Bent Life History of the Great Gray Owl

Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.

Bent Life History for the Great Gray Owl - the common name and sub-species reflect the nomenclature in use at the time the description was written.

Latin name now Strix nebulosa


This great owl is most deceptive in size; in external dimensions it exceeds in size all other American owls; but in bodily bulk it is exceeded by the snowy and great horned owls and is but little larger than the barred owl; its long wings and tail, its large, round head, and its long, fluffy plumage make it seem much larger than it really is. I have skinned several of these owls and have always been impressed with the surprisingly small, and apparently weak, body in a great mass of feathers.

Rev. C. W. G. Eifrig (1906) gives the following figures on one that he skinned:

The great gray owl is in appearance our largest owl, it measures in length 25 - 30 inches, extent (wings spread) 54 - 60 inches, tail 11 - 13 inches. Its large facial disk, much larger than in other owls, heightens the impression of largeness, besides making it appear somewhat solemn, mysterious and uncanny. The body taken out from this owl, i. e. the trunk, without skin, head and wings, measured only, length 6~ in., depth, i. e., from breastbone to back 3 3/8 in., width across thorax 2 1/2 in., weight 8 - 10 oz. * * * It is hard to understand how such a tiny body compared to the bulk of the bird could keep up the huge wings, heavy claws and enormous head, whose circumference measures 20 inches, the facial disk alone, 6 inches.

Mr. Eifrig's bird was somewhat emaciated, which would account for the light weight of the body, but this would not materially affect its measurements. The weights of four entire birds, of which I have records, vary from 1 pound 15 ounces to 2 pounds 14 1/2 ounces.

The range of the great gray owl is in the timbered regions of central and western Canada, from Hudson Bay westward to Alaska and the Pacific coast, and southward in the mountains to central California. Grinnell and Storer (1924) have recently reported it as "probably permanently resident" in the Yosemite region, "found by us only in the fir woods of the Canadian Zone", at altitudes of 7,400 and 7,900 feet. They say that it "seems prone to be active during the daytime, but keeps within thick timber."

Nesting: Baird, Brewer, and Ridgway (1905) say: "On the 23d of May, Dr. Richardson discovered a nest of this Owl, built on the top of a lofty balsam-poplar, composed of sticks, with a lining of feathers. It contained three young birds, covered with a whitish down, to secure which it was necessary to cut down the tree. While this was going on, the parent birds flew in circles around the tree, keeping out of gunshot, and apparently undisturbed by the light." Roderick MacFarlane (1891) found a nest "on the 19th July, 1862, near Lockhart River, on the route to Fort Good Hope. It was built on a pine spruce tree at a height of about twenty feet, and was composed of twigs and mosses thinly lined with feathers and down. It contained two eggs and two young, both of which had lately died."

During his trip down the Mackenzie River in 1904, Edward A. Preble (1908) discovered a nest, of which he writes:

While passing an extensive "brule" on the left bank during the afternoon of June 6 I noticed a large nest on a tree about a hundred yards up the side of the valley from the river. On a nearer approach a large gray head became visible over the edge of the nest, and I realized that I had discovered a nest of the great gray owl. Making a landing, I made my way through the tangled mass of fallen timber to the base of the tree and by a few raps with the ax induced the sitting bird to leave the nest. She darted with a rapid swooping flight toward the nearest woods, but as I desired her for a specimen, I shot her before she gained its shelter. The nest was about 50 feet up in a large dead and leaning spruce; and as I did not dare to climb it, I felled the tree to secure the young birds which I felt sure the nest contained. They proved to be two in number, evidently 2 or 3 weeks old, and were clothed with grayish down. In the nest were the partially eaten remains of three young rabbits about the size of red squirrels. The nest was a platform of sticks, nearly flat and practically without lining, and measured about 2 feet in diameter.

A. D. Henderson sent me a set of three eggs of the great gray owl which he took near Belvedere, Alberta, on April 30, 1922; the nest was about 40 feet up in the crotch of a balsam poplar, in poplar woods; it was an old hawk's nest built up by the owls with twigs, well cupped and lined with bark strips and a few feathers; incubation was slight.

Mr. Henderson (1915 and 1923) has published some notes on eight other nests of this owl, found by him near Belvedere. These were all in poplar woods or mixed poplar and spruce woods. One was placed in a dead poplar and the others were in live balsam poplars or aspen poplars; two were 50 feet, one 45, one 40, three 35, and one 30 feet from the ground. They were all old nests of goshawks, red-tailed hawks, or broad-winged hawks and had very little or no lining brought in by the owls.

Frank L. Farley writes to me that this owl nests in the muskeg country "less than 100 miles north of Edmonton. On May 7, 1931, A. C. Twomey found a nest in which were four eggs. This nest was placed in the crotch of a poplar tree about 50 feet from the ground.

