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A
chapter from the electronic book:
Life Histories of Familiar North American
Birds
Red-winged
Blackbird
Agelaius phoeniceus [Eastern
Redwing]
[Published
in 1958: Smithsonian Institution United States National Museum
Bulletin 211: 123-150]
Everyone who notices birds at all knows the red-winged
blackbird, or redwing as it is now called; at least they recognize
it as a black bird with red on its wings. It is very conspicuous
and self-revealing whenever one approaches its haunts. It could
hardly be overlooked by even the most casual observer, as the male
flies up to announce his presence and display his colors.
The numerous subspecies of the redwing are widely spread all
over the continent of North America, except in the arid desert,
the higher mountain ranges, the forested and the Arctic regions,
wherever they can find suitable marshes in which to breed. The
presence of water, or at least its proximity, is essential; and
the birds must have certain types of dense vegetation in which to
conceal their nests. Marshes or sloughs supporting extensive
growths of cattails, bulrushes, sedges, reeds, or tules are their
favorite breeding haunts; but where similar types of vegetation,
or water-loving bushes or small trees, grow in ponds, around the
shores of lakes or along the banks of sluggish streams, the
redwings find congenial homes. Wherever such conditions exist
throughout this continent, from Central America nearly to the
Arctic Circle and from the Atlantic to the Pacific, some form of
this species is likely to be found.
Spring.--The redwings are among our
earliest spring migrants; the eastern redwing leaves its winter
haunts in the southern states before the end of February, reaches
New England in March (rarely earlier), and arrives in
eastern Canada in April or earlier. In Massachusetts, we look for
the first of these harbingers of spring about the second week in
March. I wrote in my notes for March 22, 1900: "The first
interesting sight that met our eyes, as we walked down the country
road, was a detached flock of some ten robins in an old stubble
field, the first I had seen that year; it was a welcome sight and
their bright red breasts seemed to reflect the warmth of coming
spring. A flock of about fifteen redwings, adult males, also
arose from the same field and circled about, wheeling with better
precision than the best of trained soldiers, their jet black
uniforms and scarlet epaulets flashing in the sunlight as they
turned. All their movements seemed to be governed by the same
impulse, instantly obeyed, as they swooped down upon a small apple
tree and alighted with every head pointing toward the wind. Our
approach started them off again toward some swampy woods, where
they scattered and alighted among the tops of the taller
trees."
William Brewster (1906) says: "For several weeks after
their first appearance in early spring Redwings are usually found
in flocks composed wholly of males. At this season they are seldom
seen about their breeding grounds excepting in the early morning
and late afternoon. At most other hours of the day they frequent
open and often elevated farming country, where they feed chiefly
in grain stubbles and weed-grown fields. When disturbed at their
repasts they fly to the nearest deciduous trees and immediately
after alighting burst into a medley of tumultuous song,
inexpressibly wild and pleasing when heard at a distance, but
rather overwhelming if the flock be a large one and close at
hand."
Chapman (1912) writes attractively of this early spring
behavior: "A swiftly moving, compact band of silent birds,
passing low through the brown orchard, suddenly wheels, and,
alighting among the bare branches, with precision of a trained
choir breaks into a wild, tinkling glee. It is quite possible that
in the summer this rude chorus might fail to attract enthusiasm,
but in the spring it is as welcome and inspiring a promise of the
new year as the peeping of frogs or the blooming of the first wild
flower."
No better life history of the redwing has ever been published
than that written by Arthur A. Allen (1914), based on an
exhaustive study of the bird near Ithaca, N.Y. I regret that space
will not permit quoting from it as fully as it deserves. His study
throws new light on the migratory movements of the species, and
suggests that similar studies of other species might be equally
enlightening.
As a result of his studies at Ithaca in 1911 and 1910, he
divides the migratory waves into seven classes as follows:
"Vagrants" arrived from February 25 to March 4; migrant
adult males from March 13 to April 21; resident adult males from
March 25 to April 10; migrant females and immature males from
March 29 to April 24; resident adult females from April 10 to May
1; resident immature males from May 6 to June 1 (1910); and
resident immature females from May 10 to June 11 (1910).
The "vagrants" come during the first warm days of
spring, although the marshes may still be frozen and the ground
still covered with snow; they are supposed to be birds that have
wintered not very far south; they do not appear every year, but
when they do come they are seen in February; they "are for
the most part adult males, but immature males and females may be
found among them. They are never in large flocks, and often occur
singly. The reproductive organs are very small. . . . They do not
frequent the open marsh." Of the arrival of the migrant
males, Allen (1914) says:
The first true migrants arriving in the spring are adult
males. They appear in flocks, some of which contain a hundred or
more birds, and ordinarily are first noted in the marsh, although
occasionally seen in tree tops or stubble fields on the uplands. .
