The brightly colored male Yellow-headed Blackbird is a stunning sight, and though similar in behavior and morphology to Red-winged Blackbirds, Yellow-headed Blackbirds are usually found either in wetlands with deeper water, or in the center of wetlands, while Red-wings occupy the edges. Migration takes place during the day, and usually in small flocks.
Male Yellow-headed Blackbirds establish nesting territories and each male typically has about 16 females nesting nearby. Nest parasitism by the Brown-headed Cowbird is rare, even though the blackbirds seem to readily accept cowbird eggs.
Photograph © Greg Lavaty
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Description of the Yellow-headed Blackbird
The Yellow-headed Blackbird is sexually dimorphic, though both sexes have a yellow breast and dark upperparts.
Males have a bright yellow head, nape, and breast, a black belly, black upperparts and black wings with large white wing patches.
Females have a dingy yellow breast, and brownish upperparts, belly, and wings.
Seasonal change in appearance
Winter adults of both sexes resemble breeding females.
Juveniles are buffy above with black barring, and have buffy underparts and two buffy wing bars.
Yellow-headed Blackbirds inhabit freshwater marshes, though they can also be seen in pastures and feedlots.
Yellow-headed Blackbirds eat insects and seeds.
Yellow-headed Blackbirds forage on the ground in open areas.
Yellow-headed Blackbirds breed across much of the western U.S. They winter in the southwestern U.S. and Mexico. The population is probably stable.
During the winter months, Yellow-headed Blackbirds often occur in large flocks numbering hundreds or thousands of birds.
Like most blackbirds, Yellow-headed Blackbirds often associate with other blackbird species outside of the breeding season
The song consists of an unpleasant screeching or scraping sound. A “chek” call is given, along with a whistled trill.
- Yellow-headed Blackbirds are usually unmistakable.
The Yellow-headed Blackbird’s nest is a cup of aquatic plants and is lined with finer materials. It is placed in marsh vegetation over water.
Number: Usually lay 4 eggs.
Color: Grayish with darker markings.
Incubation and fledging:
The young hatch at about 11-13 days, and fledge at about 9-12 days, though remaining dependent on the adults for some time.
Bent Life History of the Yellow-headed Blackbird
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 Yellow-headed Blackbird – the common name and sub-species reflect the nomenclature in use at the time the description was written.
XANTHOCEPHALUS XANTHOCEPHALUS (Bonaparte)
Many years ago I wrote (Bent, 1903) of my first impressions of the showy yellow-headed blackbird in North Dakota:
Seated in a comfortable buckboard, with two congenial companions, and drawn by a lively pair of unshod bronchos, we had driven for many a mile across the wild, rolling wastes of the boundless prairies, with nothing to guide us but the narrow wagon ruts which marked the section lines and served as the only highways. It was a bright, warm day in June, and way off on the horizon we could see spread out before us what appeared to be a great, marshy lake; it seemed to fade still farther away as we drove on, and our guide explained to us that it was only a mirage, which is of common occurrence there, and that we should not see the slough we were heading for until we were right upon it.
We came at last to a depression in the prairie, marked by a steep embankment, and there, ten feet below the level of the prairie, lay the great slough spread out before us. Flocks of Ducks, Mallards, Fintails, and Shovellers, rose from the surface when we appeared, and in the open water in the center of the slough, we could, with the aid of a glass, identify Redheads, Canvasbacks and Ruddy Ducks, swimming about in scattered flocks, the white backs of the Canvasbacks glistening in the sunlight, and the sprightly upturned tails of the Ruddies serving to mark them well. A cloud of Blackbirds, Yellowheads and Redwings, arose from the reedy edges of the slough, hundreds of Coots were scurrying in and out among the reeds, a few Ring-billed Gulls and a lot of Black Terns were hovering overhead, and around the shores were numerous Killdeers, Wilson’s Phalaropes and other shore birds. The scene was full of life and animation.* * *
But by far the most abundant birds in the slough were the Yellow-headed Blackbirds, the characteristic bird of every North Dakota slough; they fairly swarmed everywhere, and the constant din of their voices became almost tiresome. The old male birds are strikingly handsome with their bright yellow heads and jet black plumage, offset by the pure white patches in their wings, the duller colors of the females and young males making a pleasing variety. * * * The song most constantly heard, suggests the syllables Oka wde wee, the first a guttural croak, and the last two notes loud, clear whistles, falling off in tone and pitch, the whole song being given with a decided emphasis and swing.
Although it was some 50 years ago that I heard it, the rhythmic swing of that impressive chorus still seems to ring in my ears whenever I think of a North Dakota slough and its yellow-headed blackbirds.
Throughout its wide range in western North America, from Canada to M6xico and from the eastern border of the prairie regions to the Pacific slope, small or very large colonies of yellow-headed blackbirds. may be found wherever there are lakes bordered with suitable aquatic vegetation, or marshes or sloughs with permanent water of sufficient depth. Damp marshes are not suitable for them, neither are the shallow-water sloughs; they prefer to nest over water that is from two to four feet deep, or even much deeper.
Deep water serves to protect the nests and young from prowling predators, and a thick growth of tall vegetation, tules, reeds (Sc&pus or Pkragmiees), or cattails (Typhus), serves to shield them from birds of prey.
In the Rocky Mountain region, the breeding range extends to somewhat higher levels. Fred M. Packard (1946) says that, in Colorado, these birds “nest commonly from the plains to about 5,500 feet in the foothills, rarely as high as 6,000 feet.” There is some evidence that the bird is extending its range somewhat farther east than formerly. And Gordon W. Gullion writes to me (in 1948) that this blackbird is becoming widely distributed as a breeding bird in the Willamette Valley, in western Oregon.
Spring: The yellow-headed blackbird winters as far north as some of the Southwestern States, not far north of the southern limits of its breeding range. The northward movement starts about the middle of March, continues through April and reaches the breeding grounds before the middle of May. Thomas S. Roberts (1932) writes:
In the northward spring movement the vanguard of the Yellowheads that are to breed in Minnesota arrives during the first half of April, the males preceding the females by a few days. Stragglers may enter the southern part of the state during the very first days of that month, but it is not until toward the last of April or early in May that they become numerous. While the females are busy building their nests in the sloughs, the males assemble in little parties and feed on the adjoining uplands. Should they select a grassy plot where dandelions are in full bloom, the bright yellow of the blossoms and the heads of the birds match so well that they are almost indistinguishable.
Arthur C. Twomey (1942) noticed the first migrants in Utah on May 2, when “from forty to two hundred males could be seen flying in compact flocks, but no females were in evidence. It was not until May 15 that females were noticed, and they likewise were in segregated flocks. * * * By May 20 there were females among the flocks of males, and soon after this the nesting season commenced.”
At a colony studied by George A. Ammann, in northwestern Iowa, the adult males were first seen on April 8 and were numerous on April 23; the adult females came on May 2, but were not common until May 12; the first-year males arrived on May 11, and were numerous on May 22, the young females coming about the same time. These dates are taken from a manuscript copy of his thesis (submitted to the University of Michigan), which he has very kindly loaned me. I shall quote freely from parts of this excellent and extensive monograph on the yellow-headed blackbird .
Courtship: While exploring in a canoe, on May 31, 1913, the extensive marshes surrounding Lake Winnipegosis, we found the yellow-heads fairly swarming in the tall buirushes (Seirpus), growing in water 3 or 4 feet deep and extending higher than a man’s head above the water along both sides of the Waterhen River. Courtship was in full swing. The males were chasing the females all over the marshes; the female usually returned to the place from which she started, after which the male alighted near her, as this was probably the chosen territory for the pair. Grasping a tall, upright cane, or perhaps two in a straddling attitude, he displayed his fine plumage by spreading his black tail and half opening his wings to show the white patches; he leaned forward, pointing his bright yellow head downward until it was almost parallel with his tail and poured out his grotesque love notes. The female seemed indifferent.
