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A chapter from the electronic book:  Life Histories of Familiar North American Birds

Baltimore Oriole
Icterus galbula  

Contributed by Winsor Marrett Tyler
[Published in 1958: Smithsonian Institution United States National Museum Bulletin 211: 247-270]

Here in New England, during the long-drawn-out spring migration, there are several red-letter days. The first of these is the day, sometimes late in February, when the wintering song sparrows, which have been long silent in the shrubbery, begin to sing their spring song, a tinkling melody which foretells the ending of winter. As the year advances, there is another welcome day, the real beginning of the migration, when the bluebird, flying over the brown fields of March, comes back to his summer home, and we hear the softest, sweetest voice of all our birds--"the herald of spring," Alexander Wilson calls him. But the greatest day of the whole year is in early May when the season is well established, when the apple blossoms are opening. Many of the birds are already here and have been singing for days. On this day, not far from the 8th of the month, the Baltimore oriole makes his dramatic entrance into New England. On every hand, in our orchards, among the high branches of our roadside elms, the little trumpeter is heard blowing his tiny bugle; all out-of-doors is animated by his buoyant personality.

Spring.--Bendire (1895), speaking of the return of the bird to its breeding ground, says: "The Baltimore Oriole usually arrives in the southern New England states, in central New York, and Minnesota, with almost invariable regularity, about May 10, rarely varying a week from this date; it arrives correspondingly earlier or later farther south or north. About this time the trees have commenced to leaf, and many of the orchards are in bloom, so that their arrival coincides with the loveliest time of the year. The males usually precede the females by two or three days to their breeding grounds, and the same site is frequently occupied for several seasons. . . . It is very much attached to a locality when once chosen for a home, and is loath to leave it."

The orioles come home with a stirring fanfare, but as each bugle is playing a different tune and the tunes are so distinctive, so characteristic of the individual bird, we can almost verify Major Bendire's statement that the birds come back to their old homes. If we take note of the peculiarities in the song of the oriole which we hear from our windows, we can recognize him, provisionally at least, as the same bird year after year until, after a time, he is replaced by another bugle, playing a different tune.

There is a banding record, however, which proves absolutely that an oriole returned three times to its breeding ground. A. Milliken (1932) banded in 1929 a female Baltimore oriole captured in an open-top Chardonneret trap baited with string and yarn. She returned in 1930 and 1931. "The bird nested very near the same place for three successive years, though the exact spot is not known."

There is a businesslike air in the returning orioles. The males go directly to our orchards, visiting the open apple and cherry blossoms, where they find food, and to the elm trees, where their nests will soon hang. The females, too, when they arrive a few days after their mates, seem eager to undertake at once the duties of the new season and begin to build so promptly that the breeding cycle is well underway, here in New England, by the end of May.

Very seldom, in a long series of years, have the birds arrived before the Massachusetts apple trees blossom. The birds then seek their food nearer the ground, among sweet fern or other small plants.

Courtship.--We note the courtship of the Baltimore oriole chiefly in the brief period between its arrival and the laying of the eggs in early June. Forbush (1927) speaks of its behavior thus: "When their modest consorts arrive, the ardent birds soon begin their wooing. In displaying his charms before the object of his affections the male sits upon a limb near her, and raising to full height bows low with spread tail and partly-raised wings, thus displaying to her admiring eyes first his orange breast, then his black front, and finally in bright sunlight the full glory of his black, white and orange upper plumage, uttering, the while, his most supplicating and seductive notes."

Francis H. Allen says: "A male courting a female uttered a succession of low sweet whistling notes, rather monotonous and in anything but the typical oriole tone," and of another bird he says: "A male courting a female flitted about in an affected manner and sang on the wing in a longer flight."

Some years ago, after watching the courting action of a male oriole, I (Tyler, 1923) made an attempt to construct in my mind's eye how this display would appear to the eye of the female from her vantage-ground on the perch in front of him:

A male Baltimore Oriole (Icterus galbula) of strikingly brilliant plumage was singing loudly in a maple tree when a female Oriole took a long flight and alighted in the same tree. The male flew to her, placed himself directly before her, facing her at a distance of a few inches and here struck successively two attitudes; in one his body was nearly upright, straight and tall, in the other it was bowed downward and forward with the head at the level of the feet. The wings were held closely at the sides. In passing quickly from one attitude to the other, over and over again, he moved up and down with a sharp jerk, rather than in an easy sweeping motion, and he made a very short pause each time before changing direction.

This is a very simple motion, one may say--just an exaggerated bowing--not very different from the bowing, nodding, or swaying of many birds in the excitement of their courting displays. True enough, and it is not until we look at the action from the point of vantage of the female bird and see in our mind's eye, as nearly as we can, just what she sees, that we understand its significance.

In the first position noted above, the orange of the breast glows before her, and so near her that it fills a wide arc with blazing color. Then, as the male bird bends swiftly forward, and the head comes down, the orange is blotted out by black, as by a camera shutter, and immediately, as the bird continues to bend forward, out flashes the orange color again, now on the rump. Witnessed at close quarters, the appearance of this maneuver must be as the bursting out of a great sheet of flame, its instantaneous extinction into darkness, a flaring up again--then darkness once more.

Nesting.--In constructing its nest, a woven, hanging pouch, the oriole is perhaps the most skillful artisan of any North American bird. In southern New England we think of the little cradle as hanging most often high in the air near the end of a long drooping branch of an elm tree, where it swings and tosses in the wind, but the bird often builds here in poplars, maples, and even in the apple and pear trees of our orchards, where it is anchored to a more stable branch.

