Part 29
_Eggs._--The California woodpecker lays ordinarily four or five eggs; six eggs are not very rare; and as many as ten have been found in a nest, probably the product of two females. The eggs vary from short-ovate to elliptical-ovate. They are pure white, with very little or no gloss. The measurements of 52 eggs average 25.98 by 19.78 millimeters; the eggs showing the four extremes measure =29.9= by 19.0, 27.9 by =22.6=, =22.0= by 18.6, and 24.38 by =18.29= millimeters.
_Young._--The period of incubation is said to be about 14 days, in which both parents assist. Both also help to feed the young. Harriet Williams Myers (1915) made some interesting observations on a late brood of young California woodpeckers, which she found in a hole in a telephone pole, on September 11, between Los Angeles and Pasadena. She says:
In an hour’s watching the birds fed 28 times, the shortest interval being one-half minute, the longest eight. In nine minutes they fed eight times.
On the 15th of the month, when I believe the young must have been about ten days old, they were fed 24 times in 58 minutes. The food given them now was mostly acorns which the adults took from the nearby poles, sometimes digging them out in pieces, and sometimes taking them to the top of a flat pole where they pounded away for some minutes before coming to the nest with their bills stuffed full of the white bits. From this time until the young left the nest they were fed mostly on these acorns.
One of her most interesting observations was that an apparently young bird, presumably a fully grown member of an earlier brood, joined the two parents that were feeding the young in the nest. At one time, this immature bird entered the nest, while the parents were away, apparently for the purpose of being fed by them, and remained there for some time. Meanwhile--
when the adults came to feed they did not go inside but reached over, fed, and flew away. Three times one of them did this, but the fourth time, when the male came, he stood on one side of the hole and I heard him give low, guttural notes. * * * Presently, the truant young, for such he proved to be, appeared in the doorway and, with open mouth, begged for just one bite. * * * But the old bird was unrelenting and stayed in his position by the hole until the bird inside, which was undoubtedly a former nestling, came out and flew onto the wire above, when the adult male went within.
Just to prove that he was not all baby, the former nestling turned in and helped feed. Several times he went into the hole and came directly out, and I might have thought that he was in there in hopes of getting fed had I not distinctly seen a big fly in his bill as he entered. Each time as he bobbed into the hole several white bars showed plainly on the underside of the outer tail feathers. It was this marking of a young bird which convinced me that he was a former nestling. In every other respect he resembled a male California Woodpecker. Once more, during my watching, he slipped into the nest, staying eight minutes before they got him out. The first time it had been twenty minutes.
From the above, and from the observations of Frank A. Leach (1925), to be referred to later, it seems that the California woodpecker often, if not regularly, raises two or even three broods in a season.
_Plumages._--The young are hatched naked and blind, but the juvenal plumage is acquired before the young bird leaves the nest. In this plumage the young male closely resembles the adult male and the young female is much like the adult female in general color pattern, but the red of the crown and nape is duller and more or less mixed with dusky or black; sometimes the crown is nearly all black mixed with some scarlet feathers; the colors everywhere are duller, lacking in gloss, and the plumage is softer, less firm; the yellow of the throat is less pronounced; the streaks on the breast are less sharply defined; the tertials and scapulars are tipped with white, and there are narrow white tips on the two outer tail feathers on each side, but these tips wear away during winter, or sooner; there are at least two white spots on each web of the outer tail feather, which are in evidence all through the first year; as the juvenal wings and tail are retained until the next summer molt, birds of the year may be thus recognized; the bill is smaller and weaker than that of the adult. The molt of the juvenal contour plumage begins in August or September.
Adults have a complete annual molt between July and September, mainly in August.
_Food._--Some prominent California ornithologists have named this bird the “California acorn-storing woodpecker,” a rather long but very appropriate name, for it designates one of its most characteristic habits and names the largest item in its food supply. W. L. Dawson (1923) has this to say on the subject:
From time immemorial this bird has riddled the bark of certain forest trees and stuffed the holes with acorns. Speculation is still rife as to the cause or occasion or necessity or purpose of this strange practice, but the fact is indisputable and the evidence of it widely diffused. * * *
What he accomplishes the photographs show well enough,--the close, methodical studding of bark or wood of any kind with acorns, chiefly those of live-oaks, over immense areas. The cultures, once started, are wrought upon continuously year by year, as material avails or the colony flourishes. Live-oaks themselves are the commonest hosts, together with the white, or post, oak, and the black oak of the southern counties. After these come sycamore and yellow pine or, more rarely, eucalyptus. Telegraph and telephone poles, gables, cornices, and, in fact, any wooden structure where they are permitted to work, if near the source of acorn supply, may come in for ornamentation. On a small square-sawed telephone pole near Marysville I found sixty acorns (and pecans purloined from a neighboring orchard) imbedded in a space five inches wide and two feet long. At that rate the pole carried some 1500 of these tiny storehouses.
