Bent Life History of the Red-tailed Hawk
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 Red-tailed Hawk - the common name and sub-species reflect the nomenclature in use at the time the description was written.
now Red-tailed Hawk - Buteo jamaicensis
EASTERN RED-TAILED HAWK
BUTEO BOREALIS BOREALIS (Gmelin)
The red-tailed hawk, with its various races, is the most widely distributed, most universally common, and best known of all our hawks, though in certain sections some other species may be much commoner. For example, in my home territory the red-shouldered hawk outnumbers it nearly ten to one; and on the prairies and plains of the Middle West Swainson's and ferruginous roughlegs are, or were, commoner than redtails. But this fine hawk, the largest and must powerful of our eastern Buteos, is no longer common over much of its former range. The widespread prejudice against all hawks is exterminating this useful species much faster than some of the most destructive hawks that are better able to take care of themselves, craftier, and swifter awing. It. will be a sad day indeed when we shall no longer see the great redtail sailing over the treetops on its broad expanse of wing and ruddy tail, or soaring upward in majestic circles until lost to sight in the ethereal blue, or a mere speck against the clouds.
The distribution of this and the red-shouldered hawk in southeastern Massachusetts has always interested me. During my 50 years of experience with them, I have learned to regard them as competitive species, each intolerant of the other, antagonistic and occupying entirely separate ranges. In the western half of Bristol County, where the prevailing forest growth consists of hardwood trees, chestnut (forinerly), oaks, and maples, with only scattering growths of white pine (Pinus strobus), the red-tailed hawk was until recently practically unknown; this region has always been the center of abundance of the red-shouldered hawk. On the other hand, in the Cape Cod region, comprising the southeastern part of Plymouth County and all of Barnstable County, where the prevailing forest growth is pitch pine (Pinus rigida) and stunted oaks, the redtail is the common species and the redshoulder so rare that I have seen only one there in all my experience. In the intervening territory, where the prevailing forest growth is white pine, both species occur, but only in widely separated localities. In this latter region, during recent years, persecution under the bounty system has nearly exterminated all hawks. Meantime redtails began to invade the hardwood region in western Bristol County, supplanting the redshoulders in some of their long-established haunts. In 1929, 1930, and 1931, red-tailed hawks moved into three different tracts of hardwood timber that had been occupied by red-shouldered hawks for upward of 40 years, driving out the former tenants and in two cases appropriating their old nests. The larger and stronger bird seems to be the dominating species.
William Brewster (1925) noted the reverse of this replacement, for he writes: "That the Red-shouldered Hawk should have remained almost unknown in the Umbagog Region until after the Red-tailed Hawk had practically ceased to reappear, and that not long thereafter it should have apparently established itself as a summer resident in at least two localities, are matters of considerable interest, in view of the fact that throughout much, if not most, of Massachusetts there has been essentially similar and contemporaneous replacement of the greater by the lesser bird."
Spring: Throughout the northernmost part of its range the redtailed hawk is mainly migratory, a large majority of the birds wintering somewhat farther south. But a few individuals remain during winter, especially during mild seasons, not far from the northern limits of their summer range. I have seen them in Massachusetts during every winter month. Those that remain during winter or those that return early in the season begin their nest building late in February or early in March; I have seen a wholly new nest half completed and decorated with green pine twigs and down as early as February 18, over a month before the eggs are laid.
Courtship: I believe that this and other large hawks remain mated for life, but, if one of the pair is killed, the survivor soon secures a new mate. The birds are apparently in pairs when they arrive on their breeding grounds, but they indulge in nuptial demonstrations more or less all through the nesting season. I have seen a pair of these hawks, in May when there were young in the nest, indulging in their joint flight maneuvers high above the woods where the nest was located; they soared in great circles, crossing and recrossing each other's paths, sometimes almost touching, and mounting higher and higher until almost out of sight; finally one partially closed its wings and made a thrilling dive from a dizzy height, checking its speed just before it reached the woods. E. L. Sumner, Jr., refers in his notes to such a flight: "About ten times, while they were circling near together, the male would lower his legs and adjust his circles so that he came above his mate, and about four times he actually touched her back, or so it seemed." M. P. Skinner says in his notes: "These hawks at times performed wonderful evolutions high in the air, either one bird alone or several at a time. Such hawks would mount up to a high altitude, then half close the wings and drop down on an invisible incline at great speed only to open the wings again and shoot up at an equal angle. This was repeated again and again while the hawk described a series of deep V's and gradually passed out of sight in the distance."
Mr. Sumner (MS.) saw a male western redtail approach a female that was perched in a tree, hang for a moment just over her, then alight on her back and stay there about 40 seconds, with quite a bit of wing motion to balance himself; he then got off and perched beside her on the branch, but he soon flapped off and began to circle.
Clarence F. Stone writes to me about the mating antics of a pair of red-tailed hawks on a lofty horizontal limb of an elm tree near their nest:
Stopping to survoy the woods before I entered, I beheld a pair of Rod-tailed Hawks cavorting step by step, towards each other. Since they had not discovered my presence the Performance continued to a finish. Stepping sideways until they were wing to wing and facing each other almost breast to breast, both birds suddenly dropped down backwards until there was physical contact below the limb, and thus the act of copulation took place. Immediately after, both hawks took to the air around and around each other in wide circles.
Another recorded note concerning the Red-tailed Haxvk tells of a pair proceeding to reline their many years old nest, but before time for eggs one of the birds was killed by a farmer. All time remainder of that season, the bereaved hawk hunted and lived in the nest woods. On the following Spring this Red-tail returned alone and even did quile a bit of relluing of nest: so much that I climbed up to see if there were eggs. As this nest was near home I visited it frequently during the season up to June, but always the Red-tail remained unmated. I think this instance shows "faithfulness" more than lack of opportunity to mate again.
Nesting: My personal experience with the nesting habits of the red-tailed hawk in southeastern Massachusetts has been limited to the study of 19 nests over a period of 40 years, from which it appears that it is not a common bird here. Twice we found two nests in one season and one year we found three. The local distribution has been referred to above. Contrary to the experience of others elsewhere, we have found the redtail much less constant in its attachment to its nesting haunts than the redshoulder. In three cases we found them in the same patch of woods, but in different nests, for two years in succession, and once for three years. A popular nest at Blue Ridge, 35 feet up in a red oak in mixed woods, on a ridge between an open bog and a maple swamp, was occupied by a red-shouldered hawk in 1920; in 1928 it was occupied by a pair of broad-winged hawks; the following year a. pair of redtails took possession of it and raised a brood of young; in 1930 it remained unused; in 1931 the redtails were back in it again and raised another brood; but in 1932 it was deserted again; raising a brood successfully did not encourage the hawks to return.
Our longest record covers a period of 13 years, during which time the nest was actually found in only four years. The territory covers a very extensive area in Mansfield and Norton in which there are a number of large patches of heavy timber of various kinds, white pines, oaks, and maples, interspersed with open bogs, swampy woods, cleared lands, and pasture. The redtail's nest was first discovered by my field companions, F. H. Carpenter and C. S. Day, in 1920; it was in an ideal situation, 54 feet from the ground on horizontal branches, against the trunk of a giant white pine that stood on the edge of a grove of heavy pines, overlooking an open meadow. We did not find the nest again until 1924, when we discovered it fully a quarter of a mile away; it was 52 feet up in one of a small group of scattered ~vhite pines in an open situation. Two years later the hawks were back in the old original nest in the big pine. This nest remained vacant until 1932, when it was again occupied. I have no doubt that the hawks ne~ted somewhere in that big tract during all the intervening years, for we often saw them, but were unable to locate the nest in a region so difficult to hunt thoroughly. Mr. Day, who has all the eggs collected from this locality, is convinced that three different females presided over this territory, as shown by the three distinct types of eggs laid.
As mentioned above, red-tailed hawks invaded, in three successive years, three separate localities that had been occupied previously by red-shouldered hawks. I suspect that these three invasions were all made by the same pair of redtails, as the second and third localities are less than a mile and a half from the first. The "reservoir woods" in Ilehoboth was once a fine, large tract of heavy chestnut, oak, and maple timber, partially swampy and drained by a small stream. A pair of red-shouldered hawks had nested continuously in these woods from 1882 to 1923, when the last nest we found there was built in a large scarlet oak 48 feet from the ground. In 1924 this nest was occupied by a pair of barred owls and in 1928 by a pair of red-tailed hawks (p1. 44); I did not visit the locality during the intervening years. The following year, 1929, we found the redtail~ nesting in the Blue Ridge nest referred to above. In 1930, they, or another pair, invaded another big tract of hardwood timber, Goff's woods, less than a mile away, where red-shouldered hawks had nested for nearly 50 years, and built a new nest 45 feet up in a red oak. And the next year they were back again in the Blue Ridge nest. Since then we have been unable to find any hawk's nests in any of the three localities, though much of the old woods is still standing.
All the nests found in the hardwood region were in oaks, varying in elevation from 35 to 48 feet. Those in the white-pine region were all in white pines and 35 to 70 feet above the ground. On Marthas Vineyard we found the lowest nests in the oak groves on the western part of the island; one huge nest was only 15 feet from the ground and another 30 feet. In the Cape Cod region the redtails nest in the ]argest pitch pines they can find, from 18 to 35 feet up, and occasionally in white pines where these trees can be found.
The nests of the red-tailed hawks will average somewhat larger than those of the red-shouldered; typical nests are from 28 to 30 inches in outside diameter, the inner cavity being 14 or 15 inches wide and 4 or 5 inches deep. The largest nest I ever measured was 42 inches in longest by 19 inches in shortest diameter. The nests are usually quite fiat and shallow; but one that had been added to for an unknown number of years measured 3 feet in height. Dr. H. C. Oberholser (1896) gives the measurements of 7 Ohio nests that are somewhat larger than my averages; his largest nest measured 36 inches in height and 48 by 30 inches in outside diameter; the inner cavity was 7 inches deep.
The nests are well made of sticks and twigs, half an inch or less in thickness, and neatly lined with strips of inner bark, of cedar, grapevine or chestnut, usnea, and usually at least a few green sprigs of pine, cedar, or hemlock. Some nests are profusely and beautifully lined wit.h fresh green sprigs of white pine, which are frequently renewed during incubation and during the earlier stages in the growth of the young.
