different old birds perform this parental service. I was satisfied from the actions of the birds that a majority of the flock, if not all of them, participated in the care of the young woodpeckers. * * *
For others than the parent birds to feed the young was a custom that was not confined to this group or flock at the trolley pole. At about the time the young were leaving that nest, I discovered another nest in a large oak tree situated about a quarter of a mile distant from the pole, where I found from one to five old birds, and possibly more, very busy feeding the nestlings.
Major Bendire (1895) remarks: “The California woodpecker is by far the most social representative of this family found within the United States, and it is no unusual occurrence to see half a dozen or more in a single tree. It is also a well-disposed bird, and seldom quarrels or fights with its own kind or with smaller species; but it most emphatically resents the thieving propensities of the different jays, magpies, and squirrels, when caught trespassing on its winter stores, attacking these intruders with such vigor and persistency that they are compelled to vacate the premises in a hurry.”
According to some other observers, its behavior toward other species is not always as friendly as it might be. M. P. Skinner writes to me: “Once I found a California woodpecker and a California jay peaceably perched in the top of a dead cottonwood. But at other times I have noted much fighting between these woodpeckers and the jays, with the woodpeckers apparently able to hold their own. On May 1, 1933, at old Fort Tejon, I saw a California woodpecker make a vicious dive at a plain titmouse that was clinging to the bark on the trunk of an oak. On May 31 I saw one make a dive at an Arkansas kingbird on a fence and drive it away. In May 1933 I found a pair of house finches that had attempted to nest in a cavity high up in a dead stub of a black oak. When I appeared, I found a California woodpecker throwing out the straws and other nest material. The two finches were only a foot or two distant, but they made no attempt to save their home, although it is probable that they were scolding. Old acorn stores in the same stub indicated that some woodpecker had an earlier claim to that stub than the finches had.”