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Short-eared
Owl
Asio flammeus
Contributed by Charles Wendell Townsend
[Published in 1938:
Smithsonian Institution United States National Museum Bulletin 170
(Part 2): 169-182]
The short-eared owl is one of the most cosmopolitan of birds,
as it is found in every continent except Australia. In its habits
it differs from most owls in preferring open plains, marshes, and
sand dunes to thick forests, where it is almost never seen, and in
the fact that it frequently hunts by day. Although it sometimes
takes small birds, its feeding habits in general are of great
value to man, for its favorite food consists of rodents. When
field mice or voles increase so as to become veritable plagues,
various owls, especially of this species, have been known to
congregate in the infested region and to have done great service
in destroying the pests. There are several such records in various
counties in England extending back to the sixteenth century. Such
a plague of mice is described by Hudson (1892) as occurring in
South America in 1872-73, when short-eared owls were most
important agents in stopping the plague. Notwithstanding their
proved value, ignorant and thoughtless gunners continue to shoot
these beneficial birds, and their numbers are diminishing.
Courtship.--The remarkable
courtship flight and song of this bird have been well described by
A. D. DuBois (1924), who not only made observations on the song at
night, but on both song and flight by day. The song consisted of a
series of toots "repeated fifteen to twenty times, at the
rate of four toots per second, in a low-pitched monotone."
The sound seemed
to come from all directions. Finally, upon gazing upward, I
discovered the owl directly overhead, and for a time was able to
watch him, with the field-glass, in the fading light. He was
flying at a great elevation; so great in fact that it was
difficult to see him at all without the aid of the field-glass.
For the most part his flight was with slow, silent flapping wings,
although he sometimes soared. His course led in easy curves which
kept him in the same general locality. His song, on this occasion,
was made up of 16 to 18 toots. Now and then he made a short
slanting dive which terminated with an upward swoop. The dive was
accompanied by a peculiar fluttering noise. . .a sound as might be
produced by a fluttering small bird imprisoned in a box, or by the
flutter of a small flag in a very strong wind.
Later, DuBois observed the flight in full sunlight and was able
to solve the mystery of the "fluttering flag."
"When the owl began the short dive he brought his wings
together beneath him, stretching the back posteriorly and striking
them rapidly together with short clapping strokes. The dive ended
simultaneously with the clapping, when the bird spread his wings,
abruptly and noiselessly turning his course upward with a swoop.
The clapping was clearly visible with the field-glass and the
fluttering sound produced by it was distinctly audible. He seemed
to be applauding his own aerial performance." Mr. DuBois
observed this flight song during four years, on the Great Plains
in Montana between March 17 and August 28. In the later dates the
young are already partly grown. On one occasion when he had
examined a nest of four young and had seated himself at a
distance, one parent disappeared, "the other flew and soared
in circles above me, gradually climbing until it was at a great
height. During the time that I watched, he twice indulged in
wing-clapping. Having thus spiraled upward above me to his maximum
height, he shifted his center of flight to a point more nearly
over the nest, at the same time reducing his elevation."
Francis Harper writes that he observed the courtship flight of
this owl at Gardiners Island, N.Y., in 1911 and thus describes it:
"Late in the afternoon of June 14 I noticed one of the owls
high up in the air, flying with exceptionally slow and somewhat
jerky wing strokes at the rate of 150 a minute and making scarcely
any headway. There seemed to be almost a perceptible pause of the
wings as they reached their highest point, before beginning the
downward stroke. Now and then the bird would swoop downward,
meanwhile striking its long wings beneath its body, perhaps 8 or
12 times in the space of a second or two. It was a remarkable act,
quite unlike anything known to me among other birds. The owl kept
more or less over a particular part of the pasture and was
probably 200, or even 300, feet in the air at times."
Edward A. Preble (1908) reports that several individuals of
this species were seen on April 30, 1901, to the north of
Edmonton, Alberta. "They were usually flying in pairs, and
the males frequently swooped down toward their mates from a
considerable height, holding their wings high above the back and
uttering peculiar quavering cries."