I have spent considerable time, with rather meagre results. atternpting to wateh the nest-building activities of these hawks. They "stake out their claim" late in February or early in March,.a month before the eggs are deposited, by marking the nest they propose to use with a sprig of green pine. Nest building is a very deliberate process; the birds visit the nest at very infrequent intervals and are very cautious about it. If they suspect that the nest is watched they will not come near it. In order to watch them successfully it is necessary to have a blind that offers perfect concealment; a brush blind is utterly useless, as the hawks can see the slightest movement in it, and will not come near the nest again until the intruder departs. I believe that both sexes assist in nest building, though I have not proved it. Old nests are sometimes repaired in the autumn.
The nesting habits of the red-tailed hawk in other parts of its range differ somewhat from the above. Major Bendire (1892) quotes Dr. William L. Ralph as to its nesting in Oneida and Herkimer Counties, New York, as follows:
In this vicinity the Red-tailed Hawk prefers birch trees above all others to build in, and about 80 per cent, of their nests will be found in such situations. The remaining 20 per cent, is about equally divided among beech, maple, hemlock, elm, and basswood trees. Why these birds should prefer birch trees I do not know, for they are usually not very hard to climb, while the most difficult of their nests to reach were built in elm, hemlock, and basswood trees. They generally select the largest and tallest trees they can find to build in, and their nests are situated near the tops, in crotches formed by two or more large limbs, or at the junction of large limbs with the trunks. They are usually placed from 60 to 70 feet from the ground.
William A. and George MI. Smith. of Lyndonville, N. Y., have sent me data on 46 New York sets, showing very different preferences; 23 of their nests were in beeches, 9 in maples, 5 in oaks, 4 in elms, 3 in basswoods, and 1 each in ash and hemlock. The heights from the ground varied from 341/2 to 78 feet, measured; and 24 were 00 feet or over. There were 16 sets of three, but no larger sets. S. F. Rathbun tells me that he has taken a set of four in central New York, and about half of Dr. Ralph's sets were fours.
The largest nest I have heard of was found by Verdi Burtch (1911) near Branchport, N. Y.; it was placed in a big pine tree and measured 3 by 4 feet in diameter. He says: "My first set from these woods was taken March 31, 1890 (20 years ago) and there has been a nest in there or the adjacent woods nearly every year since that time." A. D. DuBois mentions, in his notes, a nest found near Ithaca, N. Y., that was 80 or 90 feet from the ground in a big pine tree. He also sent me notes on three nests found in Sangamon County, Ill. One was 50 feet from the ground "in the uppermost main crotch of an elm tree"; another was at the same height in a white oak; and the third was in the top of a big sycamore.
Throughout the greater part of its range the red-tailed hawk seems to he more constant in its attachment to its nesting site than we have found it in New England; it often returns year after year to the same patch of woods. As it usually selects the tallest tree it can find the nest is often at a great height, even over 90 feet from the ground. It does not seem to be at all particular as to the choice of a tree, except as to size; various pines, oaks, maples, hickories, elms, sycamores, and poplars have been used. Small patches of heavy tall timber are preferred, and the nest is usually on or near the edge so that the bird can have a good outlook, end nests are often built in more or less isolated trees in open situations. I believe that the birds prefer to build a new nest each year, but they sometimes use the same nest for consecutive years, though oftener they return to it after an interval of a year or two. Lewis 0. Shelley writes to me that he has known a pair to use the same nest each season for four or five years. Often they appropriate a nest previously used by another hawk, ow1, or crow or build on an old squirrel's nest. A. W. Brockway tells me that one of his nests was built on top of a gray squirrel's nest in which he could hear the young squirrels chatter as he pressed against the nest. For three seasons in succession J. A. Singley (1886) found a nest occupied by great horned owls early in the season and later by red-tailed hawks; this was in Texas where the owls nest early in the winter. If their first set of eggs is taken, the hawks will lay a second set, three or four weeks later, but usually in another nest; very rarely a third set may be laid; and Bendire (1892) says "on very rare occasions even a fourth."
Eggs: In the eastern and southern portion of its range the redtailed hawk lays almost invariably two eggs; I have never found three and twice have found incubated sets of one. In central and western sections sets of three are commoner, sets of four are not rare, and as many as five eggs have been found in a nest. The eggs are ovate, elliptical-ovate, or oval in shape, and the shell is finely granulated or smooth, without gloss. The ground color is usually dull or dirty white, sometimes faintly bluish white, or more rarely pale greenish white. The eggs average much less heavily marked than red-shouldered hawks' eggs. They are often nearly or quite immaculate, but they are usually more or less sparingly spotted; some are handsomely marked in even or irregular patterns, but very rarely heavily blotched. The markings are in various shades of dull reddish or yellowish browns, "snuff brown" to "ochraceous-tawny", more rarely "warm sepia~~, "auburn", or "russet"; some show underlying spots of "pale Quaker drab", or "pallid purple drab." A series of eggs from one female usually runs true to type, as to shape, color, and markings; and when a new female replaces her, a different type of eggs often results. The measurements of 59 eggs average 59 by 47 millimeters; the eggs showing the four extremes measure 66 by 50, 64.5 by 51, 55 by 45.5, and 59.5 by 44 millimeters.
Young: Incubation lasts for about 28 days; the male assists the female somewhat in this, brings food to her while she is incubating, and helps to feed the young. I have seen the male bring food to the nest, and his mate feed it to the young. The incubating bird is watchful and very shy; it is almost impossible to approach within 100 yards of the nest without flushing her, if she is watching. One of my nests was fully that distance from a rocky ledge, from behind which I often attempted to watch the nest; almost invariably, as soon as I showed my head above the crest of the ledge, if I could see her head on the nest, she would immediately stand up in the nest and fly away; and she would not return until after I left the woods.
On other occasions, when she was invisible on the nest, I could walk to within 10 yards of the tree before she would fly; I believe that at such times she was asleep on the nest. Even after the young have hatched these hawks are very cautious about returning to the nest; repeatedly I have waited in vain for their return, even when well concealed, after they had once seen me; and their eyes are exceedingly keen. They seem to be much more concerned about their own safety than about the welfare of their eggs or young.
The young hatch at intervals of one or two days and remain in the nest for four weeks or more. Often one of the eggs proves to be infertile, and oftener one of the young dies and is thrown out of the nest, or is forced out of the nest and is killed by the fall. Norman Criddle (1917) writes:
The number of eggs laid by each female varies somewhat and seems to depend, at least to some extent, upon the food supply. In 1917, the six nests under observation close to the writer's home, contained but two eggs each and in only one of the six did the parents succeed in rearing more than one young though both were hatched In every instance. The first nest was discovered on May 6, containing two eggs. Other nests with eggs were located as late as June 14. It is difficult to account for the mortality among the young, though it is noteworthy that the deaths occurred while they were still quite small, and that the latest hatched, and consequently smallest, was invariably the one to die. Dead examples presented no Indication of violence but seemed to show that, in all probability, death was due to starvation, the lack of food being due in its turn to a scarcity of ground squirrels (gophers) and to the unusual number of hawks nesting In the district.
The curious habit of the old birds in gathering a green leafy bough and placing it in the nest, characteristic of Swainson's hawk also, is very marked In the Red-tall, a fresh bough being gathered at least once daily during the time when the young are small. There has been some doubt hitherto as to the cause of this habit, but by observing the nestlings I am led to believe that the bough acts as a sun shade, as the young have been seen to repeatedly pull the bough over themselves and crouch beneath It. Doubtless it also acts as a shield and hides the young from their enemies. The leaves are also occasionally eaten.
As the young develop they acquire a good deal of boldness and defend themselves with both beak and claws. They have a habit of closely watching the intruder backing up meanwhile at the approach of a hand; then suddenly they leap forward with wings outstretched, and it requires a rapid movement to escape their onslaught. The old birds make no efforts to defend their young, but fly high overhead uttering loud cries which are, at times, answered in a shriller key by the young beneath.
The young, when half grown, become very lively, walking about in the nest, stretching or flapping their wings, backing up to the edge of the nest to void their excrement in a long stream far over the edge; the ground under a nest of young hawks is well decorated with a circle of white. Their eyes are very keen, and they frequently raise their heads to watch passing birds or to look for the return of their parents. Their weak, peeping notes are heard occasionally, but when one of their parents is sighted they become quite excited and indulge in louder screams in feeble imitation of the adult's notes.
I have never happened to see the young leave the nest, but Mr.
Sumner's notes, applying to the western race, describe such an event.
Mr. Shelley writes:
The adults are quiet during the incubation period and until the young are on the wing. As soon as this stage is reached, they are brought east of the hill where the nest is situated to the broad, open fields and mowings of the nearby farms, where they spend the forenoons hunting their legitimate prey and noth ing else. Afternoons as a rule they skirt the country to the west of the nesting hill. Rut on the east side their calls can be heard all forenoon for a month or more, during the period the young are being taught to fare for themselves.
Many a time I have seen them catching mice. An adult plunges down 50 to 100 feet or so at a scuttling mouse, checks its rush a few feet above the ground, and, turning 01110 its back, gives a wheezy whistle of two syllables, wliereupun one of the circling young dives, holds itself suspended clumsily over the spot marked by the parent, and, quite often, obtains the rodent when it moves again. The parents do, rarely, drop disabled mice from a good height as though discarding them, but in reality it is done so that the young may catch them in midair, which they attempt to do with fair luck; I have seen it done on several occasions.
Mrs. A. B. Morgan (1915) gives an account of a young red-tailed hawk which she raised in captivity that developed into a very inter esting and most intelligent pet.
Plumages: The small downy young red-tailed hawk is well cov ered above with long, soft, silky down, huffy white or grayish white : in color; the white, hairlike filaments on the head are erected in life and fully half an inch long; the down on the under parts is shorter and scantier. This first down is replaced later by a whiter and woollier down. When ahout 17 days old the wing quills appear, closely followed by those of the tail. Before the young bird is half grown the feathers appear on the scapulars and the mid-dorsal tracts; the feathers come in next on the pectoral tracts. By the time the bird is four weeks old it is nearly fully grown and almost fully fledged, the last of the down persisting on the head, central belly, and legs. It is now ready to leave the nest and is able to fly.