Speaking of nests in Hatley, Quebec, Henry Mousley (1916) states: "The usual nesting site selected here is near the top of some fair sized tree, generally a maple." Knight (1908) reports that in Maine, although the elm is the oriole's favorite tree, "occasionally nests are placed in maples, locust, cottonwood, poplar or other hard wood trees." Eaton (1914) writing of New York state, says: "I have found this oriole's nest hanging from Norway spruce, hemlock, and horsechestnut which one would naturally expect he never would select. In different villages of western New York the preference seems to be in this order: white elm, silver maple, sugar maple, and apple." Farther west, in Minnesota, Edmonde S. Currier (1904) remarks: "Common about the lake [Leech Lake]. . . . All the nests seen were in birch trees." A. D. DuBois speaks of a nest in Illinois "in an oak tree, hung in a cluster of leaves at the topmost end of a branch, hidden so effectively that I should not have discovered it if I had not seen the male fly to it and chase away sparrows and other birds." M. G. Vaiden, in a letter from Mississippi, mentions pecans, sycamores, and elms as nesting sites, and includes this interesting record: "In my yard the pecan trees grow to a height of 50 to 75 feet, some of them even higher. Virginia creeper vines run up the trunk and out on most of the limbs. On May 22, a Baltimore oriole selected as a nesting site a limb of a tree which had fallen off, pulling the creeper with it and was hanging suspended in the air, the nest being attached to the creeper as well. After three eggs were laid the limb fell to the ground, but the bird, not to be outdone, built another nest in the dangling remains of the creeper, from which she fledged her young."

Usually the Baltimore oriole hangs its nest high over our heads; Eaton (1914) estimates the average height as 25 to 30 feet and he has seen a nest 60 feet above the ground. On the other hand, A. D. DuBois reports "the lowest nest that has ever come to my attention was in a burr oak 7 feet 8 inches from the ground." Thomas D. Burleigh (1931) cites a still lower nest in Pennsylvania, "but six feet from the ground at the extreme end of a limb of an apple tree in an orchard."

The nest is a deep pocket hanging generally from the rim; the opening is usually at the top, rarely at the side. Bendire (1895) gives the dimensions of a nest from Ontario as follows: "It is externally 5 inches deep, and the entrance, which is oval in shape, measures 3 1/4 by 2 inches in diameter. The cup is 4 1/2 inches deep by 2 1/2 inches wide." Henry Mousley (1916) says of nests in Quebec: "The nests vary somewhat in depth, which in some cases may be as much as six inches, whilst one built in a maple opposite my house only measures three and one-half inches." M. G. Vaiden records a nest over 8 inches deep.

The framework of the nest is made of long, pliable strips of dry plant fibers, grapevine bark, Indian hemp, silk of milkweed, and such materials as are capable of being closely woven into a fabric. Near dwellings and on farms where string, horsehair, and bits of cloth are available, these are used commonly. The nests over the streets of our country towns contain many white strings, which soon bleach to a soft gray color when exposed to the weather. At the bottom, the nest may have a lining of hair, wool, or fine grasses. Forbush (1927) speaks of an aberrant nest "chiefly composed outwardly of jet black hair from the manes and tails of horses. This nest, placed low down in a pear tree, was very conspicuous among the green leaves."

John B. Semple (1932) explains that the oriole has adapted itself to the scarcity, almost the complete absence in recent years, of horsehair. He says:

Thirty years ago the nests of the Baltimore Oriole, and those of the Chipping Sparrow as well, contained in their makeup a large percentage of long hairs from the manes and tails of horses. This material was then easily obtained along the roads and in the pastures. Even ten years ago an oriole's nest found on a farm in Monroe County, Pennsylvania, where horses were used, contained a good proportion of horsehair. But now, since automobiles and tractors have brought about a disappearance of horses which is almost complete, it has become a matter of curiosity to find out what the orioles would do. A nest taken this autumn from the same tree on a farm in Monroe County, in which the nest of 10 years ago had been built, was found still to contain a few horsehairs. These must have been quite difficult for the bird to find, for the farm is now worked only by tractors. And in a nest taken this autumn in Sewickley no horsehairs whatever were to be found. The nest was composed chiefly of fibers of the bark of Indian hemp (Apocynum). Felted in toward the bottom of the nest were the hair-like pappi of dandelion seed; over this was laid the fluffy, cottony covering of willow seeds (the nest was in a weeping willow tree); and the lining of the bottom of the nest was of rather stiff fibers of grape-vine bark.

Audubon (1842) says that in Louisiana the bird uses Spanish moss chiefly as a building material. In this warm climate, it weaves the walls so loosely that they permit the passage of air, and little lining is added.

It has long been a matter for wonder among naturalists how the oriole can accomplish such a finished piece of workmanship in constructing its nest, work which seems to demand a conscious planning far beyond the resources of a bird's mind. The older writers speak rather vaguely of the weaving process and have little to say about how the bird employs what Audubon calls his "astonishing sagacity."

Francis Hobard Herrick (1935) has recently made a careful, intensive study of nests of the Baltimore oriole, watching their construction from the tying of the first string to a branch until the nests were completed. The following summary embodies the main steps in the workmanship of the bird as described in Dr. Herrick's account, a comprehensive paper of absorbing interest. He says:

The first strands of bast, which are apt to be long, are wound about the chosen twig rather loosely with one or more turns, or perhaps they are passed only once across or around the branch; but subsequent modes of treatment tend to draw these threads tighter, and as their free ends are brought together, other fibers are added. From such simple beginnings a loose pendant mass or snarl of fibrous material, which I have called the primary nest mass, is slowly formed, but it is a long time before it takes on the semblance of a nest or nest frame. . . .

Behavior at each visit, after a certain number of strands had been laid and joined, was essentially the same, the oriole usually bringing in but a single fiber and carrying it around the support and working it into the nest mass by what I have called shuttle movements of the bill. Clinging to the principal twig, hanging often with head down, and holding the thread, the bird makes a number of rapid thrust-and-draw movements with her mandibles. With the first thrust a fiber is pushed through the tangle which soon arises and forms the growing mass, and with the next either that or some other fiber is drawn loosely back. . . .

While these shuttle movements are, first and last, very similar, and almost equally rapid at all times, the number made at each visit tends to increase with the growing complexity of the product. At least one hundred shuttle movements were sometimes made at a single visit, but these were often so rapid that it was impossible to count them, and many of them must have been abortive.