Nesting.--The short-eared owl
nests on the ground generally in a slight depression very sparsely
lined with grasses and weed stalks and an occasional feather.
Sometimes the nest seems to consist only of the flattened dead
vegetation of the spot chosen, or merely a slight hollow in bare
sand. It may be entirely exposed to light in an open field or
marsh or partly hidden by a clump of grasses or weeds. A. K.
Fisher (1893b) says that "in exceptional cases it has been
found in a clump of low bushes, or otherwise slightly
elevated."
Coues (1874) quotes Dall who had found the short-eared owl
"breeding in burrows on the island of Oomalashka; 'the hole
is horizontal, and the inner end usually a little higher than the
aperture; lined with dry grass and feathers.' The burrows were not
over two feet deep, usually excavated in the side of a steep
bank."
A few descriptions of individual nests will serve to show their
character. A. D. DuBois thus describes a nest in Montana:
"The nest was situated on almost level ground--on the slight
west slope of a knoll, amid the young growing wheat and the old
last year's stubble. It was a shallow depression in the earth,
sparingly lined with old wheat straws and the shredded husks of
the stubble. There were a few soft feathers about the edges. A
dried Canada thistle, remaining from the previous year, afforded
slight protection on the east."
Charles A. Urner (1923) described a nest in a salt marsh near
Elizabeth, N.J. The nest "was composed almost entirely of
salt hay and about nine inches in diameter and an inch and a half
to two inches thick. . . . The ground, immediately about the nest
for a distance of four inches had apparently been almost cleared
to furnish material and on one side the thick stubble still stood
as if the matted dried grass had been broken off by the bird's
bill. The presence of feathers (apparently owl's feathers)
throughout the mass of the nest furnished additional evidence that
this species of owl actually constructs its own nest."
J. Claire Wood (1907) thus describes a nest found in Michigan:
"It was a mere platform of dead marsh grass half an inch
thick and covering a spot of bare ground ten by eighteen inches.
The long 'saw-grass' formed an arch over the nest, but there was
an opening at the easterly end leading into an open space about
two feet wide by four long--a sort of play and feeding grounds for
the young." The nest and vicinity were kept clean of all
castings, down, feathers, etc., that would tend to betray its
existence. On the other hand, nests and their vicinity are often
foul with droppings, feathers, and pellets.
Bendire (1892) describes two nests found in Idaho on the
ground, "one in the center of a tall bunch of rye grass, the
other by the side of one of these, and both were well hidden. . .
. They were simply slight depressions not more than 2 inches deep,
lined with pieces of dry grass and a few feathers from the
birds."
That the short-eared owl may occasionally return to the same
nesting site seems to have been shown by Urner (1923) who
discovered directly under a new nest in 1922 "a more or less
discolored white egg, one side slightly cracked as if from
freezing, the dimensions corresponding to the egg of the
short-eared owl. . . . Under the cracked egg could still be seen
the outline of a well-rotted nest, presumably from the 1921
season."
Eggs.--[AUTHOR'S NOTE: The
short-eared owl may lay anywhere from four to nine eggs, and
rarely even more; but the commonest numbers are five, six, or
seven. The eggs vary in shape from oval to elliptical-ovate. The
shell is smooth, or very finely granulated, with very little, if
any, gloss. The color is white, or very faintly creamy white.
The measurements of 56 eggs, in the United States National
Museum, average 39 by 31 millimeters; the eggs showing the four
extremes measure 44 by 32.5, 40 by 33, 37.5
by 29.5, and 38.5 by 29 millimeters.]
Young.--The incubation
period according to Bendire (1892) is about three weeks. F. L.
