undoubtedly a number of different birds that came, although never more
than one at a time--there was such a curious similarity in their actions
that it is entirely proper to speak as if the same bird returned year
after year. His visits, as I have said, were usually made at the same
season. He would come silently and early, with the evident intention of
making this an all-day excursion. By eight o'clock he would be seen
clinging to a branch and curiously observant of the dining-room window,
which at that hour probably excited both his interest and his alarm.
Early in the day he showed considerable activity, flitting from limb to
limb and sinking a few holes, three or four in a row, usually _above_
the previous upper girdle of the limbs he selected to work upon. After
he had tapped several limbs he would sit waiting patiently for the sap
to flow, lapping it up quickly when the drop was large enough. At first
he would be nervous, taking alarm at noises and wheeling away on his
broad wings till his fright was over, when he would steal quietly back
to his sap-holes. When not alarmed, his only movement was from one row
of holes to another, and he tended them with considerable regularity. As
the day wore on he became less excitable, and clung cloddishly to his
tree-trunk with ever increasing torpidity, until finally he hung
motionless as if intoxicated, tippling in sap, a disheveled, smutty,
silent bird, stupefied with drink, with none of that brilliancy of
plumage and light-hearted gayety which made him the noisiest and most
conspicuous bird of our April woods.
Our mountain ash trees have told us several facts about the sapsucker:--
That he did not come to eat insects.
That he did come to drink sap, and that he probably ate the inner bark
also.
That he drank the sap because he liked it, not for some secondary
object, as insects.
That he could detect difference in the quality or quantity of the sap,
which caused him to prefer a particular tree.
That this difference apparently was in the taste of the sap, and that
the effects of a day's drinking of mountain ash sap seemed to indicate
some intoxicant or narcotic quality in the sap of that particular tree.
That the effect of his work upon the tree was apparently injurious, as
it is the only cause assigned of a healthy tree's dying before a less
healthy one of the same age and species, subject all its life to the
same conditions.
So much we have learned about this sapsucker's habits, and now we should
like to know why his work is harmful, and why that of the other
woodpeckers is not. It is not because he drinks the sap. All the sap he
could eat or waste would not harm the tree, if allowed to run out of a
few holes. Think how many gallons the sugar-makers drain out of a single
tree without killing the tree. But the sugar-maker takes the sap in the
spring, when the crude sap is mounting up in the tree, while the
sapsucker does not begin his work till midsummer or autumn, when the
tree is sending down its elaborated sap to feed the trunk and make it
grow. This accounts for the woodpecker's digging his pits _above_ the
lines of the holes already in the tree. The loss of this elaborated sap
is a greater injury than the waste of a far larger quantity of crude
sap, so that on the season of the year when the sapsucker digs his holes
depends in large measure the amount of damage he does. The injury that
he does to the wood itself is trivial. He is not a wood_pecker_ except
at time of nesting, and most woodpeckers prefer to build in a dead or
dying branch, where their work does no hurt. But we know very well that
a tree may be a wreck, riven from top to bottom by lightning, split open
to the heart by the tempest, entirely hollow the whole length of its
trunk, and yet may flourish and bear fruit. The tree lives in its outer
layers. It may be crippled in almost any way, if the bark is left
uninjured; but if an inch of bark is cut out entirely around the tree,
it will die, for the sap can no longer run up and down to nourish it.
This is the sapsucker's crime: he girdles the tree,--not at his first
coming, nor yet at his second, not with one row of holes, nor yet with
two; but finally, after years perhaps, when row after row of punctures,
each checking a little the flow of sap, have overlapped and offset each
other and narrowed the channels through which it could mount and
descend, until the flow is stopped. Then the tree dies. It is not the
holes he makes, nor the sap he draws, but the way he places his holes
that makes the sapsucker an unwelcome visitor. For an unacceptable
individual he is to the farmer,--_persona non grata_, as kings say of
ambassadors who do not please their majesties. What shall we do with
him, the only black sheep in all the woodpecker flock? Let him alone,
unless we are positively sure that we know him from every other kind of
woodpecker. The damage he does is trifling compared with what we should
do if we made war upon other woodpeckers for some supposed wrong-doing
of the sapsucker.