We must admit that the courtship is more spectacular than beautiful, but we should hardly condemn it in the following words of W. L. Dawson (1923): “Grasping a reed firmly in both fists, he leans forward, and, after premonitory gulps and gasps, he succeeds in pressing out a wail of despairing agony which would do credit to a dying catamount. When you have recovered from the first shock, you strain the eyes in astonishment that a mere bird, and a bird in love at that, should give rise to such a cataclysmic sound.”
Alexander Wetmore (1920) gives the following account of the courtship of the yellow-headed blackbird, as observed at Lake Burford, N. Mex.:
The adult males were settled in large part on their breeding grounds on my arrival, though many of them were not yet mated. Each selected a stand in the tules at the herder of the lake, and, unless away feeding, were certain to be found in the immediate vicinity constantly from that time on. * * * At this season the male seems fully conscious of his handsome coloring and in his displays makes every effort to attract attention. In the most common display the male started towards the female from a distance of 30 or 40 feet with a loud rattling of his wings as a preliminary. The head was bent down, the feet lowered and the tail dropped while he flew slowly toward his mate. The wings were brought down with a slow swinging motion and were not closed at all so that the white markings on the coverts were fully displayed, the whole performance being reminiscent of a similar wing display of the Mocking-bird. In flying from one perch to another males often dangled their feet, frequently breaking through small clumps of dead tules with considerable racket. Or they clambered stiffly along, hobbling over masses of bent-over rushes, with heads bent down, tails dropping and back humped, appearing like veritable clowns.
Jean M. Linsdale (1938) noticed a form of display which was apparently made in defense of territory. Two males which owned adjoining territories “were seen on the ground halfway between their respective singing posts which were in separate cattail patches about 20 feet apart. For 3 or 4 minutes they kept close to each other, walking back and forth along the boundary with fluffed feathers and arched necks. In turn, they made short flights, getting scarcely more than a foot above the ground and moving, altogether, only 3 or 4 feet. Once one went as far as 10 feet. In these flights the wings were flapped violently, but the bird moved slowly, and the body was held with the bill pointing upward 800 above the horizontal. Finally, each bird returned to its own singing post, having had no actual combat.”
On another occasion he noticed severe fighting for about 30 seconds, one holding the other down and pecking at it. Referring to the territorial behavior, he says in part:
Judging from continued watching at this pond through the greater parts of 2 nesting seasons, territory for these yellow-headed blackbirds was a definitely recognized area for males only. Moreover, this area was a remarkably small one, when the size of the birds is considered. Each male established itself in 1 small patch of cattails or a portion of a patch.* * *
From the first establishment of the territories one of the chief concerns of each male was to keep other male yellow-headed blackbirds off his area. The enmity seemed aroused in inverse proportion to familiarity with the trespassing individual. When 2 males owncd portions of the same cattail patch, they were much more tolerant of each other than of males from another part of the pond. Newly arrived, strange males arouse a quicker response than ones already settled in the same pond.* * *
Besides their vigorous defense against intrusion by other male yellow-headed blackbirds the males were especially active in driving red-winged blackbirds from their territories. The pursuit, however, was usually a short one. In observed instances male red-wings were pursued for only about 30 feet, or just to the limits of the yellow-head territory. If, in leaving, a red-wing crossed the territory of a second yellow-head, the latter would take up the chase and the first yellow-head would turn back.
Of the actual mating, he says:
Males were noticed flying to females especially when the latter uttered a certain type of screeching note. Sometimes these notes were given on the pursuit flight. The notes along with the posturing of the female seemed to be the signal that the female was near the mating stage.
Mating of yellow-headed blackbirds was noti,3ed in late afternoon on May 26, 1932. In territory III a female flew to the top of a currant bush where it postured, and then male III flew there from the cattail patch and t.hey copulated. The union lasted about 2 seeonds during which the male flapped his wings rapidly. After perching a few inches away for a short time, the whole procedure was repeated until it had taken place 9 times in quick succession. Then the male flew back to the cattails where it perched on a dead stem and shook its plumage. The female may have been the same one noted earlier in territory II. Posturing, with bill and tail pointed upward, had been noticed there, but male II had made no response. The circumstances seemed to indicate that male III was the only one ready for mating, and the female bunted it out.
The behavior described above suggests promiscuity between the sexes. He noted that there were many more females than males engaged in nesting. No females were noticed that were not nesting, but many males less brightly colored and with less perfect songs were seen day after day half a mile or more away from the breeding colonies, lie inferred from this that females mature and are ready to breed when 1 year old, but that the males require 2 years to mature, and that the less brightly colored males, seen away from the breeding colonies, were yearlings and would not breed until the following year.
Ammean (MS.) says: “these young males, with their distinctive plumage, were not welcome when they invaded the breeding grounds. Wherever they went they were immediately driven away by the adult males and thus became nomads by necessity. Breeding females did not resent their intrusion, however; once a female was seen to take a receptive position in front of a first-year male (thus evidently recognizing him as a male, in this plumage so similar to her own) to which he did not respond.”
He gives a full account of the actual mating, as follows: “The female stops in the midst of nest building and selects a more or less solid stand low in the bulrush clump or on a mass of floating debris and assumes the mating posture, at the same time giving the low, soft mating call. If the male is anywhere in the vicinity, he responds immediately; it seems almost incredible sometimes how far distant he may be and yet hear this call.
“He proceeds toward the female in one or more short, jerky flights: thus causing the wings to heat very loudly, with bill pointing almost straight up. Then he draws in his head, erects the feathers of breast and back, droops his tail and approaches the female indirectly by short hops through the rushes or over floating debris, sometimes completing a half circle before reaching her. Then he may strut, twist, or turn in a foolish manner and rarely give vent to the buzzing song before mounting. Meanwhile, the female remains in the mating posture: body tilted slightly forward, tail spread and pointing straight up, bill raised high in the air. As the male comes closer, she watches him attentively with open bill and alternately quivering wings, and may repeat the mating call. She turns her. head as he walks around her, or he may stop directly in front of her and both remain motionless, except for the quivering of her wings, for 15 or 20 seconds. Then the male mounts the female, placing first one foot on her back, then the other; at the same time he flaps his wings vigorously high above him and brings the bill close to his breast so that the neck is quite arched; his tail is pressed down between the two central tail feathers of the female, allowing the clonene to come in contact. While the male is on her, probably a great deal of the weight is supported by the material on which her breast is resting. The male does not maintain his balance in this position for more than a second, and probably the first attempt at copulation has been unsuccessful. He jumps off, takes two or three short hops, and mounts the female again. This may be repeated five or six times until finally it appears that a successful copulation has taken place, because of the slightly longer time (about 1~ seconds) the male remains on the back of the female. As many as 16 consecutive attempts at copulation have been counted: all in rhythmical succession. The female remains in the same position during the whole performance.”
Nesitng: Yellow-headed blackbirds nest in colonies, often of very large size. The colonies are not as densely packed with nests as are those of the tricolored redwings in parts of California, though in the most thickly populated colonies as many as 25 or 30 nests may be found in a space 15 feet square. The colonies are not always continous, and may be scattered in separate groups along the shores of a lake or slough where the vegetation is most suitable for nest construction. Red-winged blackbirds are usually more or less loosely associated with the yellow-heads on their breeding grounds, but generally the two species occupy different portions of the marsh. The nests of the yellow-heads are invariably built over water, preferably from 2 to 4 feet deep and rarely much deeper. Should the water recede during the process of nest building, unfinished nests found to be over dry land are likely to be abandoned .
