Part 18

_Eggs._--[AUTHOR’S NOTE: The yellow-bellied sapsucker lays four to seven eggs to a set, though five or six eggs are more commonly found. They vary from ovate to elliptical-ovate and sometimes to elliptical-oval. The shell is smooth and either dull or moderately glossy. They are pure white, like all woodpeckers’ eggs. The measurements of 52 eggs average 22.44 by 16.92 millimeters; the eggs showing the four extremes measure =24.9= by 17.0, 23.8 by =18.0=, =20.57= by 16.26, and 22.1 by =15.5= millimeters.]

_Young._--As in the case of most nestling birds reared in a hole in a tree, little is known of the young sapsuckers while they are in the nest.

Frank Bolles (1892) speaks of “a nest filled with noisy fledglings whose squealing sounded afar in the otherwise silent woods. * * * The parent birds came frequently to the tree, and their arrival was always greeted by more vigorous crying from the young.”

William Brewster (1876a), in his study of the bird at Umbagog Lake, Maine, says: “The young leave the nest in July, and for a long time the brood remains together, being still fed by the parents. They are very playful, sporting about the tree-trunks and chasing one another continually.”

Frank Bolles (1892) has given a very interesting, detailed account of rearing three nestlings, about to be fledged, over a period of three and a half months. The three birds were dissimilar enough in coloring to be distinguished from one another; they proved to be two males and one female; and they soon developed marked differences in conduct and personality. Mr. Bolles at first kept them in a large cage in which they had ample space to climb about and later allowed them to fly around a room. They became very tame, letting him handle them freely. They subsisted almost entirely on maple syrup and water in equal parts, fed by hand at first, but in a few days they drank readily from a basin. They caught a few flies and ate some other insects that entered the cage, attracted by the syrup. Mr. Bolles says, however, that “the number of insects caught by them in this way was small, and I do not think amounted at any time to ten percent of their food.”

The birds were lively and apparently in perfect health from the time they were captured, July 7, until October 11, when one of them, the female, began to droop. Two days later she had a convulsion in the morning and died in the afternoon. Autopsy showed that her body was well nourished and that the organs were apparently normal except the liver, which was “very large, deeply bile-stained, and very soft.”

A week later the other two birds died after exhibiting the same symptoms as the first bird. The Department of Agriculture examined the body of one of these birds and reported enlargement and fatty degeneration of the liver.

Mr. Bolles remarks that “the most probable cause of this enlargement of the liver, which seems to have been the reason for the death of the three sapsuckers, was an undue proportion of sugar in their diet. In a wild state they would have eaten insects every day and kept their stomachs well filled with the chitinous parts of acid insects. Under restraint they secured fewer and fewer insects, until during the last few weeks of their lives, they had practically no solid food of any kind.”

Summarizing his observations, he says:

From these experiments I draw the following conclusions: (1), that the yellow-bellied woodpecker may be successfully kept in captivity for a period corresponding to that during which as a resident bird he taps trees for their sap, sustained during this time upon a diet of which from 90 to 100 per cent is diluted maple syrup; (2), that this fact affords evidence of an extremely strong character, in confirmation and support of the theory that when the yellow-bellied woodpecker taps trees for their sap he uses the sap as his principal article of food, and not primarily as a bait to attract insects.

Winton Weydemeyer (1926) in Montana “observed a pair of red-naped sapsuckers * * * gathering sap to feed their young in the nest. A regular tree-route, followed alternately by the male and female, included a quaking aspen, a larger alder, and a large willow, in which borings had been made. The birds flew directly from the nest to the aspen, and gathered the sap that had accumulated since the last visit; then flew to the alder and to the willow, repeating the process; and finally flew back to the nest, without hunting for insects. Occasionally the male would vary the process by catching a few flies from the air, eating some and carrying some to the nest.”

Forbush (1927) gives the incubation period of the yellow-bellied sapsucker as “probably about 14 days.”

A. Dawes DuBois furnishes the following note: “Yellow-bellied sapsuckers were observed feeding young in a nest, in Hennepin County, Minn., on July 5, 1937. The nest was about 25 feet above ground in a partially dead tree at edge of willow-and-alder thicket adjoining woods. Both parents were bringing food. The squeaky note of the young was repeated with such regularity (about four times a second) as to indicate that only one nestling was uttering it. When the nestling was being fed at the entrance, by the poking method, these notes went up to a higher pitch, and were sometimes choked off almost to inaudibility.

