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Eastern
Screech-Owl
Otus asio
[Published
in 1938: Smithsonian Institution United States National Museum
Bulletin 170 (Part 2): 243-258]
Because the Linnaean name Strix asio was based on
Catesby's "little owl" from South Carolina, our familiar
screech owl of the northeastern United States has to be given the
above new name, which is based on the name that Pennant gave to
the "mottled owl" in his Arctic Zoology.
This species, as represented by its various races, is widely
distributed from extreme southern Canada throughout practically
the whole of the United States and well into Mexico. It is fairly
common and well known throughout most of this range. As the
eastern race enjoys the widest distribution and is the best known,
it will be treated more fully than the other races, all of which
are much alike in general habits.
Courtship.--Many of us have
heard the tremulous and lugubrious wailings of the screech owl
during the mating season, when this and the other owls are most
active in their vocal performances; but, because these
demonstrations of affection are indulged in mainly during the
hours of darkness, few of us have ever seen the birds in action.
Dr. Lynds Jones was more fortunate, and wrote to Major Bendire
(1892) as follows:
I saw this species mating once. The female was perched in a
dark leafy tree apparently oblivious of the presence of her mate,
who made frantic efforts through a series of bowings,
wing-raisings, and snappings to attract her attention. These
antics were continued for some time, varied by hops from branch to
branch near her, accompanied by that forlorn, almost despairing
wink peculiar to this bird. Once or twice I thought I detected
sounds of inward groanings, as he, beside himself with his
unsuccessful approaches, sat in utter dejection. At last his
mistress lowered her haughty head, looked at and approached him. I
did not stay to see the sequel.
F. H. Carpenter (1883) had a pair of screech owls that raised a
brood of young in captivity; he writes: "About the first of
February, 1883, their actions towards each other began to change.
Instead of snapping at one another for a bit of meat, I was
surprised to see one of them take a bit of food and carry it to
the other one that was perched on the topmost beam, which in turn
gravely received it. . . . These attentions seemed to increase.
They would sit as close together as possible, frequently preening
each other's feathers. The male bird (I was sure of it by this
time) would take a piece of meat and fly up with it to his
companion, lay it down, and invite her to take it by a series of
hops and bows."
P. T. Coolidge (1906) gives the following account of it:
About ten or eleven minutes after sunset he left the tree
and began singing his love song; he was now full of life and
ignored all disturbance. His song was in B flat of the middle
octave, a soft trill, seemingly far away, two or three seconds
long, and closing with an upward inflection, as if the bird were
asking a question--as doubtless he was. Until the flight of the
female, he sang from various perches, now from the branches of the
elm, now from some neighboring tree, now from the rim of the
cavity in the elm, his eyes fastened upon his quiet mate. His
handsome head was continually bobbing and swinging. Once in a
while the male would light beside her; flashing of wings would
follow, but darkness made more exact analysis of their movements
impossible. Occasionally he would fly out of sight. Returning from
one of these trips, he lighted upon the rim of the cavity and
touched his bill to that of his mate, but whether to give her some
tidbit, or merely a greeting, the darkness kept secret.
Nesting.--Although the screech owl
is fairly common in my home territory, I have never examined many
nests, as I have never made any special effort to find them. On
only one occasion have I been able to flush one of these owls off
the nest by rapping on the tree; had I taken the trouble to climb
to and examine every likely looking hollow, I probably would have
found many more. As it is, my notes contain the records of only
seven nests. Three of these were in natural cavities in old apple
trees in orchards; two were in dead pine trees, and one in a dead
poplar, in what where apparently old flickers' holes; and the
other was 35 feet from the ground, the highest I have ever found,
in a natural cavity in a large oak on the edge of some woods. I
found my first nest on May 18, 1889, while climbing to an osprey's
nest on a dead pine stub in some mixed woods; the owl's nest was
in an old flicker's hole below the osprey's nest and about 20 feet
from the ground; the owl was sitting on a set of five eggs nearly
ready to hatch, and had to be lifted off the eggs. On April 12,
1891, we found a pair of screech owls, a red and a gray bird,
nesting in a natural cavity in an apple tree in an old orchard;
the opening was only about 5 feet from the ground, so that we
could look in and see both owls in the nest apparently sound
asleep; under the red owl were five fresh eggs. After removing
both owls, to inspect the nest, we returned the gray bird to the
hollow, where it promptly settled down; the red one we threw up
into the air; it dove straight for the hole, but missed it and
fell to the ground, perhaps bewildered by the light and the rude
awakening; but it soon recovered its wits and flew off to some
nearby woods. On two other occasions I have found both of a pair
of owls in the nest together, always one red and one gray.
Two other nests in old orchards were evidently successive
nestings of the same pair of owls. The first was found on May 20,
1933, in a natural cavity in an apple tree, about 20 feet from the
ground; it contained five young, partially clothed in the downy
juvenal plumage, that were being brooded by a red adult; when I
released her, she flew swiftly and easily to another apple tree
and dove into a cavity. We explored this orchard thoroughly on
April 19, 1934, but could find no trace of the owls; but in
another old orchard, about 200 yards away, we were more fortunate.