It resembled other nests used by great homed owls, except that it was lined with the tips of green pine needles and twigs."

Since the above was written, Dr. Thomas S. Roberts (1936) has reported the taking of a nest and eggs of the great gray owl in northern Minnesota, on April 4, 1935. The locality was on the north slope of a hill and but a short distance south of the Canadian line. The nest, which is now in the University of Minnesota Natural History Museum, 'contains both down and feathers unmistakably those of the Great Gray Owl and the eggs agree perfectly with descriptions of the eggs of this species. The nest was in a dense tamarack swamp and rested about 13 feet from the ground in the crotch of a medium sized tamarack tree. It was built externally of tamarack branches and twigs and lined rather thickly with deer hair with an admixture of shredded bark, rootlets, and sphagnum debris. The three eggs were perfectly fresh."

Eggs: The great gray owl has been known to lay anywhere from two to five eggs, but three seems to be the commonest number. In the nine nests reported by Mr. Henderson, there were 5 sets of three, 3 sets of two, and 1 set of five. The eggs are small for the size of the bird, and are not so rounded as the eggs of most other owls, being between oval and elliptical-oval. The shell is rather roughly granulated and not glossy. The color is dull white. The measurements of 52 eggs average 54.2 by 43.4 millimeters; the eggs showing the four extremes measure 58.7 by 49, 48 by 42, and 53.4 by 41 millimeters.

Plumages: The three, presumably very small, young found in the nest by Dr. Richardson (Swainson and Richardson, 1831) are described as "covered with a whitish down." Two that I examined in the Biological Survey collection, evidently the two taken by Mr. Preble, referred to above, are about 7 inches long and perhaps two weeks old; they are scantily covered with "olive-brown" down, which is just replacing the long white down of the earlier stage, the latter attached to the tips of the new down.

A young bird in my collection, taken in Alaska on August 6, shows the wings and tail nearly grown and like those of the adult; the under parts are still in the soft, downy, juvenal plumage, each feather grayish white, with three or four dusky bands and broadly tipped with white; the juvenal feathers of the back and wing coverts are "olive-brown", broadly tipped with white; the long fluffy down on the flanks and thighs is grayish white, obscurely banded with pale dusky; similar down around the neck is banded with "olive-brown" and pale buff; the adult plumage is coming through on the back, scapulars and wing coverts; the facial disks and the shape of the head are not yet developed.

An older bird, taken in Alberta on September 8, is practically fully grown and in nearly fully adult plumage; the head and facial disks are like those of the adult but smaller; the upper parts are fully feathered, but there is still some downy plumage on the throat and under parts.

Adults apparently have a complete annual molt ending in November and December; an adult female, taken on December 11, had nearly completed the molt of the wings, and the body molt was in progress; two others were molting in these two months. Ii. S. Swarth (1930) reports a bird taken on July 28 that was "beginning the annual molt. New and old flight feathers appear in the wings."

Food: The food of the great gray owl consists mainly of the smaller mammals, such as young rabbits and hares, squirrels, rats, mice, and shrews, with occasionally a few small birds. Mr. Swarth (1930) found in the stomach of one an adult red squirrel, "the animal's head bitten off, but swallowed otherwise entire. The owl was shot at 5 p. in., and as digestion had not begun upon the carcass the squirrel evidently had been killed and eaten in broad daylight, revealing diurnal activity on the part of this owl, which I had not suspected of it."

Dr. A. K. Fisher (1893b) reports that of nine stomachs examined, one contained a small bird, seven mice, and four other mammals. He also says: "Dr. W. H. Dall took no less than thirteen skulls and other remains of red-poll linnets (Acanthis) from the crop of a single bird."

Francis H. Allen (1904) saw a great gray owl near Dedham, Mass., on February 7, 1904. "It held in its claws a dead and partly eaten crow, which when it was finally dropped by the owl in flight, I found to lack the head and fore part of body and the viscera."

Behavior: The great gray owl is apparently a very tame and unsuspicious bird, or a very stupid one. Mr. Allen (1904) says of his bird:

The owl seemed perfectly fearless of me, but showed nervousness when the crows cawed nearby, and followed with its eyes the flight of the single crows that flew over its tree from time to time. I drove it about from tree to tree with snowballs. It flew low and always took a rather low perch: from ten to twenty feet from the ground, and usually on a large branch of a pine tree, near the trunk, though twice it alighted on the very top of a red cedar. I could get as near as height of its perch permitted and ~vas frequently within twenty feet of it during the hour or two that I spent in its company.

