Western North America’s counterpart to the Eastern Screech-Owl, the Western Screech-Owl is broadly distributed but seldom seen due to its nocturnal habits. Western Screech-Owls are year-round residents, and are also territorial year-round. In some habitats where prey is abundant, the territories may be close together.
Natural cavities are used for nesting, as are old cavities excavated by flickers or Pileated Woodpeckers. Western Screech-Owl broods fledge at night, and do not return to the cavity once they leave it. A lifespan of up to thirteen years has been recorded in the wild, though most birds don’t live that long.
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Description of the Western Screech-Owl
The Western Screech-Owl is a small owl with grayish or brownish upperparts, short ear tufts, vermiculated underparts, and yellow eyes. There are brown forms and gray forms.
The sexes are similar.
Seasonal change in appearance
Juveniles resemble adults.
Western Screech-Owls inhabit desert and streamside groves and wooded canyons.
Western Screech-Owls primarily eat small mammals and insects.
Western Screech-Owls forage at dusk and at night, watching for prey from a perch and flying out to grab it.
Western Screech-Owls are resident across much of the western U.S. and Canada. The population is not well monitored.
Scorpions are among the prey items of Western Screech-Owls.
The male Western Screech-Owl brings food to the incubating female.
The songs include a series of whistles accelerating in cadence, as well as a whistled trill.
- Flammulated Owls are smaller and have dark eyes.
The Western Screech-Owl’s nest is in a tree cavity or large cactus cavity, often an old woodpecker hole.
Number: Usually lay 2-5 eggs.
Incubation and fledging:
The young hatch at about 26 days, and begin to leave the nest in about another 4 weeks, though continuing to associate with the adults for some time.
Bent Life History of the Western Screech-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 Western Screech-Owl – the common name and sub-species reflect the nomenclature in use at the time the description was written.
CALIPORNIA SCREECH OWL
OTUS ASIO BENDIREI (Brewster)HABITS
When William Brewster (1882a) named this race, he gave as its characters:
Above essentially similar to asio in its gray dress. Beneath ashy-white, everywhere thickly barred and streaked with black; the transverse bars being fine, numerous and regular, the shaft-stripes coarse and generally distributed from the throat to the crissum, both markings occurring as thickly on the median line of the breast and abdomen as along their sides. * * * The chief difference is in the ground-color and markings of the plumage beneath. In osie the central line of the breast and abdomen is nearly always immaculate, while there is frequently a broad, entirely unspotted golar space: in bendirei these parts are as thickly barred and streaked as are the sides, while the ashy tinge of the entire lower surface and the much finer character of the transverse pencilling gives the plumage a clouded appearance which, although difficult of description, is very characteristic. The ear-tufts, also, are usually shorter than those of S. asio.
This race inhabits the coast region of California, from near the Oregon line, where it intergrades with brewsteri, to the San Francisco Bay region.
Nesting: The nesting habits of the California screech owl are essentially similar to those of other screech owls. Mrs. Irene G. Wheelock (1904) found one nesting in a red-shafted flicker’s nest, sitting on three eggs of the flicker and two of the owl’s. The flicker’s eggs disappeared entirely, but the owl hatched out her own eggs. Mrs. Florence A. Sumner (1933) reports finding a brood of four sparrow hawks and one screech owl, which were all reared successfully by the hawks, in the same nest.
W. Otto Emerson (1885) succeeded in getting a pair of these owls to nest in a starch box, with some leaves and sawdust in the bottom of it, which he had nailed up on a tree in a grove. He adds further: “I found one the past Spring that had taken up quarters in an old wood rat’s nest placed on a limb of a Bay tree, some thirty feet from the ground. A large mass of dead leaves from the tree had been put together, and a hollow formed in the centre, lined with feathers of fowls and birds.”
Eggs: The California screech owl lays three to five eggs, which are like those of the eastern screech owl but average slightly smaller. The measurements of 45 eggs average 34.8 by 29.9 millimeters; the eggs showing the four extremes measure 38 by 28, 36 by 32, and 32 by 28 millimeters.
Plumages: Dr. Louis B. Bishop, who has good series of all the different California races of the screech owl, tells me that they all have two color phases, a brown and a gray one, but no red phase as in the eastern bird.
Food: The California screech owl is apparently rather more beneficial than otherwise in its food habits. Where English sparrows are numerous it seems to show a decided preference for them. In a nest in a large oak on the University of California campus, Ernest D. Ciabaugh (1926) found as many as six English sparrows in the nest at one time, and others on three other occasions; he also found wing feathers of birds, mostly sparrows of different species, feathers of a California jay, a pocket gopher, meadow mice, a salamander, and a large beetle. One of the young, which had been injured by a fall, was apparently eaten by its nest mates.
now Western Screech-Owl – Otus kennicotti
KENNICOTT’S SCREECH OWL
OTUS ASIO KENNICOTTI (Elliot)
This large, dark-colored screech owl is found in the humid, northwest-coast region, from Sitka, Alaska, to northwestern Washington. Ridgway (1914) describes it as: “Large, like 0. a. macfarlanei, but coloration much darker and browner, the general tone of upper parts inclining, more or less strongly, to tawny brown, with lighter markings brownish buff or pale cinnamon, the under parts more or less strongly suffused with pale cinnamon, the legs (especially thighs) light tawny; gray phase (which is relatively rare) similar to 0. a. bendirei and 0. a. macfarlanei but very much darker (the general color of upper parts approaching fuscous) and with lighter markings light brownish huffy instead of white, and the under parts much more heavily penciled and spotted.”
J. Hooper Bowles (1917a) says of the haunts of this owl: “The most favored localities are in the immediate vicinity of water, either fresh or salt, where the country is to some extent open. Deciduous timber seems to be given a slight preference over the fir woods, as a rule, though during the day the birds are usually found hiding amongst the dark foliage of some young fir.”
Nesting: He says that the nests are very rarely found, and that “the eggs are almost invariably deposited in natural hollows in trees, the only exceptions being extra big holes made by the Northwestern Flicker (Colaptes cafer saluratior). One of these two cases was a hole that had been excavated to a depth of only about six inches, in a lone dead fir stub that stood in a vacant lot in the city. A most unusual nesting site in every way for these owls, as the cavities used are most often two or three feet in depth and situated in well wooded localities. The nests that I have seen were placed from four to twelve feet above the ground, but it is impossible to say what the average height may be in this country where trees two hundred feet tall are the rule rather than the exception.”
F. R. Decker (1912) mentions a nest that he found about 60 feet from the ground in a cavity in a cottonwood tree; doubtless these lofty cavities are seldom investigated by collectors.