In all this admirable work there was certainly no deliberate tying of knots, yet, as the sequel will show, knots were in reality being made in plenty at every visit. There certainly was no deliberate directing of the thread, as when a coat is mended or a hammock is woven in a certain way by human hands. The work was all fairly loose at first, yet naturally some of the threads became drawn more tightly than others. I do not wish to imply that the same thread that is first thrust through the nest mass or the nest wall is immediately drawn back, but only that some thread or other is blindly seized by the bill and withdrawn. . . . The irregularity of the weave of the finished work shows conclusively that the stitching is a purely random affair, though, for all that, none the less effective.

Thus in the course of 2 or 3 days' work, a loose, tangled mass of fibers, which will ultimately become one side of the nest, hangs from the supporting twigs. Many long strands dangle from this mass, their ends hanging free. When this stage of the construction is reached, the bird is working from what is to become the inside of the nest, and as Herrick describes her actions, with "decision and feverish rapidity, with strokes of her bill pushing the threads through the nest body and then catching up the free ends of other strands and drawing them in the opposite direction; with one foot grasping a twig and the other the nest mass, thrusting and pulling, she is now astride the mass and balancing herself with spread wings, now working from above, from below, or at either side; and at each visit she is not only incorporating any new strands that are brought, but gathering up many others which, though fixed at one end, are still hanging free."

Finally, the bird takes in another twig, other twigs, for support, outlines the framework of the other side, and then fills it in by weaving with the shuttle movements as before. The long streamers are ultimately worked into the wall of the nest. Herrick speaks of the finished nest as "an indescribable chaos of looped and knotted fibers" that is, nevertheless, "strong, durable, and adaptive." In constructing these nests "the female was the chief builder, but the male would occasionally take a share."

In the late stages of construction "the bird settles down in the nest and shakes all over in an effort to bring the pressure of the breast to bear upon its inner surface; he [in this case the bird was assumed to be the male] rises, turns, settles, and shakes again. These are the typical molding movements, and they are applied all over the lower parts of the pouch, their violence at times being such that the surrounding leaves, and even the slender tree itself, are all a-tremble."

One of Herrick's nests was completed in 4 1/2 days. Harry C. Oberholser (1938) says the nest "is usually completed in not more than 6 days"; Bendire (1895) says: "From 5 to 8 days are usually required for its completion"; while Knight (1908) states that "nest building requires about 15 days."

The oriole begins to build so soon after its arrival on its breeding ground that the elms, a favorite tree, are barely leafing out when the nest is building. But soon, as the season advances, the leaves afford both protection and some concealment to the nest. In January 1946 A. C. Bent showed me a nest hanging, as plain as a rag on a clothes-line, on one of the elm trees in his garden. "Last summer," he said, "that nest was completely hidden in the dense foliage at the end of that long, pendant limb; I could not see it from any angle, although I often tried and knew just where it was. All the other nests I have located have been visible, from some angle at least."

It is the bird's custom to build a new nest each year. This habit is evidenced by the remains of former nests, in varying degrees of dilapidation, which sometimes hang in the same tree. An apparent exception to this rule is reported by George F. Tatum (1915) who tells of a female Baltimore oriole repairing a last  year's nest. He concludes "that the old nest had been reconstructed, the only evidence of the former one being the black (old) fiber now interwoven with a little of the light (new) fiber, which bound the edge of the nest to the branch."

When we consider the sequence of steps taken in the construction of the oriole's nest, as outlined by Herrick, and recall the propensity of birds to follow a cycle in their behavior, one act following another in orderly succession throughout the year, we can conceive that it may be more in accordance with the bird's nature to progress straight through the making of a new nest from beginning to end, rather than to patch up an old nest in ill repair.

Eggs.--Bendire (1895) writes:

From four to six eggs are laid to a set, most frequently four, though sets of five are not uncommon, while sets of six are rather rare. One is deposited daily, and only one brood is raised in a season. . . .

The ground color is ordinarily play grayish white, one of those subtle tints which is difficult to describe; in a few cases it is pale bluish white, and less often the ground color is clouded over in places with a faint, pale ferruginous suffusion. The egg is streaked, blotched, and covered with irregularly shaped lines and tracings, generally heaviest about the larger end of the egg, with different shades of black and brown, and more sparingly with lighter tints of smoke, lavender, and pearl gray. In a few instances the markings form an irregular wreath, and occasionally a set is found entirely unmarked.

The average measurement of 56 eggs in the United States National Museum collection is 23.03 by 15.45 millimeters, or about 0.91 by 0.61 inch. The largest egg of the series measures 25.91 by 16.76 millimeters, or 1.02 by 0.66 inches; the smallest, 20.83 by 14.99 millimeters, or 0.82 by 0.59 inch.

Young.--The nesting orioles are comparatively safe for the first 2 weeks, or thereabouts, of their lives, during the time they remain concealed in their little, woven pocket well above the ground at the end of a slender branchlet. Young orioles seem very quiet as nestlings; at all events we do not hear their voices until just before they leave the nest. At this time, near the summer solstice in southern New England, they begin their characteristic cry. On a certain day, over a whole township we hear it, over and over all day long, and for a week or more it continues hour after hour, a monotonous series of five or six notes, falling in pitch a little, with a ringing or resonant quality. It is a pathetic little childish cry or complaint, beseeching, yet insistent, half way between entreaty and demand, dee-dee-dee-dee-dee. The pitch is about F sharp, on the top line of the musical staff. This note has given the fledgling oriole the epithet "cry baby."

William Brewster (1937) gives his impression of the young oriole's note. He says: "As she [the female parent] came flying back, I was struck by the tone of mingled anxiety and interrogation of her low call. 'Where? Where?,' she seemed to say. 'Here-we-are, here-we-are' (falling inflection), both young would promptly drawl in answer and then, as she alighted near them, would repeat and extend this to: 'Here-we-are, mam-ma, her we are, mam-ma.' It really required almost no imagination to fit these words to the calls in question and now that they have occurred to me the calling of young Orioles will no longer be to my ears, as it always has been, a disagreeable sound."