In fresh juvenal plumage, in June and July, the upper parts are "warm sepia" to "bone brown", with narrow edgings of "tawny" or "ochraceous-tawny"; the tail is "bister", barred with brownish black, tinged and tipped with buffy white, and silvery white on the under side, with the bars showing through; in western birds the tail is often tinged with "tawny" or "orange-cinnamon", sometimes extensively so, but in eastern birds this color is seldom, if ever, seen; the under parts are largely white, more or less tinged with "ochraceous-buff", which fades out to white later in the season; the throat and sides of the neck are narrowly streaked with sepia, and the belly and flanks are heavily streaked or spotted with a dark sepia, suggesting the adult pattern. This plumage is worn throughout the first winter with little change except by wear and fading, the buffs being replaced by dull white.
A complete molt from the juvenal into the adult plumage begins very early in the spring, is very gradual, and is prolonged through the summer or into the fall, with much individual variation. I have seen a young bird with new red feathers in its tail in February, and birds with missing flight feathers are often seen during the nesting season. At the completion of this molt in fall young birds are practically indistinguishable from adults. Young birds raised in captivity have molted from the juvenal into the red-tailed adult plumage when a little over a year old. I have examined a large series of eastern birds and have not been able to recognize a second-year plumage, such as seems to occur in harlani; immature specimens of calu~'us often have reddish tails with numerous narrow black bars; these are probably first-year birds with erythristic tendencies. Neither erythrism nor melanism seems to occur in eastern birds, but cases of nearly, or quite, perfect albinism have been reported. Adults have one complete annual molt, which may begin in spring or early in summer and may be completed in September or October.
Food: It is generally conceded that the red-tailed hawk is a highly beneficial species, as its food consists mainly of injurious rodents and as it does very little damage to domestic poultry or wild birds. Dr. A. K. Fisher (1893) writes:
Of 562 stomachs examined by the author, 54 contained poultry or game birds; 51, other birds; 278, mice; 131, other mammals; 37, batrachlans and reptiles; 47, insects; 8, crawfish; 13, offal; and 89 were empty. It has been demonstrated by careful stomach examInation that poultry and game birds do not constitute more than 10 per cent of the food of this Hawk, and that all the other beneficial animals preyed upon, including snakes, will not increase this proportion to 15 per cent. Thus the balance in favor of the Hawk is at least 85 per cent, made up largely of various specIes of injurious rodents: a fact tl)at every thoughtful farmer should remember. * ï The increase of any animal is always followed by a relative increase of its natural enemies. This is clearly shown on the river front in the vicinity of Washington, D. C., where the recent improvements have redeemed several hundred acres of ground from the tidal flats; and aiready in many places rank vegetation has grown up, affording shelter and sustenance for hordes of mice. At present in winter and early spring it is not uncommon to see ten or fifteen Red-tailed Hawks in different parts of this flat attracted hither by the abundance of their natural food. Prior to the reclamation of the flats not more than a pair or two were to be seen in the same neighborhood during the winter.
Of 173 stomachs of this hawk examined by Dr. B. H. Warren (1890) in Pennsylvania, 131 contained the remains of mice, 0 of rabbits, 3 red squirrels, 2 skunks, 18 smaLl birds, 14 poultry, 3 insects, 3 snakes, and 4 offal or carrion. He says: "I have repeatedly found three and four mice in the viscera of one bird, oftentimes five, and in a few instances as many as seven of these destructive little rodents were obtained from the crop and stomach of one hawk."
Dr. George M. Sutton (1928) reports on the stomach contents of 32 redtails, taken in Pennsylvania in October, as follows:
Twelve stomachs were empty; in the twenty stomachs which held food were eleven Field Mice, four Short-tailed Shrews, three Red-backed Mice, three Chipmunks, three small Garter Snakes, two Red Squirrels, one Winter Wren, one Song Sparrow, one Hermit Thrush, one Gray Squirrel, one Rrown Rat, one half-grown White Leghorn Chicken, one large grasshopper, two crickets, and one large beetle of the family Elateridae. Such an array of food Items in only twenty-two stomachs is noteworthy. Only seven of these stomachs held but one Item; the others had a variety in each. If the above stomach contents are at all normal the red-tail captures about five harmful or unimportant organisms to one economically valuable one.
'The following mammals have been detected in the food of this hawk: House mice and various species of field and wood mice, rats, various squirrels, both arboreal and ground species, raccoons, gophers, prairie dog, spermophiles, woodchuck, rabbits, moles, bats, shrews, chipmunks, muskrat, porcupine, weasles, and skunks; as many as nine red squirrels have been found in a nest at one time. The following interesting account of a redtail attacking a cat is published by E. D. Nauinan (1929) A large Red-tailed Hawk (Buteo borealis borealis) came out of the timber and leisurely flew around over the meadow, hovering over one point a moment for special Inspection. Then he flew back to the woods again. A few minutes later he flew out and hovered over the same place, then returned to the woods as before. After having performed this round trip movement several times, the Hawk finally flew to this point and plunged down into the meadow. Instantly there was a mighty commotion. Hissing, flopping, spitting, caterwauling; and one could see feet, claws, wings and tails whirling about just over the grass. The air was full of fur and feathers for a few moments, then the Hawk made his getaway, and with feathers much ruffled flew for the timber as fast as his wings could carry him. And an 01(1 gray tom cat went with great bounds in equal haste for the farm buildings! Both Tommy and hawk wore licked but still able to go.
The bird list includes domestic poultry, young turkey, pintail, teals, and other wild ducks, gallinules, rails, pheasants, i-uffed grouse, Hungarian partridge, various quails, doves, screech owl, kingfisher, woodpeckers, crow, starling, grackles, rneadowlas-k, horned larks, orioles, various sparrows, juncos, thrushes, iobin, and bluebird. Verdi Burtch (1927) found a freshly killed red-shouldered hawk and later saw a red-tailed hawk feeding on it. Lucy V. Baxter (1906) surprised an adult red-tailed hawk feeding on a fieshly killed immature hawk of its own species. Probably most of the small birds are killed during t.he nesting season as food for the small young, though the young hawks ai-e fed largely on mice and squirrels. Ralph J. Donahue (1923) writes: "Before the eggs of the redtails hatched, the parents fed on rodents: mostly the striped ground squirrels (Spermophile). After the young got out of the shells, the whole bill of fare was young chicken. At different times we found chickens to the number of seven. There were times when we could not go to the nest for a week or two, and it may be there was other food fed to the young during that time."
Miscellaneous items of food include rattlesnakes, bull snakes and smaller snakes, lizards, turtles, frogs, toads, salamanders, crawfish, grasshoppers, crickets, beetles, grubs, caterpillars, centipedes, spiders, earthworms, and maggots.
Two common hunting methods of the red-tailed hawk are the lofty soaring flight, from 'which its keen eyes detect its prey far below, and its slow flapping or sailing flight low over the fields and meadows, much after the manner of the marsh hawk or roughleg; a third, and perhaps the commonest, method is watchful waiting on some commanding perch on tree or post from which it can quickly pounce on any moving object that it sees. Much of its hunting must be in the forests, for many woodland mice and squirrels are included in its food. To capture such active animals as red or gray squirrels, it is often necessary for these hawks to hunt in pairs; these lively animals can easily avoid the swoops of a single hawk by dodging around a tree; but, if there is a hawk on each side, the squirrel is doomed unless it can scamper into a hole. Col. N. S. Goss (1891) says that these hawks while "sailing often fill their craws with grasshoppers, that during the after part of the day also enjoy a sail in the air." Mr. Shelley says in his notes that "it is also a great experience to see these large Buteos alight in a newly hayed field to catch grasshoppers and crickets; as they hop along the wings are always maneuvered to give the bird a rising impetus and timed so that the feet no more than touch the ground when the insect is plucked and the bird is clear of the ground on the next bound for the insect ahead. More than anything else, this maneuver resembles the floppings of a hen with its head cut off, only more mathematical, to give a crude description."
Behavior: The ordinary flight of the red-tailed hawk is rather slow and heavy, as it travels along in a st.raight line, with rather slow wing strokes. But its soaring flight high in the air is inspiring, as it mounts gracefully, gathering altitude rapidly, with no apparent effort, with its broad wings and tail widely spread and motionless except for occasional adjustments to changing air currents. Once, as I stood on the brink of a precipice looking down over a broad valley, I saw below me a red-tailed hawk floating over t.he valley and looking downward for game; it was facing a strong wind and was perhaps buoyed up by rising air currents, as it was poised as motionless as if suspended on a wire; it remained in one spot for three or four minutes and then sailed over to another spot a few rods away, where it hung for a similar period. Its spectacular "nose dives", referred to above, are thrilling and well illustrate its mastery of the air. Dr. B. H. Warren (1890) describes some interesting maneuvers as follows:
fled-tailed Hawks in their fall migrations are gregarious. One clear, cold autumn afternoon in 1876, I saw, near West Chester, a flock of these hawks. The sky was destitute of clouds, except a cumulus stratum directly beneath, and apparently about half way between the hawks and the earth. In the center of this vapor was an opening of sufficient size to enable me to watch the gyrations of the birds; two of them suddenly separated from the main body, approached each other screaming, and apparently in great rage. They descended screaming, and, to all appearances, clinched, to within about one hundred yards of the earth, when they parted. Evidently neither bird had received much injury, as they both, after taking short flights across the meadow, ascended in company with two or three of their companions that had accompanied them part way down, to the main body. Another individual closed his wings until the body presented a triangular outline, descended with almost lightning-like rapidity to the top of a sycamore, where it alighted, and remained for some seconds pluming itself. This party of hawks, after perform. ing for nearly twenty minutes, these, and numerous other aerial antics, continued their southern flight.
Illustrating its marvelous powers of vision, he says: "A clear morning early in March, I saw a Red-tail circling over the meadows; every circle took him higher and higher in the air, until at an altitude where he appeared no larger than a blackbird, he stopped, and with nearly closed wings, descended like an arrow to a tree near by me; from this perch, almost the same instant he had alighted, he flew to the ground and snatched from its grassy covert a mouse. The moinentum with which this bird passed through the atmosphere produced a sound not very unlike that of the rush of distant water."