VIII
EL CARPINTERO
In California and along the southwestern boundary of the United States
lives a woodpecker known among the Mexicans as El Carpintero, the
Carpenter.
Carpentering is both his profession and his pastime, and he seems really
to enjoy the work. When there is nothing more pressing to be done, he
spends his time tinkering around, fitting acorns into holes in such
great numbers and in so workmanlike a fashion that we do not know which
is more remarkable, his patience or his skill. Every acorn is fitted
into a separate hole made purposely for it, every one is placed butt end
out and is driven in flush with the surface, so that a much frequented
tree often appears as if studded with ornamental nails. "What an
industrious bird!" we exclaim; but still it takes some time to
appreciate how enormous is the labor of the Carpenter. Whole trees will
sometimes be covered with his work, until a single tree has thousands of
acorns bedded into its bark so neatly and tightly that no other
creature can remove them.
[Illustration: Work of Californian Woodpecker.]
We may take for examination, from specimens of the Carpenter's work, a
piece of spruce bark seven inches long by six wide, containing ten
acorns and two empty holes. As spruce bark is so much harder and rougher
than the pine bark in which he usually stores his nuts,[1] this
specimen looks rough and unfinished, and even shows some acorns driven
in sidewise; but for another reason I have preferred it to
better-looking examples of his work for study. As we shall see later, it
gives us a definite bit of information about the bird.
[Footnote 1: They often use white-oak bark, fence-posts, telegraph
poles, even the stalks of century-plants, when trees are not convenient.
(Merriam, _Auk_, viii. 117.)]
Think of the work of digging these twelve holes. Think of the labor of
carrying these ten large acorns and driving them in so tightly that
after years of shrinking they cannot be removed by a knife without
injuring either the acorn or the bark. Yet how small a part of the
woodpecker's year's work is here! How long could he live on ten acorns?
How many must he gather for his winter's needs? How many must he lose by
forgetting to come back to them? We cannot calculate the work a single
bird does nor the nuts he eats, for several birds usually work in
company and may use the same tree; but all the woodpeckers are large
eaters, and the Californian has been singled out for special mention.
Can we estimate the amount of work required to lay up one day's food?
Judging by the amount of nuts some other birds will eat, I should
think that all ten acorns contained in this piece of bark could be eaten
in one day without surfeit. The estimate seems to me well inside of his
probable appetite. I have experimented on this piece of bark, using a
woodpecker's bill for a tool, and it takes me twenty minutes to dig a
hole as large but not as neat as these. Doubtless it would not take the
woodpecker as long; but at my rate of working, four hours were spent in
digging these twelve holes. Then each acorn had to be hunted up and
brought to the hole prepared for it. This entailed a journey, it may
have been only from one tree to another, or it may have been, and very
likely was, a considerable flight. For these acorns grew on oak-trees,
and we find them driven into the bark of pines and spruces.
[Illustration]
This it is which gives our specimen its particular interest. While oaks
and pines may be intermingled, though they naturally prefer different
soils and situations, and in the Rocky Mountains the pine-belt lies
above the oak region, spruce and oak trees do not grow in the same soil.
The spruce-belt stands higher up than the pine. As these nuts are stored
in the bark of a spruce-tree, we have clear evidence that the bird must
have carried them some distance. For every nut he made the whole
journey back and forth, since he could carry but one at a time,--ten
long trips back and forth, certainly consuming several minutes each.
Then each acorn had to be fitted to its hole. We have already spoken of
the accuracy with which this is done, so that the Carpenter's work is a
standing taunt to the hungry jays and squirrels which would gladly eat
his nuts if they could get them. A careful observer tells us that when
the hole is too small, the woodpecker takes the acorn out and makes the
hole a little larger, working so cautiously, however, that he sometimes
makes several trials before the acorn can be fitted and driven in flush
with the bark. Some of these acorns show cracks down the sides, as if
they had been split either in forcibly pulling them out of a hole not
deep enough for them, or in driving them when green and soft into a hole
too small for them. Of course after each trial the acorn must be hunted
up where it lies on the ground and driven in again, and this takes
considerable time.