Eggs: Kennicott’s screech owl lays two to five eggs. Mr. Bowles (1917a) says: “I think that complete sets will usually be found to contain three eggs, although two are nearly as often the full number. In only one instance have I seen as many as four. In color they are pure white and somewhat glossy, with more or less nest stain according to the state of incubation. They are usually nearly spherical in shape, like the eggs of most owls, but occasionally there is a slightly elliptical tendency.”
He evidently changed his mind, as to the number of eggs laid, for, in an earlier article (1906a) he says that the eggs “are from two to four in number, four being most commonly found.” Mr. Decker (1912) mentions two sets of four and one of five.
The measurements of 33 eggs average 37.8 by 32 millimeters; the eggs showing the four extremes measure 42 by 35.6, 33.3 by 31, and 35.3 by 30 millimeters.
Plumages: Kennicott’s screech owl has two well-marked color phases, a gray one and a brown one, which are described above. The color phases in this race are more pronounced than in the other Pacific coast races, and more generally recognized, though nearly all the races, if not all of them, show some tendency to dichromatism.
Food: Mr. Bowles (1917a) has published some interesting items on the food of this owl; he says that a: bird was taken on January 6, 1917, at which time the thermometer was somewhat above freezing with no snow on the ground. The stomach contained eleven cutworms, two centipedes, one mole cricket, one good sized beetle, and other insect remains. With all this on the credit side of their ledger, these owls are at times subject to some most astounding falls from grace. The fact dees not reflect very greatly to their credit that nests containing incubated eggs or young are usually well sprinkled with the feathers of smaller birds. However, this might be more or less natural if rodents and other small animals were scarce, but the following incidents seem beyond all comprehension. One friend told me that he heard an outcry among the ducks in his yard one night and, upon going out with a lantern, “found a Screech Owl riding around on the back of one of his big ducks, hanging onto its neck.”
Then he goes on to tell of the experience of his friend, Dr. G. D. Shaver; a pair of these owls: came and nested on his place within a short distance of his pens of gamebirds and fancy bantams, and, as the entrance of the nest was only four feet from the ground, the doctor took great pleasure in watching the sitting bird and her family as they grew up. One morning during the winter of 1914: 1915, which was a very mild season, he was nearly overcome upon visiting his yards to find two dead Golden Pheasants, four dead Ring-necked Pheasants, and one Ring-neck cock so badly hurt that it died a few days later. All were, of course, grown birds at that time of the year. The injuries were nearly all gashes and rips in the head and neck, so the blame was laid to rats although none were ever seen or caught there. * * * On the morning of February 4, 1916, the doctor visited his yards and found a scene of murder similar to that of the previous year. In one pen were four of his prize Buff Coehin Bantams mangled and dead, some being in their house and others out in their yard, while in another pen were two fine cock Golden Pheasants in a similar condition. The wounds were similar in location and character to those made on the birds killed about a year before, but this time part of the head of one of the bantams had been eaten. There was no indication whatever of what had caused the damage, nor of how any predatory creature could have entered, so the doctor put a liberal dose of strychnine into the body of the partly eaten bantam and replaced it in the same spot where he found it. Next morning the seemingly impossible was made a practical certainty, for he found the body of a screech owl with the claws of one foot firmly imbedded in the body of the bantam.
Elsewhere, Mr. Bowles (1906a) says: “On one occasion at an evening lawn party in the city, one of these owls spent more than half an hour catching what I am positive were angle-worms. He would swoop down onto the lawn and stay for perhaps a minute, returning each time either to one of a small group of maples or to the roof of the house. It was too dark to distinguish what he was catching, but he paid no more attention to the people walking near him than an occasional turn of the head, busying himself with poking about in the short grass with his bill.”
S. F. Rathbun writes to me: “In my collection is a fine specimen of this owl, which I collected after dusk one night in spring. At the time the owl was lurking about the eaves of a barn on a farm. I had an idea that the owl was after some cliff swallows that were nesting under the eaves of the outbuilding. But I did the bird an injustice, I think, for when I skinned it I found its stomach and gullet packed with ants, the large, black pismires sometimes found so common about farm buildings. The owl was so full of the insects that a few of them hung from the corners of its mouth, and its stomach was hard to the touch, so tightly was it packed with ants. I have always regretted that I shot the bird.”
Mr. Bowles (1906a) writes:
During the greater part of the year these owls are entirely beneficial, their food consisting mostly of mice. Large beetles are often added, and nearly every small stream shows signs of where an owl has successfully angled for craw-fish, carefully splitting and picking the meat from the shell. After the eggs are hatched, however, the parents are at their wit’s end to procure food enough for the hungry babies, and it is at this season only that birds are used in the bill of fare. The northwestern flicker seems to be found especially delectable, tho feathers of the Steller jay, western robin and a few other species are sometimes found in the hole with the young. Curiously enough it is most unusual to find remains of juncos, sparrows or other small-sized birds; and, all things considered, these owls unquestionably do many times as much good as they do harm.
Voice: In the same paper Mr. Bowles says on this subject: “The high-keyed, tremulous hooting cry of these birds is, strangely enough, most often heard during the fall months. In spring and summer, tho repeatedly spending the night in localities where they were tolerably abundant, I have never heard them utter a note of any description.”
now Western Screech-Owl – Otus kennicotti
ROCKY MOUNTAIN SCREECH OWL
OTUS ASIO MAXWELLIAE (Ridgway)
This large, pale race is the whitest and, to my mind, the handsomest of our screech owls. Ridgway (1914) describes it as: decidedly larger and very much paler than 0. a. aikeni; nearly as large as 0. a. macfarlanei and 0. a. kennicottii, but conspicuously lighter than any other form, with the white purer and more extended and the colored parts paler; ground color above pale gray or grayish brown, relieved by the usual ragged mesial streaks of black and irregular mottlings and vermiculations of lighter and darker shades of grayish, the general color more rufescent, and no darker than very light ash gray or drab; white spots on outer webs of primaries frequently confluent along edge of quills, the darker spots sometimes hardly visible on proximal portion when wings are closed; under parts with pure white greatly predominating.
Its range is given in the 1931 Check-List as “foothills and plains adjacent to the eastern Rocky Mountains from eastern Montana and western South Dakota to central Colorado.” I suspect that it may range even farther north along the eastern edge of the mountains. It is said to be resident all through the year throughout its range.