He adds in a footnote: "A week later when this call had become louder and mellower, it often bore a strong resemblance to the whistle of the Greater Yellow-leg, the form being almost exactly the same."

Audubon (1842) remarks: "A day or two before the young are quite able to leave the nest, they often cling to the outside, and creep in and out of it like young Woodpeckers. After leaving the nest, they follow the parents for nearly a fortnight, and are fed by them." William Brewster (1906) says: "After the breeding season is over both old and young resort more or less freely to bush-grown pastures and the edges of woods. On July 19, 1889, I saw upwards of forty collected within the space of half an acre in Norton's Woods, and I have met with smaller flocks at Rock Meadow and in the Maple Swamp."

Small companies of orioles in immature or female plumage are frequent here in New England up to the time when the species departs late in August. As a rule, however, there are no adult male birds in these gatherings.

Forbush (1927) and Bendire (1895) give the incubation period as 14 days; Eaton (1914) gives it as about 12 days, and DuBois as12 days. Bendire (1895) says that the young birds remain in the nest about 2 weeks; DuBois reports a case in which they left in 11 or 12 days.

Plumages.--[AUTHOR'S NOTE: Jonathan Dwight, Jr. (1900), describes the juvenal plumage of the Baltimore oriole, in which the sexes are alike, as follows: "Above, olive-brown, slightly orange tinged, brightest on head and upper tail coverts. Wings clove-brown, the primaries narrowly, the tertials broadly edged with dull white, two wing bands at the tips of greater and median coverts pale buff. . . . Tail chiefly gallstone-yellow, centrally much darker and brownish. Below, including 'edge of wing' ochre-yellow, sometimes orange with ochraceous tinge, palest on chin and middle of abdomen, brightest on breast and crissum."

A partial postjuvenal molt, involving the contour plumage and the wing coverts but not the rest of the wings nor the tail begins in early July and produces the first winter plumage. Dwight says of this plumage in the young male: "Similar to previous plumage but dull orange brown above and much brighter orange below, although lacking the black areas of the adult. The greater and median wing coverts become dull black, white tipped, the latter and the lesser coverts orange tinged."

The first nuptial plumage is acquired by an extensive prenuptial molt involving most of the plumage except the primaries, their coverts, and the secondaries. The full orange and black body plumage is assumed at this molt, the tertials and wing coverts being broadly edged with white, and the black and yellow tail is acquired. Worn brown primaries remain to distinguish young birds from adults.

A complete postnuptial molt occurs in July, producing the adult winter plumage. This is practically the same as the adult nuptial plumage, but the "feathers of the back are narrowly edged with dull orange (absent in older birds), which also suffuses the median and lesser coverts. The greater coverts, secondaries and tertiaries are broadly edged with white."

The adult nuptial plumage is acquired by wear, during which the white edgings in the wings largely disappear and the orange edgings on the back are lost, producing the bright, clear orange and black spring plumage in the male.

In the female, the molts are similar to those of the male, but there is no striking change in the color pattern from one season to another. The upper parts are yellowish olive, the wings dusky with white tipped coverts and white edged flight feathers, and the under parts are dull orange or yellowish. There is often more or less black on the chin or throat, but it is usually very restricted in extent. However, in Manitoba we collected a breeding female, now in my collection, in which the throat is wholly black, as in a male, and the whole head and neck are mainly black.]

Food.--Waldo L. McAtee (1926) gives the following comprehensive summary of the Baltimore oriole's food:

Caterpillars are the most important single element of the Oriole's food, forming over a third of the total. The Baltimore is one of the birds that decidedly are not afraid of spiny or hairy caterpillars and it has a good record against such well-known pests as the fall webworm (Hyphantria textor), spiny elm caterpillar (Euvanessa antiopa), tussock caterpillar (Hemerocampa leucostigma), forest tent caterpillar (Malacosoma disstria), and larvae of the gipsy moth (Porthetria dispar), and browntail moth (Euprociis chrysorrhea). Orioles of this species have been known to destroy entirely local infestations of orchard tent caterpillars (Malacosoma americana).

Beetles, ants, parasitic wasps, bugs, grasshoppers, spiders, and snails are the principal additional components of the Hangnest's animal food. Among forms injurious to woodlands that are known to be preyed upon by the bird are tree hoppers, lace bugs, scale insects, plant lice, leaf chafers, junebugs, nut weevils, adults of flat-headed and round-headed wood borers, leaf beetles including the locust leaf miner, click beetles, oak weevil (Eupsalis minula), and sawfly larvae.

The wild fruits eaten by the Baltimore Oriole are mostly june berries, mulberries, and blackberries. A few vegetable galls are also consumed.

The Oriole does some damage to cultivated peas and small fruits, but has such praiseworthy food habits in general that it certainly is the best policy to take special measures to prevent access to the peas and fruits, rather than to get legal permission to destroy the birds.

Bendire (1895) eulogizes the bird's feeding habits even more enthusiastically: "Aside from its showy plumage, its sprightly and pleasing ways, its familiarity with man, and the immense amount of good it does by the destruction of many noxious insects and their larvae, including hairless caterpillars, spiders, cocoons, etc., it naturally and deservedly endears itself to every true lover of the beautiful in nature, and only a short-sighted churl or an ignorant fool would begrudge one of the few green peas and berries it may help itself to while in season. It fully earns all it takes, and more too, and especially deserves the fullest protection of every agriculturist."

Additional items in the bird's diet are mentioned by Ellison A. Smythe, Jr. (1912), who says: "They frequent the potato patches with the fledged young and feed freely on potato beetles"; and A. D. DuBois reports seeing the bird "in a sycamore tree, picking to pieces one of the seed balls--holding it against a branchlet with his foot and apparently eating the seeds." William Youngworth (1931) notes an "unusual food"; he says: "While looking from a window on July 23, 1930, the writer saw three immature Baltimore Orioles (Icterus galbula) clinging to the tall hollyhock stocks that were growing along the side of the house. Close watching showed that these birds were pecking into the newly formed pericarps of the hollyhocks and were greedily eating the soft, tender seeds." Samuel Lockwood (1872) gives good evidence that Baltimore orioles decapitated countless numbers of the stingless male carpenter bees (Xylocopa carolina) which were collecting honey in horsechestnut trees, and sucked out the honey. Elisha Slade (1881b) reports that he "detected a Baltimore Oriole eating the leaves [of the American aspen] with evident relish. The bird stood on a branch and picked at and tore off the leaves, eating them with as much apparent enjoyment as our domestic fowls eat the leaves of the plantain." He noted the same performance the following year. In both years the observations were made late in May.