As nearly as we can estimate it, not less than half a day must have been
spent in putting these acorns where we find them. With smaller acorns,
stored in pine bark, less time would have been required; but weeks, if
not months, of work are spent in laying up the winter's stores.
How the woodpecker's back and jaws must have ached! Surely he is human
enough to get tired with his work, and it is not play to do what this
bird has done. Some of the acorns measure seven tenths of an inch in
diameter by nine tenths in length, and the bird that carried them is
smaller than a robin. How he must have hurried to reach his tree when
the acorn was extra large! Yet he took time to drive every one in point
foremost. Even those that lie upon their sides must have been forced
into position by tapping the butt. He knows very well which end of an
acorn is which, does our Carpenter.
But what is the use of all this work? Why, if he wants acorns, does he
not eat them as they lie scattered under the oaks, instead of taking
pains to carry them away and put them into holes for the fun of eating
them out of the holes afterward? The absurdity of this has led some
people to surmise that the Carpenter chooses none but weevilly acorns,
and stores them that the grub inside may grow large and fat and
delicious. This would be very interesting, if it were true. There must
of course be more weevilly acorns on the ground than he picks up, so
that he could get as many grubs without taking all this trouble, and
there is no reason why they should not be as large and good as those
hatched out in holes in trees. When I wish to keep nuts sweet, I spread
them out on the attic floor in the sun and air, keeping them where they
will not touch each other. The Carpenter does practically the same
thing. Is it probable that he tries to raise a fine crop of grubs in
this way? If so, one or the other of us is doing just the wrong thing.
But if weevils are what the Carpenter wants, then the nuts in the bark
should be wormy; yet only two of them show any sign of a weevil, and of
these one appears from its dull color and weather-beaten look to be a
nut deposited several years before the others by some other woodpecker.
Every other acorn is as hard, shining, and bright colored as when it
fell from the tree. Evidently the bird picked these nuts up while they
were fresh and good; perhaps he chose them _because_ they were good and
fresh. The possibility becomes almost a certainty when we observe that
naturalists agree that the Carpenter uses no acorns but the
sweet-tasting species. Now there are likely to be as many grubs in one
kind of an acorn as in another, and he would scarcely refuse any kind
that contained them, if grubs were what he wanted. The fact that he
takes sweet acorns, and those only, shows that it is the meat of the nut
that he wants. And all good naturalists agree that it is the kernel
itself that he eats.
Why he stores them is not hard to decide when we remember that the
Californian woodpecker, over a large part of his range, is a mountain
bird. Though we think of California as the land of sunshine, it is not
universal summer there. The mountain ranges have a winter as severe as
that of New England, with a heavy snowfall. When the snow lies several
feet deep among the pines and spruces of the uplands, the Carpenter is
not distressed for food: his pantry is always above the level of the
snow; he need neither scratch a meagre living from the edges of the
snow-banks, nor go fasting. His fall's work has provided him not only
with the necessities, but with the luxuries of life.
But why does he spend so much time in making holes? He might tuck his
nuts into some natural crevice in the oak bark, or drop them into
cavities which all birds know so well where to find. And leave them
where any pilfering jay would be able to pick them out at his ease? Or
put them in the track of every wandering squirrel? Jays and squirrels
are never too honest to refuse to steal, but they find it harder to get
the woodpecker's stores out of his pine-tree pantry than to pick up
honest acorns of their own. So, like the woodpecker, they lay up their
own stores of nuts, and feed on them in winter, or go hungry.
We have had very little aid from anything except the piece of bark we
were studying, yet we have learned that the Californian woodpecker is a
good carpenter; that he works hard at his trade; that he shows
remarkable foresight in collecting his food, much ingenuity in housing
it, good judgment in putting it where his enemies cannot get it, and
wisdom in the plan he has adopted to give him a good supply of fresh
nuts at a season when the autumn's crop is buried under the deep snow.