The nest is built entirely by the female, without any help from the male. In his study of a nesting colony in Minnesota, Roberts (1909) gives the following good description of the construction of the nest:
The body of the nest was invariably constructed of water soaked dead grass blades picked out of the water of the marsh. This sort of material being soft and pliable was easily woven and wound around the reed stems to the smooth surface of which it closely adhered; and ‘when the structure, which was at first very wet, soggy and dark colored, dried in the sun and wind, it contracted and drew the included reed stems nearer together thus forming a compact, firm, and securely attached basket-like nest. The lining consisted of pieces of broad, dry, reed leaves and the rim of the nest was well finished off with fine branches of the plume-like fruiting tops of the reeds. Occasionally the lining was not placed for a day or two until the nest had dried somewhat, but usually the coarse lining was added, in part at least, to the bottom and around the walls while the body of the nest was still in course of construction and soft and wet. The finishing touches to the nest consisted in adding the fine material about the upper walls and rim which, in the more perfect nests, partially closed and formed a sort of canopy over the entrance .
These nests were all built in quill-reeds (Phragmites), and were placed from 2 to 3 feet above the water. Of the 62 nests started in the colony, 28 were abandoned before completion, “due to faulty workmanship or poor judgment in selecting a site. * * * In one instance it was positively determined that the same bird built four imperfect nests before being able to construct one that was habitable. * * * A skillful, industrious bird would build one of these large beautifully woven and lined nests, all complete, in from two to four days. Of twenty well built nests, nine were finished in two days, nine in three days, and two in four days. * * * From one to five days was allowed to elapse after the completion of the nest before egglaying began. Eggs were invariably deposited one each day.”
In the North Dakota slough, referred to at the beginning of this story, red-winged blackbirds were nesting commonly around the edges of the marsh in the shorter vegetation growing in the shallow water, but all through the deeper parts of the slough, in the tall reeds (Scirpu.s) and flags (Typhus), the yellow-headed blackbirds fairly swarmed, with nests often close together .
The nests were firmly attached to the reeds or flags at height ranging from 6 inches to 3 feet above the water of varying depths. Four of these nests are now before me. They were evidently built, after the manner described above by Roberts, of wet, dead material picked up from the water, which dried and shrunk enough to hold the nest firmly to its support. This material consists of strips of dead leaves of flags, coarse grasses, items of dead reeds, roots of water plants, and general swamp rubbish. My nests are not decorated around the rim with the fruiting tops of the quill-reeds for the simple reason that there were no Phragmites growing in the vicinity. All the nests that I saw were neatly and smoothly lined with narrow strips of dry grass blades of a dull orange color, evidently carefully selected and probably brought from dry land; these formed a very distinct feature in all the nests.
The nests are all bulky and very firmly woven; all but one of them were somewhat crushed in packing, but one that is apparently in its original shape measures 5 by 6 inches in outside diameter, fully 4 inches in depth, and the inner cup is about 3 inches in diameter and 2~ inches deep. A nest figured by Roberts (1909) measured 11 inches from the rim of the nest to the long extension between the reeds below it; it was also partially canopied at the top.
In southwestern Saskatchewan, where Bear Creek enters Crane Lake, that wonderful bird paradise more fully described in my account of the western grebe (Bent, 1919), we found yellow-headed blackbirds’ nests in abundance. The nests were firmly attached to the tall, waving buirushes, from 10 to 30 inches above the water, which was m many places more than waist deep. They were much like those described above, but instead of the distinctive lining seen in the North Dakota nests they were lined with fine strips of dead flags or with fine grasses, and they were not decorated like those described by Roberts.
We noticed that many nests were abandoned because of unfortunate location in growing tules; the nests had been attached to several stalks which had grown unevenly, overturning the nests and rendering them useless.
In Nevada, Linsdale (1938) found these blackbirds nesting in willows. “In the early summer of 1932 water from streams in the Toyabe Moujitains flooded parts of Smoky Valley. Within the flooded area was a patch of willows 5 to 7 feet high and approximately 100 by 50 yards in diameter. At this place the water was 1 to l~ feet in depth. Yellow-headed blackbirds took over the willow patch and nested there.” On June 3, he counted 30 nests there, all but 3 of which contained eggs or young.
Ammann (MS.) gives a very full account of the process of building the nest: “Once a nest is begun the female works feverishly, picking up long wet strands from the surface of the water and bringing several at a time, in her bill, to the nest site. These are suspended between conveniently arranged stems of vegetation several inches apart: sometimes as much as six inches. They are probably wound around the supporting stems singly or a few at a time and the loose ends attached to other supports.
“Soon a number of nearby stems are connected by a loose network of these coarse, wet fibers. At first 4 or 5 supporting stems are used but as the structure grows, more are included: sometimes as many as 25 or 30: if the nest is built in buirushes or quill-reeds.* * *
This frail network is reenforced by more fibers until a strong saucershaped base with a rather angular outline is formed. * * * As soon as this structure can support her body, the female begins adding material around the margin for the outer wall, the next stage in construction. It is that part of the nest which envelops the supports and forms its main bulk. After gathering suitable material in her bill from the surface of the water, the female flies straight to the edge of the nest, jumps into the cavity, drops her load on the edge, and immediately begins to arrange it. With quick, deft movements of her head, she snatches individual strands and winds them around the nest supports that have already been included in the construction of the base. Usually the strands are given a half twist around each support as follows: an end is pushed beyond the rim adjacent to the support, then the female reaches around and snatches this end from the other side, pulls it down and anchors it with a thrust of the bill to the inside of the nest. The other free end may likewise be anchored.
“Often the strands are given a complete turn around each of several nest supports in a row, or may be placed along the rim and woven in and out among the upright supports. Of course,.there is great variation in placing each individual shred, but the resultant meshwork of fibers forms a wonderfully strong and compact basket. When the female has disposed of all the loose material on the rim, she tugs at any loose ends in sight, especially on the outside of the nest. She reaches far over the edge and pulls such strands over the rim, if possible, and thrusts them into the inside of the wall.”
For shaping the inside of the nest, she “supports herself by her head and tail on the rim and stamps her feet alternately in rapid succession on the bottom and sides of the cup. The nest is dsually so wet that the stamping can be beard several meters away. After a few seconds she rises and settles down at a slightly different angle and duplicates the performance. This procedure may be repeated a number of times in quick succession.* * *
“After the outer wall is high enough the female adds material to the inner side of the wall and in the bottom in order to make the cavity the right size and shape. This may be called the inner cup. She does not loop the strands around the supports but drops each load directly in front of her as she enters the nest. Her breast is then applied to this newly brought material while she stamps her feet in the manner already described, thus making the nest compact, and the inside smooth, round, and of the correct diameter. The general appearance of the inner wall when finished is different from the outer wall. The direction of nearly every strand is in an arc, parallel to the circumference, and the brim is generally smooth and on a horizontal plane.
“A final stage of construction that is by no means universal is the addition of some fine, dry grasses which serve as a lining. When present they are usually confined to the wall and often only immediately below the rim on the inside, thus constricting the opening.”
Ira N. Gabrielson (1914), writing of a Nebraska swamp, says: “The Yellow-headed Blackbirds were by far the most abundant breeding form of the swamp. In the part examined there were probably several hundred nests; in the remaining half of the swamp the number is only a matter of conjecture. The nests which we examined were practically identical in location, being built in the wild rice growing some distance from the shore. They were woven in basket shape about three or more stems from eighteen inches to two and one-half feet above the water. The water in the region of the nests was about hip deep and they seemed to be confined to a belt of this depth around the part of the swamp studied.”
Eggs: The yellow-headed blackbird lays from three to five eggs to a full set, most commonly four, and only very rarely five. Of 504 nests examined by Ammann (MS.), only 8 contained 5 eggs, while 282 held 4, and 110 sets consisted of 3 eggs.