Irene G. Wheelock (1905) gives evidence concerning the food given to the nestling orioles. She says:

On the first day, feeding by regurgitation took place at intervals averaging twenty minutes for each nestling. As the nest was not more than three feet from the window, it was possible to watch just what was being done and to make examination of the young as often as seemed expedient. . . . The food given was the soft part of grasshoppers and dragonflies, and the larvae of different species of insects mixed with green leaves--all thoroughly macerated and partially digested. No traces of fruit were found. On the third day, the male was seen to give the soft part of a dragonfly, having removed the wings in full view of the observer, without first swallowing it himself. After the fourth day all food recorded was given in a fresh condition. In the case of this brood no fruit was fed the nestlings, possibly because of the difficulty in procuring it.

Gordon Boit Wellman (1928) adds another item of food to the oriole's diet, and describes the skillful way in which the bird obtained it. He writes:

On May 13, 1928, I found a pair of Baltimore Orioles (Icterus galbula) feeding on the larvae of a needle miner, probably Paralechia pinifoliella, in a pitch pine (Pinus rigida). The tree could be observed closely from my study window and the Orioles were seen feeding there each day until the twenty-second of the month. Both birds worked alike; resting on one foot, the bird would pull down a needle with the other foot, tuck it under the supporting foot with the bill, remove the larva and continue to feed in this manner until the five or six needles within reach were opened and held under the foot, then a new position would be taken. The larvae were to be found about halfway down the needle, invisible from the outside. The operation of removing the larva from a needle was done with such skill that in no case did I find a needle broken or permanently bent.

In regard to the birds eating fruit and vegetables, Walter B. Barrows (1912) says: "It is true that it has a special fondness for green peas, sometimes stripping the pods so freely as to cause considerable complaint. It also punctures ripening grapes whenever it has opportunity, but particularly where vines have run up into trees or over arbors or shrubbery in such a way as to hide the bird while at work. It is rare to hear complaints from grape growers, for where the vines are numerous and properly pruned the Oriole seldom injures them. Occasionally it attacks early apples and pears, digging holes into the soft pulp and of course ruining each apple attacked."

"By watching an oriole which has a nest," says F. E. L. Beal (1897), "one may see it searching among the smaller branches of some neighboring tree, carefully examining each leaf for caterpillars, and occasionally trilling a few notes to its mate." Francis H. Allen has seen this oriole catch files in the air; he has also watched the birds taking nectar from trumpet creeper flowers. "They would peck into the base of the corolla and into the mouth of the calyx after the corolla had fallen. I could see the nectar glistening between their mandibles."

William Brewster (1937) speaks of an adult female oriole eating cherries: "She operated on them in a deliberate, somewhat fastidious manner, piercing the skin with her sharp bill and then slowly tasting and swallowing the juice and perhaps some of the pulp also. In no instance was the cherry removed from the stem. This was in marked contrast to the behavior of the greedy Robins about her, the Robins first plucking the cherry and then swallowing it whole, not without some difficulty."

Late in July, when cherries are ripe, the now fully grown young orioles come to the cherry trees alone or with their parent. Here they lean downwards, draw up a cherry and, steadying it in some way, appear to pick out mouthful after mouthful without detaching the fruit from its stem or the branch. They eat calmly and daintily, as a rose-breasted grosbeak eats a cherry, not like a robin who snatches it off and bolts it down. But the orioles swallow the little cornel berries whole.

Alexander F. Skutch sends to A. C. Bent the following account of the bird's food during the winter: "While in Central America, the Baltimore orioles subsist upon a considerable variety of both animal and vegetable foods. In humid regions, where the boughs of the trees are thickly overgrown with moss and lichens, they find many small creatures in the mossy covering. In the dry months of February and March, when the madre de cacao trees (Gliricidia sepium), which are planted for living fence posts, have shed their foliage and covered their long, slender branches with delicately pink, pealike blossoms, the orioles spend much time probing the flowers. The bright orange-and-black birds are a lovely sight amid the cluster of pink blossoms. Whether they seek chiefly the nectar or the small insects of various sorts that swarm about the flowers, I do not know. When the winged brood of the termites fills the air at the end of an afternoon shower, the Baltimore orioles, along with a host of other birds of the most varied kinds, take advantage of this manna and snatch the slow-flying creatures from the air. But with their slender bills they are not particularly adept at flycatching, and often miss their intended victim. During the early months of the year, when succulent fruits are not abundant among the forests of southern Costa Rica, the Baltimore orioles eat the dry green fruits of the Cecropia tree, clinging to the slender branches of the dangling inflorescence and tearing off small billfuls; in this feasting they are joined by many kinds of toucans, honeycreepers, tanagers, thrushes, and even flycatchers.

"For several years I have maintained a feeding shelf in a guava tree beside my house in southern Costa Rica, daily placing there ripe bananas or plantains. The Baltimore orioles were not so quick to find this new source of food as some of the resident birds; but once they made the discovery they became regular patrons, and for the past two winters have continued to visit the table in increasing numbers. They made particularly good use of it during the fortnight of almost continuous rain at the end of October 1944, when many of the local birds seemed to experience difficulty in finding enough to eat. Then birds of a dozen species came in colorful crowds and consumed the bananas and plantains faster than they ripened. In 1945, the last Baltimore oriole of the season was seen at the feeding shelf on April 20."

