from 15 to 20 inches in diameter. The hole commonly, though not
invariably, faces the east or the south. Such is the preferred
position, but, as may be supposed, the slope of the surface of the tree
trunk and the quality of the wood are factors in the choice; and holes
sometimes are found drilled in west and north faces of the trunks.
The hole may be drilled through bark; more frequently it is through
the bleached and bonelike surface of a stub from which the bark has
long been stripped away. Though sometimes quite circular, the hole
tends to be of triangular outline, peaked above and leveled below. The
lower margin of the hole is outwardly and downwardly beveled and very
nicely finished. The orifice varies from 3¼ to 4½ inches in diameter,
and typically may be 3¼ inches in width and 3½ in vertical extent. The
only other notable item in external appearance is that, if the tree
be bare of bark and smooth surfaced (as is usual), an area of surface
a few inches below the hole will be seen to have become polished by
the rubbing of the tail feathers of the parent birds. And this spot,
perhaps in consequence of difference in the absorption of moisture and
fungus growth, may persist and be still plainly discernible in later
years.
A nesting tree that may be regarded as typical stood in a dense forest,
entirely of hardwood--maples, elms, and yellow birches--on the plain of
a high and ancient beach of Lake Superior, cut through by a mountain
stream, and about a hundred yards from the water. It was the smooth
and barkless stub of a dead elm, about 45 feet high and having a
girth, breast-high, of 76 inches. The hole was smooth and white, and
the wood was still firm. The stub stood well shaded beneath the living
trees. A few flecks of morning sunlight fell upon its eastern face;
but throughout the greater part of the day it remained in shadow. It
had been the woodpeckers’ nesting place certainly for four years. The
highest hole seemed to be the oldest--in the south face and near the
top. The uppermost 6 feet of the stub had since become weathered and
checked and manifestly unsuitable. Next, on the north face, there was
an old and black-looking hole about 36 feet up. The third and lowest
hole was in the east face and about 25 feet up; and, lastly, there was
the hole of the year, 34 feet up and also in the east face.
The chamber within is capacious and is ordinarily of conical form,
tapering slightly from a low domed roof downward to a bowllike bottom.
There may be a slight bulging of the walls below a narrowed median
portion. The depth may vary from 10 to 24 inches (extreme figures
of 6 and 26 have been recorded). The average of 15 measurements is
19 inches. The entrance hole leads to the upper widest portion, and
there the chamber is 7 or 8 inches across. The distance from the outer
surface of the hole of the tree to the remote wall of the chamber is
about 11 inches. The entrance passageway about 2 inches inward is
ridged across, and from this median ridge the floor of the passageway
slopes downward, both inwardly and outwardly, and this outward slope
forms the bevel already mentioned. The bowl at the bottom is 6 or 6½
inches across. In a specimen before me as I write, the wall of the
chamber below the entrance hole is 4 inches thick. The ridge across the
floor of the entrance passageway is rounded. Its crest is 2¼ inches
inward from the outer surface of the tree trunk, and the vertical
depth of the outward bevel is 2 inches. All the surfaces of the cavity
are neatly and uniformly chiseled. Along the sides of the entrance
passageway extend in parallel curves the tool marks of the bird’s beak.
No nesting materials are brought in. A feather or two will be the only
trace of occupancy remaining after the young are flown. In some though
not in all cases it is possible for a man to thrust in his arm and
reach the bottom of the chamber.
As a general rule, certainly, a new cavity is drilled for every
brood. Such exceptions as have been recorded have explanation in
human interference. Samuel Scoville, Jr. (1920), quotes Richard C.
Harlow to the effect that but once in his experience had a second
use of a nesting cavity occurred. Afterward Mr. Harlow said to me in
conversation that even in that instance the cavity had been deepened
before it was used for a second time. The only other instance that
has come to my attention is one recorded by Morrell (1901) in which a
single cavity was used three times--in 1895, in 1897, and in 1898. In
preparation for the third nesting the cavity had been deepened by three
inches. This nesting was in “a small patch of good sized trees * * *
separated [from] the main growth by cutting,” and it may be supposed
that the woodpeckers had been unduly limited in the choice of nesting
sites. In both cases the birds were subject to the disturbance of
persistent egg-collecting. It stands to reason that, in avoidance of
parasites, the practice should have evolved of drilling a fresh cavity
for each brood.