Major Bendire (1895) writes:
The eggs of the Yellow-headed Blackbird vary in shape from ovate to elliptical and elongate ovate; the shell is finely granulated, strong, and rather glossy. The ground color varies from grayish white to pale greenish white, and this is pro-. fusely and pretty evenly blotched and speckled over the entire surface with different shades of browns, cinnamon rufous, ecrn drab, and pearl gray. The markings are usually heaviest about the larger end of the egg, and sometimes a specimen is met with which shows a few fine, hair-like tracings, like those found on the eggs of the Orioles.
The average measurement of 134 eggs in the United States National Museum collection is 25.83 by 17.92 millimetres, or about 1.02 by 0.71 inches. The largest egg in the series measures 28.96 by 19.81 millimetres, or i.14 by 0.78 inches; the smallest, 23.11 by 17.53 millimetres, or 0.91 by 0.69 inch.
Incubation: Incubation is performed entirely by the female with no help from the male, except that he sometimes feeds her on the nest. The period of incubation has been reported by different observers within rather wide limits.
Roberts (1909) says that in “seventeen nests the period of incubation, inclusive of the day on which the last egg was laid, to the day on which the first egg hatched, was nine days in one instance, ten days in twelve, eleven days in three, and twelve days in one. Thus ten days may be considered the usual period of incubation. The nine-day period was in the case of the only set of five eggs that hatched.” The eggs hatched irregularly, though in three nests all hatched on the same day, and in three others one hatched each day.
Reed W. Fautin (1941b), who made some very extensive studies of the nesting of the yellow-headed blackbird in Utah, writes:
The females were not assisted by the males in any way in the incubation of the eggs, 56.6 percent of them beginning incubation at the time the second egg was laid, with a tendency for the beginning of incubation to be delayed longer the larger the clutch. The length of the incubation period varied from 12 to 13 days, 74.6 percent of the eggs hatching in 12 days.
The attentive periods during incubation ranged in length from 1 to 41 minutes, with an average of 9.1 minutes. These periods were longest during mid-day when the females were seemingly protecting the eggs from the sun. During 83 hours of observation the females spent an average of 63.9 percent of their time on the nest, with a range from 53.1 to 69 percent.
The inattentive periods ranged in length from 1 to 18 minutes, with an average of 5.4 minutes. These periods tended to be longest during the morning and evening hours when feeding was most intensive.
The hatching success of the larger Provo River colony amounted to 75.7 percent, while that of the smaller Lakeview colony was only 60.6 percent, giving an average of 70.9 percent for the two. Wind and predation were responsible for the destruction of 90 (20.3 percent) of the eggs before the time of hatching, and 39 (8.8 percent) failed to hatch because of being addled or infertile .
Eighty-three females nested in the Provo River colony and 40 in the Lakeview colony. There were about 35 males in the former colony and only 12 in the latter, suggesting promiscuity or polygamy. There were no yearling males in either colony, but plenty of them were seen in the surrounding regions.
Young: In another excellent paper, Fautin deals with the development of young yellow-headed blackbirds. Both studies were conducted in the same two colonies, near Provo, Utah, during the spring and summer of 1937, from April to September, some 128 nests being kept under observation. He (1914a) found that: “The average weight of the nestlings at the time of hatching was 3.3 grams and at 10 days of age was 51 grams; the greatest percentage of increase in weight occurred during the first day after hatching, while the greatest actual increase in body weight occurred between the fifth and sixth days, amounting to 6 grams at that time.” He noticed that nestlings of the same age varied as much as 15 to 20 grams in weight at the time of leaving the nest, though the smaller ones were as well feathered and as active as the larger ones; inasmuch as adult males are much larger than females, averaging about 35 grams heavier, it is likely that the larger nestlings were males .
Feather development began soon after batching; the sheaths of the primaries appeared the second day. At eight to nine days of age the contour feathers were sufficiently developed to cover all the apteria except possibly the one on the abdomen.
The males aid very little in caring for the nestlings. Only two males were observed to make any attempt to feed the young. One of these fed the young eight times during a period of eight hours and six minutes while the female fed them 102 times during the same interval. The other male fed another brood of nestlings eight times while the female fed them 92 times during the same period.
Food of the nestlings consisted principally of insects and spiders. The spiders and smaller insects constituted the greater part of the diet during the first few days after hatching, while larger insects such as dragonflies and grasshoppers together with some vegetable matter formed the hulk of the food as the young became older. * * * For the first day or two after the young are hatched they are fed either by regurgitation or else on food materials so small that they escaped notice, for during that time the females were seldom seen carrying food in their mouths although the young were visited six to seven times per hour. Probably they were fed by regurgitation during that time.* * *
The nestlings left the nests when nine to twelve days of age and remained among the dense vegetation of the nesting area until they were able to fly.* * *
The young are unable to fly at the time they leave the nest but they are very adept at making their way through the vegetation. After abandoning the nest they never return to it but are to be found among the vegetation down near the surface of the water, sometimes sitting on the dead floating vegetation. * * * For the first four or five days they move about by hopping from one stem or leaf to another with remarkable agility. Following this hopping stage they make short flights of about two to four feet and thus gradually develop their ability to fly. By the time they are three weeks old they are frequently seen to make short flights of about 25 yards. From this stage on, their ability to fly develops very rapidly and they are soon seen pursuing their parents, coaxing noisily for food.”
Mortality among the nestlings was very high, due largely to a heavy rainstorm accompanied by high wind which destroyed the nests~ eggs, and young. Many eggs and young birds were devoured by predators, largely unknown but probably snakes, small mammals, and perhaps birds of prey or crows. “Out of 314 nestlings, hatched from 443 eggs, 215 were destroyed before they were old enough to leave the nest. This gives a percentage of success (i.e., young fledged from the total number of eggs laid) of 22.4.” In the Minnesota colony studied by Roberts (1909), all the young disappeared, 100 percent loss, from some unknown cause.
Fautin (1941a) says that: “A partial post-juvenal molt occurred about the last of July when the plumage of the fledgling was changed to that typical of the first-year birds. During this time the birds left the nesting areas and remained in seclusion in the dense cattail marshes. After most birds had completed their autumn molt they wandered about the fields in large flocks during the day, and returned to the marshes at night.”
Gabrielson (1914) made two interesting observations:
The method by which the young left the nest was interesting. At 5:38 a. m. one of the young clambered to the edge of the nest, seized one of the supporting reeds with each foot and climbed up them a short distance above the nest, advancing each foot alternately. After going about eighteen inches, the bending of the stalks under his weight brought them in contact with others onto which he went. After travelling in the tops for a little way, he commenced to work toward the water, and reaching a broken reed rested a while. In a few moments he proceeded along this reed to another and was soon out of sight.* * *
I had one glimpse of some of the dangers to which the young Yellowheads are exposed. One of the young from a neighboring nest was sitting on a reed about two inches above the water when the jaws of a hungry pickerel rose from the water and the nestling disappeared. It was done so quickly that if I had not been looking directly at the bird it would never have attracted my attention.
Roberts (1909) says of the food of the nestlings: “Grasshoppers, various insects and a large black larva of some sort which the birds obtained from among the decayed vegetation in the shallow water along the edges of the slough formed the chief food supply. These larvae were ugly and formidable objects and were thrust down the throats of the young birds with considerable difficulty. On one occasion a female was seen carrying a large flat object, squirming and curling about her bill, which was evidently a leech.”
Mrs. Wheelock (1905) writes: “The young are fed by regurgitation for two days, afterwards by both methods for two days, then entirely by fresh food. Examination of the crops of the broods reared in late June showed, on the first day, snails, waterslugs and larvae all partially digested. On the second day, insects denuded of wings, legs, and all hard parts, and thoroughly crushed as well as predigested, were found mixed with occasional water moss. The third day showed little change in the mcnu, but the food was less digested and, on this day, occasional meals of fresh food began to supplant the regurgitated.”