Behavior.--To many of us who live in the northern states the Baltimore oriole represents the spirit of spring. He arrives at the high tide of the season's beauty when he is at the peak of his magnificent spirits. But how soon his spirits fade! A month, and he begins to step back from the footlights, leaving the stage to less dominant personalities, such as the red-eyed vireo and the robin.

The oriole fits easily into the community of the breeding birds about him, often building in the same tree with one of his neighbors. Mr. G. Vaiden tells of a large pecan tree in which a wood pewee, a red-eyed vireo, a wood thrush, an orchard oriole, and two Baltimore orioles had nests at the same time and lived "a fairly agreeable life together." A. D. DuBois reports that "a pair of kingbirds had a nest in a burr oak only 5 or 6 yards from an oriole's nest, and the two species seemed to live amicably as close neighbors."

E. H. Forbush (1907) presents a dark side of the oriole's character:

The bird, a valiant fighter, does not hesitate to attack its enemies with its sharp beak--a weapon not to be despised. It does the fiercest battle with the Kingbird, and may be seen sometimes struggling in mid air with this doughty adversary, until both birds fall to the ground breathless and exhausted. It sometimes succumbs, however, to the swarming numbers and extreme pugnacity of the "English" Sparrow, and where the Sparrows become most numerous they often drive out the Orioles. The Oriole itself, however, is not always guiltless in respect to other birds. Occasionally it destroys other nests, either to get material for building its own, or out of pure mischief. Mr. Mosher observed a male Oriole attempting to drive another way from its nest. The stranger would make a rush at the nest, and then the owner would grapple with him. This running fight was kept up for fully 3 hours. In the meantime the rogue Oriole went to a Redstart's nest, threw out the eggs, and threw down the nest. The next day an Oriole, probably the same bird, was seen to throw out an egg from a Red-eyed Vireo's nest, when he was set upon and driven way by the owners. Three other instances have been reported to me by trustworthy observers who have seen Orioles in the act of destroying the nests or eggs of other birds; but so far as I know, few writers have recorded such habits, and they are probably exceptional.

M. G. Vaiden remarks: "The Baltimore is a very good watchman; he defends his territory with great vigor and daring. Most of his fighting is with our red squirrels, jays, and mockingbirds, but occasionally he attacks other birds when near its nest."

Audubon (1842) speaks of the migration thus: "During migration, the flight of the Baltimore Oriole is performed high above all the trees, and mostly during the day, as I have usually observed them alighting, always singly, about the setting of the sun, uttering a note or two, and darting into the lower branches to feed, and afterwards to rest. To assure myself of this mode of travelling by day, I marked the place where a beautiful male had perched one evening, and on going to the spot next morning, long before dawn, I had the pleasure of hearing his first notes as light appeared, and saw him search a while for food, and afterwards mount in the air, making his way to warmer climes."

Last year I was reminded of this observation of Audubon. One morning, about 10 o'clock, late in August, a male Baltimore was singing in a maple tree across the way. He had separated from his family, which had been fledged weeks before from a nest a little way down the street, and he had been singing alone each morning for a week. As I watched him, he left the tree and, rising well above the surrounding buildings, held an undeviating course slightly to the west of south until he disappeared in the distance. I did not see or hear him again.

Frank L. Farley, of Alberta, Canada, sends to A. C. Bent this interesting note: "The Baltimore oriole is one of the many species of birds that have greatly extended their range in western Canada as a result of the settlement of the country. On my arrival in central Alberta in 1892, this bird was found in fair numbers in the woodlands, and along the rivers and smaller streams where trees were present. However, on the treeless plains of the eastern half of the province it was entirely absent, except in isolated spots where trees had been spared from the ravages of prairie fires which each spring or fall swept over the country.

"At the beginning of the present century great numbers of settlers moved into this open country lying eastward of the parklands, and took up land. Shortly thereafter, large areas of the prairies were brought under cultivation, and many of the road-allowances were plowed up. Such acts spelled doom to the fires, and it was not long before small clumps of willow-poplar and various kinds of shrubs appeared. As a result, the country took on an entirely different aspect. The trees and bushes were in most cases jealously guarded by the farmers, and they grew rapidly. In a few years these oases became the home of many summer birds that until now were entire strangers to the region. Shelter, food, and nesting sites were now afforded to thrushes, flycatchers, vireos, warblers, and many other kinds of forest-loving birds. The Baltimore oriole was not long in accepting this opportunity of extending its range, and in a few years it was well represented in many of the settled districts. Even before the saplings were large enough to offer suitable branches for the suspension of their nests, the orioles learned to build them attached to small limbs close up to the main stem of the tree. On several occasions I have found them within 8 feet of the ground."

Voice.--The song of the Baltimore oriole possesses little pure beauty but it stands out prominently in the spring chorus. We are not attracted to the song as we are to the rose-breasted grosbeak's by syrupy sweetness, nor by the robin's cheerfulness, the wood pewee's artistry, or by the red-eyed vireo's almost endless singing, but by its vigor--a sort of robust manliness.

Another feature of the song which attracts our interest is its infinite variety: no two orioles, we say, sing the same tune, but each bird, in the main, sticks to his own theme. It is one of the songs which, if you note it down, you must punctuate at the end with a period; the bird has said his say and stops; he has finished, for the moment anyway. The song clearly corresponds to a short sentence of half a dozen syllables or so. A point of difference between it and the songs which resemble it somewhat is that many of its single notes, often most of them, are inflected sharply downwards, as the pitch of our voice falls in pronouncing the word "yolk." We notice the same peculiarity in the loud, vibrant call of the evening grosbeak.

In the simplest form the song consists of a short series of notes on the same pitch, like blasts from a tiny trumpet, or there may be but a single blast, scarcely a song. The longer songs, with their changes in pitch and short pauses between the notes, often form rather pretty phrases, although somewhat jerky because the notes are not run together smoothly. These songs give the impression of exclamations.

Francis H. Allen speaks of "a beautiful and unusual song, a low, sotto voce warbling, interspersed with snatches of the characteristic chattering note," and of another, "an uncommonly pretty song, containing a trill near the end, a full-voiced song, not the low warble we sometimes hear, but longer than the song usually is."