An upright branch, or fork of the main trunk, of an old apple tree
had an open cavity, facing upward; looking downward into this we
could see the gray owl clinging to the rough side of the cavity
and sound asleep; about 30 inches below the open cavity was a
knothole, barely large enough to admit my hand; this was only
about 6 inches above the nest of leaves and rubbish, on which we
could dimly see the red owl, sitting on her eggs, blinking and
snapping her bill. I succeeded in relieving her of six, nearly
fresh, eggs; she made no resistance, as I reached under her, but
finally climbed up and clung to the side of the cavity below her
mate.
All the above nests were in Bristol County, Mass. In most cases
the eggs were laid on the rotten chips and other rubbish that the
owls happened to find in the cavities; I believe that they never
carry in any nesting material and that where such material is
found it merely indicates that some other bird or mammal had
brought it there previously. But the nests often contain a few
feathers of the owls, or the feathers, fur, or other remains of
their victims. Though I do not claim that it has any great
significance, it is an interesting fact that it has always been
the red bird, in a mixed pair, that I have found sitting on the
eggs, or brooding the young.
The above nestings were apparently typical of the nesting
habits of the screech owl in other sections. A. D. DuBois writes
to me of a nest he found, about 50 feet from the ground in a large
sycamore; the owl sat with its head out of the hole, watching him,
until he climbed to within ten feet of the hole; this habit has
been noted by others. Major Bendire (1892) says: "Mr. Oliver
Davie mentions his having found several nests between the broken
siding of ice houses along streams. Mr. C. S. Brimley found a set
of three eggs of this species placed in a cavity of a stump, the
bottom of which was below the level of the ground outside."
Screech owls have been known to nest in bird boxes, set up for
that purpose on trees or buildings, and they would probably do so
oftener if given more encouragement; a little sawdust or excelsior
in the bottom of the box is quite to their liking. They have also
nested in dove cotes and in purple martin houses, and not always
to the injury of the rightful occupants, as the following
experience, related by Ralph R. Wilson (1925) will show:
During the winter of 1923-24 two Screech Owls took up their
quarters in one of the roomy compartments of the largest nest-box.
I was away that winter and the following spring, but when school
closed (May 26) I returned and found ten Purple Martins nesting in
the boxes. Three days later, at twilight, I saw a gray phase
Screech Owl frequently alight at the entrance of the compartment
of the largest nest-box and quickly fly away after a very noisy
reception from within. I was surprised at this as Martins were
nesting in all the other compartments.
Investigation next day disclosed a husky young Screech Owl,
apparently the last of a brood, in the box. It was observed that
the Martins carefully avoided that compartment. Ten days later the
Owl was gone and a pair of Martins at once built a nest in and
occupied that part of the box.
By June 30 the Martins were all scouring the air and feeding
their young. That evening one parent Owl reappeared at the box. I
scared it away but next day I noticed that the two Martins that
nested where the Owl had nested were not feeding their young. A
second inspection showed an empty nest.
The screech owl also has been known to nest frequently, even
regularly, in cavities in trees close to houses in towns and
cities, thus showing more confidence in human beings than most
other owls show. I have had several such cases reported in my home
city.
Eggs.--The screech owl lays three to
seven eggs, but usually four or five, with the average in favor of
five; the extremely large or small sets are rare; even as many as
eight or nine have been reported, but these reports seem doubtful.
Bendire (1892) says that they "are pure white in color,
usually oval or nearly globular in shape, and moderately glossy.
In the majority of specimens the shell is smooth and finely
granulated, while in a few it is rough to the touch."
The measurements of 56 eggs in the United States National
Museum average 35.5 by 30 millimeters; the eggs showing the four
extremes measure 38 by 31, 37.5 by 32, 32 by
29.5, and 33 by 28.5 millimeters.
Young.--The
period of incubation is variously reported as from 21 to 30 days,
but the average is probably around 26 days, as determined by the
careful observations of Miss Althea R. Sherman (1911). As the eggs
are laid at intervals of two or three days, sometimes at longer
intervals, and as incubation may begin after the first egg is
laid, or not until after two or three are laid, the exact period
of incubation is difficult to figure.
Apparently the female does most, if not all, of the incubating
and the brooding of the young. Miss Sherman (1911) describes the
egg laying and incubation as follows:
The first egg was found in the nest on the morning of March
27, and was still alone on the evening of the 29th. The following
day the nest was not visited, the only day in two months and a
half, when visits were omitted. No doubt the second egg was laid
some time on the 30th of March; the third one was deposited on
April 1, but two days intervening between the laying of the second
and third eggs, while three or more days were the period between
the other layings. The fourth egg was in the nest at half past
four o'clock in the afternoon of April 4, but it was not there at
eight o'clock on the previous evening. This shows that it took
from eight to nine days to complete the clutch of four eggs.
Whether the Owl laid in the night, or in the morning as other
birds do, was not ascertained. . . . Constant incubation appears
to have begun on the first day of April after which she was
frightened out on two evenings. . . . Eggs No. 1 and No. 2 were
found to have hatched on April 27; No. 3 hatched the following
night, and No. 4 about five o'clock in the afternoon of April 29,
showing that the period of incubation was about twenty-six days.
Following are some of Miss Sherman's observations on the young:
This owl may have been called the Shivering Owl, because it
shivers. It certainly shivers, that it screeches may be a question
for dispute. This peculiarity is one of the early things to be
observed in the life of these nestlings; but the shivering does
not become very pronounced until the bird is two days old, and
continues until it is about two weeks old, at which time the young
owl is well covered with thick down; therefore it seems quite
possible that it shivers because it is cold. . . .