Burns (1915) states it to be 21 days. Both sexes incubate and take
care of the young. According to Urner (1923) the young fly in from
31 to 36 days after being hatched and remain in the vicinity of
the nest for six weeks, although they stray from it and hide in
the surrounding grass long before they can fly, sometimes as early
as two weeks from hatching. Owing to their protective coloration,
they are found with difficulty in the grass, and as they stretch
out motionless on the ground this difficulty is increased. When
aroused they turn on the back and fight. Mabel Densmore (1924)
describes the actions of a young bird full grown but unable to fly
that she discovered, "a bundle of feathers, dumped down in
the short prairie grass, with no semblance to a bird except the
eyes." While the parents flew excitedly around, the young
continued to "play possum" and could be moved about and
handled freely without showing a sign of life except in its eyes.
Nearly all the young of short-eared owls found at or near the
nest differ in size and in development of plumage. Aretas A.
Saunders (1913) measured each of nine young of one pair and
concluded that their ages ranged between 3 and 14 days. He also
found that each owl at about the age of two weeks strayed from the
nest, going farther and farther each day even to a distance of 100
or 150 yards. He was always able to find the young by the action
of the parents in feigning injury nearby.
Urner (1923) concluded from his observations in the salt
marshes of New Jersey that short-eared owls sometimes move their
eggs or helpless young to escape unusually high tides, and it is
probable that when the eggs are destroyed by high tides or prairie
fires, a second set is laid.
Urner (1921) describes the "wounded bird" actions of
a short-eared owl flushed from a nest of young in New Jersey:
"The first bird flushed strove vainly by imitating injury and
distress to draw me away, these exhibitions including sheer drops
or tumbles from the air and flutterings and cries with wings
outspread while on the ground. When not thus engaged the bird
maintained a position directly overhead facing the wind. The
second adult when flushed from the nest, joined the vigil
overhead." The wounded-bird act differs in intensity and may
or may not be accompanied by calling. On one occasion the excited
bird struck his hat twice. The same author (1923) has this to add:
"An interesting performance occasionally seen when the nest
is visited is a steep dive toward the ground by the adult, the
outstretched wings being brought together under the body as the
bird descends, the ends being clapped together rapidly, the sound
being distinctly audible when the bird is within one hundred
feet." This is an illustration of use of part of the
courtship performance by birds at moments of intense excitement,
even when not connected with the amatory instinct.
Saunders (1913) describes the wounded-bird act as follows:
The bird circles at a height of about fifty feet, then drops
straight down close to the intruder until within two or three feet
of the ground, then sails low over the grass and brush in the
opposite direction from the nest until a hundred feet of more away
when he lights on the ground facing the intruder, squealing as
though in great pain, and with wings widespread and flapping. If
followed he will wait till one gets within about twenty-five feet,
then slowly and carefully folds his wings one at a time, rises and
sails a little farther away and repeats the wing flapping and
squealing. If one is not watching him when he first drops to the
ground, he frequently calls attention to himself by flapping his
wings against his sides or breast as he drops, producing a sudden
loud and startling noise that is very surprising in a bird whose
flight is ordinarily perfectly silent.
An amusing variation of the wounded-bird act is given by
Kitchin (1919): "We were here treated to a most ridiculous
performance by the male bird. While watching the female we
suddenly heard an awful groaning and chuckling sound behind us.
This was the male and he was mad clear through, darting back and
forth and uttering these awful sounds. Finally, he could stand it
no longer and literally dove into a bunch of high weeds, where he
twisted and turned, and to watch the tops of the weeds one would
think that nothing less than a death struggle was going on."
Plumages.--[AUTHOR'S NOTE: When
first hatched the nestling is fairly well covered with rather
short soft down, grayish white or buffy white above and nearly
pure white below. Witherby's handbook (1924) says: "Base of
down dark brown along wing, at base of wing and on each side of
mantle, forming dark lines or narrow patches."