Mr. Harlow (1914) found that in one instance the drilling of the
nesting cavity was in progress in March and was continued “all during
March and April.” The female worked alone, and the male continued near
by. This nest, an unusually early one, contained, on April 30, three
eggs. In the Northern States the eggs commonly are laid early in May.
Incubation continues, according to Burns (1915), for 18 days. The young
leave the nest about the middle of June.
The range of date in nesting is illustrated by two records that come
from Centre County, Pa. (Scoville, 1920; Burleigh, 1931). One is
of a set of eggs that hatched on May 11. These eggs must have been
laid before April 23. The other record is of a set collected May 11
and found to be practically fresh. The interval at which these two
cases stand apart is about 25 days. Scoville (1920) quotes Harlow, a
collector whose experience was chiefly in Centre County, to the effect
that “May 10 is the standard date for a full clutch of eggs.”
Records of nests are at hand from Maine, New Hampshire, New York,
Pennsylvania, Ohio, and Wisconsin. The total body of data, however, is
small; and it is not possible to discover what the difference may be in
mean nesting date from south to north within the region covered. There
is a record from Maine, for instance (Morrell, 1901), of a set of eggs
found to be heavily incubated as early as May 13.
_Eggs._--The eggs are white, with a gleaming smoothness and
translucence of shell. They rest at the bottom of the cavity, on the
bare bed of finely splintered wood. Three eggs often complete the set,
but more commonly four. Of 17 recorded sets, 4 are sets of three,
and 13 are sets of four. Some of the earlier writers (Wilson, for
instance, 1811) said the number of eggs might be five or even six; but
no specific record of so large a number has been found. The eggs are of
ovate outline.
The measurements of 51 eggs average 33.16 by 25.21 millimeters; the
eggs showing the four extremes measure =38.2= by =27.1=, =30.2= by
25.2, and 33.05 by =23.75= millimeters.
There are cases on record in which a pair of these birds, robbed
of their eggs, have laid again (and in the same cavity); with this
qualification, there is but a single brood in a season.
_Young._--In a particular instance; which I take to be typical, of a
nesting (in northern Fulton County, Pa.) I found the male to be no less
attentive than the female to the duties of incubation and nurture. In
one respect, indeed, the male seemed to be the more attentive, for
on both of the two occasions when I had opportunity to observe--once
shortly before, the other shortly after the hatching of the eggs--it
was the male bird who at sunset retired within the hole and who at
sunrise the following morning appeared from within. And I mention this
the more confidently since I find chance confirmation in the narrative
of another observer, Morrell (1901), and since like observations have
been made upon other species of woodpeckers--upon the flicker, for
instance, and upon the ivory-billed woodpecker (Allen, 1937).
When incubation was in progress I found the parent birds to be
relieving one another at intervals of about two hours; and a week
later, when the young were still small, they were coming in with food
and replacing one another at intervals of approximately one hour. It
may have been accidental, and yet it seemed to me noteworthy, that the
routine of hourly visits was broken when the female returned after an
absence of 10 minutes to afford the male freedom for 40 minutes before
he returned to retire within the cavity for the night.
At the time when hatching was near, and afterward when the young were
newly hatched, one or the other of the parent birds was constantly
present in the nesting chamber and, the weather being warm, was much
of the time perched immediately within the hole. And I then realized
the value of the larger dimensions of the upper portion of the chamber.
The waiting bird was constantly moving about, thrusting its head out
and withdrawing it again, turning about within the chamber so that it
had free view outward, preening, reaching upward with its foot and
scratching its head. And all this movement was free because the space
was wide.
Each of the parents seemed to have its own path of approach to the
nest. One of them came almost invariably to a particular position on
the trunk, about 6 feet below and to the right, and hopped up thence to
the entrance, but the other bird followed a different course.
I was impressed, too, with the comparative silence of the birds
at their nesting tree. Such small converse as took place there (a
flicker-like _wuck-a-wuck_--and it occurred irregularly) was so soft as
to be scarcely audible to human ears at a distance of fifty yards.