Until the shivering period was past they sought the warmth
found under the mother's wings; after this, as one would naturally
suspect, they, as do other young birds, continued to sleep much,
standing in a bunch with their heads pressed together; they
preened themselves but not so much as do some nestlings;
frequently they yawned, monstrous, big-mouthed yawns. Stretching
was the favorite exercise, during it the birds seemed to be made
of india-rubber. On May 16 the height to which one stretched
itself was seven inches by actual measurement. . . .
During their nest life but three varieties of cries were
heard from them, the first, beginning as soon as they were out of
the shell, had some resemblance to the peep of a chicken, and was
uttered by them when out from under the mother's wings, seemingly
a cry for shelter and for food; this ceased when they were about
three weeks old. At this age a second cry was heard for the first
time, which had a decidedly squeaking sound and was made when they
were squabbling for the warmest place in the family circle. The
remaining cry, a sort of chatter, appeared to be the tone for a
dinner discussion, friendly enough in quality, for they were never
seen to quarrel at meals. Besides these there was the snapping of
the bill which commenced the day they began to show fear, and a
hissing sound made when they were frightened. . . .
The male Screech Owl appears to have been the general
purveyor for the family. In the fist fortnight of incubation there
were nine mornings when an excess of food lay beside his mate; of
this she rarely ate during the day, but there were times when she
did so. On the remaining days of incubation she had food beside
her twice, but as soon as the eggs commenced to hatch there was a
super-abundance provided. An example of this was furnished on
April 29 when there lay in store four meadow mice weighing about
two-fifths of a pound altogether. This excessive provision lasted
only a few days, the supply decreased daily, and none was seen
after May 15. Nine o'clock, half past nine, and ten o'clock were
hours upon which he was known to have brought food to the nest,
eight o'clock in the evening being the earliest time. . . .
Bits of flesh clipped from meadow mice in store, that were
placed in the mouth of a nestling, were swallowed with some
difficulty and no apparent relish. Their beaks were stained upon
the outside with bloody matter, and as they grew older they would
nibble at the mother's bill as if teasing for food. All these
things led to a belief that in their earlier days they were fed
predigested or partially predigested food, which they pulled from
the beak of the mother. . . . On the tenth an owlet was seen for
the first time pulling at food (the body of a frog), as if eating
it. The next morning during observations the mother lifted her
head from the corner and appeared to eject something from her
mouth; at once the owlets scrambled to the spot and seemed to eat
for a few minutes. . . .
Pellets ejected by the young were found for the first time
on May 10; it may be well to note that this was the first date
upon which they were seen eating the food that lay in the nest. A
pellet disgorged on May 27 weighed sixty-two grains, which was
one-thirtieth of the weight of the bird that ejected it.
Dr. Arthur A. Allen (1924) made a series of careful
observations on the method of feeding a brood of young screech
owls, which he confined in a cage in front of a blind, equipped
with a lantern, flashlight, and camera. He writes:
From the outset it was obvious that both parent birds were
engaged in caring for the young. . . . They never both came
together to feed but frequently when the flash light disturbed one
bird before it had time to feed, the other would return with food
and both would be near with food in their bills at the same time.
The old birds were ordinarily silent in their hunting and feeding
but the young birds, after they had been put in the cage, kept up
a continuous humming during the night which lasted as long as they
were hungry. If one of the young did not give the food call, the
old birds paid no attention to him but fed the ones that called.
The food was always brought in the bills of the old birds and
placed directly into the mouths of the young. Large objects like
birds or mice were often brought already partially torn or eaten
or they were sometimes torn to pieces in front of the cage before
being passed through the wire. Just as often, however, the entire
bird was given to the young and they would fight among themselves
for it. It was after one such tug-of-war that two of the young
attacked the third and picked most of his bones by morning.
In order to determine the number of feedings, the amount of
food, and its nature, George McNeill (Allen, 1924) remained in
this blind nearly all night for seven successive nights, June 29
to July 6, inclusive. The earliest time at which feeding began was
8:25, and the latest was 9:12 p.m.; the earliest time at which
feeding ceased was 2:50, and the latest was 4:15 a.m. The number
of feedings was very variable, being 20, 73, 36, 14, 75, 67, and
72, respectively, on the seven nights. The most intensive feeding
was on the night of July 4, when "the young Owls were first
fed at 8:34 and between then and 1:40 were fed 75 times, two
beetles and 73 moths. The birds then became quiet and as it was
very chilly Mr. McNeill left. The next morning I gathered the
feathers of six birds that had evidently been fed to the young
after 1:40: Phoebe, Scarlet Tanager, Cedar Waxwing, Chipping
Sparrow, Redstart, and Catbird."
From the above records it appears that from the time that the
first egg is laid to the time that the young leave the nest about
eight weeks have elapsed. Probably the young are watched over, and
fed more or less, by their parents for five or six weeks more
before they are turned away to shift for themselves.