Robert B. Rockwell (1907) writes:
Both Denis Gale and W. W. Cooke state that M. a. maxwellae rarely ascends higher than 6000 feet, which would preclude the possibility of its extending more than a few miles up into the foothills, and the most easterly record is recorded by Cooke as “30-miles out on the plains”, probably referring to the Loveland, Colorado, record of W. C. Smith. * * * From this it will be seen that maxwellae is strictly a foothills form, inhabiting a long, narrow strip of country running in a general north and south direction and closely adhering to the base of the eastern foothills of the Rocky Mountains. * * *
The Rocky Mountain Screech Owl * * * is a resident thruout the year all along the eastern base of the foothills in the north central part of Colorado, but its hunting and breeding grounds are closely restricted to the well wooded creek bottoms, the only locations in this sparsely timbered region which afford him proper food, nesting sites and means of concealment.
As to whether this bird performs a slight north and south movement at migration periods, there seems to be a difference of opinion. Some observers declare that Megascops leaves its summer home around Denver, and moves south as far at least as Colorado Springs (75 miles), and its breeding grounds are occupied as a winter home by migrants from farther north. Others claim that it spends the entire year in the same haunts, laying its eggs in one of the many cavities occupied during the winter. Whichever view of the matter is correct, it is a fact that thruout the year the “owl stumps” so dear to the memory of every bird student, are occupied by these birds, and it is seldom indeed that a good sized grove of aged timber, with a few dead stumps scattered thru it, will not contain a pair of Screech Owls.
Nesting: The same observer says on this subject:
As has been stated before the nesting site is invariably along the well wooded water-courses and in more or less dense groves of cottonwoods and occasionally willow or box-elder. A peculiar characteristic of this bird is its predeliction for sluggish or stagnant water, and one of the prerequisites of a model nesting site is a small slough or pool within a short distance of the nest hole. I am at a loss to know why this is so, unless it is that frogs and crawfish form no inconsiderable portion of the bird’s food, and close proximity to a source of food supply may be a solution of the problem.
The very great majority of nests are found in cottonwood trees. This is probably due to the fact that this tree greatly predominates along all the foothill streams, and it is the variety most commonly used by the Red-shafted Flicker, the deserted excavations of which the Screech Owl nearly always occupies. However, natural cavities are occasionally resorted to; but owing to the nature of the trees these are found mostly in box-elder or black willows, the cottonwood rarely rotting out in this manner.
Major Bendire (1892) says that the first nest of this subspecies was discovered by A. W. Anthony on May 4, 1883, in the trunk of a large cottonwood; the nest contained three young about a week old and an addled egg; it was in a knothole within 4 feet of a new nest being excavated by a red-shafted flicker, but on the opposite side of the trunk. He says, also, that Mr. Anthony thinks that this screech owl breeds also in the abandoned nests of the black-billed magpie, as he has often found them roosting in them both in winter and spring. Both Denis Gale and William G. Smith told him that they had found them nesting in such places.
Eggs: Mr. Rockwell (1907) says:
The great majority of full clutches contain four eggs, tho occasionally three or five are deposited. In the twenty-five sets it has been my good fortune to examine in the nests, the following sets were found: One of 2, five of 3, fifteen of 4, two of 5, one of 6 and one of 7. The set of 2 was a second clutch, the first set of 4 having been taken 23 days previously to the date upon which the set of 2 was found in which incubation was about a fourth advanced. The comparatively large number of sets of three conveys a wrong impression, and is probably due to a little overanxiety to collect the eggs, not giving the parent sufficient time to complete the clutch. I believe one in fifteen sets would he nearer the proper ratio of sets of 3 and 4. The set of 6 was laid by a particularly prolific female which had laid sets of five on the two preceding years; while the set of seven I cannot account for unless it was laid by two females, which is very improbable. This was found May 30th, two birds were flushed from the cavity, and all seven eggs were addled.
Major Bendire (1892) says: “The eggs of the Rocky Mountain Screech Owl are pure white in color and moderately glossy; the shell is smooth and finely granulated. In shape they vary from oval to a broad elliptical oval, some being decidedly more elongated than any other eggs of the genus Megascops I have seen.”
The measurements of 54 eggs average 36.3 by 30.2 millimeters; the eggs showing the four extremes measure 39.1 by 32.1, 36.1 by 32, 30.9 by 30.7, and 35.7 by 27.9 millimeters.
Young: Bendire (1892) says: “In the latter part of June, before they are well able to fly, they may be seen sitting side by side, perfectly motionless, upon a limb close by the nest site. The young and their parents seem to desert their holes and live among the trees for the balance of the summer; but when the cold winds strip the leaves from the trees in the fall suitable tree holes are selected for their winter quarters.”
Plumages: This race is supposed to be monochromatic, but Dr. Louis B. Bishop writes to me that he has a specimen of this race in the red phase, collected in Saskatchewan, which he and Dr. H. C. Oberholser both agreed to identify as maxwelliae, though it is apparently the only red specimen known. He says that the red phase agrees with the gray phase in being very pale, with the facial disks, tarsi, and toes white, and that the red is paler and slightly browner than in the red phase of naevius from Connecticut.
Food: Major Bendire (1892) says that Mr. Anthony found “a good many fish scales” in a nest of one of these owls, and that Denis Gale found feathers of the mountain bluebird and several sparrows in a nest. He quotes him as saying that the female, while incubating, “is waited upon and fed by the male, who, being a skillful hunter, provides liberally for her wants. Searching for nests I have sometimes discovered the male hidden in a tolerably well stocked larder, in close proximity to the nest site. In one cache were portions of a Bluebird, a mouse, and a frog; in another a Junco, a Tree Sparrow, and a minnow 3 ~ inches long; claws and legs of crawfish were also present.”
Behavior: He quotes Mr. Dale further as follows:
Like others of their genus they seem to delight in a sheltered, shady location, close to a pond or creek where they select a domicile, either in a natural tree hole or in a Flicker’s old nest site. If for any reason the Flicker wishes to retain his previous year’s nest site, and Scops is in possession, strife is carried on between them with great vigor, ending as often in favor of one as the other, judging from the broken eggs upon the ground ejected by the victor. The Flicker dares not enter to turn Scops out, but if the premises are vacated for ever so short a time, he enters and holds them against all corners. His formidable bill pointing out at the door is sufficient apology for leaving him in quiet possession.
Again, when the female is taken off her eggs: “In some instances she will feign dead and lie on her back in your open palm with her eyes shut. Immediately you throw her off, however, she will right herself on wing, and gaining a bough on a neighboring tree will crouch forward, bending her eartufts back and look very spiteful and wicked. At other times when removed from her eggs she will snap her bill, moan slightly, and show fight.”