The feeding of the young is by regurgitation; and, while the young are
still small and remain at the bottom of the nesting cavity, the parents
may be seen to follow an interesting routine. The incoming bird hops
to the hole, perches on the ridge of the entrance passageway, and then
swings inward and downward, at the same time elevating the posterior
part of its body until the tail presses upon the outer upper rim of the
hole. In this position, evidently, the parent’s bill meets those of the
nestlings. This attitude is maintained often for as much as a minute,
and while it is maintained the body of the bird may be seen to shake
convulsively--plainly indicating that regurgitation is in progress.
When the young are small, the parent, after feeding, does not
immediately leave the nest but awaits the incoming of its mate. It
then glides away on wide-spread wings; and, while I suspected that the
excrement of the young is carried in the bill and dropped, I was unable
to detect this. Quite possibly, in this early stage at least, the
excrement is swallowed by the parent.
Charles W. Townsend (1925) gave account of a family observed in
Worcester County, Mass., when the young were well developed and nearly
ready to leave the nest:
On June 11, 1924, I spent five hours within twenty-five
feet of the base of the stub, unconcealed, and on June 14,
six hours, but after the first hour I took up a position
about fifty yards away, partially concealed by bushes.
My observations may be summarized as follows: the young
were fed eleven times at the first visit, four times at the
second when the adults acted in a very shy manner. As a
rule the female fed the young, but on three occasions the
male was identified at the hole. * * *
As a rule the adult appeared suddenly at the hole, flying
noiselessly through the forest. Occasionally it alighted
below the hole and rapidly ascended by hops, or it alighted
on some neighboring tree, and often calling like a Flicker,
glided on motionless outstretched wings in a graceful curve
to its young. The flight away from the hole was always
direct after a preliminary downward glide and lacked the
usual woodpecker undulations. * * *
The three young crowded to the hole as soon as a parent
appeared anywhere in the neighborhood and eagerly stretched
forth their heads and necks. * * * They were always hungry
and screamed with rasping voices for food, once or twice
they uttered low whinnies. The adult inserted its bill
to its full length into the throats of the young and
vigorously regurgitated and pumped in the nourishment. * * *
After feeding the young, the female on several occasions,
the male on one, entered the nest, to emerge after a minute
or two and glide away. Once I detected a white piece in the
bill, once, something dark, but the other times nothing at
all.
Herbert L. Stoddard (1917) has noted the “hissing” noise of the young
within the nesting cavity when the trunk is jarred, “similar to young
flickers, but a great deal louder.”
When the young have flown from the nest, the cavity is not utterly
abandoned. I once saw one of the parent birds reenter at midday a
cavity from which the young had recently flown and remain within for
40 minutes. Why, I know not. The mate accompanied this returning bird
and waited near by. Maurice Brooks writes (MS.): “Nest cavities are
sometimes used as roosting places after the nesting season. On the
evening of August 2, 1937, at Jacksons Mill [Lewis County, W. Va.], I
saw six birds (two adults and four young) enter a cavity that had held
a nest earlier in the season. This was probably the brood of the year,
with the parents.”
_Food._--The pileated woodpecker lives upon insects that infest
standing and fallen timber and supplements this diet with wild berries
and acorns.
Ants are the chief item of food. It is in pursuit of ants that the
woodpecker cuts its great furrows in the boles of standing trees,
living and dead. On examination the heart wood exposed by the
woodpecker’s operations will be found to have been penetrated by the
labyrinthine passageways of the great carpenter ants, _Camponotus
herculeanus_ (Linnaeus).
All the observations of others that have come to my attention
upon the woodpecker when actually engaged in cutting these great
trunk-penetrating chasms have been made in winter and early in spring,
and with them my own are in agreement. It is a natural surmise that
only in winter is such heavy work done, since in summer proper food is
more easily available. Another surmise along the same lines is that
the disappearance of the bird from particular areas, followed after
an interval of years by reappearance, may perhaps have occurred in
correspondence with precisely such a fluctuation in its essential,
wintertime food supply: it must find, when the ground is snow-covered,
ant-infested trunks of large trees.