Plumages.--When first hatched the
young screech owl is covered with pure white down, even to the
tips of its toes; it is very attractive at this age. Miss Sherman
(1911) suggests:
As they tumbled about in their nest they very forcibly
suggested human babies in fleecy white cloaks that are learning to
creep. Held in the hand with their beaks downward and out of sight
they looked like diminutive blind kittens; perhaps the most
noticeable thing about them at that age was their large heads. But
this winning aspect of the nestlings was of short duration. In a
few days the pinfeathers began to show in the white down which
soon turned to a dirty gray color. By the time they were twelve
days old they had become most repulsive, exceedingly filthy to
handle with an appearance that was decidedly repellent. Perfect
miniatures were they of a doddering, half witted old man; the blue
beak was prominent and suggested a large hooked nose, while the
down below it took the shape of a full gray beard, and that on the
top of the head looked like the gray hair that covers a low,
imbecile forehead; the eyes not fully open were bluish in color,
and had a bleared and half-blind appearance. This loathsome
semblance lasted no longer than ten days by which time the eyes
were full and bright and yellow, the bird was covered with a thick
gray down, and looked as if a facsimile of it could very easily be
made from a bunch of gray wool devoid of any anatomy.
The above somewhat fanciful but graphic description gives a
very good impression of what the young screech owl looks like in
its early days. The last stage referred to is what I call the
downy juvenal plumage. This secondary down, or, more properly,
downy plumage, is acquired before the young bird is half grown and
before the flight feathers have burst their sheaths. It replaces
the first, or natal down, the old adhering as white tips on the
new. On the upper parts this downy plumage is basally pale
"tawny-olive," or "Saccardo's umber," with
grayish white tips, and barred with "sepia"; on the
under parts it is grayish white and more narrowly barred with
paler sepia. During this stage the two color phases begin to be
distinguishable, the gray phase being grayish white and gray and
the red phase more generally tinged with "pinkish
cinnamon"; this difference becomes more pronounced as the
flight feathers begin to develop. When the bird is about half
grown the first winter plumage begins to show, first in the
scapulars, then in the wings, and then in the tail; the bird is
fully grown and the wings and tail are fully developed before
there is much change in the body plumage; the molt of the body
plumage occurs in July and August, beginning on the back, followed
by the under parts, and lastly including the head.
This molt produces the first winter plumage, which is much like
that of the adult, and is worn through the following spring and
until the next summer molt, the first postnuptial. Young birds can
be recognized in this plumage by the juvenal wings, tail, and
scapulars; the wings lack the white on the outer webs of the
primaries, which are broadly barred with "cinnamon" and
dusky; and the broad white tips of the greater and median wing
coverts and the white outer webs of the scapulars, so prominent in
adults, are less pronounced in young birds; red adults have the
central pair of rectrices nearly or quite clear red, and gray
adults have them mottled; young birds of both phases have the
central feathers more or less distinctly barred, and the lateral
feathers more heavily barred and dusky. Adults apparently have one
complete annual molt late in summer and in fall.
The screech owl gives us one of the best examples of
dichromatism, apparently entirely independent of sex, age, or
season, but shown to its perfection only in the eastern races;
some of the western races show an occasional brownish phase; and
an intermediate, brownish phase occurs rarely in the eastern
races. Many years ago E. M. Hasbrouck (1893) made an extensive
study of this subject, and published a paper based on the data
obtained from 3,600 birds. He attempts to--
show, first, that while the red, the gray, and the
intermediate phases are at present but individual variations of
the same species--the gray was the ancestral stock; second, that
the gray bird evolved the red, which at some future time will be a
recognized sub-species with a range peculiar to itself, and thus
dichromatism is one step in the evolution of the Screech Owl,
while the various phases exhibited are the transitorial stages of
development of one species from another; third, that this
condition of affairs is influenced by four powerful factors (two
of which, temperature and humidity, are dominant powers in
geographic distribution), the most potent of which is temperature;
fourth, that the predominating distribution of the respective
colors is largely confined to the faunal divisions of the Eastern
United States, and as such is approaching the sub-specific
differentiation of the two phases.
His five maps illustrate the ranges of the eastern races, the
areas occupied by each one of the phases exclusively and those in
which one of the phases predominates, and the distribution of the
phases in comparison with temperature, humidity, and forest
growths; the distribution of the phases seems to correlate fairly
well with the distribution of these factors. He makes the
statement that whereas the offspring of parents of two different
phases, or of two red parents, may be all red, all gray, or of
both colors, "not a single record can be found of the
offspring of a pair of gray birds showing the slightest trace of
red." This statement seems remarkable, but I have no evidence
to the contrary.
Food.--The screech owl enjoys a
varied bill of fare including almost every class of animal life.
Dr. A. K. Fisher (1893b) summarizes its food as follows: "Of
255 stomachs examined, 1 contained poultry [pigeon]; 38, other
birds; 91, mice; 11, other mammals; 2, lizards; 4, batrachians; 1,
fish; 100, insects; 5, spiders; 9, crawfish; 7, miscellaneous; 2,
scorpions; 2, earthworms; and 43 were empty." He says of
their hunting methods: "At night-fall they begin their
rounds, inspecting the vicinity of farm-houses, barns, and
corncribs, making trips through the orchard and nurseries, gliding
silently across the meadows or encircling the stacks of grain in
search of mice and insects. Thousands upon thousands of mice of
different kinds thus fall victims to their industry."