Mr. Rockwell (1909) says that this screech owl makes frequent use of the abandoned nests of the black-billed magpie “when not occupying a cavity in a tree. It is a rather amusing spectacle to see a round, fluffy little screech owl (dislodged from his cosy corner in a hollow tree) making desperate efforts to reach the nearest magpie nest before the noisy throng of mischief-loving magpies overtakes him, and even more comical to see the plain look of disappointment and incredulity upon the ‘countenances’ of the pursuers, as the owl reaches the welcome refuge and instantly merges himself into its surroundings; for strange as it may seem magpies will not follow an owl into an abandoned nest, and seem utterly at a loss to understand the prompt disappearance of the object of their pursuit.”
Winter: That the Rocky Mountain screech owl remains all winter throughout its more northern breeding grounds is indicated by the following account by Major Bendire (1892):
While stationed at Fort Custer, Montana, during the winter of 1884: ’85, I took five of these birds, but was unable to find their nests. I discovered their presence quite accidentally. On December 1,1884, while out hunting Sharp-talled Grouse in a bend of the Big Horn River, a few miles south of the post, as I was walking by a thick clump of willows I indistinctly noticed a whitish looking object dropping on the ground, apparently out of the densest portion of the thicket and on the opposite side from where I was standing at the time, and simultaneously heard several plaintive squeaks from that direction. Carefully skirting around the thicket, which was some 20 yards long and perhaps 5 yards wide, I saw the object of my search savagely engaged in killing a meadow mouse which it had just captured. I promptly shot it. It proved to be a female and excessively fat; in fact all the specimens I secured subsequently showed conclusively that they managed to secure an abundance of food in that Arctic winter climate, and that a portion of this at least seems to be obtained in the daytime. The four other specimens collected by me were all obtained in similar locations.
Dr. Joseph Grinnell (1928a) has described a new race of the screech owl from eastern California, which he calls Otus asio inyoensis. He says that it is “characterized in comparison with other southwestern races by large size and extremely pale coloration; ground-color of dorsum near drab-gray; streaking of both upper and lower surfaces narrow, sharply outlined, and black; white about head, on lower surface of body, and on feathering of legs, clear and extensive.” He says that it most closely resembles mazwelliae, but differing from it “in still paler, more ashy and less brownish tone of general coloration; dark vermiculation beneath and on legs more sootily black; the white spots on the outer webs of primaries in closed wing much the smaller in inyoensis, and the intervening correspondingly broader dark bars decidedly grayer in color.”
now Western Screech-Owl – Otus kennicotti
MEXICAN SCREECH OWL
OTUS ASIO CINERACEUS (Ridgway)
The Mexican screech owl occupies the Upper Austral Zone in central Arizona, southern New Mexico, central western Texas, and parts of Lower California and Sonora. Further remarks on the local distribution of this race, in relation to the closely related gilmani, will be found under that race.
Ridgway (1914), under the common name Arizona screech owl, describes this race is “similar to 0. a. aikeni, but more delicately penciled, both above and below, the pencilings on under parts averaging denser or more numerous.”
Nesting: Major Bendire (1892) says:
In the oak regions of southern Arizona they nest in the natural cavities of these trees, most 0? which are hollow. On March 26, 1872, I found one of their nests in an old woodpecker’s hole in a willow stump not more than 7 inches in diameter and about 6 feet from the ground. The cavity was slightly over 2 feet deep, and the four eggs it contained, which had been incubated for a few days, were lying on bits of rotten wood and a few dead leaves, not sufficient to call a nest. The female was at home and had to be taken out forcibly, protesting and uttering a hissing sound, and, after being turned loose, snapping her mandibles rapidly together from her perch on a small walnut tree, into which she had flown. I was in hopes she might continue to use the same sits again, but was disappointed in this.
On April 16, 1922, in a row of immense cottonwoods along an irrigation ditch, near Fairbank, Ariz., we found one of these owls asleep in a lofty hole in one of these trees. Again, on May 17, in the same region, we found another in a cavity in a low willow. But there were no eggs in either hole.
Eggs: Major Bendire (1892) says: “The number of eggs laid is usually three or four, rarely five. They are similar in shape and color to those of the rest of this genus. Now and then a set is found which is so badly stained by the excrement of fleas inhabiting their burrows in large numbers that the eggs, judging by their color, might be taken for those of the Sparrow Hawk.”
The measurements of 37 eggs average 34.3 by 28.8 millimeters; the eggs showing the four extremes measure 35.5 by 29, 34.9 by 29.9, 32 by 28.8, and 34.1 by 24.1 millimeters.
Plumages: This screech owl seems to be wholly monochromatic, as nothing approaching a gray or a brown phase has yet been discovered, the universal color being pale, ashy gray.
Food: Mrs. Florence M. Bailey (1928) lists, as the food of the Mexican screech owl, “kangaroo rats, gophers, mice, rats, small birds, frogs, lizards, snakes, crawfish, scorpions, grasshoppers, locusts, and beetles. It is one of the most insectivorous of our owls.”
Behavior: Henry W. Henshaw (1875) writes:
This bird was very common both in Arizona and New Mexico, and is, I think, the most numerous of the family in this region. Whenever our camp chanced to be made near one of the groves of oaks, which are numerous, these owls were sure to be heard soon after dusk, and, not infrequently, several would take up their stations in a tree within a few feet of the camp fire, and remain for an hour or more, apparently to satisfy their curiosity, uttering, from time to time, their low, responsive cries. Their notes vary much in length, but, when full, consist of two prolonged syllables, with quite an interval between, followed by a rapid utterance of six or seven notes, which, at the end, are run together. They are very sociable in their disposition, and, as soon as it is fairly dusk, the first call of a solitary bird may be heard issuing from some thicket, where it has remained in concealment during the day. After one or two repetitions, this will be answered by another, perhaps half a mile away, and soon by a third and a fourth, apparently all coming together; and I have heard at least eight of these owls, congregated within a short distance in the tree tops. When the band was complete, they would move off, still apparently keeping together, till their notes were lost in the distance.
Enemies: Mrs. C. J. Whitfield (1934), of Globe, Ariz., tells the following interesting story:
A heavy flapping of wings attracted our attention to an Arizona oak tree (Quercus erizonice) about five yards from the house. Approximately 12 feet from the ground, and quite close to the trunk, a snake over three feet long (probably Pifuophis catenifer rutilus) hung suspended by its tail from a small dead limb. The large part of the snake’s body was coiled once around a small owl, judged from its color and size to be a screech owl (Otus asio cineroceus). The bird struggled more and more feebly for three or four minutes, and finally was still.