. . At this season of the year, about 4:30 in the afternoon, let
us take a stand at the upper end of the marsh and gaze southward
up the Inlet Valley. Presently we discern what appears like a puff
of smoke in the distance, drifting in at a considerable height.
After a minute or two the smoke is resolved into an aggregation of
black specks, and then, as it drops lower and lower, it takes on
that irregular form so characteristic of Redwinged Blackbirds.
With one last swoop and flutter of wings, they alight on the more
prominent of the few scraggly trees at the southern end of the
marsh. The migration has begun. For a few moments they shake out
their feathers and give vent to their feelings in song. It is but
a short time, however, before they start again for the north.
A few birds drop out of the passing flocks and settle down into
the marsh for a while, but they soon rise again and join another
migrating flock. Flocks coming late in the day fly low and settle
for the night in the scanty shelter of the still dormant flags.
Every available perch, not so high as to be conspicuous, is
filled with birds down to the water's surface, but were it not for
the unspeakable din that arises from the hundred throats, one
would scarcely be aware of their presence, so inconspicuous are
they against the dark water. If one disturbs them now, there is a
rush of wings, but they do not fly far. Raillike they drop back
into the marsh a short distance away, and soon resume their
indescribable discord. . . .
This period of the migration, which I have termed the
arrival of migrant adult males, continues for about two
weeks before the resident birds begin to arrive. Each evening
there is a well-defined flight into the marsh; each night the
birds all roost together; and each morning they all leave for the
north. The marsh to them at this period is a shelter for the night
only, and the entire day is spent on the uplands.
The birds referred to at the beginning of this chapter by
Brewster, Chapman, and the author probably belonged in this class,
migrating adult males. Allen (1914) says of the arrival of
resident adult males:
The arrival of resident males is first made clear by the
actions of the birds themselves. To one unfamiliar with their
habits the exact time of arrival is not apparent. Up to this time
the birds, for the most part, have kept in more or less
well-defined flocks. They have been difficult to approach, the
slightest annoyance setting them off. . . . About the end of
March, however, certain birds arrive, in whose actions a
difference is noticed. They do not fly away at one's approach, or,
if frightened, soon return to the same spot. These birds do not
associate with the migrating flocks, and they roost alone. If one
is enabled to identify an individual bird among them by such
characteristics as abnormal feet or the loss of its tail or a
primary feather, as has frequently been done in this study, one
finds that it never changes its station in the marsh after its
arrival. . . . From their first arrival, they assume all rights to
the domain in which they have established themselves. Frequently
these domains adjoin one another closely, but the birds seldom
trespass on one another's rights. When they do so, they seem to
recognize the owner's prerogative, so that serious quarrels never
ensue.
The resident males have been at their stations only a few days
before the first females and immature males appear among the
migrating flocks. The last days of March and first of April
usually usher them in. Says Allen (1914): "Within a few days,
as their numbers increase, small flocks made up entirely of
females are observed. It is about this time--the end of the first
week in April--that the males begin to show a slight interest in
the presence of the females. The former now spend more of their
time in the marsh, and resent intrusion into their domains. By
this time their reproductive organs show considerable increase in
size. Among the migrating birds at this time there is an
increasing preponderance of immature males and of females. The
latter shun the presence of the males, and whenever they do
approach one of the residents, they are immediately driven
off."
During the early part of the third week in April, another group
arrives, the resident adult females. According to Allen (1914):
The flocks break up and the single birds scatter over the
marsh, as did the resident males upon their first arrival. Usually
they select a place near some male or group of males. They are
much more retiring than the latter, however, and keep mostly near
the water's surface, where they are inconspicuous. Whenever they
appear on the tops of the cattails, or more especially, when they
attempt to fly, they are immediately pursued by one or more of the
males. Occasionally a male drives a female in great circles over
the marsh and even to a considerable height. Eventually, however,
he relinquishes the pursuit and returns to his post. The earlier
migrant females, when pursued in this way, immediately leave the
marsh. But now, as the male ceases pursuit, the female checks her
flight and is soon again at her station near the male. Such
maneuvers announce the arrival of the resident females.
About the first week in May, after most of the adult resident
birds have begun to nest, the resident immature males begin to
appear in numbers. From the second week in May until the last of
the month, these flocks continue to arrive. The resident immature
females begin to appear with the immature males about the middle
of the month. They increase in numbers until the first of June,
when they far outnumber the males, and by the second week, when
the last migrating birds are recorded, they compose entire flocks.
