ground in Pennsylvania: “In late May and June the mewing cry was
familiar and they occasionally indulged in strange courtship antics,
flashing through the tops of the trees, calling excitedly in tones
resembling those of a flicker, and dancing about with wings and tail
spread in a manner utterly foreign to the usually stolid bearing of
migrant individuals.”
Of the spring drumming, perhaps a part of courtship, Dr. Harry C.
Oberholser (1896b) says:
In spring the drumming of the yellow-bellied sapsucker
may usually be easily recognized by the following
peculiarities. Four or five taps given in quick succession
are followed by a short pause, this being soon succeeded
by two short quick taps; then another pause, and two more
taps in somewhat less rapid succession than the first;
followed by yet another pause, and two additional taps
still a little slower. This is sometimes slightly varied
with regard to the number of taps; and occasionally also
the latter part consists only of single quick taps with an
increasing interval toward the last.
The difference between the tapping of the sapsucker and of the hairy
and the downy woodpecker is described in the life history of the latter
bird. Wendell Taber told Mr. Bent that he succeeded in calling up three
of these birds by imitating their drumming with a fountain pen on a
dead tree; one of them alighted on the tree on which he was drumming.
_Nesting._--William Brewster (1876a), writing of the nesting of the
sapsucker at Umbagog Lake, Maine, says:
They arrive from the South, where they spend the winter,
from the middle to the last of April, and, pairing being
soon effected, commence at once the excavation of their
nests. The trees usually selected are large dead birches,
and a decided preference is manifested for the vicinity
of water, though some nests occur on high ground in the
interior of the woods, but never so abundantly there as
along the margin of rivers and lakes. Both sexes work
alternately, relieving each other at frequent intervals,
the bird not employed usually clinging near the hole and
encouraging its toiling mate, by an occasional low cry.
With the deepening of the hole arises the necessity for
increased labor, as the rapidly accumulating debris must
be removed, and the bird now appears at frequent intervals
at the entrance, and, dropping its mouthful of chips,
returns to its work. A week or more is occupied in the
completion of the nest, the time varying considerably with
the relative hardness of the wood. A small quantity of the
finer chips are left at the bottom to serve as a bed for
the eggs. * * * The labor of incubation, like all other
duties, is shared equally by the two sexes. * * *
All nests examined upon this occasion [an occasion when
he found half a dozen nests] were of uniform gourd-like
shape, with the sides very smoothly and evenly chiselled.
They averaged about fourteen inches in depth by five in
diameter at the widest point, while the diameter of the
exterior hole varied from 1.25 to 1.60 inches. So small,
indeed, was this entrance in proportion to the size of the
bird, that in many cases they were obliged to struggle
violently for several seconds in either going out or in.
The nests in most instances were very easily discovered, as
the bird was almost always in the immediate vicinity, and
if the tree was approached would fly to the hole and utter
a few low calls, which would bring out its sitting mate,
when both would pass to and from the spot, emitting notes
of anxiety and alarm. The bird not employed in incubation
has also a peculiar habit of clinging to the trunk just
below the hole, in a perfectly motionless and strikingly
pensive attitude, apparently looking in, though from the
conformation of the interior it would be impossible for it
to see its mate or eggs. In this position it will remain
without moving for many minutes at a time.
Henry Mousley (1916) states that the bird “often nests year after year
in the same tree (but not necessarily in the same hole) the favourite
ones here [Hatley, Quebec] being elm, poplar, and butternut. * * *
Of two nests examined the average dimensions are as follows, viz.:
entrance hole 1⅜ inches in diameter, extreme depth 10¾ inches, and
width 2⅞ inches.”
Philipp and Bowdish (1917) say of the nesting site in New Brunswick:
“The favorite situation was the dead heart of a live poplar, most
often on the bank of a stream, and facing same, but some nests were in
totally dead trees, of different kinds. They ranged from eight to forty
feet from ground.”
Bendire (1895) says that the birds “are devoted parents, and when
incubation is somewhat advanced, or the young have been recently
hatched, the bird on the nest is loath to leave it, and will sometimes
allow itself to be captured rather than to desert its treasures.”
_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.”