In Tecolote Canyon, west of Santa Barbara, there is a giant sycamore which I count one of the handsomest examples of Carpintero’s workmanship--an unbroken shaft, at least forty feet high and three feet across the inlaid face, covered with a “solid” mass of acorns totalling, say, some 20,000. Strawberry Valley in the San Jacinto Mountains appears to be a paradise for the California Woodpecker. Here majestic oaks (_Quercus californica_) alternate with still more majestic pines (_Pinus ponderosa_), the former for sustenance and the latter for storage, and the doughty “California” is probably the most abundant bird in the valley. The boles of the most enormous pines are methodically riddled with their acorn-carrying niches, and in some of the trees the work is carried through from base to crown. In one such tree I estimated that there were imbedded no less than 50,000 acorns.
Dr. William E. Ritter has made an intensive study of this interesting habit of the California woodpecker and has published the results of his observations and theories in three extensive papers (1921, 1922, 1938). There is much food for thought in these scholarly papers, to which the reader is referred, but space here will permit only brief quotations from or references to them. As to whether the hole drilling is injurious to the trees, he says (1921): “Although I have examined many storage pines in widely separated localities, I have never seen anything even suggestive of harm to the trees from the holes. Never, so far as I have noticed, do the holes pierce through into the deeper living layers of the bark.” He noticed that “almost without exception the nuts were inserted tip in and base out, most of them fitting the hole snugly,” having been driven in good and hard, and flush with the surface of the bark, or even countersunken below it; and that “to a certain extent the store holes are made to fit the size of the acorns they are to receive”; this latter point was discovered when he noted that, in a region where the black oak (_Quercus kelloggii_) predominated, the holes were considerably larger than they were in the live-oak region, the acorns of the black oak being sharply larger than those of the live oak. In some cases the acorns were not driven in flush with the bark, the base being left protruding somewhat and thus leaving them vulnerable to pilfering by rodents and perhaps some birds; in this connection, he says: “Conclusive evidence that nut-eating rodents (squirrels, rats) prey upon the acorns stored by the woodpeckers was first obtained on the present visit. Two trees were found on which the bark immediately around acorn holes had been gnawed by rodents, as unmistakably proved by the tooth marks. The acorns were gone from some of these holes, but not from all, thus showing that the marauders had failed in some of their efforts.”
Summarizing his first paper, he makes the following statements:
As to hole drilling: While the holes are made expressly for the reception of acorns, many holes are probably made which are never used, holes are made at seasons of the year when there are no acorns to store, and large numbers of perfectly serviceable holes seem to be abandoned even in localities where both birds and acorns are abundant, and new holes are being made.
As to the storing business itself: While this is of distinct service to the food necessities of the woodpeckers, the instinct sometimes goes wrong to the extent of storing pebbles instead of acorns, thus defeating entirely the purpose of the instinct. Again, large numbers of acorns are sometimes stored, the use of which is so long delayed that the acorns become wholly or largely unfit for food, and this in places where the bird population seems normal. Finally, acorns are sometimes stored in such fashion as to make them easy prey for marauding rodents, when with some definite foresight and a little more work such exposure could easily be largely avoided.
In his second paper (1922), after further observations, he states[1]:
My previous surmise that the birds are more interested in the grubs contained in the acorns than in the acorn meats has not been substantiated. What I could make out while in camp among them, by watching them gather and eat their breakfasts, was to the effect that good uninhabited acorns were chiefly used. Again and again birds were seen to pick nuts from the top-most branches of the black oak, fly with them in their beaks to some approximately horizontal surface of a large limb on a pine or another oak, make the surface aid them somehow (I never could see exactly how, as the “breakfast tables” were, of course, all on the upper surfaces of the limbs, and too high for my vision) in breaking and tearing open the nuts. Apparently cracks and chinks in the table top serve as holders for the acorns while they are being opened and eaten. This is indicated by the fact that dead and partly decayed trees or parts of trees were mostly used. I saw no indication of the feet being used in handling the nuts. The litter on the ground under the dining trees, consisting of shell fragments and lost bits of meat, indicated grubless nuts almost entirely. This result as to the use of mast is in agreement with Beal’s examination of the stomach contents of our woodpecker.