This natal down is soon replaced by the secondary down, which
appears simultaneously with the fist downy plumage, very loose and
soft in structure. A nestling about 6 inches long shows the first
plumage appearing on the back, but the under parts are now covered
with long, soft, "cinnamon-buff" down, tinged with
grayish on the chest. A still larger nestling, about 10 inches
long, is feathered on the back with the first plumage,
"Verona brown" or "bister," broadly tipped
with "cinnamon-buff"; the wings have just started to
grow, but the tail has not yet appeared; the long, soft, thick
down of the under parts is "cinnamon-buff," suffused
with dusky on the chest and throat; the facial disks are now
brownish black. The first winter plumage, which is much like that
of the adult, soon begins to appear through the downy plumage, and
the latter is gradually molted while the wings and tail are
growing. By September or October, or perhaps earlier in early
hatched birds, the young bird is fully clothed in a firm plumage,
which is practically adult.
Adults have a complete, annual molt between August and
November. Witherby (1924) says that a molt of the body plumage
occurs between January and March. Although the manuals do not
mention it, I have noticed that adult males, perhaps the oldest
birds, average much paler in color than the females. Some of the
old males have an almost pure-white ground color on the belly,
only faintly cream-white on the breast, and pure white on the
tibiae and under tail coverts; in these birds the light edges
above vary from "cream-buff" to white. On the other
hand, the darkest females are colored "ochraceous-buff"
to "warm buff" on these parts. These differences may be
color phases or partially due to age or seasonal changes, but
there seems to be an average sexual difference.
T. Russell Goddard (1935), while studying short-eared owls in
England, discovered "that there were two distinct colour
forms. . .a brown form and a grey form. Of the six birds under
observation during April and May three were brown and three were
grey. They were paired in the following manner--two browns, two
greys, and a grey male paired with a brown female. The grey form
was literally a cold grey without any warm brown about it at all.
The feathers on the breast and tarsi, which in the brown form are
a warm buff, were white in the grey form. The grey form of the
Short-eared Owl was, in fact, quite as cold in colour as the
extreme grey form of the tawny owl (Strix aluco)."]
Food.--The short-eared owl is the
friend of man, and if he had been treated as he deserved and not
shot on sight--as is man's stupid and cruel habit--the damage to
our young orchards by mice, now so common, would be less. Rodents
of various kinds, particularly meadow or field mice (Microtus),
which do so much harm, are his favorite food. Dr. A. K. Fisher
(1893b) reports the findings in the stomach of 101 short-eared
owls as follows: "1 contained small birds; 77, mice; 7, other
mammals; 7, insects, and 14 were empty." Of the mice, nearly
all were meadow mice, a few white-footed, pine, and house mice.
Six shrews, a cotton rat, a rabbit, and a pocket gopher were the
other mammals listed. A grackle, a red-winged blackbird, 4 juncos,
11 sparrows of various species, and a robin were the bird victims.
Junius Henderson (1927) states that 75 percent of the food of
this owl consists of mice and that it is more insectivorous than
any other of our owls except the burrowing and perhaps the screech
owl. One stomach contained 50 grasshoppers, one 18 May beetles,
and one 13 cutworms. Of 254 stomachs examined, 15 percent
contained birds. Cahn and Kemp (1930) examined 137 pellets of this
owl and found the remains of 110 small mammals of five species and
of three birds; two were meadowlarks and one a vesper sparrow.
Errington (1932c) from a study of pellets found the remains of
68 meadow mice, 115 deer mice, 1 snow bunting, and 1 meadowlark,
and he says that this owl "seemed to show a distinct
preference for small mammalian over small avian prey, even at
times when small birds may have actually far outnumbered the
rodents which were depended on for food."
Although rodents are the chief of this bird's diet there are
occasional exceptions generally under unusual circumstances. Thus
William Brewster (1879) found at Muskegat a small colony of
short-eared owls that preyed on the nesting terns. At least a
hundred had been killed and eaten, judged from the remains, and in
each case the breast had been picked clean, but nothing but the
breast had been eaten. At this island in June 1913, I found about
50 terns treated in this way by the short-eared owls. Nothing but
the breasts and entrails had been eaten. The remains of the terns
were found singly or in groups of three to six. Laurence M. Huey
(1926b) reports an entire California black rail, swallowed in two
pieces, in the stomach of a short-eared owl. He also reports in
detail the contents of two pellets of this bird from a salt marsh
near San Diego. In one of these were the skulls and other bones of
two species of bats and the remains of a meadow mouse, of a
Belding's marsh sparrow, and of a Savannah sparrow. The other
contained the remains of the two species of bats, of an American
pipit, and unidentified bird bones, feathers, and mouse hair.