Dr. Fisher (1893b) says:

Dr. Dall considers it a stupid bird and states that sometimes it may be caught in the hands. Its great predilection for thick woods, in which it dwells, doubtless to the very limit of trees, prevents it from being an inhabitant of the barren grounds or other open country in the North. It is crepuscular or slightly nocturnal in the southern parts of its range, but in the high North it pursues its prey in the daytime. In the latter region, where the sun never passes below the horizon in summer, it is undoubtedly necessity and not choice that prompts it to be abroad in the daylight. It is stated that the flight is heavy and somewhat labored, and has not the buoyancy noted in that of most of the Owls.

Mr. Henderson (1923) writes: "As I was looking through my glass at one of the birds about four hundred yards away it started to fly toward me. It came sailing along about two feet from the ground and finally lit on a fence post in front of me which I found afterwards to be just eleven paces distant. It stayed there, staring at me for about a minute and then flew to a small dead snag, and from there to the ground and then to a small stump about two feet high."

In another article (1915) he tells of the behavior of the owls at the different nests that lie found. In several cases he had to rap vigorously on the tree to snake the owl leave the nest; in one case "the bird remained on the nest until it was touched by the hand." Once, when the owls were perched in a low tree, he "walked right under both birds only a few feet beneath them and neither flew, only turned their heads and stared at" him as lie passed.

Voice: Mr. Henderson (1923) says of the notes of this owl: "A rather musical whistle was uttered frequently like oo-ih, sometimes very softly, and at others quite loudly. They also hooted several times, a deep booming Who-oo-oo-oo." Several authors have referred to the voice of this owl as a tremulous, vibrating note, somewhat resembling that of the screech owl.

Field marks: This is our largest owl in over-all dimensions, but not in bodily bulk or weight. Its wings and tail are very long and broad, giving it great expanse in flight. It has a very large, round head, which seems out of proportion to the rest of its outline, with no ear tufts. Its general color is dark gray. It can be distinguished from the barred owl, the other round-headed large owl, by its much greater apparent size and by its relatively smaller yellow eyes.

Winter: Edward H. Forbush (1927) writes:

When the northern forests fail to produce cones for winter food of small arboreal birds; when deep snows cover the runways of mice, and grasses and weeds that feed ground-birds and when bush rabbits and ptarmigan are scarce in the northern wilderness; then we may expect an unusual invasion of Great Gray Owls. Such a combination of circumstances probably does not occur often, but in the winter of 1842: 43, according to Dr. Samuel Abbott, seven of these birds were taken in Massachusetts, and probably many more were seen and went unrecorded. In the winter of 1890: 91 such numbers of this species were killed in eastern Maine that Mr. Grosby, taxidermist of Bangor, received 27 specimens. Some birds from this flight reached eastern Massachusetts, where a few were taken. * * * The bird is reported here and there in northern New England nearly every winter, but is noted seldom in any of the three southern New England states. Although it is a forest bird, it may be found almost anywhere in winter outside the cities and very rarely even within city limits, but it prefers deep woods, and as it is here chiefly in winter and moves about mainly at night, it is rarely seen.

In his paper on the birds of Toronto, Canada, J. H. Fleming (1907) thus refers to it:

Winter migrant of irregular occurrence. The great flight that took place in the winter of 1889: go is recorded by Mr. Win. Gross. "I have received twenty three specimens, and have had them reported from various parts of the Province. One of my acquaintances stationed at Barrie, received twenty-six this season. They began to come into this region in November, and increased in numbers up to February, after which they became very scarce again." This is the largest flight recorded, but specimens have been taken in December 1890, January 1894, January and March 1895, and January and February 1896; the visits appear to have ceased after this.


Range: Northern parts of the Northern Hemisphere.

Breeding range: In North America the breeding range of the great gray owl extends north to Alaska (Nulato, Nenana, Saicha Slough, and Fort Yukon); Yukon (La Pierre House); and northern Mackenzie (Lbckhart River). East to Mackenzie (Lockhart River and Fort Resolution); and Alberta (Fort Chipewyan and Whitemud Lake). South to Alberta (Whitemud Lake); southern Mackenzie (Fort Providence, Willow River, mouth of Nahanni River, and Fort Wrigley); and central Alaska (Birch Lake and Hooper Bay). West to western Alaska (Hooper Bay, Yukon Delta, and Nulato). See also casual records below.

There are a few observations in more southern latitudes at dates that suggest nesting. Among these are: Quebec, an individual seen near Riviere Madeleine, Gas$ County, on August 16, 1924; Minnesota, one seen on July 12, 1928, at Bigfork, northern Itasca County; Montana, three, believed to be immature were seen on July 4, 1931, near Stryker, and an old-time trapper and woodsman reported that one summer he had seen two adults with four young near Fortine.