This hawk is generally regarded as a sluggish, inactive bird, for it spends much of its time standing erect on some lofty perch, slo~vly seanning its surroundings. It is one of the shiest of our hawks; a man on foot can seldom approach one to within 100 yards, and often it will fly at twice that distance. But it seems to be less afraid of a man on a horse or in a vehicle; in regions where hawks are not much I)ersecuted one can sometimes ride up within gunshot range.
A wounded redtail is a formidable object, as it throws itself on its back and present~ its sharp and powerful talons; it will grab a gun barrel or stick and allow itself to be lifted up; or it will fasten its claws in the hand or arm of one who tries to handle it and can only with great difficulty be made to let go. Once, while I was hunting with John B. Semple in Florida, a wounded redtail dropped a long way off among some patches of saw palmetto; after a long search in vain we sent his springer spaniel to hunt for it; the plan worked successfully, but the dog was surprised and much frightened, as the infuriated hawk rushed out and attacked him.
These hawks are not at all courageous in the defense of their nest; they generally keep at a safe distance or disappear entirely; only on rare occasions has one been known even to attempt to attack a climber; I have seen it only once. Only twice have I seen one return to its nest when I was in plain sight near the nest tree; once when I was almost under the tree the hawk settled on the nest and would not leave until I rapped the tree.
Its behavior toward other birds is generally an attitude of stolid indifference. I have seen it drive away other hawks from the vicinity of its nest and, as st.ated above., have known it to preempt old-time nesting haunts of red-shouldered hawks. I have repeatedly seen it attacked by a party of crows; it often pays no attention to them but sometimes turns on its back and displays its talons, at which the crows heat a hasty retreat; occasionally the crows pay the extreme penalty for their temerity; crows have often figured in the food of this hawk. Kingbirds and blackbirds often attack the redtail and drive it away from their nesting sites, but I doubt if the hawk ever retaliates. Mr. Skinner says in his notes: "Once I found one near Southern Pines being tormented by four robins. It protected itself fairly well while in the top of a tall pine, but when it flew 26 more robins, which had been concealed in the foliage, gave chase and joined their efforts to the pecks of the first four tormentors."
Mr. Sumner (MS.) once saw a redtail attack and drive away a horned owl that had ventured too near its nest. Great horned owls habitually occupy old nests of the eastern redtail, probably preempting them before the hawks are ready to use them. I have always regarded these two as supplementary species, one hunting by day and one by night in similar regions and preying on similar victims. I once surprised one of these owls feeding on the remains of a freshly killed red-tailed hawk.
Voice: The red-tailed hawk occasionally utters a note similar to that of the red-shouldered hawk, but usually it is quite distinct. The characteristic cry is described in my notes as a long drawn out, harsh, rasping squeal, kree-e-e-e-e-e, suggesting the squeal of a pig. It has also been written cree-e-e, cree-e-ep, or pee-ch-k. Bendire (1892) gives it as kee-aah, the redshoulder note, so often imitated by the blue jay; he also gives another note, chirr or pii-chiir, "when perched on some dead limb near their nest." The note has been said to resemble the sound made by escaping steam, but I could never quite see the resemblance.
Field marks: Its outline, broad, somewhat rounded wings, and broad, rather short tail mark it as a Buteo. In adult plumage it should be easily recognized. As it flies straight away in the woods, or as it wheels in soaring flight, it shows a glimpse of its red tail, with no barring on the under side of it, in marked contrast with the conspicuously black and white barred tail of the redshoulder. The under side of the wing is whitish, without bars, but with a dark border formed by the dusky tips of the primaries and secondaries and there is usually a dark wrist mark near the bend of the wing. The sides of the head are very dark and the breast is largely whitish, with dark streaks only on the belly and flanks. The young bird looks very much like the young redshoulder; it has a faintly barred tail, and the streaking on the under parts is more like that of the adult redtail, very scanty on the breast, than like the young redshoulder, which is more uniformly streaked below.
Fall: Early in September, red-tailed hawks begin to drift southward from New England and other northern parts of their range. These fall flights are very spectacular and usually contain a variety of species; they are seen to best advantage on clear cool days with a northwest wind. These large mixed flights often contain hundreds of individuals, spread out over a wide area and continuing to pass for several hours. Dr. Fisher (1893) has seen a flock containing 65 red-tailed hawks "flying in a comparatively compact body, probably not more than a few feet from each other." H. S. and H. B. Forbes (1927) thus describe a flight as witnessed in New Hampshire on September 14, 1926:
Far out to the northwest two Hawks, perhaps a mile away, were seen wheeling over the valley at a slightly lower level than our point of observation. Then, as If from nowhere, other Hawks rapidly appeared, swooping, turning and soaring upwards in Irregular steep spirals. More and more individuals appeared until the specks resembled a swarm of large insects, black against the pearl gray clouds. The total number was estimated to he between thirty and forty. Now they soared slowly, now flew with rapid wing beat at great speed. Each individual chose his own course without evidence of leadership. In from five to ten minutes (the exact time unfortunately was not noted) the flight had gained great altitude and to our astonishment the highest birds began to disappear in the clouds, some of them reappearing and again diving Into the mist. Finally the whole flight had spiralled upward into the cloud mass and was lost to view. Once, half a minute later, a few specks wheeled out toward us and for a moment could he dimly seen through the edge of the cloud. That was the last glimpse.
Dr. Thomas S. Roberts (1932) writes from Minnesota:
While driving from Ten Mile Lake, Otter Tail County, to Breckenridge on the Red River, on October 7, 1927, the writer, accompanied by Mr. Kilgore and Mr. Breckenridge, passed through what was evidently a large migration of Redtails. There were a few scattered all over the country, but on the open prairie between Nashua and Campbell, in Wilkin County, many of the fence posts, telephone and telegraph poles, and straw-stacks and hay-stacks, were occupied by birds, while others circled in the air, and a few were walking about OD the ground. Forty-eight were counted, most of them in a limited area.
Maurice Broun (1935) says of the fall migration at Kittatinny Ridge, Pa., in 1934:
It may come as something of a surprise to learn that these splendid birds made up fully 50% of the entire Hawk migration. The first Red-tails recorded were two on September 30. No conspicuous movement took place until October 12, whcn 205 birds were counted. Thereafter during the month there were nine days of relatively heavy flights, the greatest number of 427 birds occurring on October 23. The first part of November, however, hrought the major flights, with an average of 244.5 birds per day for 12 days. On November 1, I recorded 592 Red-taIls: as many as 213 in a single hour; on November 2, 853 Red-tails. Kramer reported diminishing numbers of Red-tails during the latter part of November, except for 67 on the 24th. He saw 9 ott December 2, and 4 on the next day.
Range: North and Central America and the islands of the Caribbean Sea.
Breeding range: The red-tailed hawk breeds north to Alaska (Innoko River, Saicha Slough, and Joseph); Yukon (Forty Mile); Mackenzie (Fort Good Hope, Fort Norman, and the Grandiii River) ; northeastern Manitoba (Fort Churchill, and probably York Factory); probably northern Ontario (Missinaibi River, Mattagaini River, and Moose Factory); and Quebec (probably English Bay, Mingan Island, Piashti Bay, and probably Natasliquan). East to Quebec (probably Natashquan and Gasps County); Prince Edward Island (North River); Nova Scotia (Kentville and probably Digby); Maine (Bucksport, probably Lewiston, and Portland); eastern Massachusetts (Danvers, Boston, and Cape Cod) ; New Jersey (Princeton, Vineland, and Sea Isle City) ; eastern Virginia (Spottsville and Dismal Swamp) ; North Carolina (Raleigh and Pinehurst); South Carolina (Columbia) ; Georgia (Savannah, Blackbeard Ishnd, and St. Marys); Florida (San Mateo, Fruitland Park, and Fort Pierce) ; the Bahama Islands (Little Abaco) ; probably northern Haiti (Terrier Rouge) ; Puerto Rico (Mayaguez, Manati, near Cayey, and probably Hacienda Catalina); and the Virgin Islands (Vieques Island, probably Culebra Island, and formerly St. Croix Island). South to the Virgin Islands (formerly St. Croix Island); probably southern Dominican Republic (Beata Island) ; Cuba (Trinidad) ; Jamaica; probably Panama (Chiriqui) ; Costa Rica (Santa Maria de Dota and Cartago) ; and Colima (Socorro Island). ~Vest to Colima (Socorro Island); Nayarit (Tres Marias Islands); Lower California (Guadalupe Island and San Pedro Martir Mountains); California (San Diego, San Clemente Island, Santa Catalina Island, Los Angeles, Santa Barbara, Port Harford, Monterey, Santa Cruz, Alameda, Petaluma, Cazadero, Mount Sanhedrin, and probably Crescent City); Oregon (Glendale, Bandon, Elkton, Newport, and Olney); Washington (probably Tacoma, Seattle, Everett, and probably Bellingham); British Columbia (Beaver Creek, probably Cumshcwa Inlet, and Porcher Island) ; and Alaska (St. Lazaria Island, probably Yakutat, Chitina River, Nushagek, Iditarod River, and Innoko River).
The range as above outlined is for the entire species (B. jamaicensis of some authors), which has, however, been separated into several geographical races. True borealis occupies the greater part of this vast area from Yukon, Mackenzie, Manitoba, and Quebec south to 'rexas, Oklahoma, Arkansas, Alabama, and northern Florida. The western redtail (B. 6. calurus) is found from Alaska and central western Mackenzie south to Lower California and. east to the edge of the Great Plains. Krider's hawk (B. b. krideri) breeds from south-central Canada, North Dakota, and Minnesota south in winter to Louisiana and Mississippi; accidental in Georgia and Florida. Harlan's hawk (B. 6. harlani) breeds in northwestern British Columbia, southeastern Alaska, and southwestern Yukon, wintering south to the Gulf coast; casual in California. The Florida redtail (B. b. umbrinus) is found in the Florida Peninsula, Cuba, the Isle of Pines, and probably the Bahama Islands. Buteo 6. jamaicensis occupies Hispaniola, Jamaica, Puerto Rico, the Virgin Islands, and probably the Leeward Islands; B. 6. fui~nosus is found on the Tres Marias Islands off the west coast of Mexico; B. 6. socorroen~sis is confined to Socorro Island, also off the west coast of Mexico, and B. 6. costarioenss is found from the highlands of southern Mexico south to Costa Rica and probably western Panama.