If I were a Californian boy, I think I should spend my time in trying to
find out more about this wise woodpecker, concerning which much remains
to be discovered.
IX
A RED-HEADED COUSIN
Besides his half-brothers, the narrow-fronted and ant-eating
woodpeckers, the Carpenter has a numerous family of cousins,--the
red-headed, the red-bellied, the golden-fronted, the Gila,[1] and the
Lewis's woodpeckers. These all belong to one genus, and are much alike
in structure, though totally different in color. Most of them are
Western or Southwestern birds, but one is found in nearly all parts of
the United States lying between the Hudson River and the Rocky
Mountains, and is the most abundant woodpecker of the middle West. This
well-known cousin is the red-headed woodpecker, the tricolored beauty
that sits on fence-posts and telegraph poles, and sallies out, a blaze
of white, steel-blue, and scarlet, a gorgeous spectacle, whenever an
insect flits by. He is the one that raps so merrily on your tin roofs
when he feels musical.
[Footnote 1: So named from being found along the Gila River.]
In many ways the red-head, as he is familiarly called, is like his
carpenter cousin. Both indulge in long-continued drumming; both catch
flies expertly on the wing; and both have the curious habit of laying up
stores of food for future use. The Californian woodpecker not only
stores acorns, but insect food as well. But though the Carpenter's
habits have long been known, it is a comparatively short time since the
red-head was first detected laying up winter supplies.
The first to report this habit of the red-head was a gentleman in South
Dakota, who one spring noticed that they were eating _young_
grasshoppers. At that season he supposed that all the insects of the
year previous would be dead or torpid, and certainly full-grown, while
those of the coming summer would be still in the egg. Where could the
bird find half-grown grasshoppers? Being interested to explain this, he
watched the red-heads until he saw that one went frequently to a post,
and appeared to get something out of a crevice in its side. In that post
he found nearly a hundred grasshoppers, still alive, but wedged in so
tightly they could not escape. He also found other hiding-places all
full of grasshoppers, and discovered that the woodpeckers lived upon
these stores nearly all winter.
But it is not grasshoppers only that the red-head hoards, though he
is very fond of them. In some parts of the country it is easier to find
nuts than to find grasshoppers, and they are much less perishable food.
The red-head is very fond of both acorns and beechnuts. Probably he eats
chestnuts also. Who knows how many kinds of nuts the red-head eats? You
might easily determine not only what he will eat, but what he prefers,
if a red-headed woodpecker lives near you. Lay out different kinds of
nuts on different days, putting them on a shed roof, or in some place
where squirrels and blue jays would not be likely to dare to steal them,
and see whether he takes all the kinds you offer. Then lay out mixed
nuts and notice which ones he carries off first. If he takes all of one
kind before he takes any of the others, we may be sure that he has
discovered his favorite nut. Such little experiments furnish just the
information which scientific men are glad to get.
[Illustration]
It is well known that the red-head is very fond of beechnuts. Every
other year we expect a full crop of nuts, and close observation shows
that the red-heads come to the North in much larger numbers and stay
much later on these years of plenty than on the years of scanty crops.
Lately it has been discovered that they not only eat beechnuts all the
fall, but store them up for winter use. This time the observation was
made in Indiana. There, when the nuts were abundant, the red-heads were
seen busily carrying them off. Their accumulations were found in all
sorts of places: cavities in old tree-trunks contained nuts by the
handful; knot-holes, cracks, crevices, seams in the barns were filled
full of nuts. Nuts were tucked into the cracks in fence-posts; they were
driven into railroad ties; they were pounded in between the shingles on
the roofs; if a board was sprung out, the space behind it was filled
with nuts, and bark or wood was often brought to cover over the gathered
store. No doubt children often found these hiding-places and ate the
nuts, thinking they were robbing some squirrel's hoard.
In the South, where the beech-tree is replaced by the oak, the red-heads
eat acorns. I should like to know whether they store acorns as they do
beechnuts. Are chestnuts ever laid up for winter? How far south is the
habit kept up? Is it observed beyond the limits of a regular and
considerable snowfall? That is, do the birds lay up their nuts in order
to keep them out of the snow, or for some other reason?