Aretas A. Saunders sends to A. C. Bent the following analysis: "The song of the Baltimore oriole is loud, clear and of flutelike quality. It consists of a series of short notes and 2-note phrases, with short pauses between them, and commonly a somewhat longer pause somewhere in the middle of the song. It is so exceedingly variable in form that one cannot pick out any one song, or even several songs, that could be said to be more typical of the species than others. The number of notes in a song varies, according to my 102 records, from 4 to 19, but as only 1 record has 19 and no others more than 16, the 19-note one is quite unusual. The average song is about 8 notes long. It is a common habit of the bird, however, to sing single notes or short 2-note phrases between songs, and if one considered these to be separate songs, there would be many 1- or 2-note songs.

"The pitch of the songs varies from F'' to A'''. The range in pitch of single songs varies from 1 tone to 6 tones, or an octave. The average range is 3 1/2 tones. It is interesting to note that the only record I have that is definitely the song of a female bird has a range of only 1 tone.

"In time, songs vary from 4/5 to 2 3/5 seconds. Though all the notes are rather short, there is often considerable variation in the lengths of the notes of a song, so that, though the song has a rhythm, it is not often an even rhythm."

The bird not infrequently sings while on the wing in early spring, and occasionally in August.

Ralph Hoffmann (1904) says: "The female during the mating season whistles two or three notes similar to the male's," and Tilford Moore has heard a female sing "short, finished songs." Both sexes give a long grating chatter which often seems to indicate anxiety, and this is sometimes incorporated into the song.

The period of singing is short. The bird arrives on its breeding ground in full song and continues to sing all day long during the mating and nest-building stage of the cycle, but by the end of June there is a noticeable falling off in the singing, and during the molt the males are almost silent. Then, about mid-August, a fortnight before they leave, the males sing freely again, chiefly in the early morning.

Brand (1938) gives the approximate mean vibration frequency of the Baltimore's voice as 2,500 cycles per second, slightly below that of the robin and not far from that of the bluebird.

Enemies.--Elon Howard Eaton (1914) speaks thus of the Baltimore oriole's enemies: "In spite of the skillful placing of the oriole's nest, it is frequently visited by plunderers. I have seen crows on several occasions succeed in getting young birds from the nest and the home of the screech owl very often shows that the young orioles have been taken and fed to the owlets. Red squirrels also descend to the nest to get the eggs and young birds, and I have seen the gray squirrels do this on one or two occasions. Generally, however, the young are reared successfully and I am inclined to think that dangers in migration and severe weather are the principal checks to the increase of this species." Referring to the incessant calling of the young birds, he says that from their notes the young "are unquestionably located by many predaceous animals and thereby destroyed."

Forbush (1927) tells of a case in which nine bronzed grackles attacked a pair of orioles, "but after two minutes of swift action the Grackles retired from the combat, leaving the 'orioles' the victors." John T. S. Hunn (1926) reports "An Oriole Tragedy." The male oriole "was caught by a small cord firmly woven into the nest structure, and so tightly twisted about his neck that he strangled to death."

The following is quoted from Herbert Friedmann's "The Cowbirds" (1929):

An uncommon victim. Bendire (1895, p. 486), says "this species is rarely imposed upon by the Cowbird." Gregg, in Chemung County, New York (Proc. Elmira Acad. of Science, vol. I, no. 1, June, 1891, p. 26), records finding a nest of this bird with two young Orioles hardly fledged and one young Cowbird big enough to fly.

S. E. Parshall (Orn. and Ool. IX, no. 11, Nov. 1884, p. 139), found a deserted nest containing three eggs of the Orioles, and three of the Cowbird and three more of the Cowbird covered up.

B. H. Warren (Birds of Pennsylvania, 1890, pp. 209 - 210) writes that ". . .on three occasions I have discovered the shattered remains of these eggs (Cowbirds), directly beneath the pendant nests of Baltimore orioles. . . . It may be that this species sometimes. . .tosses out alien eggs."

There are other records from Indiana, Iowa, and Michigan.

Fall.--Walter Bradford Barrows (1912) summarizes the behavior of the Baltimore oriole in late summer:

Before the middle of July both old and young have disappeared from garden, orchard and park, and except for an occasional almost silent individual at rare intervals, none are seen again until about the middle of August, from which time until their departure for the south in September they are fairly common and the male frequently sings almost as sweetly as in May. This disappearance for a month or more is rather apparent than real, for a careful search of the woods and swamps will reveal a fair number of orioles, spending most of their time, however, in the leafy crowns of the higher trees, where they are hardly visible, and, being almost silent, are pretty sure to be overlooked. They may also be found at this season about wild cherry and service berry trees, feeding on the ripening fruit.

Francis Beach White (1937) remarks: "In July, a few Orioles are about till the second week, and occasionally a pair is seen or an adult with young; but after that they are very scarce. These late birds are likely to be seen low in thickets--where, indeed, they spend a good deal of time feeding in the breeding season--but once in a while one will silently flash across from one tree to bury itself in the foliage of another."

Apparently the old males do not remain with their families very long after the breeding season. I find in my notes these references to this subject: "July 30, 1916--Mr. Faxon and I saw nearly a dozen birds all in female or juvenal plumage more or less associated and not a single adult among then. I recall noting the same thing in past seasons," and "August 13, 1917--Two male orioles were feeding silently this morning in the locust trees, where they found a small green larva. These birds, although near each other, did not follow one another about and they acted as if perfectly independent of each other. Yesterday I saw an adult male in another part of the town, feeding alone. This appears to be a habit of the male at this season, to separate himself from his family and remain alone."

Winter.--There are several references in the literature to orioles found in winter, stranded far to the north of their normal winter range. Two of these birds, one in Virginia, the other in Ohio, were feeding on apples. Doubtless most of these lost birds perish, but Robie W. Tufts reports on an immature female bird found in Nova Scotia in such a weakened condition that he captured her on December 13, and kept her indoors over the winter, "during which time she ate chiefly grapes"; he liberated her the following May.