Dr. Paul L. Errington (1932c) says: "My Wisconsin record
for Screech Owl vertebrate and large invertebrate prey totals up
to 137 individuals, in the following proportions: Norway rat, 1;
meadow mouse, 49; deer mouse, 37; shrew (Blarina, 6; Sorex,
1), 7; small bird (predominantly English Sparrow according to
feather evidence of kills), 36; fish, 4; crayfish, 3."
Dr. Allen (1924) says: "To summarize: remains of
birds were found on 35 days, insects on 28 days, crawfish on 24
days, amphibians on 15 days, mammals on 12 days, fish on 6 days,
and spiders, snails, and reptiles on one day each." He gives
a list of the species of birds fed to the young, making a total of
24 species and at least 98 individuals, and says: "Since the
feathers in the nest undoubtedly represent many more than one bird
of each species, the grand total of birds required to feed the
three young Owls from the time of hatching until left by the old
birds was certainly over a hundred."
The long list of items in the food of the screech owl includes
the following mammals: mainly mice of various species, but also
shrews, rats, moles, flying squirrels, chipmunks, and an
occasional bat. Illustrating the usefulness of the screech owl as
a mouser, Forbush (1927) writes: "All one season I watched a
pair that were rearing a brood near my cottage. . . . All the
pellets and other refuse from their food that season showed only
remains of mice, shrews, and insects. . . . While the owls were
there, the mice did no damage to our young orchard, but two years
later their box fell down and was not replaced for the next two
years. The second winter the mice girdled nearly all of our apple
trees. The next year a number of boxes were erected. The owls
returned and we had no trouble from mice thereafter."
Although birds do not form so large a proportion of the food as
mammals, the list of species is a long one, as follows: domestic
pigeons, quail, ruffed grouse, woodcock, sparrow hawk, screech
owl, downy woodpecker, kingbird, phoebe, wood pewee, horned lark,
blue jay, starling, blackbirds, Baltimore oriole, goldfinch,
junco, canary, indigo bunting, English and various other sparrows,
cedar waxwing, swallows, scarlet tanager, vireos, water thrush and
various other warblers, house wren, chickadee, nuthatches, brown
creeper, catbird, bluebird, and various thrushes.
A farmer once brought to me a screech owl that had been living
in his pigeon cote, and had killed nine of his pigeons; and there
are several other similar records. I had one in captivity that
broke into a cage and devoured a captive sparrow hawk; I could
find only its feathers. Many young birds are taken from the nests
of various small birds and fed to the young owls. Dr. Fisher
(1893b) records a report of a screech owl, much emaciated and
driven by hunger, attacking a large hen and attempting to carry it
off. An instance of a screech owl killing a ruffed grouse is
recorded by Dr. George M. Sutton (1927) as follows:
At about midnight on December 20, 1924, Mr. George Ryder, of
LeRoy, Bradford County, Pennsylvania, captured a Screech Owl in a
steel trap which he had set earlier in the evening on the body of
a grouse which he had just found freshly killed, and from which he
had frightened what he recognized as a small owl of some kind.
Examination of the snow about the body of the grouse showed that
no quadruped had caught the bird. Furthermore, the Screech Owl's
stomach, which was examined at the writer's office, contained much
of the head and neck of the grouse, as well as several sumac
seeds, portions of rose-hips, and tiny twigs with buds attached,
which must have been swallowed with the gizzard of the grouse. The
owl was caught by both feet only a few minutes after the setting
of the trap, so it is fair to assume that the eating had been done
prior to the setting of the trap, probably just after the owl had
killed its prey.
H. E. Tuttle (1920) says: "I came upon a Screech Owl one
day, carrying what seemed to be a small kitten. I followed his
line of flight, and as the burden proved too great a handicap for
him in his effort to place a safe distance between us, he dropped
it, but lingered near as if reluctant to yield it to my
inspection. To my astonishment I discovered that it was an infant
Owl, quite downy and quite dead."
Mrs. P. N. Jackson and G. Carleton (1931) write: "About
two weeks ago, in Mendham, N. J., a Screech Owl came down the
chimney of a house and ate up the Canary. . . . Feathers showed
that the Canary had been pulled between the bars of the
cage."
Screech owls feed quite extensively on insects; the list
includes June beetles and other beetles, cutworms, grasshoppers,
locusts, crickets, cicadas, katydids, noctuid moths, caterpillars,
and hellgrammites. Many of these are caught on the wing. Dr.
Sutton (1929b) watched a screech owl thus engaged, and writes:
At first we were somewhat mystified by her actions. Soon we
made out, however, that she was capturing insects which were
flying about the peripheral twigs of the tree. Some of these she
evidently snatched from the twigs or leaves with her feet; others
she caught in mid-air, with her beak. Since I had never known
Screech Owls to capture prey thus I changed my position so as to
be able to see the bird more clearly. From my new station under
the elm tree I saw the bird catch thus, Flycatcher-wise, at least
twenty insects, most, if not all of them, the large beetles
locally called June bugs or May beetles. We watched her for at
least three quarters of an hour. She caught about two insects a
minute, returning promptly to feed the noisy young. . . .
This habit of capturing insects with the mouth, on the wing,
instantly called to mind the characteristics common to the Orders
Strigiformes and Caprimulgiformes. Birds of both Orders have soft,
lax plumage permitting noiseless flight; both are at least to a
degree, nocturnal, possessing relatively large eyes. The mouth of
the Screech Owl, while hardly to be compared with that of the
Whip-poor-will from the standpoint of size, is, nevertheless,
relatively large or wide, and the hair-like feathers of the nasal
portion of the facial disc probably perform the same insect
catching function as the enormously developed rictal bristles of
the Whip-poor-will.