The nesting success in the 504 nests studied by Ammann (MS.) was not so good as that reported by Fautin (1941b). The 504 Iowa nests contained 1,565 eggs, an average of 3.1 eggs per nest. “Of the 173 successful nests, 40 were completely and 133 partially successful, an average of 2.5 young were raised. Eggs hatched in 44.2 percent of the nests and young were fledged in 34.3 percent. Of all the eggs laid, 53.6 percent hatched and 27.5 percent became successfully fledged young. In comparing the nesting success of this species with others it is found to be much lower in every respect. The percentage of eggs hatched and young fledged of 481 nests of six other species of passerine birds is 61.4 and 43.0, respectively.”
Fred G. Evenden, Jr., writes to me that he found a yellow-headed blackbird’s nest in a swamp near Corvallis, Oreg., that had been thoroughly torn up by northwestern redwings that nested in abundance in the swamp, and says that “the yellow-heads were not tolerat.ed by the redwings, being chased and attacked whenever they were in the swamp area.”
Plumages: The small nestlings are only thinly covered with huffy down on the feather tracts of the head and back, but the first plumage soon begins to appear, pushing the down out on the tips of the feathers, where it persists longest on the top of the head. Chapman (1921a) gives tbe best description of the juvenal plumage of the yellow-headed blackbird as follows: “The whole head and breast are warm buff, giving the effect of a brown-headed bird; the abdominal region whitish; the back blackish, both more or less fringed with buff; the tail and wings black, the wing-coverts tipped with white. At the post-juvenal molt the tail and wing-quills are retained, while the rest of the plumage is exchanged for a costume which resembles that of the female, but is usually without streaks on the breast, or if streaks are present, they are yellow.” I think this description must refer to a young male, for the female has no white in the wings.
Fautin (1941a) says: “The first-winter plumage of the young is acquired by a partial post-juvenal molt as a result of which the buffy feathers of the head, neck, and breast regions of the fledglings are replaced in the males by yellowish feathers tipped with brownish on the sides of the head, throat, and breast, with a collar sometimes extending around the back of the neck. The feathers of the back nape, crown and wings are a deep brown while those of the under parts and especially those of the belly and crural regions are somewhat paler around the edges. The autumn plumage acquired by the juvenal females is much the same as that of the adult females.”
Ridgway (1902) describes the immature male in first-winter plumage as “similar to the winter female, but larger; general color darker (nearly black on piileum. auriculars, and orbital region); superciliary stripe deeper ocher yellow; malar region, chin, and throat chrome yellow, and chest dull cadmium yellow or orange-ochraceous; no white streaks on breast; primary coverts narrowly tipped with white.”
This plumage is worn without much change until the first postnuptial molt the following summer. Apparently, young males do not breed in this plumage.
Young females in first winter plumage are much like the adults, but colors and more veiled; the breasts are streaked with dull whitish; they evidently breed the following spring, when less than a year old.
The prenuptial molt of adults and young, is apparently very limited, confined mainly to the region of the head and neck, the nuptial plumage being produced chiefly by the wearing away of the dusky tips of the autumn plumage. A complete molt occurs in late summer, at which the fully adult plumages are acquired. In the adult male the bright yellow, or orange, of the head and neck is obscured, sometimes nearly concealed, by dusky tips; and in the adult female the colors are duller, less distinct, and the white streaks on the breast are less clear.
The adult male in his nuptial plumage is a handsome bird; Ridgway (1902) describes a high-plumaged male as having “head, neck, and chest yellow or orange (varying from canary yellow to almost cadmium orange, rarely to saturn red); bras, orbital region, anterior portion of malar region, and chin black; rest of plumage uniform black, relieved by a white patch on the wing, involving the primary coverts (except their tips and shafts) and portions of the outermost greater coverts; anal region yellow or orange.”
Food: Beal (1900) analyzed the contents of 138 stomachs of the Yellow-headed blackbird:
As indicated by the contents of these stomachs, the food for the seven months LApril to October, inclusivel consists of 33.7 percent of animal (insect) matter and 66.3 percent of vegetable matter. The animal food is composed chiefly of beetles, caterpillars, and grasshoppers, with a few of other orders, while the vegetable food is made up almost entirely of grain and seeds of useless plants. Predaceous beetles (Carabidae) constitute 2.8 percent of the season’s food,… other beetles a little more than 5 percent.
Caterpillars constitute 4.6 percent, but nearly two-thirds of them are taken in July, and in that month they form 21.5 percent of the month’s food. Remains of the army worm (Leucanie unipunda) were identified in 6 stomachs.
Grasshoppers are eaten to the extent of 11.6 percent for the season, but mainly after August. “The remainder of the animal food, 9.7 percent, is made up of other insects, chiefly Hymenoptera (ants, wasps, etc.), with a few dragon-flies and an occasional spider and snail.”
Of the vegetable food, grain collectively amounts to 38.9 percent, more than half of the vegetable food and more than one-third of all the food.
Of grain, oats hold first place, as in the food of the redwing, and are probably eaten in every month when they can be obtained, although none were found in the 5 stomachs taken in September. The 3 October stomachs contained an average of 63 percent, but a greater number of stomachs would in all probability give a smaller average. August, apparently the next month of importance, shows 43.2 percent. Next to oats corn is the favorite grain, and was eaten to the extent of 9.8 percent, nearly all in the months of April, May and June, with a maximum of 48.8 percent in April, when no wheat was eaten. Wheat appears from May to August, inclusive, and is the only vegetable food that reaches its highest mark in August. The average for the season is 3.5 percent.
Beal (1900) found weed seeds to be an important item in the Food: “Beginning with 18 percent in April, it increases to 34 percent in June, drops to 6.6 in July (to make room for caterpillars and grasshoppers), rises to 36.1 percent in August and finally to 64.4 percent in September. * * * The weeds found in the stomachs are almost precisely the same as those eaten by the redwings, and in practically the same proportions. Barngrass (Choetochloa), Panicum, and ragweed (Ambrosia) are the leading kinds, supplemented by Polygonum, Rumex, and others.”
The yellow-headed blackbird is mentioned by La Rivers (1941) as one of the birds seen eating the Mormon cricket. Kaimbach (1914) records it as feeding on the alfalfa weevil. “Of 21 stomachs collected in June, only 4 failed to contain the weevil. The insect formed 43.48 percent of the yellow-head’s food and was taken at an average of more than 6 adults and 47 larvae per bird. The largest number taken by any of this species was 190 larvae and 2 adults. Another record was 160 larvae and 2 adults. Three adults and 117 larvae were eaten by one bird, while five others had taken more than 170 individuals apiece.”
Linsdale (1938) says of the feeding habits in the marsh: ‘~Forage places varied, but nearly all the marshy parts of the pond were explored for food. Both males and females spent much time feeding close to the water among the plants (cattails, sedges, Hippuris). A favorite food hunting place was the mud or shallow water close to the shore line. As soon as the air warmed sufficiently for flying insects, the blackbirds spent much time capturing the insects in the air. Females flew into the air after insects as often as or more often than did males.”
In the spring, these and other blackbirds are often seen following the farmer as he plows his fields, to pick up the grubs and insects turned up by the plow. W. J. McLaughlin of Centralia, Kans., writes (Am. Naturalist, vol. 3, p. 493): “During their stay they make themselves very valuable to the farmers by destroying the swarms of young grasshoppers. On the writer’s land the grasshoppers had deposited their eggs by the million. As they began to hatch, the yellow-heads found them out, and a flock of about two hundred attended about two acres each day, roving over the entire lot as wild pigeons feed, the rear ones flying to the front as the insects were devoured.”