Alexander F. Skutch supplies this comprehensive report of the bird on its winter quarters: "The Baltimore oriole arrives in Central America during the second week of September, but does not become abundant before the end of the month. During the northern winter, it resides throughout the region from Guatemala to the Isthmus of Panama, on both the Caribbean and Pacific coasts and high up into the mountains. Scarcely any other winter visitant is so widely and uniformly distributed throughout the area.

"To appreciate the wide tolerance of environmental conditions implied in the winter distribution of the Baltimore oriole, one must be familiar with the local variations in climate and the corresponding differences in the nonmigratory section of the avifauna. Thus the arid coast of El Salvador, where I found these orioles abundant among cacti and low thorny trees early in the parched month of February, has exceedingly few resident birds in common with the humid coastal districts on the opposite side of the continent, in Honduras and Guatemala, where also the Baltimore orioles pass the winter in large numbers, amid lofty rain-forests, lush thickets, and extensive banana plantations. And very few of the birds which breed in the lowlands on either coast are found in the highlands above 5,000 or 6,000 feet. Yet in December 1933 I found a few Baltimore orioles which had apparently settled down for the winter among the oaks, pines, and alders on the Sierra de Tecpan in Guatemala, at an altitude of 8,5000 feet above sea level, where at this season nights were penetratingly cold, and every clear dawn revealed all the open spaces white with frost. Thus, in Central America, this adaptable bird makes itself at home, for a period covering half the year, almost everywhere that trees supply fruits, and insects lurk amid the foliage. It is especially fond of plantations, orchards, and pastures with abundant shade trees; but it also hunts through the treetops of the tall rain-forests, although it never, in my experience, descends into the deeply shaded lower regions of the forest, and so it is not often seen by the bird-watcher who wanders through the heavy woodlands.

"During the winter months, the Baltimore orioles roam about singly, or in small groups of two, three, or four, more often than in larger groups. Although a dozen or so may at times be seen feasting together in some especially attractive flowering or fruiting tree, or may share the same roost, the birds are only slightly gregarious during this season and form no big, closely knit flocks like those of wintering dickcissels and cedar waxwings. Adult males pass the winter in brightest orange-and-black plumage, and are excelled in beauty by few even of the most brilliant of the native birds; but females and young males predominate.

"Although less songful while in Central America than the orchard orioles, Baltimore orioles often voice their clear, full whistles, especially during the first weeks following their arrival in the fall, and with greater frequency for a month or so before their northward departure in the spring. Rarely, as when the sun breaks through the clouds at the end of an afternoon shower in April, they charm the hearer with a somewhat sustained performance; but for the most part they utter only single notes and brief fragments of song--tantalizing suggestions of the full, mellow verses they will soon be broadcasting from northern elm trees. A sharp churr is the oriole's most frequent utterance while in its winter home.

"I have often discovered the sleeping places of the Baltimore orioles, and found them as catholic in their choice of a roosting site as of habitat and food. In the cleared portion of the Lancetilla Valley in northern Honduras, a number of them roosted, during the winter of 1930 - 31, in an extensive stand of tall 'elephant grass' (Pennisetum purpureum), a tangled and impenetrable gramineous jungle higher than a tall man's head. Here they slept along with wintering orchard orioles, resident Lesson's orioles (Icterus prosthemelas), four species of small resident finches, and migrating kingbirds which rested here for a while before continuing southward. In the hamlet of Buenos Aires in southern Costa Rica, Baltimore orioles roosted among the broad close-set foliage of the tall Dracaena fragrans--a tree of the lily family--that bordered both sides of the path leading up to the little church. The orioles began to gather shortly before sunset, and as the day waned continued to fly in, one or a few at a time. They darted into the trees very suddenly and from all sides, and then sometimes shifted about from tree to tree before they became comfortable for the night. This manner of going to roost made it impossible to make an accurate count of their numbers, but certainly a score of the orioles took shelter in these trees. When finally they had settled down, they were completely screened from my view by the broad bases of the leaves; even the glowing orange of the adult males failed to shine forth from the dark green foliage. Taken together, observations show that, in one place or another, Baltimore orioles share roosts with a large variety of other birds. Their relations with their neighbors seem always to be amicable, and I have never seen quarrels among them.

"About my home in southern Costa Rica Baltimore orioles roost amid the dark, abundant foliage of the orange trees. Sometimes they slumber upon so low a perch that I might touch them while standing on the ground. They are not always careful to conceal themselves amid the leafage. Viewed by the light of an electric torch, with their heads turned back and buried in their outfluffed plumage, they look like brighter oranges scattered among the dark, glossy leaves. It addition to the orioles that roosted in the big trees, during the early part of the year 1943, three slept in a small tree south of the house. One of these was a male in exceptionally deep orange plumage; his companions were an adult male in more yellow plumage and a female or young male. At dawn on April 15, the three birds were in the tree as usual; but during the day two apparently began to migrate; for that evening the more brilliant male came alone to the orange tree. For a week after the departure of the others, he roosted alone here, where he was seen for the last time that spring at daybreak on April 22. After his disappearance, I saw no others of his kind until the following September 10, an unusually early date, when a female or young male appeared in the trees in front of the house. At daybreak on October 10, there was an unusually handsome male in the orange tree south of the house, where apparently he had roosted. That evening he went to rest in this tree in company with an immature male. Although the bird was not banded, I like to think that he was the same brilliant male who had roosted in the same place during the preceding spring. During those wet October days he whistled enchanting fragments of song, just as he had done before his departure in April. May not the bournes of the long semiannual journeys of the Baltimore oriole be in two trees--perhaps an elm tree in New England, where he nests, and an orange tree in Costa Rica, where he sleeps during the winter months?"

 


Baltimore Oriole*
Icterus galbula
Contributed by Winsor Marrett Tyler

*Original Source: Bent, Arthur Cleveland. 1958. Smithsonian Institution United States National Museum Bulletin 211: 247-270. United States Government Printing Office

 


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