Pierce Brodkorb (1928) reports two juncos and two swamp sparrows
found in one stomach and in another a snow bunting. Urner (1923)
found a nest of this owl "literally carpeted with the
feathers of small birds. At its edge was a freshly-killed
Sharp-tailed Sparrow. I found no remains of mice and only one
small pellet composed apparently of feathers." Ludwig Kumlien
(1899) found a nest in Wisconsin made up of feathers and matted
grass in which he found the remains of more than 40 species of
birds varying in size from a kinglet to a meadowlark and,
curiously enough, no trace of any mammal. He took the three young,
about two weeks old, to his house and found they required 12 to 15
English sparrows daily to satisfy them.
J. A. Munro (1918) records the following:
Between September 28 and October 16, 1909, I spent several
days collecting in a small dry meadow, on the south shore of
Ashbridge's Marsh [Toronto]. Short-eared Owls were more
numerous than usual and were apparently feeding entirely on small
birds. Four stomachs examined contained feathers and bird bones
exclusively. In a small tract of dry grassy meadow, roughly
estimated at fifty acres, I found feathers of the following
species marking the spot where they had been eaten by owls; one
Hermit Thrush, one Sora, three Yellow-bellied Sapsuckers, one
Slate-colored Junco, one White-crowned Sparrow, and eighteen
others, of which there were not enough feathers left to identify
the species.
During April and the early part of May of the following
spring, the owls were again plentiful, preying on the hosts of
migrants that rested along the sandbar after crossing Lake
Ontario. With one exception all the castings contained the bones
and feathers of small birds. This meadow was swarming with voles,
but only one pellet, of the many examined, was composed of the fur
and bones of voles.
Ivan R. Tomkins sums up and draws interesting conclusions on
the findings of pellets collected near Savannah, Ga., and examined
by the Biological Survey. He says: "The 50 pellets collected
during January and February contained remains of 34 birds, of 14
identifiable species, and 54 mammals, of two or more species. The
18 pellets collected in the same places during late February and
March contained remains of 4 birds and 45 house mice. Several
points of interest are: The unusual proportion of birds in the
first lot (there was also an abundance of birds during the last
period, but mammals seem to be the choice of food then) and the
presence of such species as fox and white-throated sparrows,
woodpecker, flicker, and kinglets, all species preferring thickets
or woods, coupled with the absence of Savannah and song sparrows,
these last very abundant in the precise locality most inhabited by
the house mice and rats."
Behavior.--Owing to its diurnal
habits and its love of open places the short-eared owl is one of
the owls most frequently seen by man. It avoids forested regions,
although in its extensive migrations it passes over them as well
as over the sea and has therefore been observed on rare occasions
in the midst of a forest or many miles at sea. William A. Bryan
(1903) reported one that was seen to circle down from a great
height and alight on one of the yards of a vessel bound for the
Hawaiian Islands and 680 miles from Puget Sound. This was in
October 1902. In the same month, in 1900, another was observed
some 500 miles from these oceanic islands.
In hunting its prey the short-eared owl adopts the same habits
as the harrier, or marsh hawk, and may often be seen circling
close to the ground or flying over it, sometimes gliding,
sometimes flapping and dropping down on its victims with
down-stretched feet. Occasionally it sustains itself by hovering
over one spot before it pounces. When the wind is blowing
strongly, it takes advantage of the up-currents over rolling
county especially among sand dunes, where it may be seen gliding
into the wind with great speed and skill. At times it may be seen
sailing lightly about at a height of 20 or even 30 yards, turning
its round head now this way now that and closely scanning the
ground. On some occasions it alights on the ground and watches for
its rodent prey to appear. R. H. Lawrence (1892) reports that in
the salt marshes near South Bend, Wash., "they sat much on
the edges of many deep sloughs waiting for a species of rat. I
found many evidences of their success in getting them." There
is a cut in the Argentine ornithological journal, El Hornero,
of one of these owls sitting on the ground with its feet on either
side of a mouse hole, ready to clasp its victim should it emerge
from the ground.