Louis B. Kalter writes to me: "A Screech owl practically
snatched from my hands two male cecropia moths (Samia cecropia),
around 4:30 a.m., when I was attempting to catch the moths with my
hands. In the evening I had hung a live female cecropia moth, by
means of a thread, in the open window of my bedroom. It had lured
a number of males by its scent and, when I leaned from the window
to catch them, a screech owl swooped down twice and caught them;
once it came within 3 or 4 feet of my hands."
Mr. Forbush (1927) says: "Professor Aughey dissected 8 of
these owls in Nebraska during locust invasions and in their
stomachs found 210 locusts, 2757 other insects, 2 mice and 1 small
bird. The one that had eaten the bird contained also 32 locusts
and 8 other insects."
In addition to mammals, birds, and insects, the screech owl has
been known to eat snakes, lizards, frogs, toads, various fishes,
crayfishes, snails, salamanders, spiders, scorpions, millipedes,
and earthworms. M. A. Frazar (1877) found in a screech owl's
roosting hole sixteen horned pouts, four of which were alive; all
the ponds in the vicinity were under 2 feet of snow and ice, but
in one pond, fully a mile away, a hole had been cut in the ice by
fishermen, where he inferred that the owl had caught the fish;
this involved a total flight of 32 miles for the 16 fish.
With such an extensive and varied bill of fare, it is difficult
to arrive at any general conclusion as to the economic status of
this owl. It depends largely on its environment and the most
readily available food supply, for this owl evidently is satisfied
with what animal food it can most easily obtain. Where mice, rats,
and other small mammals are abundant, it apparently prefers them;
in destroying them and in eating so many locusts, cutworms, and
other noxious insects, it is decidedly beneficial. There are
several cases on record, to its credit, where it has been useful
in keeping in check, or driving away, an overabundance of English
sparrows, which had become a nuisance in barns, hangars, and
vine-clad houses.
But in a bird sanctuary a screech owl is an unwelcome guest.
Miss Sherman (1911) found that her screech owls killed a great
many small birds, especially juncos and song sparrows; all the
latter disappeared in time; her verdict on the owls was that
"their ravages were so great that it was decided if we
desired a little bird paradise where all good birds were welcome
through the summer time there Screech Owls could not be encouraged
to remain"
Dr. Allen (1924) draws the following conclusions from his
studies:
A census of the birds nesting in the sanctuary in 1923
showed a slight increase in the total number rather than a
decrease, though all species exterminated in 1922 failed to
reappear in 1923. . . .
There can be little doubt that the number of insects and
small mammals destroyed by this pair of Owls could never
compensate for the destruction of one tenth of the insectivorous
birds eaten by the young. Though the Owls might spend the rest of
the year feeding entirely upon insects and meadow mice, they could
not possibly consume the equivalent of what would have been eaten
by the 98 birds destroyed during the short space of eight weeks.
From the data here presented it seems evident that the
Screech Owl is a powerful factor in maintaining the balance of
nature but, from the standpoint of increasing insectivorous birds,
he is an equally powerful menace.
Dr. John B. May tells me that he had some young screech owls
confined in a latticed shed. "Through the openings of the
lattice nasturtium plants climbed, and I found that the owls ate
considerable of the stems and leaves of these vines. Pellets
composed of the woody fibers of the leaf stems were frequently
found in the shed." Perhaps they needed additional
"roughage" in their food.
Behavior.--If the great horned
owl can rightly be called a "feathered tiger," the
screech owl deserves to be called a "feathered wildcat,"
for it certainly is a savage little brute, as some of the
foregoing remarks on food indicate. Its courage in attacking birds
much larger that itself is admirable, but cruelty and cannibalism
are not so much admired. I once took a mated pair of these owls
from a nest in which they were sitting on five eggs. The eggs went
to a friend's collection, but I put the two owls in a cage by
themselves in my aviary. I was surprised a few days later to find
that one of them had killed and partially eaten its mate; I
wondered if the loss of the eggs had anything to do with it. Fred.
H. Carpenter (1883) says that his captive screech owl savagely
attacked a long-eared owl which he put into the enclosure with it,
so that it was necessary to separate the two birds. William
Brewster (1907) published a thrilling story, on the authority of
Mrs. John W. Ames, of Cambridge, of a pair of very aggressive
screech owls that were raising a brood of young near a house in
Concord, Mass. The occupants of the house were savagely attacked
whenever they ventured near the trees where the owls were living
after dark; even the neighbors were attacked when they passed the
gate. People were repeatedly struck on the head and face,
sometimes blood drawn, and this happened so often that they
adopted the habit of wearing hoods or baseball masks when they
went out in the evening. This was a rather extreme case of
persistent hostility and boldness, but I have found in the
literature no less than six somewhat similar accounts of screech
owls attacking men, women, and children, in fancied defense of
their young. This is apparently a common habit, but it oftener
results in threats rather than actual injury to human beings.