Winter range: The species winters throughout the southern part of its breeding range and north to southern British Columbia (Chilliwack and Okanagan); Utah (Provo); Colorado (Boulder); southeastern South Dakota (Vermillion) ; Iowa (Sioux City and Keokuk) ; central Illinois (Rantoul) ; southern Michigan (Detroit) ; New York (Rochester, Geneva, Auburn, and Rhinebeck); Connecticut (Hartford) ; and eastern Long Island (Gardiners Island). It is occasionally noted at this season and may sometimes winter north to Alaska (Admiralty Island and Eagle); North Dakota (Jamestown); Minnesota (Lanesboro); Wisconsin (Viroqua, Madison, and Princeton); southern Ontario (Coldstream, London, Mill Brook, and Ottawa) ; Vermont (Montpelier); New Hampshire (Meriden and Monadnock); and Maine (Cumberland County).
Spring migration: Early dates of arrival in the spring are: Maine: .Lewiston, March 15; Portland, March 17; Auburn, March 20; and Avon, March 21. Quebec: Montreal, April 22. New Brunswick: Scotch Lake, March 25; and St. John, March 27. Nova Scotia: Wolfville, March 22. Prince Edward Island: North River, April 20. Ontario: Toronto, February 14; Port Dover, February 26; and London, March 12. North Dakota: Larimore, March 20; Grafton, March 21; Wahpeton, March 23; and Argusville, March 29. Minnesota: Minneapolis, February 22; and Becker County, March 11. Manitoba: Treesbank, March 15; Margaret, March 23; and Winnipeg, April 10. Saskatchewan: Dinsmore, March 17; Wiseton, March 21; Muscow, March 30; and Skull Creek, April 11. Wyoming: Laramie, March 25; and Yellowstone Park, March 29. Idaho: Rathdrum, March 20; Coeur d'Alene, March 25; and Mendian, March 27. Montana: Missoula, March 12; Fortine, March 17; and Fort Custer, March 21. Alberta: Camrose, March 17; Stony Plain, March 30; Alliance, April 1; and Flagstaff, April 5. Yukon: Forty Mile, April 11. Alaska: Kupreanof Island, March 5; Craig, March 12; Wrangell, April 15; Beaver Mountains, April 20; and Tanana Crossing, May 7.
A redtail (no. 309391) banded on March 27, 1926, at McGregor. Iowa, was killed on May 16, 1926, at Howard Lake, Minn.
Fall migration: L ate dates of fall departure are: Alaska: Savage River, September 18; and Bettles, October 5. Yukon: Selkirk SettIement, October 12. Alberta: Belvedere, October 14; Glenevis, October 14; and Athabaska Landing, October 31. Montana: Missoula, October 1; Anaconda, October 9; Gallatin County, October 12; and Three Forks, October 17. Idaho: Priest River, September 29. Wyoming: Yellowstone Park, November 17. Saskatchewan: Muscow, October 3; Indian Head, October 20; and Eastend, October 21. Manitoba: Winnipeg, October 19; Treesbank, October 29; and Aweme, October 30. Minnesota: Minneapolis, November 23; and Isanti County, November 20. North Dakota: Charlson, October 19; Argusville, October 21; and Red River Valley, October 29. Ontario-Ottawa, October 22; Kingston, October 30; Point Pelee, November 1; and Toronto, November 7. Prince Edward Island: North River, October 24. Nova Scotia: Pictou, October 12; and Wolfville, November 20. New Brunswick: St. John, October 2; and Scotch Lake, October 25. Quebec: Montreal, October 24; Quebec, October 24; and Hatley, October 29. Maine: New Vineyard, October 23; North Livermore, November 3; Matinicus Island, November 8; and East Hebron, November 30.
Records of banded birds throw some light on the general migration routes of this species. Five young redtails banded during June and July at Muscow, Saskatchewan, were recaptured later in the same year as follows: No. 661180 was taken on September 22 near Grafton, N. Dak.; no. 309016 was killed on October 12 at Butterfield, Minn.; no. 200645 was shot near Chetopa, Kans., on November 6; no. 309019 was recovered on November 3 at Brumley, Mo.; and no. 200641 was shot at Chelsea, Okla., on November 24. One banded at L\Iilwaukee, Wis. (no. 233936) in November was retaken the following month at Blue Island, Ill.; while another banded in May at Denzer, Wis. (no. 235860) was shot in November at Rusk, Tex. One banded in May at Chester, Mass. (no. 312005) was killed the following November at Brandywine Summit, Pa.; and one banded at Middlefield, Mass. (no. 386652), in June was recovered in November at Springfield, Va.
Casual records: The red-tailed hawk was listed by Macoun (1909). as breeding in Newfoundland, but no supporting evidence was cited; Noble (1919) states that it is found in Labrador but not in Newfoundland, while Austin (1932) does not list it among the birds of Newfoundland Labrador.
A specimen of B. b. borealis is said to have been shot in Nottinghamsbire, England, in the autumn of 1860.
Egg dates: Alaska and Canada: 53 records, April 3 to June 12; 26 records, May 4 to 18.
New England and New York: 148 records, March 25 to June 21; 74 records, April 4 to May 17.
Maryland to West Virginia: 15 records, March 26 to April 26; 7 records, March 27 to April 8.
Ohio to North Dakota: 85 records, March 6 to June 30; 42 records, April 7 to May 3.
Iowa to Colorado: 44 records, February 28 to June 28; 22 records, April 3 to 28.
Washington to California: 292 records, February 14 to May 29; 146 records, March 19 to April 1.
Arizona and Texas to Florida: 97 records, February 18 to June 17; 48 records, March 7 to April 3.
BUTEO BOREALIS KRIDERI Hoopes
Krider's hawk is a well-marked pale race of the red-tailed hawk, occupying the plains and prairie regions of the Middle West. It was described and named by Bernard A. Hoopes (1873) from a pair of immature birds taken by John Krider in Winnebago County, Iowa, in September 1872. An excellent colored plate, published with the description, illustrates the extreme white phase in immature plumage. The adult is much like the eastern red-tailed hawk, but lighter colored; there is much white on the upper parts, the tail is pale rufous, and the under parts are nearly pure white, with very few markings and with only a pale buffy tinge in the thighs. Krider's hawk is easily recognizable in all plumages by extreme lightness, although the immature plumages of the light phase of Harlan's hawk are nearly as light colored and closely resemble it.
Nesting: The nesting habits of Krider's hawk are similar to those of other red-tailed hawks, due allowance being made for its environment. It evidently prefers to nest well up in big trees, but in the prairie regions, where heavy timber is scarce, it is often obliged to nest at a low elevation. It apparently nests somewhat later than the eastern redtail, as the records given below show. The Rev. P. B. Peabody (1895) has published data on eight nests found in southern Minnesota, on dates ranging from April 22 to May 11, six of the dates being in May. This hawk shows no partiality for any particular kind of tree; the eight nests were divided thus:2 in elms, 2 in white oaks, and 1 each in basswood, rock maple, black oak, and black walnut. The heights from the ground were 30, 40, 50, 60, and 75 feet. Two interesting nests he describes as follows:
Locality, a heavily wooded Island. Nest In a great elm, nearly Inaccessible, far out on horizontally spreading branches of a large main bough, at the very top; an old, broad and flat nest, roughly made of large sticks, with hollow, twelve Inches in diameter. Lining, fibrous bark, twigs, feathers of small birds. ï * * Locality, the very steep, deep, and heavily wooded bank of river, fringing a cultivated plateau. One mile from nest IlL A flat, old nest, far out, nearly over the water, on leaning branch of rock maple, sixty feet up. Large sticks. Lining, soft fibrous bark and grass.
Dr. R. M. Anderson (1897) describes five nests found by him in Iowa. One of these was an old Swainson's hawk's nest, and another had been previously occupied by a red-tailed hawk and the following year by a great horned owl. Three of his nests were in burr oaks, 46, 50, and 57y2 feet up, and one was in a black oak 35 feet from the ground. He noted that the nests all contained green, leafy twigs, mainly cottonwood and poplar, which appeared to be renewed daily.
M. A. Carriker, Jr. (1902), found an interesting nest of this hawk, near Warbonnet, Nebr., on a ledge about 20 feet from the base of a cliff in a canyon. He says of it: "The site had evidently been used by the birds for several successive years, for the pile of sticks composing the nest was at least one and one-half feet in thickness and three feet in diameter, occupying a pocket on the ledge. Fragments of skulls, vertebrae, and feet of various rodents lay scattered about, together with the vertebrae of a large snake and some fragments of a recently killed prairie-dog."
The only nest I ever examined was found on June 1, 1901, near Stump Lake, N. Dak. It was about 30 feet from the ground in the topmost branches of a small elm. One of the parents, a very light colored bird, was sailing about overhead and screaming anxiously lcreealt, kree-a-a-ak, a prolonged squealing whistle. It was a large nest of sticks, lined with dry grass, and contained three very young bawks, a pipped egg, parts of a cottontail rabbit, two ground squirrels, and two field mice. Within a few feet of the tree was an old elm stub, in which a goldeneye had a set of 10 eggs and a house wren a set of 7 eggs.
Eggs: The eggs of Krider's hawk are practically indistinguishable from those of other redtails, though Mr. Peabody (1895) says that some of them are more like red-shouldered hawk's eggs in their markings. The measurements of 52 eggs average 59.8 by 49.9 millimeters; the eggs showing the four extremes measure 63.4 by 48.3, 62.7 by 50.1, 55.7 by 44.0, and 58.4 by 44.2 millimeters.
The sequence of molts and plumages is the same as in other redtails, but the racial characters are always evident. Its food habits, general behavior, and voice are all similar. It migrates away from the northern portion of its range for the winter. A. G. Lawrence tells me that it is very rare in southern Manitoba, departing in September and returning in April.
WESTERN RED-TAILED HAWK
BUTEO BOREALIS CALURUS Cassin
From the western edge of the Great Plains westward this very variable form of the red-tailed hawk breeds from southeastern Alaska and central western Mackenzie southward to Mexico. I~ chief characters are its interesting color phases, varying from a light phase, which is practically indistinguishable from the eastern bird, to a melanistic phase, which is wholly dark sooty brown, except for the red tail. Between these two extremes are numerous intermediate plumages, to be referred to later. The immature bird is consistently darker, more heavily streaked below and with a more or less distinctly streaked throat, and more spotted tibiae.