“Two days later, the parents were still feeding very frequently. The male, who on the first day had been seen to bring a bright red berry about the size of a pea, again brought a bit of small red fruit. On one occasion, when the parents were away, the nestling put its head out of the hole; but it did not do so when being fed. In general, alarm calls of the parents had little if any effect upon the squeaking of the nestling, though at one time, July 7, the squeaking seemed to cease for a short interval when the parent gave the alarm notes. For the most part the series of squeaky notes is continuous. It was by hearing these sounds that this nest was discovered.”

_Plumages._--[AUTHOR’S NOTE: The young sapsucker is hatched naked, as is the case with other woodpeckers, but the juvenal plumage is acquired before the young bird leaves the nest. The sexes are alike in the juvenal plumage. A young bird, not fully grown and probably not long out of the nest, taken June 25, has the black crown largely concealed by the long brownish tips of the feathers, “ochraceous-tawny” to “buckthorn brown”; each of the black feathers of the back has a large terminal spot of grayish white, or yellowish white, producing a boldly spotted pattern; the nape and sides of the neck have smaller spots of the same color; the wings and tail are as in the adult-fall plumage; the chin and upper throat are dull white or pale buffy brownish; the lower throat and chest are pale brownish, broken by crescentic bars of dusky; and the center of the breast and the abdomen are pale yellow or yellowish white. Changes soon begin to take place, at irregular intervals, during which the sexes begin to differentiate. Young males may begin to show traces of red in the throat patch as early as July; and in August some may have the crown largely crimson; the black patch on the chest does not usually appear until much of the red has been assumed, but some birds show considerable of both red and black before the end of August. Other young males may not acquire much red before the end of September. Progress toward maturity continues all through fall, winter, and early spring by protracted partial molts; probably most individuals acquire the fully adult plumage by early spring, but I have seen birds that had not fully completed this prenuptial molt by the end of April.

Young females follow the same sequence of molts but are somewhat later in developing the red crown, which apparently is not acquired until October or later. The adult body plumage of both sexes is acquired during winter and early spring. Adults have a partial prenuptial molt about the head and throat early in spring and a complete molt late in summer and fall. In fresh fall plumage, the lighter markings are more or less suffused with yellowish or buffy tints, and the belly is deeper yellow.]

_Food._--W. L. McAtee (1911) learned by stomach examinations that the yellow-bellied sapsucker consumed cambium and bast averaging 16.71 percent of its diet. He continues:

It must be noted also that cambium is a very delicate, perishable material, at certain times no more than a jelly, and thus never receives a percentage valuation in examinations of long-preserved stomachs corresponding to its bulk when first swallowed. Neither do we get any record of the sap consumed by these birds [the three species of sapsucker] and they are inordinate tipplers. Hence the value of the percentages cited lies not so much in their accuracy as to the quantity of cambium eaten as in the fact that they indicate a steady consumption of this important substance. There is no doubt that cambium, bast, and sap are depended upon by sapsuckers as stable diet.

We may get some idea of the amount of sap consumed by the bird from Frank Bolles’ (1892) record of his three young captive sapsuckers. He says: “Ordinarily they disposed of eight teaspoonfuls [of diluted syrup] each during the twenty-four hours. Part of this evaporated, and part was probably secured by black ants which visited the cage by night.”

Bolles (1891), describing the method of feeding of birds in the wild, says: “The dipping was done regularly and rather quickly, often two or three times in each hole. The sap glistened on the bill as it was withdrawn. I could sometimes see the tongue move. The bill was directed towards the lower, inner part of the drill, which, as I found by examination, was cut so as to hold the sap.”

This is the common method of feeding, but sometimes, when two or more holes have coalesced into a vertical groove, the bird will run its bill upward along the edge of the wound, sipping the sap much as we might, with our finger, wipe off a drop running down from a pitcher’s lip.

McAtee (1911) states that “about four-fifths of the insect food of the three species of sapsuckers consists of ants, the eating of which may be reckoned slightly in the birds’ favor. The remainder of the food is made up of beetles, wasps, and a great variety of other insects, including, however, practically no wood-boring larvae or other special enemies of trees. The birds’ vegetable food can not be cited in their behalf, as it consists almost entirely of wild fruits, which are of no importance, and of cambium, the securing of which results in serious damage.”

F. E. L. Beal (1895) mentions, as articles in the sapsucker’s diet, the berries of dogwood, black alder, Virginia creeper, and wild black cherries. Winfrid A. Stearns (1883) says: “Nuts, berries, and other fruits vary its fare; and to procure these it may often be seen creeping and hanging in the strangest attitudes among the terminal twigs of trees, so slender that they bend with the weight of the bird.” Audubon (1842), in his plate of the sapsucker, gives an animated picture of the bird thus engaged.