The screech owl is one of our most strictly nocturnal owls. It
does not hunt, and is said not to eat, during daylight. Soon after
dusk it sallies forth on its large, silent wings and glides
swiftly along over the lowland fields and meadows in search of
mice, or courses over the treetops to catch the larger flying
insects. During the day it is inactive, dozing in some hollow
tree, some dark corner, or huddled up close to the trunk of some
densely foilaged tree; often, however, it will perch motionless
all day in some opener situation, relying on its concealing pose
and protective coloration to escape detection. Often it will sit
for hours at the entrance to a hole in a tree, or some opening in
a building, facing the bright sunlight. Its eyesight is strong
enough, with the pupil fully dilated, to see well at night, but,
with the pupil contracted, it can also see perfectly in the
brightest daylight, though it seems confused when suddenly brought
from darkness to sunlight. The only one I ever induced to leave
its nest voluntarily in daylight flew perfectly and swiftly off
through the woods for a long distance.
Captive owls that I have tethered in the open could see clearly
every bird that flew across the sky and would follow them with the
eyes until out of sight.
As with all owls, the screech owl's hearing is very acute and
of great assistance to it in its midnight hunting. The rustling of
a mouse in the dry leaves or grass, the stirring of a bird on its
roost, the buzz or soft flutter of an insect's wings, or the
splash of a fish in a dark pool, all serve to guide it to its
prey. Likewise its keen ears often warn it of an approaching
enemy. Probably its ears are fully as useful as its eyes at night.
Screech owls are ordinarily quiet, gentle birds; they can be
lifted from their nests or roosting holes without offering any
resistance; they may indulge in ominous bill snapping but seldom
use their claws, which are sharp as needles. They make very good
pets provided they do not come in contact with other species, or
even other individuals of their own species, which may result in
tragedies; they love to be stroked or have their heads scratched;
they are very cleanly, drink water freely, and are fond of
bathing. Wild owls have been known to bathe in bird baths, often
exhausting the supply.
Dr. Fisher (1893b) says: "Once about dusk the writer came
upon a small family which had emerged the moment before from the
water. They were sitting on some low alders over a shallow portion
of the stream, ruffling up and shaking the water from their
feathers, and presented a soaked and forlorn appearance.
Apparently they were too wet to be able to fly well, for when
approached they fluttered off heavily into the thicket and soon
escaped from sight in the growing darkness. The number of times
this Owl has been drowned in water barrels indicates its fondness
for bathing."
W. I. Lyon (1922) had an interesting experience with one of
these owls that was nesting in the same tree with a pair of
flickers; the owl's eggs were destroyed, and for five consecutive
days thereafter the owl was found in the flicker's nest, brooding
the young flickers; the latter were regularly fed by their parents
and were always uninjured; the owl had even brought in a small
bird to feed to the young.
The screech owl is well aware of the concealing value of its
well-known hiding pose; it will maintain this pose, even though
closely approached, and remain immovable until it realizes that it
is discovered; then a decided change takes place. The following
extract from Owen Durfee's notes gives a very good idea of the
whole performance: "I had the pleasure of finding two screech
owls sitting side by side on a horizontal limb. The attitude was
long drawn out, the whole body being stretched to its limit, the
wings and feathers held as close to the body as possible. This
gave them the appearance of two long stubs, the top of the head
being nearly square across. The eyes were slanted slits, and while
the head was directly toward me, the body was swung sideways so as
to keep the wing in front as a shield; in other words, they were
looking over their shoulders. In fact, one of them, as I walked
part way around them, suddenly swung halfway around, so that it
was looking at me over the other shoulder. After a few moments one
of them evidently realized that it was discovered and underwent a
sudden transformation; from a vertical position it quickly assumed
a horizontal one, of only about one-half as great a height. It
thus assumed a squatting position across the branch, the feathers
being fluffed out, the head a round ball, the round eyes wide
open, and with one click of the bill, it flew heavily away. A few
moments later, the other bird followed in exactly the same line of
performances."
Louis O. Shelley writes to me: "As we were walking up a
hill road we spied a screech owl, in gray phase, perched on a
short limb tight up against the bare trunk of an ash tree. As we
came into sight, very slowly the bird attained the protective pose
of a dead stub. We approached to within 12 feet, waved our arms,
called and even tossed pebbles. But the bird was fain to move as
it sat, eyes half closed, in the warm sun. We each had an orange
and were debating tossing them up at the bird. But the instant we
drew them forth and the sun struck them, emphasizing their golden
color, the bird quickly resumed its normal attitude, edged along
the limb and, spreading its wings, noiselessly swept away."
Voice.--The name of this owl is
somewhat unfortunate, as it very seldom indulges in anything that
can rightly be called a screech. Mr. Forbush (1927) heard such a
note from only one individual, of which he says: "It
resembled the note of the siren whistle, beginning low and full
and gradually rising without the usual tremolo until it ended in a
shrill shriek."
Frances H. Allen has given me his description of two of the
notes: (1) "the well-known wail, or whinny, the so-called
love song, consisting of a succession of short, even, low notes
delivered with varying degrees of rapidity. It also varies in
pitch. Sometimes the first part is slow and the latter part rapid,
virtually a trill"; (2) "wheeoo, a mellow whistle
with a falling inflection, often followed by three shorter notes,
each a very little higher in pitch than the preceding note--wheeoo,
woo, woo, woo."