Because of its similarity in the light phase to the eastern bird, some very good ornithologists think that the western bird should not be given a separate name. The color phases are no less variable than, or strikingly different from, those that occur in Swainson's hawk, the ferruginous roughieg, and some other hawks.
Spring: Throughout the northern portion of its range the western redtail is migratory. M. P. Skixmer's records for 10 years in Yellowstone National Park show that it was first seen there very regularly between March 29 and April 3, departing again about the middle of October. He thinks its arrival in spring is dependent on the appearance of the ground squirrels, which come out of hibernation about the first of April.
That these hawks know where to find a good food supply while migrating is shown by their spring visits to the Earallon Islands, of which Walter E. Bryant (1888) writes: 'Tvery spring the island is visited by numbers of these hawks. In 1882 they came in April, about the time of the arrival of the murres, leaving again in May.
During their short stay they fed almost exclusively upon the murres, killing, in the estimation of Mr. Emerson, several dozen a day. In 1887 the lighthouse man killed about seventeen of these hawks, and during the month of May, 1885, twenty-eight, mostly of this species, were destroyed."
Nesting: After making due allowance for the difference in environments and in available nesting sites, the nesting habits of the western redtail and all its habits are similar to those of its eastern relative. It prefers to place its nest at some lofty situation in the tallest tree it can find, but, as its distribution is governed more by the food supply than by suitable nesting sites, it is often obliged to nest at low elevations or on cliffs.
I have recorded in my notes only 12 nests, 8 seen in Arizona and 4 in California. Of the Arizona nests three were on rocky cliffs, two in abandoned nests of the golden eagle, and one in an old raven's nest. Only one of the eagle's nests was closely examined; this was on the face of a bulging rocky cliff on the steep side of a mountain, 75 feet from the bottom of the cliff and 25 feet from the top, giving a fine outlook over the valley far below. It could be reached only by going over the cliff on a rope. The old nest had been repaired somewhat and lined with strips of yucca and other soft fibers. 1 collected two eggs from it.
Two nests were found in open country as we drove along the roads, one 40 feet up in a cottonwood and one 25 feet up in a mesquite. In the deep canyons of the Catalina Mountains, where the giant cottonwoods and sycamores grow, we saw the loftiest nests, approximately 90 and 100 feet above the rocky beds of the streams.
The lowest nest, and one of the most interesting, was only 10 feet from the ground in a double-headed soapweed yucca, which stood out alone on an open plain; it was a bulky old nest that had been in use for years and was securely held between the branches of the yucca. It held two pretty eggs (p1. 49).
Of the California nests only one was on a cliff; this may have been an old raven's nest, but it had been extensively rebuilt. The other three were in large sycamores, 40, 00, and 70 feet from the ground. All the above 12 nests were in commanding situations where the birds could have a good view of their surroundings.
In Arizona the western redtail often nests in the giant cactus, or saguara, placing its nest where one or two main branches project from the trunk and bend upward. J. H. Clark (1900) describes four such nests at heights varying from 6 to 30 feet from the ground. He also mentions two nests in palo verdes 10 and 12 feet up.
An unusually lofty nest is described and fully illustrated by William L. Finley (1905) and Herman T. Bohlman. The nest was 120 feet from the ground in a giant cottonwood on the bank of the Columbia River in Oregon. It required a vast amount of energy and daring to take the fine series of photographs of eggs and young at different ages that they secured.
J. A. Munro (1919), referring to the Okanagan Valley in British Columbia, writes: "This is the characteristic hawk of the lower mountains. They are equally at home in the dense coniferous forests at the edge of cultivated land, in the open park country of the yellow pine (Pinus ponderosa) or in the midst of deep canyons and rock cliffs. The same nests are used for several years, usually built in tall coniferous trees, forty to sixty feet above the ground. A site commanding a view of open range or valley is preferred."
W. Leon Dawson (1923) shows a photograph of a redtail's nest only a few feet from the ground in an ocotillo bush; this ~vas in the Imperial Valley desert, where trees are scarce.
E. L. Sumner, Jr., writes to me of a nest in which the three eggs were surrounded and partially covered by a piece of white wrapping paper; how the paper came there is unknown, but it resulted in the desertion of the nest. James B. Dixon (1902) reports a somewhat similar case in which "the hawks had secured a large piece of barley sack and with this made a lining for the nest, the eggs being covered by it."
Referring to a thickly populated area in San Diego County, Joseph Dixon (1906) writes:
We found the western red-tail and sparrow hnwks and the Pacific horned and barn owls especially abundant. In one valley in a distance of six miles we found twenty-two hawks' nests. Seven of these nests were occupied by redtails, three by horned owls and one by a red-bellied hawk. Each pair of redtails usually had two and sometimes three nests, for they seem to occupy different nests from year to year. Two nests were often fonnd built close together and in one instance there were three nests in one clump of trees.
These twenty-two nests were all located in sycamores which often stood at a bend In the creek or near the edge of the grove. By actual measurement we found that the average height from the ground of twenty-two nests was fiftyfive feet. The extremes were seventy-five and forty-three feet. We estimated that there was a pair of hawks to every one-hall square mile of territory. What becomes of the offspring in this densely populated district Is a problem that I have been unable to solve. But some of them evidently stay near their birthplace, as we found that out of seven pairs, two pairs had moved in since inst year.
Eggs: The western redtail usually lays two or three eggs, perhaps oftener two; four eggs are occasionally laid, and five or even six have been recorded. The eggs are practically indistinguishable from those of the eastern redtail, although they may average a little more heavily marked. The measurements of 48 eggs average 59.2 by 46.4 millimeters; the eggs showing the four extremes measure 64.5 by 48.3, 61.5 by 49.6, and 53 by 43.5 millimeters.
Young: Incubation lasts for 28 days and is shared by both sexes. Bendire (1892) says that "the eggs are deposited at intervals of a couple of days." Both parents assist in the care of the young, which remain in the nest for about six weeks. In the nest that Mr. Finley (1905) studied the young were hatched on April 20 and they left the nest on the first' of June.
Mrs. Irene G. Wheelock (1904) tells the following remarkable story of a young hawk that was thrown out from a nest and fluttered helplessly to the ground:
It fluttered about on the grass, and after resting a time managed to scramble into a low bush, where it felt more secure, though it really was much wore exposed. In the meantime the adults had circled wildly about with discordant screams, and the mother still remained near. Curious to see how she would manage to get that unlucky youngster hack into his nest, we moved off fifty yards and watched through the glasses. Both parents swooped down and looked at him, from on the wing, again and again, screaming when away, but silent whenever near him or the nest. At length a more sudden swoop and a momentary flutter, as a butterfly flutters over a flower. Then she rose carefully and slowly, with the young in her claws, and carried him to the nest. It was impossible to see whether she was holding him between them or grasping him by them.
Mr. Sumner, in his notes, thus describes the departure of a young bird from its nest:
One bird, when frightened, walked to the edge of ihe nest and facing the breeze spread his wings and then, half balancing, walked out on a small dead branch until 4 feet from the nest, where he remained, now with folded wings, quite at ease, although swaying in the wind. All at once the branch broke under his weight, whereupon he sprang into the air with vigorously flapping wings and flew partly against, partly beaten back and buoyed up by, the wind for 100 feet. He lit on the slough hank, stayed there a moment, and then, of his oxvn accord, jumped off and flapped low over the water across the slough and lit again on the other side. Presently he began to run, head low, wings partly unfolded, In typical hawk fashion, always putting distance between him. self and me. Presently he squatted down, in the same prone position as in the nest: a move that mny well be one of self protection, and here he stayed, even though I hid beneath a dead tree limb 100 feet away, with his eyes fixed on me, until after 15 minutes I got tired and left.
Leslie L. Haskin says in his notes that these young hawks "are the noisiest of all young land birds. This is especially true just after they have left the nest. They follow the old ones around at feeding time: which seems to be all the time that it is light: screaming at the tops of their voices. Txvo or three young redtails hungrily following the old ones sound like the squalling of a litter of pigs. In feeding the young birds the old hawk often mounts high in the air while the young ones circle, squalling, below her. Then she drops the food, and the young birds catch it before it reaches the ground. Snakes are a favorite article of diet, and when dropped in this way are easily seen."
Plumages: The downy stage and the sequence of plumages and molts are the same as in the eastern red-tailed hawk. Therefore it is necessary to consider here only the interesting color phases that seem to occur only in these western birds. In the extreme melanistic phase the entire adult plumage, except the tail, is very dark brown, varying from "bone brown" above to "warm sepia" or "bister" below; the tail varies from "Sanford's brown" to "hazel", a deep rich red, with a broad subterminal band and numerous more or less broken bars of black. In a common variation from the above the breast and belly are more or less tinged with tawny or rufous shades and the tibiae are spotted or barred with these colors. The erythristic, or red, phases are quite variable. An extremely red adult has "tawny" edgings on the head and neck; the scapulars are notched with huffy shades; the entire under parts from chin to tail are rich reddish brown, varying from bright "hazel" or "cinnamon-rufous" on the breast to "amber brown" on the tibiae; the upper breast is lightly streaked and the belly heavily spotted with black ; the tibiae are faintly barred with a darker brown; the tail is much as in the black phase but slightly paler. Intermediates between these two phases have duller, sootier browns on the under parts, the breast and belly showing two quite distinct colors. There are also intermediates between both of these phases and the common light phase. Immature birds of the dark phase are much darker above and much more heavily marked below than in the light phase. They look very much like young luzrlani, but can be recognized by the scarcity or almost complete absence of the conspicuous white spots on the upper parts so prominent in Mrlan.i.
I am not sure that we can recognize the young of the red phase, though we might expect them to show richer buff or tawnier shades.
Food: The feeding habits of the western redtail are similar to those of the eastern bird, but the western form is even more beneficial to the agriculturalist, for it lives in a region where injurious rodents are very abundant and troublesome. Joseph Dixon (1906) says: "Each pair of hawks had its own squirrel pasture and the birds resented the trespassing of other hawks on their domain. The remains of gophers, ground squirrels. meadow mice, young cottontails and two species of snakes, the striped racer and gopher snake, were found in red-tails' nests, but ground squirrels seemed to be their principal diet. I found as many species of small mammals in hawks' and owI~' nests in two days as I did by trapping for a week."