It remains to be discovered if other woodpeckers have hoarding-places.
We know that the sapsucker eats beechnuts, and the downy and the hairy
woodpeckers also; that the red-bellied woodpecker and the golden-winged
flicker eat acorns; and I have seen the downy woodpecker eating
chestnuts, or the grubs in them, hanging head downward at the very tip
of the branches like a chickadee. It may be possible that some of these
lay up winter stores.
[Illustration: Head of the Lewis's Woodpecker.]
It is known that the Lewis's woodpecker occasionally shows signs of a
hoarding instinct. It was recently noted that in the San Bernardino
Mountains of California the Lewis's woodpecker, after driving away the
smaller Californian woodpeckers, tried to put acorns into the holes the
Carpenter had made, but, being unused to the work, did it very clumsily.
Soon after this observation was published, a boy friend living near
Denver told me that a short time before he had seen a woodpecker that
had a large quantity of acorns shelled and broken into quarters, on
which he was feeding. This woodpecker was identified beyond a doubt as
the Lewis's woodpecker. So we begin to suspect that the habit of storing
up food is not an uncommon one among the woodpeckers.
X
A STUDY OF ACQUIRED HABITS
Something interesting yet remains to be discovered of the hoarding habit
of the red-head. How strange that so familiar a bird should have a habit
so easily detected, and yet that no one in all these years should speak
of it! Who does not know how mice and chipmunks hide their food? Who has
not watched the blue jay skulking off to hide an acorn where he will be
sure to forget it? Who does not remember the articles his pet Jim Crow
stole and lost to him forever? The hoarding habit has long been observed
of many dull-colored, rare, or insignificant creatures. That one so
noisy, gay-colored, tame, and abundant as our red-headed woodpecker
should have the same habit and escape observation is certainly
remarkable. But though it is over twenty years since the storing of
grasshoppers was recorded and twelve since the practice of laying up
beechnuts was observed, very little seems to have been learned of the
habit since these records were made.
There are two points to be considered: the habit long remained unknown;
after it was discovered, it was long in being reaffirmed. It seems that,
if it were a general habit, more would be known about it. Now if it is
not a universal habit, it must be one of two alternatives, either a
custom falling into disuse, or a new one just being acquired. That a
habit so remarkable and so advantageous should be discarded after being
universal is scarcely possible; that a habit so noticeable, if it were
general, should remain unknown is improbable; that a habit which made
life in winter both secure and easy should, if introduced by a few
enterprising birds, become a universal custom, is not without a
parallel. The probabilities point to the custom of hoarding food as a
recently _acquired habit_.
Acquired habits are not rare among birds. The chimney swift has learned
to nest in chimneys since the Pilgrims landed; for there were no
chimneys before that time. There is the evidence of old writers to show
that they acquired the habit within fifty years of the time of the first
permanent settlements in New England. The eaves swallow learned to
transfer its nest from the side of a cliff to the side of a barn in less
time. Most birds will change their food as soon as a new dainty is
procurable, and they will even invent methods of getting it, if it is
much to their taste. The way the English sparrows have learned to tear
open corn husks so as to eat the corn in the milk is a good example, for
our maize does not grow in England, and they have had to learn about its
good qualities in the few years since they have become established
outside of the cities. Yet it is already a well-established habit. So
quickly does a habit spread from one bird to another, until it becomes
the rule instead of the exception! Acquired habits always show
adaptability, and often much forethought and reason. It is the shrewd
bird that learns new tricks.
Now there is not known among birds any evidence of greater forethought
and reason than working hard in pleasant weather, when food is plentiful
beyond all hope of ever exhausting it, to lay up provision for winter.
How does the woodpecker know that winter will come this year? That there
was a winter last year and the year before does not make it certain, but
only probable, that there will be one this year. We cannot know
ourselves that the seasons will change until we learn enough of
astronomy to understand the proof. Nor does instinct explain the habit,
as some would declare: since not all red-heads have the habit, though
all must have instinct. It would seem as if memory and reason had
devised this plan for outwitting winter, the bird's old enemy.