I am tempted to quote Thoreau's (Langille, 1884) graphic
description of the love song; he says: "It is no honest and
blunt tu-whit, tu-who of the poets, but, without jesting, a
most solemn, graveyard ditty, the mutual consolations of suicide
lovers remembering the pangs and the delights of supernal love in
the infernal groves. . . . Oh-o-o-o-o that I had never been bor-r-r-r-r-n
sighs one on this side of the pond, and circles with the
restlessness of despair to some new perch on the gray oaks. Then--that
I had never been bor-r-r-r-n echoes another on the further
side with tremulous sincerity, and bor-r-r-r-n comes
faintly from far in Lincoln woods."
The screech owl's call is seldom heard until after dark, but
Mr. Kalter tells me that he has heard it calling on at least three
occasions in bright daylight, at 11:30 a.m. and 1:15 and 2 p.m. On
two occasions he has heard one calling while in flight, once while
being chased by a robin. Dr. Winsor M. Tyler contributes the
following good description of the screech owl's notes:
"The commonest note of the screech owl is a whistle, well
within human range, which, rising a little in pitch, becomes
tremulous, then slides down below the starting point, the
tremulous quality becoming so marked that, near the end, the voice
is almost divided into separate notes. The whole has a sad, dreary
effect, due rather to the tone of voice and the sliding change of
pitch than to any minor intervals.
"The owl varies this cry in several ways. The note may
begin on various pitches--that is, one wail may be markedly higher
or lower than the wail preceding it; the pitch may rise very
little, or it may rise two or more tones before it falls at the
end; the pitch may fall a varying degree, sometimes three or four
tones; and a fourth variation is at the beginning of the cry when
the quavering quality is delayed appreciably.
"A second note, less common than the wail in proportion of
about 1 to 10, may be suggested by the letters ho-ho-ho-ho,
pronounced with a good deal of aspirate quality. This series of
notes is generally given alone, but it may sometimes immediately
follow the wail. The pitch of this call is about five tones below
the highest note of the wail, and as a rule does not vary,
although it occasionally runs upward a little. It is sometimes
heard in the daytime.
"I have often heard another note in August and early in
September, when several owls--presumably a family out hunting--had
gathered 'in the dead vast and middle of the night' and were
calling to one another from the trees about Lexington Common.
Among the subdued whinnyings and tremulous owlish coos, there
comes out of the darkness a sharp cry--almost human, or like a
little child's voice--a cry like keerr, sometimes rolling
at the end. It is about as long as a flicker's call note, and
moves about as the bird flies from one perch to another. Sometimes
the note is uttered with so much energy that it suggests
excitement or eagerness.
"It seems probable that this is the call of a fledgling
owl, signaling its whereabouts to its parents while they are away,
searching for food among the branches of the trees, or on the
grass underneath. On one occasion, when the owls were about
the house, at 1 o'clock in the morning, I heard the shriek of a
robin burst out of the night."
Field marks.--A small owl, with
yellow eyes and prominent ear-tufts, is quite likely to be a
screech owl, as the long-eared owl is considerably larger and
slenderer. It is very seldom seen on the wing in the daytime,
unless driven from cover. The bright reddish-brown color of the
upper parts in the red phase is quite distinctive; no other North
American owl has any color approaching this. In the gray phase it
is much grayer than the long-eared, and very much shorter and
stouter. In the gray phase the color pattern resembles the rough
bark of an old tree, and the hiding pose, described above,
increases the resemblance in the attitude in which the bird is
oftenest seen in the daytime.
Enemies.--The larger owls and
occasionally some of the larger hawks have been known to kill the
screech owl; prowling cats or other predatory animals may pounce
on one while it is securing its prey on the ground. Its less
dangerous, but far more annoying, enemies are the crows, blue
jays, and other small birds, which never lose an opportunity to
pester, scold, and annoy one of these little owls when they can
find it sleeping peacefully. The location of an owl can often be
detected by the presence of a noisy mob of small birds, flitting
about, chirping, and shrieking at the enemy they rightly fear and
detest, but seldom daring to venture too near. The owl may stand
this abuse with stolid indifference for some time but may be
driven eventually to seek seclusion in some dark hollow. I once
followed up a noisy mob of blue jays in a dense thicket and shot
one of them, as I wanted a specimen; when I picked it up, I was
surprised to find a dead screech owl lying near it, which I had
killed unexpectedly. Many screech owls have been found dead along
the much-traveled highways, apparently killed by automobiles.
Winter.--Screech owls are supposed
to be permanent residents throughout their range, but probably
some migration takes place from the northern portion of their
summer range. They certainly wander about more in search of food
in winter, as they are often seen at that season in places where
they are not found in summer. The scarcity of food in the northern
woods when the ground is covered with deep snow drives them to
more fruitful hunting grounds about farms and even into towns and
cities, where they find plenty of mice, rats, and English
sparrows, as well as dark and secluded nooks in which to find
shelter, about farmhouses, barns, corncribs, and outbuildings.
Many of these owls have been found in winter in a sadly emaciated
condition, which indicates that they have been driven by hunger
from some less hospitable region.
Eastern Screech-Owl*
Otus asio
*Original Source: Bent,
Arthur Cleveland. 1938. Smithsonian Institution United States
National Museum Bulletin 170 (Part 2) : 243-258. United States
Government Printing Office
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