When we shot the snake, its body grew slack, and its tail loosened its hold on the limb and began to slip. The owl freed itself and flew away, seemingly uninjured. The owl had apparently been roosting in the tree, and was “stalked” and caught by the snake.
now Western Screech-Owl – Otus kennicotti
AIKEN’S SCREECH OWL
OTUS ASIO AIKENI (Brewster)
The A. 0. U. Check-List (1931) gives the range of this subspecies as “foothills and plains of eastern Colorado and Kansas north to northeastern North Dakota and northwestern Minnesota and south to New Mexico.” Ridgway (1914) extends its range farther southward into western and central Texas, arid into northern Durango.
William Brewster (1891) describes it as “of about the size of MLegascops] bendirei, with the ground color more ashy; the dark markings coarser, and more numerous and conspicuous, than in any other North American member of the genus.” Ridgway (1914) describes it, from another angle, as “similar to 0. a. cineraceus but larger, the upper parts more coarsely mottled or vermiculated and with blackish mesial streaks broader and more strongly contrasted with the general color; blackish pencilings of under parts heavier, rather less numerous. Smaller and much darker than 0. a. maxwelliae.”
Mr. Brewster (1891) says: “I had the skin of Mr. Aiken, who, if I remember aright, asserted that it was a fair representative of the form which inhabits cottonwood timber along streams in the plains region about Colorado Springs, mazwelliae, of which lie showed me several typical specimens, being confined to the neighboring mountains.”
Nesting: Charles E. H. Aiken (Aiken and Warren, 1914) says that he “has never found it anywhere except in cottonwood trees along the streams. * * * A pair bred in 1913 in a flicker’s hole in a tree on St. Vrain Street, Colorado Springs beside the home of Dr. W. W. Arnold, raising four young. The owls drove away the flickers which had bred in the hole the year before, taking possession for themselves.”
Major Bendire (1892) writes: “Dr. H. W. Shuffled, U. S. Army, found a Screech Owl breeding near Fort Wingate, New Mexico, which I think is referable to this subspecies. He took three well incubated eggs on April 18, 1887, from a cavity in an oak tree 10 feet from the ground, capturing alive both parents at the same time. I have seen photographs of these specimens, and they show every indication that the originals belonged to this race.”
There are two sets of eggs of this owl in the Thayer collection. One was taken at Rowse Junction, Cole., on May 9, 1899; the two fresh eggs lay on a lot of trash and rubbish in a cavity 8 inches deep in a live cedar. The other set of four eggs was taken in Decatur County, Kans., on April 13, 1913; the nest was in an abandoned flicker hole, 14 inches deep, in a poplar tree 18 feet from the ground; the eggs were deposited on decayed chips and a few feathers.
Eggs: Three or four eggs are usually laid by this owl; these are indistinguishable from the eggs of other screech owls of similar size. The measurements of 28 eggs average 36 by 30.7 millimeters; the eggs showing the four extremes measure 38.2 by 30.5, 37 by 35.9, 34 by 30, 36.5 by 29.4 millimeters.
Plumages: Aiken and Warren (1914) write: “January 9, 1904, a Screech Owl in the red phase was taken near Colorado Springs, the skin of which is now in the Aiken Collection. This skin was examined by Mr. William Brewster, who pronounced it to be typical Otus asio asw. Later Mr. H. C. Oberholser also examined it, and considers it to be the red phase of aikeni, and tells us that he has seen several other specimens of the red phase of this subspecies, and that while very close to the red phase of typical asio they may be distinguished by being slightly paler in color.” Dr. Louis B. Bishop writes to me that he also has the red phase of this race in his collection.
Voice: Mr. Aiken (Aiken and Warren, 1914) gives the following account of the notes uttered by a young female that he had in captivity:
Its baby or birdling call was like the smothered mew of a kitten; this was frequently uttered as a call for food or in answer to its name, or as a call to me for notice. After completing its moult this cry was not often uttered unless she was hungry and demanding attention. A note that was uttered when excited was a short wow, wow, repeated several times, reminding me of a puppy’s bark. This was uttered at times when very hungry and demanding immediate notice, and was also uttered as notice of the presence of a dog: very vehemently when a dog came into the shop. A note like cr-r-oo-oo-oo-oo-oo-oo uttered gently and so low as to be heard only a few yards away was seemingly a love note and was an affectionate greeting to me as it would be to her mate. Then another note similar, possibly the same under other conditions was like the whistling of ducks’ wings in overhead fight at night.
now Western Screech-Owl – Otus kennicotti
MacFARLANE’S SCREECH OWL
OTUS ASIO MACFARLANEI (Brewster)
This large race of the screech owl occupies an interior range in southern British Columbia, eastern Washington and Oregon, western Montana and Idaho, and northeastern California. Major Bendire (1892) says of its haunts: “MacFarlane’s Screech Owl is a constant resident wherever found and its habitat as far as known seems to be restricted to the timbered bottom lands of the lower sagebrush and bunch grass covered valleys and plains of the dry interior portions of the States above mentioned. It seems to avoid the mountains, and I do not believe that it is found at much greater altitudes than 4,000 feet.”
William Brewster (1891), in naming and describing this subspecies, characterized it as “of the size of M. kenicotti, but with the color and markings of M. bendirei. This race has a gray phase and a brown phase, but in the latter phase it is not as dark as kennicotti.
Nesting: Major Bendire (1892) writes: “Its general habits are in no way different from those of the other members of the genus Mega scops, excepting that on account of its larger size it is compelled to nest entirely in natural cavities of trees, the excavations made by the larger Woodpeckers breeding in the same localities, like Melanerpes torquatus and Colaptes cafer, being too small to accommodate them.”
He says of his first nest, found in southeastern Oregon on April 16, 1877.
This nest was found in a hollow willow stump, in a small grove of these and cottonwood trees among which I camped while on a hunt after waterfowl on Lower Silvies River, near Malbeur Lake, 20 miles southwest of Camp Harney, Oregon. The hole was about 5 feet from the ground, 18 inches deep, and contained six partly incubated eggs. There was no nest, the eggs lying on some rubbish which had accumulated in the hole; the female was caught on the nest, and beyond snapping her mandibles made no resistance; the male was not seen.
* * * In 1881 a pair of MacFarlane’s Screech Owls nested in a natural cavity of a good sized cottonwood tree, about 25 feet from the ground, and within 100 yards of my quarters, giving me ample opportunity to watch them. Whenever I rapped on the tree the occupant would stick its head out and look about, but did not fly away.
All the nests found near Walla Walla, Washington, were placed in natural ïcavities in cottonwood trees, from 15 to 30 feet from the ground, and invariably near water.