The short-eared owl may often be found perched motionless on
fence posts or stubs of trees, in tufts of grass, or even on the
bare ground. Here among dead grass, especially in sand dunes, it
is very difficult to see. On one occasion after being deceived
several times by owls that resembled stumps or small posts flecked
with lichen or sand or snow, I was willing to consider a certain
obvious stump to be an owl, but after changing my mind and
deciding it was not one, the "stump" opened its wings
and flew away! In such situations, the owl remaining perfectly
motionless until the fatal moment, doubtless snaps up many a
wandering mouse.
Although this owl hunts freely by day it hunts more freely at
dusk and in the early dawn, and it also hunts at night. It sleeps
at intervals both day or night usually concealed in tufts of grass
and sometimes in thick evergreens, in the latter no doubt in
storms. In walking over an upland pasture or marsh, or among sand
dunes, one may suddenly flush a short-eared owl, disturbed from
its nap or watching for a victim, or feasting on one already
killed. Once I flushed one in dunes that, judging from the many
feathers about, had been eating a robin. At such times the owl
flies away, sails gracefully about, and often alights again at no
great distance.
Charles A. Urner (1923) reports the following interesting
behavior of a short-eared owl. After he had answered the call of a
yellowlegs--
Suddenly a Short-eared Owl came out of the growing darkness
and dove at my straw hat. He missed it by inches. I whistled the
Yellow-legs call again. He turned and dove at me a second time
with no end of determination in his manner. Six times I whistled
and six times he turned and swooped at me, finally alighting on a
mud pile nearby to look the situation over more carefully. I stood
in the open marsh with no protection. Had I whistled in the
daylight he would have shown no interest. Apparently he did not
recognize me as a human in the dusk. He struck on the impulse of
his ears--not his eyes. And apparently he knew the taste of
Yellow-legs.
Short-eared owls may be seen pursuing crows and even marsh
hawks. Eugene Bicknell (1919) watched a pair of owls repeatedly
attacking a single crow. "The Crow, perhaps to escape the
Owls, perhaps intent on depredation of their nest, several times
swept down to the ground about a certain spot, the Owls pursuing
it or awaiting its return into the air when attack and
counter-attack were renewed. The following year at the same place
a pair were observed on February 22, attacking a Marsh Hawk."
In the following incident the tables were turned against the
short-eared owl as reported by H. P. Attwater (1892). He was
attracted by cries of two red-shouldered hawks and, walking toward
them, flushed three or four short-eared owls. "One in
particular mounted to a great height, followed by the Hawks, and
in the fierce attack which followed it held its own bravely for
some time till they finally appeared tired of the fight and flew
away."
This owl sometimes attacks large birds, possibly only in a
spirit of mischief or play and not with any intention of killing
them. Thus William Brewster (1925) reports one swooping at black
ducks in a pond, and another soaring in circles above a soaring
great blue heron and swooping at and striking it repeatedly on the
back. For several minutes this performance went on, the heron
circling and "croaking incessantly and, when struck by the
Owl, squalling so lustily that it might have been heard half a
mile away. Quite evidently it was badly frightened. The Owl,
without doubt, was merely amusing himself."
Clarence S. Jung (1930) describes an aerial fight between a
short-eared owl and a marsh hawk. "The Owl pursued the Hawk,
flying above the retreating bird. Hovering some ten feet above the
Hawk, the Owl would suddenly swoop down in a fierce attack. In the
same instant the Hawk would half turn like a tumbler pigeon, in
such a manner so as to strike the Owl with its talons as that bird
passed. The dexterity and maneuver of the two birds was amazing.
The attack was repeated seven or eight times. It is to be supposed
that the Hawk disturbed the Owl's nest and was being driven
away."