In September I once made leisurely observation upon a bird at work upon
a dead but standing hemlock tree. With swinging, obliquely directed
blows it was splitting off the outer leaves of the scalelike bark and
pausing intermittently with head turned to the trunk, licking up, as
I supposed, the insect life thus exposed. Again, in September, I came
upon a pair feeding together upon the ground. They had been tearing up
a carpet of moss that spread over damp surfaces both of wood and of
rock, and I thought that their prey must be insect life that they were
finding in the moss itself.
And yet again, on September 21, I watched for many minutes an adult
female feeding on a charred and decayed stump that remained in a young
forest of jack pines. She was perched about a foot from the ground. Her
method was by deliberate and swinging blows to break away platelike
fragments of still firm wood, and then to intrude her bill and search
with her tongue (as was evident) the opened cavity. This licking was
always, or nearly always, upward, and often the head was turned, crown
inward, throat outward. A jay might call or some other forest sound
be heard, and the bird would pause, listen for an instant, and then
resume her work. A day or two later I visited the stump and with my
knife made an incision in it, and I found it to be the home of a colony
of ants--not of the large _Camponotus_ but of a smaller, wine-black
species about a quarter of an inch long. The body of the stump was
honeycombed with their galleries.
Of the major wintertime operations Vickers (1910) has written:
Like the flicker, the [pileated woodpecker] is a great
lover of ants, which accordingly occupy a large place in
his bill-of-fare. So, to dine on the big black timber ants,
which are his special delight, he drives holes to the very
heart of growing forest trees, tapping the central chamber
of the colony, where, in winter, he finds the dormant
swarm unable to move and feasts upon them at leisure....
And the Log-cock makes no mistakes, though man might find
no outward sign of an ant-tree. Doubtless that strong
formic smell, coupled with his experience in sounding tree
trunks,--as a man tells a ripe watermelon by the _plunk_ of
it,--enables him not only to find the tree, but, what is
more remarkable, to drive his hole with such precision that
he taps the heart of the community.
O. M. Bryens (1926) wrote from St. Joseph County, Mich.:
On February 16, 1925, I was able to approach within twelve
feet of one of these Woodpeckers busily engaged in digging
in a maple stub, two feet in diameter and about twelve feet
high. He was after insects whose borings I found later upon
examining the wood. I watched him for about an hour.
He seldom gave more than three or four pecks at a time, and
would then swing his head round to one side or the other,
sometimes raising his scarlet crest. He seldom threw back
his head without tossing a chip back of him, and when I
examined his work after he had left, later in the day, I
found some chips near the stub, which were three inches
long and one inch wide. Others half this size had been
thrown out on the snow a distance of four feet. The hole
was on the west side and measured six inches across and ten
inches long, and extended to a depth of six inches toward
the heart of the stub. There was another hole six inches
square on the south side. The bird seemed to chisel out a
section three inches wide across the hole and then move
down and cut out another section. The two holes were dug in
about two hours.
Of summertime feeding Ora W. Knight (1908) says: “Except the Flicker
this is the only species of Woodpecker I have observed feeding on the
ground, but this species likes to tear open the ant hills found in open
places in the woods and feed on the ants and their larvæ.” He also says
that in the fall these birds eat “dogwood berries, choke and black
cherries and other wild fruits and berries, also beechnuts and acorns
for which it has a decided fondness.”
Dr. Sutton (1930) says:
The food of this species in Pennsylvania, according to
official examination of four stomachs, is largely of
ants. The stomach and crop of a male specimen weighing
nine ounces, collected at Northumberland, Northumberland
County, on November 10, 1928, contained 469 carpenter
ants (_Camponotus herculaneus_), most of them so recently
swallowed as to permit of counting them easily. The stomach
of a female taken at Aitch, Huntingdon County, on November
30, 1928, contained the remains of at least 153 carpenter
ants, one small carabid beetle, the legs of a small bug
(apparently a squash-bug), and 17 wild grapes, swallowed
whole.
F. E. L. Beal (1911) gave the results of examination of the contents of
80 stomachs collected far and wide throughout the range of the species.
Animal food amounted to 72.88 percent; vegetable, 27.12 percent.
Beetles made up 22.01 percent of the total, and ants 39.91 percent.
As many as 2,600 ants were counted in a single stomach. The ants were
“mostly of the larger species that live in decaying timber.” Ants and
beetles together made up the bulk of the animal food (61.92 percent).