Brewster (1876a) shows the bird as an expert flycatcher. “From an humble delver after worms and larvae, it rises to the proud independence of a Flycatcher, taking its prey on wing as unerringly as the best marksman of them all. From its perch on the spire of some tall stub it makes a succession of rapid sorties after its abundant victims and then flies off to its nest with bill and mouth crammed full of insects, principally large _Diptera_.”

_Behavior._--The sapsucker, a bird of wide distribution and in some parts of its range the commonest woodpecker, has come to be regarded with disfavor by man, who accuses it of harming the trees it drills to obtain its food. Man accuses the bird of weakening trees by drawing away their life-blood and of killing many by girdling them with multiple punctures, and he blames the bird for marring the beauty of trunk and limb by pitting and scarring them.

A study of the habits of the sapsucker shows that its work on the trees varies with the season and, on the Atlantic coast, is spread over a territory 3,000 miles long or more. During the migrations, northward and southward, when the birds are scattered and on the move, comparatively little harm is done. Here and there a limb may be killed--either girdled or opened so that infection enters--and rarely a tree may die, but the chief effect is an esthetic one, the scarring of the bark with pits, notably in orchards where it is a matter of common observation that most of the pitted trees are in perfect health. On their breeding ground and in their winter quarters, however, where the birds are concentrated and remain in one locality for a considerable time, the effect is more serious. In the Southern States especially, the lumber industry suffers material financial loss due to the fact that deep in the wood cut from trees on which sapsuckers have worked extensively, when the trees were small, the grain is distorted and made unsightly by the scars of the wounds inflicted by the birds years before.

From an exhaustive study of the economic status of the woodpeckers by W. L. McAtee (1911), the salient points in reference to the yellow-bellied sapsucker are quoted below:

The results of sapsucker attacks on trees are so uniform and characteristic as to be distinguished easily from the work of other woodpeckers. Sapsucker holes are drilled clear through the bark and cambium and often into the wood. They vary in outline from circular to squarish elliptical, in the latter case usually having the longer diameter across the limb or trunk. Generally they are arranged in rings or partial rings around the trunk, but they often fall into vertical series. Deeply-cut holes arranged with such regularity are made only by sapsuckers.

After the original pattern of holes is completed, the sapsuckers often continue their work, taking out the bark between holes until sometimes large areas are cleanly removed. This often occurs on small limbs or trunks, where long strips of bark up and down the tree are removed, leaving narrow strings between. This effect is also produced by continually enlarging single punctures by excavating at the upper end, * * * which is done to secure fresh inner bark and a constant supply of sap. Occasionally, after a tree has been checkered or grooved after the above-described systematic methods, it may be barked indiscriminately, leaving only ragged patches of bark. * * * Even in such cases, however, traces of the regularly arranged punctures are likely to remain, and there is no difficulty in recognizing the work as that of sapsuckers, for no other woodpecker makes anything like it on sound, living trees.

All holes, grooves, or irregular openings made by sapsuckers penetrate at least to the outermost layer of sapwood or nongrowing part of the tree. This results in the removal of the exterior rough bark, the delicate inner bark or bast, and the cambium. Since the elaborated sap (upon which the growth of trees depends) is conveyed and stored in these layers, it is evident that sapsuckers attack the trees in a vital part. Each ring of punctures severs at its particular level part of the sap-carrying vessels, another ring made above destroys others, and so the process continues until in extreme cases circulation of elaborated sap stops and the tree dies. When the injury to the vital tissues is not carried so far, only a limb here and there may die, or the tree may only have its vitality lowered for a few years. If the attacks cease, it may completely recover. * * *

Recovery, however, does not mean that the tree has escaped permanent injury. Patches of cambium of varying size may be killed. Growth ceases at these points and the dead and discolored areas are finally covered by wood and bark. Until this process is completed, the tree is disfigured by pits with dead bark and wood at the bottom, and even when completely healed, the spot remains a source of weakness. In fact, all sapsucker pecking is followed by more or less rotting and consequent weakening of the wood, and renders trees more liable to be broken by the wind or other causes.

Sapsucker injuries usually stimulate growth of the wood layers at the points attacked, so that they become much thicker than usual. This results in a slight swelling of the bark, and when the birds reopen the old wounds year after year, as they habitually do, succeeding wood layers make excess growth and in time shelflike girdles develop.

McAtee (1911) gives a long list of trees attacked by the bird. Summarizing, he says: “Condensing the information contained in the foregoing lists, we find that the yellow-bellied sapsucker attacks no fewer than 246 species of native trees and 6 vines, besides 31 kinds of introduced trees. Twenty-nine of these trees and 1 vine are known to be sometimes killed and 28 others are much disfigured or seriously reduced in vitality.”