Economic Status: The foregoing remarks on food throw considerable light on the economic status of this bird, for although the yellow-headed blackbird destroys a few useful predaceous beetles and shows a fondness for dragonflies that help destroy other annoying insects, to its credit is the fact that the bulk of its insect food consists of injurious species. It does, however, along with other blackbirds, cause considerable damage to the grain crops, pulling up the seedlings to eat the kernels, feeding on ripening grain, attacking grain in shocks, and injuring corn on the ear while it is in milk. But, as the records show that the various grains were eaten throughout most of the spring and summer, much of this must have been waste grain of no economic importance. On the whole, the bird is probably more beneficial than harmful, except in a few places where it is sufficiently numerous to cause appreciable damage to crops.
Behavior: DuBois (MS.) noticcd that at certain nests containing young, the parents chirped and hovered over their nests when approached, showing much more solicitude than the birds which had only eggs; the latter usually sat off at a little distance and looked on, without any demonstration whatever. Fautin (1941b) found the females very shy about their nests, Leaving very silently as the nest was approached, but they never hesitated to drive away another bird from the immediate vicinity of the nest. “The emitting of an alarm call by one of the members of the colony would also cause’ them to leave their nests and fly to the assistance of the one that had sounded the alarm. Such cooperative behavior was witnessed on several occasions. On one occasion, when an American Bittern (Botaurus lerdiginosus) visited the marsh, it was so severely attacked that it could not escape by flight and crawled down among the dead bulrush stems to avoid the onslaught until the confusion subsided and part of the Yellow-heads had retired from the scene of the conflict.”
While I was watching a colony of these blackbirds breeding in a North Dakota slough, a marsh hawk which had a nest not far away happened to fly over the colony; whereupon the blackbirds, yellow heads, and redwings, arose in a cloud all over the marsh and flew about for a few minutes, cackling and squealing, until the hawk departed; this happened several times, whenever the hawk appeared. Others have noticed similar behavior. Linsdale (1938) saw a blackbird fly after a marsh hawk, “but the pursuit was spiritless.” He noted that, when a prairie falcon circled overhead, they gave the alarm and “hurried to the cover offered by a bush.” They also gave alarm and flew at a Swainson’s hawk that flew over; they were disturbed by a nighthawk, but did not attack it; two crows were driven away. Wetmore (1920) saw them driven to shelter by a marsh hawk.
On the ground, the yellowheads walk sedately, seldom hopping, or run rapidly in pursuit of a moving insect. Of their flight, Linsdale says:
“The flight of the yellow-headed blackbirds contrasted markedly with that of the red-winged blackbirds. It was slow and deliberate and seemed to reflect the whole manner of the species. The dull whistle made by the wings could be heard distinctly for 50 yards or farther as the birds flapped heavily from one perch to another.”
Wetmore (1920) comments on the perching ability of the birds as follows:
The feet of the Yellow-head are relatively very large with long, strong toes and the birds use them to advantage in walking about on floating aquatic vegetation or soft mud. In the rushes they prove themselves expert gymnasts. Often they alighted near the tips of the tall round-stemmed tules and as they swayed under their weight the birds supported themselves by their wings while they slid their feet quickly down to a new hold, trying several grips until finally they were low enough so that the rush supported them. This was done with great quickness as the birds shifted from grip to grip rapidly. At times instead of sliding down they reached out and grasped a second stem with one foot, dividing their weight between the two and standing suspended with the feet five inches or so apart.
On the subject of combativeness, Ammann (MS.) writes: “Judging from the behavior of nesting Yellow-heads toward humans, the male is more pugnacious and aggressive than the female. On several different occasions while I was banding four- or five-day-old young the male darted at my head and narrowly missed me. Once after I had picked up a fledgling the male flew at me quite forcefully, striking the side of my head with his bill. On another occasion I was in a blind and saw an adult male molesting a fledging. Much to my surprise another adult male immediately attacked the intruder and a short combat in mid-air ensued. Both feet and bills were brought into action. In a few seconds the assumed father of the fledgling got the better of the intruder and while holding him down, half submerged on some floating vegetation, pecked viciously at the back of his head. The blows were delivered slowly, deliberately, and sharply with the aid of body and neck movements. This lasted fully eigbt minutes. The subdued male continuously uttered alarm calls, and whenever he turned his head around to offer resistance he pecked him about the eyes. The one-sided battle ended when some other males were attracted to the scene; they, however, did not join in the combat. The victim was slightly bloody about tbe nape, had lost a number of feathers, and I supposed that he was almost dead, but he got up, shook himself, and flew weakly away. * * * Females were never seen fighting among themselves, nor attacking men.”
Voice: My impressions of the striking song of the yellow-headed blackbird, as heard many years ago while my hearing was good, are mentioned in the beginning of this story; the oka wee wee, oka wee wee, oka wee wee notes were the dominant sounds in the slough, and I can seem to hear their rhythmic swing even now. But I cannot find in print any rendering of the song that is quite like what I wrote in my notes at the time. What Dawson (in Dawson and Bowles, 1909) calls the alarm cry “uttered with exceeding vehemence, klookoloy, klookoloy, klook ooooo,” seems to have a similar rhythm and may be a variation of what I heard. Then he adds: “Ok-eh-ah-oh-oo is a musical series of startling brilliancy, comparable in a degree to the yodelling of a street urchin, a succession of sounds of varying pitches, produced as tho by altering the oral capacity. * * * The last note is especially mellow and pleasing, recalling to some ears the liquid gurgle of the Bobolink.” Mrs. Bailey (1928) quotes from some manuscript notes from Merrill, of Mesilla Park: “While nothing can be more raucous than the note of a single individual, the united voices of a few hundred * * * produce an effect very pleasing, if not strictly harmonious.” These are all the words I can find of even faint praise of the song.
Everybody else condemns it as unmusical and unattractive. Aretas A. Saunders tells me that, from his memory of it in Montana, “the form and length of the song is quite like that of the red-wing, there being several short notes at the beginning and a more prolonged note at the end. The quality is most unmusical, however, and the last note sounds ]ike a ludicrous squawk.”
The severest condemnation comes from P. A. Taverner (1934):
The song of the Yellow-headed: if song it can be called, as it lacks every musical quality: is like that of no other Canadian bird. Climbing stiff-leggedly up a reed or tule stalk the male, with wings partly raised, lowers his head as if to be violently ill, and disgorges a series of rough, angular consonants, jerkily and iregularly, with many contortions and writhings, as if their sharp corners caught in the throat and they were born with pain and travail. They finally culminate and bring satisfied relief in a long-drawn, descending buzz, like the slipping of an escapement in a clock spring and the consequent rapid unwinding and futile running down of the machinery. The general effect of the performance may be somewhat suggested by the syllables ‘Klick-kluck-klee: : klo-klu-kiel: kriz-kri: zzzzzzz-zeeeeee.’
Jean M. Linsdale (1938) describes the song as follows:
The number of notes in the song of the males varied; sometimes it was only one drawn out, harsh call. However, the most usual song was composed of 5 notes. The first one was explosive and loud, the next two lower and shorter, followed by 2 long drawn out notes at slightly higher pitch. When the males were at the pond this song was given at rather regular intervals and from habitually used singing perches. These were most often at exposed points where the announcing bird could be seen from, and could see in, many directions. The song appeared to be useful as much to repel invasion by other males as for any other possible service.* * *
Other types of notes were heard, as follows. A series of high-pitched notes, with a few guttural sounds when heard at close range, was given on the circular flight made when a march hawk came near. When potential danger first appeared, a plaintive whistle much like that of the red-wings was given. In flight the females gave single chucks, much like the notes of red-wings. About the nesting sites they had a variety of harsh, screeching notes .