Eggs: Bendire says that the eggs “vary from three to six in number, usually four or five, and are deposited at intervals of one or two days. * * * The eggs like those of a]l owls are pure white in color, rather glossy, and mostly oval in shape; some are nearly spherical; the shell is smooth and closely granulated.”
The measurements of 39 eggs averaged 37.6 by 31.9 millimeters; the eggs showing the four extremes measure 39.3 by 32.2, 39 by 33.5, 35 by 31.5, and 37 by 30 millimeters.
Food: The feeding habits of MacFarlane’s screech owl are apparently similar to those of other screech owls; it has been known to kill domestic pigeons.
Bendire (1892) writes: “In two of the holes occupied by them I found trout froln 6 to 8 inches long and a small whitefish (Core gonus wilhiamsonii) about 10 inches long. It still puzzles me to know just how they manage to catch such active fish, but believe that, where obtainable, these as well as frogs form no inconsiderable portion of their daily fare, while the smaller rodents and grasshoppers supply the remainder. I do not believe it catches birds to any extent, and must be considered an eminently useful species.”
now Western Screech-Owl – Otus kennicotti
HASBROUCK’S SCREECH OWL
OTUS ASIO HASBROUCKI Ridgway
The screech owls of centrel Texas have been separated from mecalli under the above name. The 1931 Check-List says: “Central Texas, from Travis County to Palo Pinto and Dallas counties, and probably other adjoining counties.” Ridgway (1914) adds, with some doubt, Cooke, McLennan, Eastland, and Lampasas Counties, as probably within its range. He describes this race as “similar in pattern of coloration to 0. a. mecaliji but decidedly larger, darker, and much less buffy gray above, and under parts much more heavily penciled, the transverse bars, especially, being much broader, as well as more numerous; mottling of legs much darker brown; rufescent phase similar to that of 0. a. naevius.”
E. M. Hasbrouck (1889), for whom this owl was named, describes part of its supposed habitat as follows:
Eastland County, Texas, is situated between latitudes 32 deg 33 deg and longitudes 98 deg – 99 deg or a little northeast of the geographical centre, and is known throughout the country as the poorest and most unattractive portion of the State. The elevation varies from twelve hundred to sixteen hundred feet, and the entire County, as well as a number of those lying to the east, is one series of terraces, beginning a little west of Cisco and extending through Erath and Bosque Counties, until the valley of the Brazos is reached. Water is extremely scarce and the timber, although pretty generally distributed, is almost entirely of oak, and comprises four species, known as post-oak, bur-oak, black jack, and “shinnery.” This last is a short, stunted hush, frequently covering hundreds of acres and rarely exceeding four or five feet in height.
Nesting: George Finlay Simmons (1925) says of its nesting habits in the Austin region: “Nest location, 6 to 25, usually 16, feet up in natural hollow in cedar elm, live oak, post oak, or sycamore tree or stump, generally standing on creek bank; once in old woodpecker hollow in telephone pole in town. Hollow, sometimes bare, generally scantily carpeted with small decayed wood chips, a few feathers, or debris of dead leaves, twigs, straw, grass, Spanish moss, or crawfish crusts.”
Mr. Simmons (1915) describes a nest in another locality, probably of this subspecies, as follows: “April 5, 1913, in the woods on Buffalo Bayou about four and a half miles west of Houston, I found a nest in a natural hollow of an elm tree standing on the slope of the bayou; it contained four eggs, incubation far advanced. The entrance to the cavity was nine feet from the ground at a bend in the trunk of the tree; from the bend the cavity extended almost vertically down into the heart of the tree, about thirty inches deep and six inches in diameter; trunk of tree about ten inches in diameter. Only a few leaves and grasses, with a slight lining of feathers, were between the eggs and the bottom of the cavity.”
Howard Lacey (1911) writes:
A pair of these birds tried to breed in a small heating stove in the house in 1896 and again in 1897, coming down the stovepipe which had a double elbow and laying in the stove: they made too much noise scratching up and down the stovepipe and so had to be discouraged. They often lay their eggs in houses put up for the martins or for pigeons and I think destroy the young birds. In May, 1908, a pair nested in the martin box at the ranch. Finding a dead martin under the box, I got a shotgun and sent a friend up the pole to investigate: an owl flew out and was promptly shot and then my friend found three young owls in the box, and brought them down, and put them under a live-oak tree in the yard. The remaining parent fed the young for a night or two on the ground, bringing them, among other things, two or three sphinx moths and a crawfish, and then persuaded them to climb into the tree. The next evening my friend was smoking after supper and the owl knocked his pipe out of his mouth. The owl next attacked the lady of the house as she was bringing in the milk, and as a final exploit struck me full in the face as I was standing near the tree, using force enough to draw blood. The next morning the whole owl family was put to death.
Eggs: According to Mr. Simmons (1925), this owl lays three or four eggs, “sometimes 5, rarely 6, globular oval, pure white, with moderately smooth, finely granulated shell.” The measurements of 27 eggs averaged 34.8 by 30 millimeters; the eggs showing the four extremes measure 37.1 by 31, 32.5 by 30, and 35.7 by 28 millimeters.
Plumages: Dr. Louis B. Bishop tells me that in the red phase this owl is “bright red above, a paler and browner red than asio, with broad, black shaft streaks; the red is browner than red maxwelliae.”
Behavior: Mr. Hasbrouck (1889) says of this screech owl: “Common everywhere, and as bold and daring as others of the genus. I remember one occasion when I had a fine string of Teal hanging in camp. I was awakened by the hooting of one of these birds on a limb directly over my head and but a few feet above me; securing him and returning to rest, I had no sooner rolled up in my blankets than his perch was taken by another which, it is needless to say, followed the fate of the first.”
Voice: Mr. Simmons (1925) calls the voice a “weird, blood-curdling, quavering tremulo” and says: “There are two short notes, often uttered alone, occasionally used to begin the tremulous screech, a very low, short hoot, hoot, and a puttering, beating put, again, a low goop-goop.”
now Western Screech-Owl – Otus kennicotti
BREWSTER’S SCREECH OWL
OTUS ASIO BREWSTERI Ridgway
The range of this race is given in the 1931 Check-List as “Oregon, west of the Cascades, and Chelan County, Washington, south to Humboldt County, California.” Ridgway (1914) mentions only “western Oregon.” Dr. Louis B. Bishop has 11 Specimens, ten from Oregon and one from Humboldt County, Calif., which he refers to this race.
Ridgway (1914) describes it as “similar to 0. a. kennicottii, but smaller, and coloration much less brownish, the lighter markings on the upper parts less pronouncedly huffy, the under parts much less (sometimes not at all) Suffused with buff. (Intermediate between 0. a. kennicottii and 0. a. bendirei.)” It has a gray phase and a brown phase, intermediate between the phases of the two forms named above. This is admittedly an intermediate form which, in the author’s opinion, should never have been named.