Charles W. Michael (1926), in the Yosemite Valley, made the interesting discovery that the California woodpecker has been known to learn by experience and to show some intelligence in its acorn storing. For a number of years when acorns were abundant no extensive storing was done, yet the woodpeckers lived in the valley all winter. Then came a lean year, with no acorn crop, when no storing _could_ be done; and that winter the woodpeckers were forced to leave the valley for lack of food. The following year there was a bountiful crop of acorns, and the woodpeckers, having learned by experience, were busy filling up their storehouses. “From the above observations,” he says, “one might conclude that an abundance of acorns is not directly responsible for prodigious storing. In a land of plenty the necessity of laying aside stores for future consumption is obviated. It is the barren years that teach the value of thrift. Intelligence plus experience may well have been the cause of the excessive storing of this year. A few of the more intelligent woodpeckers that were forced last winter to abandon the valley for lack of food are now preparing against the next lean year.”
Claude Gignoux (1921) reports finding almonds stored in the bark of an oak tree on a ranch near Marysville, Calif., as well as in the side of a barn.
Dawson (1923) says: “A regrettable taste for fruit is occasionally cultivated, but this has not reached economic proportions, save in the case of almonds. Almond orchards thrive best at a very considerable distance from oak groves.”
Although acorns, almonds, walnuts, and pecans constitute nearly 53 percent of its food, and much more than that in fall and winter, the California woodpecker eats quite a variety of other food at different seasons. Prof. F. E. L. Beal (1910) examined the contents of 75 stomachs, which contained “22.43 percent of animal matter to 77.57 percent of vegetable.” Bendire (1895) says: “During the spring and summer its food consists, to a great extent, of insects, including grasshoppers, ants, beetles, and different species of flies, varied occasionally with fruit, such as cherries, which are carried off whole, apples, figs, and also berries and green corn.”
Mr. Skinner says in his notes: “At times this bird feeds very much like an eastern red-headed woodpecker. On May 9, 1933, one was seen on the trunk of an oak, only 4 feet above ground, making flycatcherlike sallies up under the foliage of the oak. And many times thereafter I saw the birds operating similarly within the foliage itself. In some instances I have seen these woodpeckers dart out from high up in tall yellow pines after passing insects, then gliding back on set wings. Sometimes they do this from tall electric poles, at times going out as much as 50 feet. Since there was every reason to suppose that the bird saw the insect before it started, this speaks well for its keenness of eyesight. At times, these woodpeckers glean insects from the bark of trees. In July, in the Yosemite Valley, hunting the twigs and bark for insects seemed the favorite method of getting food.”
Dr. Joseph Grinnell (1908) saw one of these woodpeckers, in the San Bernardino Mountains, drive a sapsucker away from its borings in an alder and then go “the rounds of the borings” drinking from each. Dr. Harold C. Bryant (1921) saw a California woodpecker robbing a nest of a pair of western wood pewees; he was “calmly perched on the pewee’s nest and eating one of the eggs. I could see the white and the yolk of the egg on the woodpecker’s bill, as he raised his head. After watching for some time, I attempted to frighten the robber away, but experienced considerable difficulty in doing so. When he finally left the nest the pewees continued to dart at him, to drive him farther away. Soon one of the pewees, apparently the female, returned to the nest, picked up an eggshell and flew off with it. I was unable to see what she did with it. In half a minute she returned and began incubating the remaining eggs.”
_Behavior._--The California woodpecker flies in true woodpecker fashion, an undulating flight, interspersed with long dips during which the wings are partly closed and somewhat pressed against the sides of the body; during the rises the wings are flapped, displaying the black and white markings conspicuously; there is an upward sweep before alighting. Grinnell and Storer (1924) say: “When alighting on a tree trunk, these birds assume a vertical posture, head out, tail appressed to the bark. They move up by a hitching process--head in, tail out; up; tail in, head out. If a bird perches on a small horizontal branch, his position is more likely to be diagonal than directly crosswise. If a bird alights on the square top of a fence post, he seems ill at ease and soon backs over the edge into a more woodpecker-like posture.”
Mr. Dawson (1923) writes: “A most characteristic flight-movement is an exaggerated fluttering wherein progress is at a minimum and exercise at a maximum. In this way, also, they ascend at acute angles, sometimes almost vertically. With this movement alternates much sailing with outspread wings, and certain tragic pauses wherein the wings are quite folded.” A similar flight is thus described by Grinnell, Dixon, and Linsdale (1930) as follows: “Individual woodpeckers were often seen making a kind of flight the object of which we did not determine. A bird would fly in a nearly vertical direction from its perch for three meters or more and then commence an irregular swooping flight, finally coming back to the original perch.”
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.”