Wetmore (1920) noted that the song “was subject to much variation, but ordinarily resembled the syllables Klee Klee Klee Ko-Kow-w-io, the last low and much drawn out.”
Anmiann (MS.) recognized two distinct types of song, the buzzing and the accenting. He describes the former as follows: “The buzzing song is practically the same for all males. It is begun with several short, slightly descending, comparatively low-pitched, melodious introductory notes (uttered with the bill closed), followed by a loud, very harsh, drawn-out wavering buzz or wail, rather suddenly increasing in volume at the first and held to the end. The most peculiar contortions of the body accompany both parts of the song. During the introductory notes the head is always turned to the left so that the bill is pointing at right angles to the front. At the beginning of the buzz or wail the angle of the bill to the axis of the body is decreased about half and held thus throughout the rest of the song; the neck is extended, bill pointed upward, the wings slightly opened, tail widely spread, and the whole body made to vibrate slightly, the entire procedure giving the general impression that the bird is in great agony.”
Of the accenting song, he says: “This song is totally different in general character from the buzzing song although it may often include a short buzzing note such as that described for the latter; even similar introductory notes are used. The head and neck are not twisted much and the entire performance is usually shorter and more precise, seeming to be delivered with less strain or agony to the bird. It is also harsh and not musical but more pleasing to me than the buzzing song. The various syllables are nearly always clearly defined since they are usually separated by short intervals. At the beginning of the main part, the throat is swelled, tail spread wider than usual, and sometimes the wings are slightly opened; at the final note, the breast is thrown forward, the neck stretched upward and the head snapped back, so that the bill is pointing almost straight up.”
Field marks: T he adult male yellow-headed blackbird is too conspicuously marked to be mistaken for anything else; the head, neck, and upper breast are bright yellow, in marked contrast to the black of the rest of the plumage, and the white patch in the wing coverts shows plainly in flight and slightly when at rest; in fall the yellow of the head is partially obscured by dusky tips. Females and young males are dark brown, instead of black, with much dull yellow or yellowish buff on the throat and chest, even in the juvenal plumage. The females are always much smaller than the males, and have no white in the wings.
Yellowheads can sometimes be recognized at a considerable distance in flight. Their flight is somewhat undulating, like that of redwings and not like the straight-line flight of grackles; they differ from the redwings in their flock formations, which are long, irregular, loose flocks, like those of the grackles and not like the wide, company-front flocks of the redwings; they can also be distinguished from the grackles by their shorter tails .
Enemies: The eggs and young of the yellow-heads are preyed upon by various forms of furred and feathered enemies. Small mammals that can swim are likely to climb to the nests and rob them. Crows, and perhaps grackles, sometimes steal the eggs or small young, which are found in abundance in the colonies. The defensive response in the colony to the appearance of a falcon, marsh hawk, or even a harmless nighthawk or bittern, shows that almost any large bird is regarded as a potential enemy, to be driven away by concerted action.
The nests are not uncommonly invaded by cowbirds; Friedmann (1929) cites several authentic cases in various parts of the bird’s range, and mentions one case in which six eggs of the cowbird and four of the blackbird were found in a single nest. It would seem that a young cQwbird would have small chance of survival in the nest of a species of this size; there seems to be no record of such survival.
Dawson (1923) once found a large “blow snake” coiled just below a nest full of young blackbirds.
According to information given to Ammaun (MS.) by Paul L. Errington, he names the chief predators on young and adult yellowheaded blackbirds, in the probable order of their importance, as mink, great horned owl, marsh hawk, red fox, and muskrat. Said Errington, “I would judge that the heaviest pressure by mink upon the blackbirds occurs in late summer and early fall, probably to a considerable extent upon inunatures at night.” Errington reported that from the spring of 1933 to July 1935, 280 great homed owl pellets were collected, many of them taken when no yellowheads were present; of these, 27 contained a minimum of 36 yellowheads, of which at least 6 were young. From the gullet collections of the young from 12 marsh hawks’ nests, during three seasons, 26 specimens of yellowheads were identified, 5 of which were young. Of the other two predators, Errington has this to say: “Foxes take a variable number of Icteridae other than meadow larks, but I believe that redwings are more apt to occur in their diet than yellow-heads.* * *
The muskrat often has a meat tooth and may very wcll eat blackbirds it finds freshly dead or may even kill an occasional cripple or a very inunature bird that it may find in the water or in some similarly accessible place. However, as an active predator upon blackbirds, I would not say that it rates at all.”
Ammann (MS.) adds: “The three largest of the known destructive agencies were a rise in water level of the lake, a cold rainstorm, a short, violent windstorm. They accounted for the loss of 28.7 percent of all nests and 31.7 percent of all eggs and young (using the total number of eggs as a basis for the latter figure). * * * Internal parasites were found in the alimentary tract of 21.4 percent of the 117 specimens examined. Acarina were found in 17 percent and Mallophaga of four species on 59 percent of the 122 specimens examined.”
Fall: Fautin (1941a) writes:
During the molting period which began in July the Yellow-beaded Blackbirds left the nesting areas and congregated in large flocks in marshes where the growth of cattails, Typha latifoHa, and buirushes was most dense. Here they remained very much in seclusion during the greater part of the day, coming out only in the mornings and evenings to feed. Very often the males were found in one part of the marsh and the females and juvenals in another. This association of the females and juvenals may have been due to the greater attentiveness of the females to the young during their nestling period.* * *
When the autumn molt was near completion, about August 1, the Yellowheaded Blackbirds, together with other species of blackbirds, came out of hiding and roved about in the fields during the day, returning to the cattail marshes to roost at night.
Migration began about September 1. By September 7 only three females could be located in the vicinity of the study areas. One week later a single juvenal male in a flock of about fifty Brewer’s Blackbirds, Euphagus cyanocephatus cycnocephalus, was all that could be found and by September 17 all had left the vicinity of the study area.
Mrs. Bailey (1902) says of the fall wanderings: “From their breeding grounds in the sloughs and tule marshes the yellow-headed blackbirds scatter out and wander over the whole of the western plains country, appearing in flocks with grackles, red-wings, or cowbirds in the characteristic hordes of the fall migration, or in flocks by themselves in fields and meadows, along the roadsides, often in barnyards and corrals, and sometimes in city streets, flocks with pompous, yellow-caped males strutting about among the dull-colored females and young, talking in harsh, gutteral tones.”
At this season the handsome adult males are often seen in flocks by themselves, and the females and young in larger separate flocks.
P. A. Taverner (1934) writes:
The days are spent on the bountiful stubble fields, and the nights in the marshes. A blackbird roost just before sunset is an interesting place indeed. The birds come in from every direction, talking and croaking loudly, in vast black clouds, looking, on the horizon, like wisps of smoke blowing before the wind. They pitch into a bed of reeds already occupied by earlier arrivals, until each stalk seems strung with big, black beads. At the onslaught of the incoming contingent, birds are dislodged right and left, there is a babel of protesting voices and a fluttering of many wings that whirr loudly in the still air as the surface of the green marsh boils with black forms seeking new resting places. The confusion gradually subsides until the next arriving flock starts the hubbub over again .
Thus it goes on as the sun sinks, until all are in, and then the evening wind chases waves over the soft green surface of the reed beds, without revealing a hint of the hordes of black bodies beneath that are resting through the stillness of the night.
Winter: The yellow-headed blackbirds, having withdrawn from the northern portions of their breeding range, spend the winter in the southern United States and northern Mexico. They are still to be found, however, in some of the extreme southern parts of their summer range in more or less reduced numbers. In their winter range, they roam about over the fields and plains in enormous mixed flocks, visiting the ranches, barnyards, and poultry farms, much as they did in the fall.
Range: Western Canada to central Mexico .