Its habits are doubtless similar to those of the neighboring races. The measurements of 10 eggs average 37.3 by 31.2 millimeters; the eggs showing the four extremes measure 39 by 31.3, 38 by 32.5, 35.6 by 31.3, and 37.2 by 29.7 millimeters.
now Western Screech-Owl – Otus kennicotti
PASADENA SCREECH OWL
OTUS ASIO QUERCINUS Grinnell
According to the 1931 Check-List this race occurs in “southern California west of the desert region and along the western flank of the Sierra Nevada north to Mt. Shasta; also on the Pacific side of northern Lower California north of lat. 30o30~.~~
Dr. Joseph Grinnell (1915), in describing and naming it, says: “Characters in general like Otus asio beruiirei; differs in paler coloration: Light drab or ashy rather than hazel tones prevail dorsally, while beneath the black markings are sharper in outline, with very little or none of the ferruginous marginings. The restriction or absence of ferruginous on the chest, around the facial rim, and on the ear-tufts, is a good character.”
Nesting: There is apparently nothing in the nesting habits of this race that calls for special comment, as they are similar to those of other races. But an unusual nesting site is thus described by John McB. Robertson (1925): “April 29, 1923, I discovered a nest in a barkfilled crotch of a large eucalyptus tree beside our driveway, and only about twelve feet from the ground. The nest was well concealed by several years’ accumulation of bark and trash and when discovered contained one adult bird and three partly feathered young.”
Eggs: The Pasadena screech owl lays ordinarily four or five eggs, sometimes only three, and perhaps rarely six. These are indistinguishable from other screech owls’ eggs of similar size. The measurements of 46 eggs averages 35.4 by 30.2 millimeters; the eggs showing the four extremes measure 38.2 by 30.2, 35.8 by 31.8, 32.4 by 30.3, and 34 by 27.1 millimeters.
Young: E. Lowell Sumner, Jr. (1928 and 1929) has made some extensive studies of the development of young Pasadena screech owls and has published two papers on the subject, to which the reader is referred. The progress of their growth is not materially different from that of the eastern screech owl, which has been quite fully explained under that race. He says, however: “In closing, two features seem to deserve special mention. One is the fact that after the eggs had first begun to pip, more than three days elapsed before the time of hatching. The other is the unaccountable fluctuation in the weights of the youngsters, as illustrated by the graph.”
Plumages: The sequence of plumages to maturity is the same as given for the eastern screech owl. As in practically all the western races, adults are to some extent dichromatic, though the color phases are not so pronounced as in the eastern races. The gray phase of quercinus is lighter gray, and the brown phase is duller brown than in the more northern races.
now Western Screech-Owl – Otus kennicotti
SAGUARO SCREECH OWL
OTUS ASSO GILMANI Swarth
Ridgway (1914) does not recognize the validity of this race, and says, in a footnote under cineraceus: “With a considerable series of specimens before me, including those upon which 0. a. gilmani Swarth was based, I am quite unable to appreciate reasons for the recognition of that supposed subspecies; indeed, few of the recognized subspecies of the group present as great uniformity of coloration as does this series as a whole.” He also thought that the difference in size is insignificant, and he could not accept the theory of two subspecies occupying such closely contiguous territory.
Mr. Swarth (1916), however, seems to have explained the situation very satisfactorily, and to have established the validity of his race, alter an extensive study of a series of thirty screech owls from various parts of southern Arizona. He concludes that: there are two distinct types represented, cineraceus from the higher mountains, gillmani from the valleys of southwestern Arizona. Breeding birds from either region are true to type in their appearance. Extremes of the gilmani characteristics appear at points farthest from the known range of cineraceus (as at Phoenix and on the Colorado River). At one point at the margin of the habitat of gilmani (as I conceive it) there occur in winter examples of cineraceus.
There are certain facts in the distribution of screech owls in Arizona which deserve to be emphasized. My conception of Otus a. gilmani is of a bird of the hot Lower Sonoran valleys, and of Otus a. cineraceus, as one pertaining to Upper Sonoran, oak-covered foothills and canyons. But I believe that a sufficient representation of specimens would show the respective ranges of the two subspecies to be capable of definition on other terms than those of life zones. In southeastern Arizona, the region of the scattered mountain ranges where cineraceus occurs, the intervening valleys and plains, of vast extent, are for the most part grass covered, or else with but a sparse growth of mesquite or larrea, in neither case supplying habitable surroundings for the screech owl. Farther west, from the Santa Rita and Santa Catalina mountains westward, the endless stretches of Lower Sonoran plains where gilmeni is found are grown up nearly everywhere with the giant cactus, which supplies so many hole-dwelling birds with homes. In other words, in southwestern Arizona the Lower Sonoran zone offers congenial surroundings to screech owls, in southeastern Arizona for the most part it does not. In southwestern Arizona, Lower Sonoran is the only life zone represented, in southeastern Arizona the higher zones occur, with associational conditions acceptable to these owls.
In naming and describing this race, Mr. Swartli (1910b) gives as its characters: “Most like Otus asio cineraceus (Ridgway), from which it differs chiefly in slightly smaller size, paler coloration and greater restriction of dark markings. Above pale ashy, darkest on crown, each feather faintly vermiculated with dusky, and with a narrow dark median stripe. Under parts somewhat darker, but still with dark markings much restricted. Legs and toes white, sparsely marked with dusky.”
Nesting: We Spent May 21 and 22, 1922, exploring the dry, hot saguaro plains near Tucson, Ariz. Here the arid, stony ground was scantily covered with low mesquite and greasewood bushes, among which the picturesque candelabra of the giant cactus, with their crowns of white blossoms, were widely scattered. My husky companion, Frank C. Willard, carried upright on his strong shoulders an 18-foot ladder, with which we investigated the numerous cavities in these strange plants. There were very few saguaros that did not contain some of these nesting holes, and many had three or four. The holes were, doubtless, all originally made by Gila woodpeckers and Mearns’s gilded flickers, which were very numerous here. These holes last for many years, as the interior walls become crusted over and hardened, making ideal nesting sites, after the woodpeckers have abandoned them, for elf and screech owls, Arizona crested and ash-throated flyflycatchers, desert sparrow hawks, cactus wrens, and western martins. Among all this interesting collection of nesting birds, we found two families of saguaro screech owls, each with two young nearly half grown, on May 21. The next day we saw evidence of overcrowding in this thickly settled community of nesting birds; we saw an elf owl looking out of one of these holes, but when we chopped it out, we were surprised to find a screech owl sitting on three elf owl’s eggs.