Mr. Sumner found in a nest parts of seven ground squirrels, one pocket gopher, and two cottontail rabbits. J. Paul Miller (1931) made a study of five red-tailed hawks' nests in the Big Bend country in eastern Washington and summarizes the food results as follows: "The food brought to the nests consisted entirely of Columbian Ground Squirrels (Citel1u~s c. columbimu8 (Ord)) with the exception of one meadow mouse (Mic'rotu.s sp.), and although birds of various species were numerous in the vicinity of all the nests, they did not seem to be disturbed by the hawks. About six squirrels per day from the time the young hatched until they were nearly feathered seem the average number provided. This is strong evidence as to the benefits which were locally derived from the activities of these birds."
Mr. Finley (1905) says of the food found in the nest he studied: "On the first visits we found the remains of quail and pheasants in the aerie. One morning we saw the mangled body of a screech owl; almost a case of hawk eat hawk. Later in the season when the banks of the Columbia overflowed, and covered most of the surrounding country, the old hawk did not abandon his own preserve. Ha turned his attention entirely to fishing. Where the carp and catfish fed about the edges of the ponds he had no trouble in catching plenty to eat. Twice we found carp over a foot in length in the aerie. On our last visit we picked up the head bones of seven catfish in the nest."
The following quotation from one of A. W. Anthony's (1893) Lower California papers is doubly interesting:
At La Grulla a pair of redtails were nesting near our camp. The male was a very light bird, while the female was so dark as to be several times mistaken for the dark phase of swai,nson~. On May 16 the female was shot as she rose from the nest, and on skinning her I found In her stomach the remains of a CuanoceMaiu8 and a nearly complete rattlesnake that must have measured over two feet in length. On the following day the male was seen flying about the nest with another female fully as dark as his former mate, and I was surprised to see her feeding young ten days or two weeks old. I had supposed the nest still contained eggs. As It was such a clear case of adoption I concluded to leave them undisturbed, but the unfortunate male was doomed a few days later to lose his second mate which was shot by a member of our party; upon dissection this bird was also found to have a large rattlesnake coIled up in her stomach. We frequently saw redtails sailing about over the meadows with large snakes hanging from their talons.
In connection with the above dangerous feeding habit, it is interesting to note that J. S. Hunter (1898) reports that a red-tailed hawk was seen attacking a rattlesnake, which bit the hawk twice and killed it. As this was in Nebraska it probably was one of the eastern redtails and perhaps not accustomed to rattlesnakes.
Behavior: Mv experience with red-tailed hawks has taught me that they are very shy birds; they usually keep well out of gunshot range even when they have young in the nest. But I once saw an unusual exhibition of boldness and aggressiveness shown by a western redtail. While out with A. M. Ingersoll and J. B. Dixon, near Escondido, Calif., his climber, Gus Hanson, attempted to collect a set of three eggs from a nest about 70 feet up in a tall sycamore. One of the hawks attacked him, darting down at him time after time and looping the loop above him several times. We all agreed that it was the greatest exhibition of the kind we had ever seen.
Mr. Skinner says in his notes:
Here in the Yellowstone National Park, where they are protected, these big hawks become so tame they can be readily studied. Often, I have passed them on stubs and telephone poles without disturbing them in the least, although I might be less than 50 feet distant.
They prey almost exclusively on rodents, and I have never seen one attack a bird. The larger birds like the ducks and geese are indifferent to a redtall's presence, but the attitude of the smaller birds Is even more astonishing. I have seen a red-tailed hawk on a river bank with an unconcerned robin on a nearby bush. I have seen a redtail fly over a flock of conspicuous rosy finches on the ground without alarming them by either its shadow or its presence.
Other small birds, such as bluebirds and juncos, have shown similar indifference. On the other hand he has seen the hawks attacked by crows, nutcrackers, sharp-shinned hawks, sparrow hawks, kingbirds, Brewer's blackbirds, and once by an Audubon's warbler. In some cases the small birds were probably driving the hawk away from the vicinity of their nests. He once saw a flock of seven robins drive a red-tailed hawk to cover in a fir tree. He has seen the hawks fighting each other quite often, usually on the wing. Once he "watched a redtail flying high that would at intervals make a long, swift shoot down toward another redtail flying below that would turn and present its talons to meet the attack, real or pretended."
Mr. Sumner's notes record an attack by a redtail on a horned owl; the hawk dived at the owl from a height of 75 feet; the owl made no effort to turn over but "received the blow of the hawk's talons in the middle of its back." Another time he saw a pair of hawks executing their flight maneuvers near their nest. "About ten times, while they were circling near together, the male would lower his legs and adjust his circles so that he came above his mate, and about four times he actually touched her back, or so it seemed." As illustrating the confidence that small birds have in these hawks, he noted an occupied kingbird's nest and an occupied Bullock's oriole's nest in the same tree with a red-tailed hawk's nest containing young.
BUTEO BOREALIS HARLANI (Audubon)
Harlan's hawk has always been regarded as a subspecies in the Buteo borealis group and is so recognized in our latest A. 0. U. check-list (1931). James L. Peters (1931), in his new check-list, treats it as a full species, and several good ornithologists agree with him. I am inclined to accept this view, because the chief character of harlani, the mottled tail of the adult, seems to be a qualitative rather than a quantitative character. I shall not attempt to discuss here, or come to any conclusion regarding, the status of the many 1)iIzzling hybrids or intermediates that have been shown to exist., but shall merely try to present some of the facts and some of the theories.
P. A. Taverner (1927) has made some extensive studies of the borealis group and has published an excellent paper on the subject, beautifully illustrated with colored plates. He has suggested that harlani is a color phase of calurus, and that krideri is a color phase of borealis, stating that "Icrideri occurs along the western boundary of the borealis range and liarlani at the northern extent of calurus territory, neither having any centre of distribution where they occur in purity." This seems like an untenable theory and to be based on incorrect premises, for it is a well-known fact that pure krideri occupies quite an extensive breeding range on the prairies and plains of the Midwestern States; and Harry S. Swarth (1926) says of hariani, in the Atlin region of northern British Columbia: "The birds were ahundant and nesting over a wide expanse of territory, and within that region they were the only form of Buteo borealis that was seen."
Recently, Mr. Taverner (1936) has published another paper on the complicated relationships in the Buteo borealis group, to which the reader is referred for his latest views on the subject. Dr. Louis B. Bishop has also made quite an extensive study of this group, based on his large collection of the various races and on his study of other collections, and does not wholly agree with Taverner's conclusions. I have discussed the matter extensively with hoth of these gentlemen, and have examined an immense amount of material in various museums and private collections; but I must confess that there are many perplexing problems yet to he worked out before the relationships can be fully understood.
Mr. Swarth (1926) says of the haunts of Harlan's hawk in the Atlin region: These dark-colored Buteos were seen by us almost daily through the summer and in all parts of the region that we visited. On May 21 several were observed soaring low over the snow-covered slopes on the east side of White Pass. During the next week, at Carcross, they were seen daily; apparently several pairs were settled on their nesting grounds near the town.
About Atlin these hawks were distributed throughout the lowlands; there were nesting pairs at intervals of a few miles in whatever direction one traveled. Although the species was thus relatively numerous, speolmens were hard to obtain; the birds were remarkably wary.
The Harlan hawk Is in the Atlia region mostly a bird of the timber. The sort of perch most often chosen is the top of one of the taller spruce trees, often in fairly dense woods but always with such a commanding view as to make approach unseen out of the question. With the exception of the dark colored hawks seen in White Pass early in the season and supposed to be of this species, none was observed in the open country above timber line. The abundance of ground squirrels might have been supposed to be an attraction to that region, too. They were extremely wary always, so much so that although both bIrds of a pair might circle about, screaming, as long as an Intruder remained in theIr territory, it was generally Impossible to approach within gun shot.
Spring: H. V. Williams, of Grafton, N. Dak., who has collected some 50 Harlan's hawks for Norman A. Wood and a few more for the author, says that he never sees them in that State except on the migrations; his spring dates range from April 3 to May 6. A. G. Lawrence's records for southern Manitoba average around April 8, the earliest April 1. He says in his notes:
On April 9, 1916, I witnessed at St. Vital, Manitoba, a large flight of redtailed hawks and Harlan's hawks. It was a fine day, and the snow had partly melted away in open places, though still deep in the woods. In the afternoon a redlail was seen high overhead, then several, then more and more, until when I came to a clearing I counted between 60 and TO redtails and Harlan's circling around in two groups, the Harlan's numberIng about 15 to 18. There was little wind, and the birds had to flap their wings fairly frequently, circling round and round, making no sound, now close together, now scattering and spreading over a wide area, then reforming into a flock to continue circling over the clearing. This performance continued for over an hour, the birds still circling when I left.
Nesting: Audubon (1840) was, of course, mistaken in thinking that Harlan's hawk bred in Louisiana. Its breeding range was f ormerly supposed to include certain south-central States in which it is now known to occur only in winter. There are several sets of eggs in collections, said to be karlani, which are undoubtedly something else. These may be eggs of the ferruginous roughleg, Swainson's, or western ted-tailed hawk, all of which have melanistic color phases. Positively identified eggs of Harlan's hawk have apparently never been taken. All we really know about the nesting habits of this hawk is contained in the following brief account by Mr. Swarth (1926):
One nest was found. It was in the valley a few miles from Atlin, in rather open spruce woods, just above a stretch of marsh land. The nest was near the top of an isolated spruce, on a branching limb, about sixty feet from the ground. It was a huge mass of sticks, a platform that had been flattened to such an extent that the young birds were in plain sight from the ground nearby. On July 6 it held two young, with feather rows showing through the down on the breast. Returning on July 20 we found the young birds gone, but discovered them in nearby trees. They had evidently just left the nest; wing and tail feathers were not yet full grown, and thcy could make but short flights. On August 11 a second brood, again of two birds, was found, obviously just out of the nest. These birds could fly but feebly; when found they were on the ground in dense spruce woods. One young bird and one parent were shot.