Voice.--During migrations and winter
the short-eared owl is one of the most silent of birds, but on the
breeding grounds especially when the young are about it is far
from silent. The courtship song, both vocal and instrumental, has
already been described above. Charles A. Urner (1923) describes
five distinct calls of the short-eared owl. The first, high
pitched and rasping, resembles the barking of a small animal. It
is usually uttered in triplets and might be written wak, wak,
wak or yak, yak yak, but there may be eight or more
rapid repetitions. The second is uttered singly and is more
prolonged, w-a-a-a-k. The third, Mr. Urner writes as wa'u
or even wow. The fourth suggests sawing or filing, a rather
long drawn rasping note, while the fifth is a clear whistle-like
squeal. Like most owls, young and adults may snap their bills and
hiss. Saunders (1913) states that the voice of the female is
"higher pitched, more squeaky and less harsh than the
male." The cries of the owls, especially when their young are
disturbed, have been likened to the "squealing of young
pigs" and to "the barking of a young puppy" (W. W.
Worthington, 1893). Lawrence (1892) says "this owl has a
shrill barking call like the 'Ki-yi' of a little dog."
Mabel Densmore (1924) describes the notes of a pair of birds
signaling to their nearly fully grown young as "subdued
noise, muffled and short, half sneeze, half bark" and that of
the young like the sound of "escaping steam turned on and off
suddenly but lasting about three seconds."
Field marks.--As the
short-eared owl skims the marshes and fields like a harrier, it
might be mistaken for a marsh hawk, but the much shorter tail and
the large round owl head, as well as the absence of white on the
rump, make its identification easy. The small "horns" or
"ear-tufts" cannot be seen in flight and only rarely
when the bird is perched. They are so short that they are
concealed when the bird is alarmed or excited and erects the
feathers of the head. The light under parts of the bird and the
small oblong black patches at the base of the primaries seen from
below are good field marks. It is about the size of the
broad-winged hawk from which it is at once distinguished by its
round head. A patch of creamy brown on the upper surface of the
open wing is also distinctive.
Winter.--As small rodents are the
favorite food of this owl, it generally migrates south to grassy
and weedy regions where there is little or snow. In such favorable
localities they sometimes collect in considerable numbers. Harris
(1919) describes such gatherings in flocks of 8 to 50 in the
prairies close to buildings in Kansas City and Tyler (1913), in
the Fresno district of California, estimated as many as 200 of
these owls hunting over stubble fields at sunset one December
afternoon.
Frank L. Farley contributes the following note: "In the
fall of 1931, when engaged in threshing their grain, farmers in
central Alberta noted an unprecedented number of mice in the
fields. Later, when winter set in and threshing operations were
halted on account of deep snow and extreme cold, it was discovered
that the grain shocks in the fields were infested with the
rodents, as many as a dozen of the destructive little animals
having taken up their winter quarters under a single shock. In
October and November, unusual numbers of short-eared owls were
observed patrolling the fields, hunting for mice, and later their
numbers were augmented by the arrival of thousands of
northern-bred birds. On December 31, 1931, H. A. MacGregor and I
drove 25 miles by automobile, south of Camrose through the Duhamel
country, and saw 24 of these owls. All were hunting in, or
adjacent to, fields of shocked grain. John W. Russell recorded in
16 days, between November 26, 1931, and February 5, 1932, 116
owls, this being at the rate of 7.25 a day. The number of mice
that this vast army of owls destroyed must have reached enormous
proportions, and the birds may have prevented what otherwise would
have resulted in a serious plague. An invaluable service was
rendered at a time of emergency, and at no cost whatever to the
people."
The short-eared owl is an interesting and beneficial bird. May
it long survive!
Short-eared Owl*
Asio flammeus
Contributed by Charles
Wendell Townsend
*Original Source: Bent,
Arthur Cleveland. 1938. Smithsonian Institution United
States National Museum Bulletin 170 (Part 2):169-182. United
States Government Printing Office
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