So far as I can learn, the saguaro screech owl has never been found nesting anywhere but in the giant cactus (Cereus giganteus), and only where this cactus grows in the lowlands. Herbert Brown told Major Bendire (1892) that he had found them “nesting in holes of sahuaras within 4 feet from the ground, and from that distance up to almost the extreme top of the plant. The sahuaras along the river bottoms, and on the mesas bordering them, are their favorite nesting grounds.” He cut down a number of large saguaros in other places, at higher elevations, that were bored full of woodpeckers’ holes, but never found any owls in any of them; so he concluded that these owls nest only in the saguaros “growing in the lowlands and not those in the higher hills or out in the deserts.”
Eggs: The saguaro screech owl lays three to four eggs. These are like the eggs of other screech owls but smaller than those of the larger races. The measurements of 11 eggs average 34.1 by 29 millimeters; the eggs showing the four extremes measure 35.5 by 29, 35 by 30, and 32.5 by 27.5 millimeters.
Food: Mr. Brown (Bendire, 1892) says: “Small birds, kangaroo rats, gophers, different species of mice, lizards, scorpions, grasshoppers, and beetles are their staple articles of diet.”
Mrs. Florence M. Bailey (1923) found one in a cottonwood stub on the bank of the Santa Cruz River and says: “The pellets taken from the cavity contained bones of wood rat, kangaroo rats, pocket mice, deer mice, and a grasshopper mouse, the skull of one young Neotoma albigula, numerous jaws and bones of Perodipus ordii and Dipodomys merriami, together with a few jaws of Ferognathus eremicus, Peromyseus eremicus and sonoriensis, and Onychomys torridus.”
Voice: Dr. Loye Miller (1928) says of some that he heard repeatedly:
When whistling they invariably occupied a perch less than five feet from the ground, in dense willow tangle grown up from beaver cuttings to a height of twenty feet or more. Out of the midst of this brush, birds were repeatedly called (or stimulated or what you will) by imitating the whistled note. They came out into the moonlight and circled my body so closely that the faint bat-like flutter of the wings was plainly audible and one bird perched within two feet of me, where it was clearly visible in the moonlight. Otherwise they always returned to the depth of the thicket where the two birds collected were searched out with the electric flash light.
The song (?) of all individuals was the same in its composition, though the absolute pitch might differ by a major third. The composition of the performance differed from the customary note of the race of the San Diegan district (Otus asio quereanus Grinnell) in being made up of two tetrads of notes of equal tempo but with the first one pitched a half tone above the second. The final note of the second tetrad slides down to a slightly flatted pitch. I heard no other whistle from the Colorado River birds.
now Western Screech-Owl – Otus kennicotti
XANTUS’S SCREECH OWL
OTUS ASIO XANTUSI (Brewster)
This small, pale screech owl is known only from the southern part of the peninsula of Lower California, Mexico. Dr. Joseph Grinnell (1928b) says: “Common resident in the Cape district, whence reported from many localities, all south of La Paz. Apparently occurs from the coastal lowlands (Arid Tropical life-zone) up to the tops of the Victoria Mountains.”
William Brewster (1902) in naming it, describes it as “most nearly like Melgascops) vinaceus Brewster, but smaller, the general coloring paler and less reddish, the crown and outer surfaces of the wings lighter, the primaries with broad, well-defined light bars on both webs, the abdomen and flanks decidedly whiter, the under tail coverts nearly pure white and practically without mesial streaks, the feathering of the legs shorter and sparser.”
Ridgway (1914) describes it as “similar to 0. a. cineraceus but vermiculations of upper parts finer and blackish streaks narrower, size smaller, and toes more scantily feathered.”
Laurence M. Huey (1926a) has described a new race from Lower California, which he has named Otus asio cardonensis. The characters given are: “Nearest to Olua asio cineraeus, but darker, especially about the head and neck, where the striping is more pronounced. Averages smaller than 0. a. cineraces and larger than 0. a. xantusi.” lie gives as the range: “As far as known, the giant cactus (Pachycereus) association of the Pacific slope of Lower California from the vicinity of the hills east of Santo Domingo and San Quintin to the region lying east of El Rosario.”
Dr. Louis B. Bishop evidently thinks this is a good race, for he writes to me: “0. a. eardonensis is the size of xantusi but darker than it or gilmani, approaching cineraceus below, though not quite so heavily streaked and basal portions of feathers paler; browner above than cineraceus; more heavily streaked above than gilmani and xantwsi, less so than cineraceus.”
Grifling Bancroft sent me a small screech owl, collected at San Ignacio with a set of two eggs, which he called xantusi. I compared it with our good series of xantusi and cineraceus at Cambridge and referred it to the latter, which it seemed to match quite closely; it certainly is not xantusi but may be referable to cardonensie, which I have not seen. The two eggs that were collected with it measure 32.6 by 27.9 and 31.8 by 26 millimeters, somewhat smaller than the average for cineraceus.
J. Stuart Rowley says in his notes on Xantus’s screech owl: “These birds were rather plentiful about our camp in Miraflores; from about dusk until 9 o’clock in the evening screech owls were heard calling noisily. From that time on the owls became quieter: no doubt food hunting and not courting. More than a dozen specimens were taken, most of them from woodpecker holes in cardons, while we were going through the routine of ladder climbing and chopping from cardon to cardon.”
Nesting: Mr. Rowley took five sets of eggs, in various stages of incubation, near Mirafiores from May 11 to May 20, 1933. He says in his notes: “The nesting cavities were old woodpecker holes in cardons, usually about halfway up one of the arms, or 15 to 20 feet from the ground, but one set of two was taken from a hole only 10 feet up. In each case, where a nesting female was taken, the male was either in another hole in the same cardon or as near as he could get to it in the nearest cardon. No signs of food remains were noted. An occupied hole could usually be detected by a telltale feather caught on the edge of the entrance.”
Eggs: Xantus’s screech owl evidently lays two to four eggs. Mr. Rowley took one set of four, two sets of three, and two sets of two. They are like other screech owls’ eggs but smaller than those of the larger races. The measurements of 14 eggs average 34.2 by 29.3 millimeters; the eggs showing the four extremes measure 35 by 31 and 32 by 27 millimeters.
Plumages: Dr. Bishop tells me that xantusi has two color phases, showing about the same degree of difference as exists in the two phases of trichopsis, that the brown phase predominates, and that in this phase the upper parts are “wood brown” or lighter; in the gray phase, xantusi is the palest of the southwestern races, a trifle paler than gilmani, and less heavily streaked above and below.