Plumages: The downy young and early nesting plumages of Harlan's hawk Seem to be unknown. Mr. Taverner (1927) has illustrated two nearly fully fledged nestlings, nearly fully grown, taken with their two parents in the Mount Logan area, Chitina River Glacier, Alaska, on July 19, 1925. These two specimens are quite unlike (see his p1. 3, figs. 4 and 5), one being the darkest and the other the lightest colored of the brood of three. The male parent is a dark bird, which Mr. Taverner calls "an almost typical black-phased calurus" but which Dr. Bishop calls the second-year plumage of /rarlani in the dark phase (see his pl. 3, fig. 2). The female parent (his p1. 3, fig. 3) we can all agree to call a typical adult luzrlani in the light phase. The reader may form his own conclusion, but it seems to me that Dr. Bishop is probably more nearly correct.
There seems to be no doubt that luirlani has two very distinct color phases, an extremely dark phase and an extremely light phase. These two phases evidently interbreed, causing considerable confusion. The spotted tail is characteristic in the adults of both phases, but the immature birds are not so easily recognized. Norman A. Wood (1932), who has made a careful study of a large series of Harlan's hawks, tells me that in the dark phase of the first-year plumage ha~ani can be distinguished from the similar stage of the dark phase of calw,us by numerous and conspicuous white spots, some of them rather large, on the webs of the feathers of the back, scapulars, and wing coverts, and by the generally blacker tone in the entire plumage. In calurug, the general tone is browner and the dark-brown feathers are white only basally.
The immature plumages of the light phase are much like similar stages of krideri and are nearly as light colored. Specimens of immature birds in this plumage have been collected in Alaska and British Columbia, which have suggested the extension of the range of Amideri into that region, which seems to be too far removed from its normal range. I believe that the two young birds collected by Mr. Dixon, at Flood Glacier on the Stikine River, on July 31, 1919, and so well described by Mr. Swarth (1922), were karlani in this plumage; It is interesting to note that Mr. Swarth was "disinclined to regard" them "as examples of kride~i, thereby extending the range of that form far to the westward."
Dr. Bishop seems to be convinced that Harlan's hawk has a wellmarked second-year plumage, and I am inclined to agree with him, though Mr. Taverner denies it. This plumage, in the dark phase as we recognize it, is characterized by a dull red tail, crossed by dark bars and often showing some spotting; the white-spotted plumage of the upper parts has been replaced by a uniform, sootybrown plumage, somewhat darker than in calurus. I have not seen any birds in the light phase that I could recognize as second-year birds. If, as seems likely, harlani has a distinct second-year plumage, which I have been unable to trace in other red-tailed hawks, it tends to strengthen the theory that harlani is a distinct species.
Food: Swarth (1926) says on the food of this hawk: "Of the six specimens I collected four had crop or stomach or both well filled. Two contained rabbit (Le pus anericanus macfariani), one held ground squirrel (Citellus plesius plesius) and chipmunk (Eutamias borealis carniceps), and one held rabbit and chipmunk."
Norman A. Wood writes to me that his collectors in Arkansas tell him that these hawks feed mostly on rabbits and quail, but also on squirrels, field rats, and mice, and more or less on small birds.
Behavior: Audubon (1840) writes:
This species, although considerably smaller than the Red-tailed Hawk, to which it is allied, Is superior to it in flight and daring. Its flight is rapid, greatly protracted, and so powerful as to enable it to seize its prey with apparent ease, or effect Its escape from Its stronger antagonist, the Red-tall, which pursues it on all occasions.
The Black Warrior has been seen to pounce on a fowl, kill it almost Instantly. and afterwards drag it along the ground for several hundred yards, when it would conceal It, and return to feed upon it in security. It was not observed to fall on Hares or Squirrels, but at all times evInced a marked preference for common Poultry, Partridges, and the smaller species of Wild Duck.
Fall: Mr. Swarth (1926) says: "During September, Harlan hawks were migrating in numbers. They were seen near Atlin daily, and between Atlin and Teslin (September 7 to 15) a number were oh. served drifting southward. On September 21, I saw two, the last observed."
Mr. Williams gives fall dates for North Dakota from September 28 to November 20, and says: "The flight usually starts with a few stragglers and gradually increases to its height (about 200 birds for a day or so), then gradually decreases. I see usually from 700 to 1,000 every spring and fall. They fly with the red-tails and circle the same way, usually very high, but after the first few days a number of them stop to feed, but are very shy and wild."
Winter: Harlan's hawk seems to be a bird of rather restricted range at all seasons. Mr. Swarth (1926) words it as follows: "Breeds in extreme northern British Columbia, east of the coast ranges, north into the valley of the Yukon, and eastward for an undetermined distance. Migrates southward east of the Rocky Mountains, through the Mississippi Valley to a winter home in the Gulf States."
According to N. A. Wood (1932) "its winter range includes a territory embracing all of Arkansas, southern Missouri, Oklahoma, and northern Texas." One of his collectors in Arkansas, Clyde Day, says: "These hawks seem to make their winter quarters in a strip about 100 miles north, and south and 300 miles east and west. I see on an average ten a day, half of them Harlan's."
FLORIDA RED-TAILED HAWK
BUTEO BOREALIS UMBRINUS Bangs
More than 30 years ago Outram Bangs (1901) gave the above name to the red-tailed hawk of southern Florida. His description was based on only a single specimen collected in April 1888 at Myakka in Manatee County. The characters given were: "Size and proportiors as in Buteo borealis borealis; color, above, darker; t.hroat and middle of belly marked with broad, conspicuous striping and banding of deep chocolate-brown; tail-feathers with dark brown markings (the remains of bands) near the shafts. From B. borealis caluru~s the new form differs in being less suffused with reddish below, and in different general tone of coloration."
At the request of Mr. Bangs and with the expert help of John B. Semple, we were able to collect, during the winter and spring of 1930, a fair series of these hawks. With the exception of one bird, probably a migrant from farther north, this series shows that this race is uniformly well marked and is permanently resident in the southern half of Florida. Birds collected by William G. Fargo in Brevard County are clearly referable to this race, but the characters are not so pronounced. Intergradation with northern borealis may occur in northern Florida. The range of this race doubtless includes Cuba and the Isle of Pines, and possibly Jamaica.
Red-tailed hawks are fairly common, as hawks go, in Florida. They are widely distributed throughout the flat pine woods, locally known as "piney woods" or "flatwoods", with which a very large portion of Florida is covered. One may drive for many miles along roads and see nothing hut an apparently endless expanse of flat country covered with an open growth of tall, slim Caribbean or longleafed pines, rough-harked and scraggly, but in their perfection sturdy, grand, and impressive. The stand is so open that dense undergrowths of low-growing saw palmettos, with their curious, halfburied root-stems trailing along the ground, form large and almost impenetrable thickets. Many shallow grass-lined ponds and open grassy savannas are scattered through them. The soil is mostly sandy, but in many places it is rich enough to support a luxuriant growth of shrubbery and many beautiful wild flowers. To the casual observer a drive through such an endless, bewildering maze of pines, stretching away into the dim distance, becomes monotonous and tiresome. But I can share the sentiments so well expressed by Dr. Charles T. Simpson (1923) There is a nameless charm In the flatwoods, there is enchantment for the real lover of nature in their very sameness. One feels a sense of their infinIty as the forest stretches away into space heyond the limits of vision; they convey to the mind a feeling of boundless freedom. The soft, brilliant sunshine filters down through the needle-like leaves and falls in patches on the flower covered floor; there is a low, humming soni A, sometimes mimicking the patter of raindrops, as the warm southeast wind drifts through the trees; even the loneliness has an attraction. To me it all brings a spirit of peace, a feeling of contentment; within the forest nature rules supreme.
Nesting: I have examined only two nests of this hawk, in two quite different situations (p1. 52). 'While driving over the Kissimmee Prairie, near Bassinger, Fla., on March 21, 1925, we saw a large nest about 40 feet up in a lone cypress that stood near a small cypress hammock. The tree was heavily draped with Spanish moss. We could see the tail of the sitting hawk projecting over the edge of the nest, and its mate was perched on a nearby tree. As I climbed to the nest the old birds attacked me, screaming vigorously; one nearly struck me in its swoops. The nest was made of large sticks, lined with fine twigs, grasses, straws, and gray moss; it measured 40 by 27 inches in diameterï and was 18 inches high. It contained a pipped egg, a recently hatched young hawk, and the remains of a young cottontail rabbit.
The other nest, found on February 15, 1930, in Glades County, was fully 60 feet from the ground in the topmost crotch of a big longleafed pine; the tree towered above the tops of all the surrounding trees in open flat pine woods, and the nest could be plainly seen from the road at a long distance. The nest was made of pine sticks and twigs, deeply hollowed and profusely lined with dead and green pine needles; it measured about 24 inches in diameter, the inner cavity being 10 inches wide and 4 or 5 inches deep. The hawk flushed off the nest but did not offer to attack me while I was collecting the two eggs. Both parent birds were secured.
Mr. Fargo has sent me some notes on some large nests that he found in Pasco and Brevard Counties, some "nearly as large as bald eagles', but wider than high. All the nests seen were in some tree where a good outlook was to be had at the loss of hiding the nest.
These birds purposely select a pine tree or cypress that stands a bit away from the forest or if in a swamp, then at its edge, so that they can see out on the open country."
Joseph C. Howell has sent me data on 10 nests that he has examined. Two of these were in oaks and only 20 feet from the ground. The others were all in pines ranging in elevation from 1,1 to 60 feet, most of them from 40 to 50 feet up. One nest that he describes as a large one measured 2 feet in diameter and 2 feet in height; the inner cavity was 9 inches across and 3 inches deep; it was an old nest that had been repaired. "The foundation of the nest was largely of good-sized pine twigs, with one oak limb and a piece of palm boot here and there. The lining was of pine needles, mostly green, pure white down from the parent, live Spanish moss, bits of dead pahn frond, and a few strips of green palm leaf."
Eggs: The eggs of the Florida redtail apparently do not differ materially from other redtails' eggs. The set I collected happened to be more heavily marked than usual, but I have seen others nearly, or quite, immaculate. The measurements of 32 eggs average 60 by 47.3 millimeters; the eggs showing the four extrenie~ measure 65.1 by 45.3, 61.3 by 49.3, 54.6 by 47.5, and 61.7 by 43.8 millimeters.
Behavior: We noticed nothing in the habits of this hawk that differed from those of its northern relatives. It is very shy, but that is true of the species elsewhere. Its food seems to consist mainly of mammals, such as rabbits and cotton rats; no evidence of bird killing was seen.