Breeding Range: The yellow-headed blackbird breeds from central Washington (Ye kima Valley, Bumping River), central British Columbia (Vernon, Cranhrook, Tachick Lake), central-western and northeastern Alberta (Clairmont, Fort MeMurray), north-central Saskatchewan, central and southeastern Manitoba (Grand Rapids, Winnipeg), northern Minnesota, north-central Wisconsin, northeastern Illinois, and northwestern Ohio (locally); south to southern California (Potholes, San Jacinto Lake), southwestern Arizona (near Yuma, Imperial Dam), northeastern Baja California (Colorado River Delta), south-central Nevada (Pahranagat Valley), southwestern Utah (formerly Virgin River Valley), central and central-eastern Arizona (~vIormon Lake, Marsh Lake), southern New Mexico (Mesilla, Carlsbad), northern Texas, Northwestern Oklahoma (Cimarron County), and northeastern Missouri (Sarcoxie, Clark County), central flhinois (Quiver Lake), and northwestern Indiana (Lake and Porter Counties). There are summer records which may indicate breeding in western Texas, central-eastern Missouri, southern Illinois, Michigan, and central Ohio.
Winter Range: Winters north to central California (Sacramento Valley), central Arizona (Clarkdale), southern New Mexico (Socorro, Carlsbad), central and southeastcrn Texas (Medina, Port Arthur), and southern Louisiana (Calcasieu Parish, Octave Pass); south to southern Baja California (San J05~ del Cabo), Jalisco, Michoac~n, Guerrero, Puebla and central Veracruz .
Casual records: Casual in southwestern British Columbia and central Mackenzie, and from northern Michigan, southern Ontario, and western Pennsylvania south to southern Louisiana, and along the Atlantic seaboard from Maine to northern Florida.
Accidental in the Arctic Ocean (100 miles west of Point Hope, Alaska), northern Manitoba (Churchill), central Quebec (Rupert House, Godbout), Nova Scotia (Sable Island), southern Florida (Royal Palm Hammock, Key West), Cuba (Havana: market specimen, Guant~namo) Barbados, and Greenland (Sardlog, Nanortalik) .
Migration: Early dates of spring arrival are: Arkansas: Rogers, March 10. Kentucky: Meade County, April 19. Missouri: Chillicothe, March 8 (median of 4 years, March 13); New Haven, March 11. Illinois: Hinsdale, T\Iarch 12; Paris, April 2; Chicago region, April 16 (average, May 3). Indiana: Goshen, April 17; Kokomo, April 19. Ohio: Sandusky, April 15. Michigan: Schooleraft County, April 9; Monroe County, April 29. Ontario: I’vliddlesex County, April 29. Iowa: Sioux City, March 10 (median of 21 years; April 23). Wisconsin: Madison, March 23; St. Croix County, April 5. Minnesota: Hutchinson, March 20 (average of 19 years for southern Minnesota, April 16); Foreston, April 7 (average of 9 years for northern Minnesota, May 6). Texas: El Paso, March 7; Taylor County, March 26. Oldahoma: Okiahoma City, February 27; Custer County, March 5. Kansas: Bendena, February 18; Harper, March 2. Nebraska: Hastings, February 24; Red Cloud, March 6 (average of 14 years, April 12). South Dakota-: Vermillion, April 1; Sioux Falls, April 2 (average of 7 years, April 30). North Dakota: Jamestown, April 14; Cass County, April 21 (average, May 4). Manitoba: Margaret, April 14; Treesbank, April 18 (median of 42 years, VIay 3). Mackenzie: Fort Chipewyan, May 24. New Mexico: Rincon, February 16. Arizona: Tucson, February 27; Phoenix, March 8. Colorado Denver, February 15 (median of 23 years, April 23); Walden, March30 (median of 11 years, April 14). Utah: Bear River Refuge, Brigham City, March 30. Wyoming: Wheatland, Apr11 10; Laramie, April 11 (average of 8 years, April 25). Idaho: Deer Flat, March 5; Rupert, March 29. Montana: Choteau, April 8; Billings, April 15; Fortine, April 23 (median of 7 years, May 3). Saskatchewan: Qu’Appelle, April 6 (median of 14 years, May 4); Wiseton, April 15 (median of 20 years, April 27). Alberta: Stony Plain, April 15. California: Siskiyou County, March 17; Fresno, March 23. Oregon: Klamath Falls, March 1; Weston, March 15. Washington: Spokane County, March 20. British Columbia: Okanagan Landing, April 22.
Late dates of spring departure are: Michoac6n: Quiroga, April 29. Sonora: Guirocoba, May 10. Arkansas: Huttig, May 6. Kentucky: Guthrie, May 20. Missouri: Palmyra, May 20. Illinois: Chicago, May 21. Texas: Corsicana, June 4; Hidalgo, May 24 Oklahoma: Cleveland County, May 29; Oklahoma City, May 28. New Mexico: Glenrio, May 18. Arizona: Tucson, May 13. California: Orange County, May 26; Death Valley, May 20.
Early dates of fall arrival are: California: Daggett, July 19. Colorado: Yuma, July 14; Weldona, July 15. New Mexico: Clayton and Glenrio, July 14. Oklahoma: Oklahoma City, July 13. Texas-Somerset, July 12; Waco, July 16. Michigan: Bruce Crossing, August 24. Indiana: Indianapolis, August 22. Missouri: Concordia, July 23.
Late dates of fall departure are: Alaska: 100 miles west of Point Hope, October 12 (only record). British Columbia: Penicton, October 19. Washington: White Bluffs, October 14. Oregon: Harney County, November 20. Nevada: Indian Springs, October 25. California: Stockton, November 19; San Geronimo, October 17. Alberta: Andrew, September 28. Saskatchewan: Indian Head, October 20; Wiseton, September28 (median of 6 years, September 25). Montana: Huntley, November 15; Fortine, October 6. Idaho: Rupert, September 18. Wyoming: Laramie, October 20 (average of 5 years, October 7). Utah: Ashley Creek, Unitah County, September 30. Colorado: Fort Morgan, November 10 (median of 12 years, September 7); Boulder, October 30. Arizona: Tombstone, November 21. New Mexico: Clayton, November 22. Manitoba: Winnipeg, October28; Treesbank, October 20 (median of 14 years, September 10). North Dakota: Rice Lake, September 17. South Dakota: Mellette, October 26; Sioux Falls, October 9 (average of 5 years, September 26). Nebraska: Neligh, November 26; Gage County, November 5. Kansas: Clearwater, October 14; Harper, October 10. Oklahoma-Oklahoma City, October 17. Texas: Houston, November 28; Commerce, November 24. Minnesota: Hutchinson, November 14 (average of 6 years for southern Minnesota, October 6); St. Vincent, October 25. Wisconsin: Appleton, October 24; LaCrosse, October11. lowa: Elkader, November 3; Northwood, October 23; Sioux City, October 17 (median of 11 years, September 15). Michigan: Detroit, October 12. Ohio: Toledo, October 22. Indiana: East Chicago, October 15. Illinois: Chicago region, October 30 (average, September 15); Rantoul, October 23. Missouri: New Haven, November 6. Kentucky: Guthrie, October 18. Arkansas: Rogers, October 11. Maine: Monhegan Island, September 11. Massachusetts: Watertown and Northampton, October 15. New York: Orient, October 4. Pennsylvania: Chester County, September 15. Maryland: Baltimore, October 1 .
Egg dates: Alberta: 8 records, June 4 to June 19.
California: 98 records, April 21 to June 28; 53 records, June 2 to June 10.
Illinois: 20 records, May20 to June21; 10 records, May25 to June 8.
Minnesota: 24 records, May 19 to June 12; 14 records, May 27 to May 31.
Nevada: 15 records, May 22 to June 3.
Utah: 8 records, May 16 to June 4 (Harris).