Winter range: This species is not regularly migratory, but at times (probably owing to shortage of food) it extensively invades more southern regions. During winter it has been recorded north to Alaska (Diamond and Fort Yukon); Yukon (Fortymile); central Alberta (Athabaska Landing and Mundare); and Quebec (Montreal). East to Quebec (Montreal); and rarely Massachusetts (Marblehead, Boston, and Taunton). South to rarely Massachusetts (Springfield); New York (Fulton County, Painted Post, and Watson); southern Ontario (Toronto and South March); Michigan (Hiliman, Elk Rapids, and Salt Ste. Marie); Wisconsin (Racine and Iron River); Minnesota (Goodhue, Hennepin, and McLeod Counties); Montana (Billings, Buflalo-horn Creek, and Corvallis); and Oregon (Prospect and Mcdford). West to Oregon (Medford and Willamette River); Washington (Shoalwater Bay and Seattle); British Columbia (Chilliwack and Barkerville); and Alaska (Stikine Flats and Diamond).

Migration: The winter movement (when it occurs) appears to be as much to ~he east as to the south. Nearly all the records for the eastern part of the continent are for the period October to March.

Flights of considerable numbers of these owls passing eastward along Lake Ontario were observed in 1889: 90 and again in 1907.

Casual records: Great gray owls have many times been taken or observed in winter south of what seems to be their normal range. Among these records are the following: One reported as seen on the Humber River, Newfoundland, on August 28, 1899. One taken at Stratford, Conn., on January 6, 1843; another taken at North Haven in March 1907, while a third was reported as seen near the latter point on February 4, 1934. In 1887 one was recorded as having been shot near Mendham, N. J., "many years ago", and another was reported to have been killed in Sussex County in December 1859. One was reported as found in the smokestack of a steamboat at Erie, Pa., about 1900. There are two incomplete records for Clark County, Ohio, and an unsatisfactory record for Huntsburg. A specimen was taken near Fowler, Md., during the winter of 1897, and another was collected at Hoveys Lake, Posey County, "some years before 1913." One was taken at Hillsboro, Iowa, in 1860, and another was captured alive at Sigourney on April 25, 1921. A specimen( was taken at Omaha, Nebr., on December 17, 1893. There are a few records for Yellowstone National Park, Wyo., and one was collected at Wells in April 1899. In southern Idaho a specimen was taken in December 1910 at St. Anthony. One was taken at McCloud, Calif., on September 26, 1913, while there are three records from Quincy, one being a specimen collected on May 12, 1894.

Closely allied races of this owl are found in northern Europe and Asia.

[AUTHOR'S NOTE: This owl may breed regularly within the limits of the United States, as the following two records, which must for the present be considered as casual, seem to indicate. On June 18, 1915, Grinnell and Storer (1924) collected in the Yosemite region a pair of great gray owls that had almost certainly bred near there and found a nest that probably belonged to this pair. More recently, Dr. Thomas S. Roberts (1936) has reported the taking of a nest and eggs of this owl in northern Minnesota, on April 4, 1935.]

Egg dates: Alaska and Arctic Canada: 3 records, May 15, June 19, and July 19.

Alberta: 15 records, March 23 to May 15; 8 records, April 9 to May 1, indicating the height of the season.

now Great Gray Owl - Strix nebulosa  



The above name appears in our latest Check-List (1931) in place of the Lapp owl (Scotiaptex lapponica), which has long been supposed to occur, as a rare straggler, from northeastern Siberia, on the Bering Sea coast of Alaska. The record of its occurrence here is based on a single specimen brought to Lucien M. Turner (1886) from the Yukon Delta, on April 15, 1876. But it now seems to be satisfactorily proved that Turner's bird, which is now in the United States National Museum, is not referable to the Siberian race. Therefore this race is not entitled to any standing as a North American bird and should be dropped from the Check-List.

Robert Ridgway, who originally recorded this specimen (1878) as lapponica, evidently changed his mind, for, in his latest work (1914), he says: "Specimens from the Yukon delta, Alaska, formerly referred to this form, prove to be rather light-colored examples of S. n. nebulosa."

Dr. II. C. Oberholser (1922) writes:

A recent study of available material fully confirms Mr. Ridgway's opinion, which indicates that Scotiaptex nebulosa lapponica should be expunged from our North American list. The specimens from the delta of the Yukon River, on which the North American record of this form was formerly based, are furthermore, no lighter than birds from Alberta in the collection of the Biological Survey in the United States National Museum, and are not to be distinguished subspecifically by either size or color from Scotiaptex nebutosa nebutosa.

The plate in Turner's work (1886) is misleading, as it shows a very light-colored bird; but, Dr. Oberholser tells me, this plate was not drawn from Turner's specimen but from a specimen of the Old World bird.