Of “the effects of sapsucker work on lumber and finished wood products” he says:

Those relations of sapsuckers to trees which are detrimental to man’s interest are by no means confined to the external disfiguration, the weakening, or killing of trees. Indeed in the aggregate sapsuckers inflict much greater financial loss by rendering defective the wood of the far larger number of trees which they work upon moderately but do not kill. Blemishes, reducing the value, appear in the lumber from such trees and in the various articles into which it is manufactured.

These defects consist of distortion of the grain, formation of knotty growths and cavities in the wood, extensive staining, fat streaks, resin deposits, and other blemishes. All of them result from injuries to the cambium, their variety being due to the differences in the healing. Besides blemishes, ornamental effects are sometimes produced during the healing of sapsucker wounds, such as small sound stains, curly grain, and a form of bird’s-eye.

McAtee (1911) estimates that “the annual loss for the whole United States [from the impairment of lumber] is more than a million and a quarter dollars.” He continues: “Sapsuckers do not prey upon any especially destructive insects and do comparatively little to offset the damage they inflict. Hence the yellow-bellied sapsucker * * * must be included in the class of injurious species.”

The situation is quite different on the breeding ground. Here the birds resort to a group of trees, and confine their feeding activities almost exclusively to them. Frank Bolles (1891), in his study of the bird in the region about Mount Chocorua, N. H., terms these stations “orchards.” He describes one of them as consisting “of about a dozen canoe birches and red maples, most of which were dead, some decayed and fallen. The tree most recently tapped was a red maple about forty feet high and two feet through at the butt.” Of another “orchard,” half a mile away, he says: “The tree in use last year was nearly dead. Two neighboring birches showing scars of earlier years were quite dead. All stood on the crest of a kame. About three rods along the ridge to the eastward a red oak and two or three canoe birches were in use by the birds.” This report shows that sapsuckers undoubtedly cause the death of many trees as they return to their “orchards” year after year, but most of these trees are of small value, especially in the heavily forested regions where the birds commonly breed.

Bolles (1891) also notes the association of the sapsuckers with the ruby-throated hummingbirds, which were attracted to the pits by the running sap. In the main, hosts and guests got along well enough together, although attacks occurred on both sides from time to time. He says: “My notes refer again and again to the spiteful treatment of the Hummers at Orchard No. 1. On the other hand at Orchard No. 2 they say ‘Male and young one dipping. Hummer comes in and dips several times _between them_ and they offer no objection.’”

Major Bendire (1895), half in jest, we may presume, brings an accusation of inebriety against the sapsucker in these words:

That it should be fond of the sweet sap of trees does not surprise me, as this contains considerable nourishment, and likewise attracts a good many insects, which the birds eat; but it is not so easy to account for its especial predilection for the sap of the mountain ash, which has a decidedly bitter taste, and I believe possesses intoxicating properties, unless it be taken for the latter purpose; and the fact that after drinking freely of the sap of this tree it may often be seen clinging to the trunk for hours at a time, as if stupefied, seems to confirm this view. It is well known that some of our birds indulge in such disreputable practices, and possibly this species must be included in the number, as there are sots among birds as well as among the genus _Homo_.

_Voice._--Just as the sapsucker in its behavior is conspicuous, almost boisterous, at one season of the year and retiring and unobtrusive at another, in the same way it is very noisy in spring and the early part of the nesting period and comparatively silent afterward.

Dr. C. Hart Merriam (1879) speaks of the bird thus: “In few species can the date of arrival, in spring, be ascertained with such precision as in the bird now under consideration; for, no sooner are they here, and recovered from the fatigue of their northward journey, than the country fairly resounds with their cries and drumming. * * * Noisy, rollicking fellows, they are always chasing one another among the trees, screaming meanwhile at the top of their voices, and when three or four vociferous males alight on the same tree, as often happens, their boisterous cries are truly astonishing.”

William Brewster (1876a) mentions a “peculiar snarling cry” used as an alarm note, and of a pair at the nest he says:

Watching once a nest for an hour or two, I remarked that the birds relieved each other in the labors of incubation at intervals averaging about half an hour each. The one that had been absent would alight just below the hole, and, uttering a low _yew-ick, yew-ick_, its mate would appear from within, when, after the interchange of a few notes of endearment, the sitting bird would fly off and the other instantly enter the hole. * * *

Both young and old utter most frequently a low snarling cry that bears no very distant resemblance to the _mew_ of the Catbird. The adults have also two other notes--one, already spoken of, when the opposite sexes meet; the other a clear, ringing _cleur_, repeated five or six times in succession, and heard, I think, only in the spring.