The Biological Survey (A. L. Nelson) has kindly made reply to my
inquiry concerning stomach examinations of the subspecies _abieticola_
alone. Data were available from 23 specimens, three collected in
January, two in June, two in July, six in October, eight in November,
and two in December. They were collected, two in Canada, two in New
Brunswick, four in New York, four in Pennsylvania, six in Michigan, two
in Illinois, two in Minnesota, and one in Iowa.
Animal food amounted to 83 percent of the whole; vegetable, 17 percent,
with but a trace of gravel (one stomach only). The chief item was ants,
principally large black ants, such as _Camponotus_ and _Crematogaster_;
this item alone constituted 60 percent of the whole. The animal
food otherwise consisted of a variety of beetles and of a very few
(2 percent) caterpillars. The vegetable food was made up of wild
berries (_Ilex_, _Cassine_, _Vitis cordifolia_, _Nyssa sylvatica_, and
_Viburnum nudum_--in all, 11 percent of the whole), mast (2 percent),
and rotten wood (4 percent).
Catesby’s (1731) assertion, repeated time and again by the earlier
writers, that the pileated woodpecker sometimes pierces the husks of
maize standing in the field, was almost certainly based on faulty
observation. No modern confirmation is to be found of this or of any
other predatory practice. To the contrary, the finding after careful
investigation (Beal, 1911) is: “The food of the pileated woodpecker
does not interest the farmer or horticulturist, for it is obtained
entirely from the forest or the wild copses on its edge. This bird does
not visit either the orchard or the grain field, and all its work in
the forest helps to conserve the timber * * *. Its killing should be
strictly prohibited at all times.”
_Behavior._--The bird is but little known--surprisingly little,
considering how large a bird it is. It is a forest dweller; it lives
almost wholly within the canopy of the treetops; it is alert, furtive
(almost) as a bear, rather silent in midsummer (the season when city
dwellers ordinarily visit the northern forests); and it easily eludes
observation. It is not strange then that, its gigantic operations
remaining in evidence, the bird itself should in common thought have
become a somewhat fabulous creature. Thoreau (1906) never saw it; and
this is what he wrote of it in the Moosehead Lake journal under date
of July 25, 1857: “Our path up the bank here led by a large dead white
pine, in whose trunk near the ground were great square-cornered holes
made by the woodpeckers. * * * They were seven or eight inches long
by four wide and reached to the heart of the tree through an inch or
more of sound wood, and looked like great mortise-holes whose corners
had been somewhat worn and rounded by a loose tenon. The tree for some
distance was quite honeycombed by them. It suggested woodpeckers on a
larger scale than ours, as were the trees and the forest.”
To one who visits its haunts the presence of the pileated woodpecker
is immediately made manifest by operations such in magnitude as to
have astonished Thoreau. Dead Norway pines may be found, gaunt and
bare, their bark split away in plates and lying heaped at the base,
and living white pines--young trees, particularly--pierced to the core
with deep pyramidal incisions. The freshly cut wood gleams clean, and
turpentine in pellucid globules rims the cut and drips downward. Great
boles of maples and basswoods stand, furrowed from broken top to base,
the ground below littered with splinters, often half a hand’s breadth
in extent. The cuts are roughly rectangular in outline. They may be
4, 5, or even 6 or 8 inches wide and are sunk deep into the heart of
the tree. They may extend vertically for a few inches or for a foot or
more. They may be aligned in vertical rows, and may run together in
furrows of several feet in length. Crumbling stumps and moss-covered
logs lying on the forest floor will often be found ripped and torn by
the woodpecker’s beak.
It is, as has been said, a wary creature, and is not easily stalked.
On one occasion, when I had successfully approached a male that was
idling in the top of a gaunt chestnut near the nesting tree, I paused,
before shifting from an uncomfortable position, until the bird should
sidle around the limb. Even so, he was quicker than I; for, before I
had completed my movement, he was peering from the opposite side, and,
detecting me, was off. Again I came upon a bird--a male--suddenly, in
open forest. He did not immediately take wing, but, hitching downward
upon the tree trunk, he reached the ground, hopped off, and then
flitted away through the undergrowth, so that I scarcely saw him go.
And when I came upon him again he repeated the maneuver.