Says Allen (1914), "It is doubtless through some of these
birds, at a time when unattached males are difficult to find, that
many of the cases of polygamy arise."
Probably the movements of the different classes of migrants are
not always as clearly defined as indicated by Allen. Fred M.
Packard (1937), while banding redwings at the Austin
Ornithological Research Station, at Eastham, Mass., found
"unsuspected variation in the behavior of the migrating birds
on Cape Cod. Some were apparently true migrants; they were caught
but once, and did not repeat. Others lingered for a few days or
even a month, repeating during that period, and then left; these
also were migrants. A third group stayed in the vicinity from the
time of their arrival through the nesting period, as true
residents. A large fourth group was composed of individuals that
were trapped once or twice on arrival, and then disappeared,
exactly like migrants; but these returned after an interval
varying form 2 months to 2 weeks, some to nest nearby, others to
disappear again." Cape Cod is a long, narrow, curving
peninsula pointing northward at its terminus and facing a broad
expanse of water. Perhaps the returning birds of the fourth group
preferred to turn back, rather than risk the long flight over the
water.
Territory.--As indicated above
and as noted by all observers, the resident adult male, on his
arrival on the breeding grounds or soon after that, "stakes
out his claim" to the territory that he has decided to
establish and to defend. This claim may be large or small,
depending on the size of the marsh and the density of its
population; in a large marsh with few redwings nesting in it, the
territories may be extensive and well outlined; but in a dense
colony, the claims are close together and boundaries are not so
well marked. The male stands his ground and defends his territory
against intruding male redwings and other trespassing birds; he
even drives away female redwings until he is ready to mate.
Ernst Mayr (1941) writes as follows on territorial behavior:
"Early in the season, when the weather was still cold and the
males had just recently established themselves in their
territories, they spent a good deal of time sitting on the top of
small bushes or old cattail stalks and calling softly chuck-chuck,
particularly when migrating blackbirds flew overhead. They were
fluffed up and only the yellow margin of their shield showed. As
soon as a singing spell 'overcame' one of the birds his whole
attitude changed, and he displayed his red brilliantly--only to
fall back into his former lethargic condition when the singing was
ended."
Courtship.--While the male
redwings are defending their territories and driving away
migrating redwings of both sexes, the resident females come,
between April 10 and May 1 at Ithaca, according to Allen (1914).
They select their own territories, where they plan to build their
nests, and these are usually near the station of some established
male or group of males. At first the male drives away the newcomer
and chases her about over the marsh, but she returns to the spot
she has selected. Eventually he is ready to select his mate and
may be seen following her about. "He never allows her to
escape from his sight, and as she hunts about near the water's
surface, he vaunts himself on the nearest cattail. They now may be
considered mated."
Probably most redwings are mated in pairs that are true to each
other, but this is a matter that is not easily determined in a
large colony. Allen (1914) says: "Certain pairs have been
observed throughout the season, and found to be mated as
steadfastly as are most birds, while in others the tie seems to
bind only so long as the male is watchful and able to exert his
lordship in driving away other males. A female has been observed
to receive one male with spreading wings and quivering feathers,
and in the next moment, when this bird had been driven off, to
welcome the victor with the same freedom and display."
Females sometimes take a more active part in the courtship
performance as observed by Thomas Proctor (1897), who says:
"And very amusing indeed it was to watch these comedians in
sober brown, but in extemporized ruffs, puffs and puckers,
pirouette, bow and posture, and thus quite out-do in airs and
graces their black-coated gallants. Their shrill whistle, the
meantime continually vied with, or replied to, the hoarse
challenges of their admirers, while in noisy chattering, and in
teasing notes, they were excessively voluble."
It is generally believed that the redwing is often polygamous,
though by no means always so. It is often evident that there are
more females and more occupied nests in a marsh than there are
males. In one swamp studied by Mayr (1941), he shows 12 nests in
his sketch in what he supposed were 6 territories; he was unable
to determine the exact number of males, but says that "there
were not less than four and not more than six." In another
swamp, two males had two females each and another had only one.
Mabel Osgood Wright (1907) writes: "When Redwings live in
colonies it is often difficult to estimate the exact relationship
between the members, though it is apparent that the sober brown,
striped females outnumber the males; but in places where the birds
are uncommon and only one or two male birds can be found, it is
easily seen that the household of the male consists of from three
to five nests each presided over by a watchful female, and when
danger arises this feathered Mormon shows equal anxiety for each
nest, and circles screaming about the general location."
Numerous banding records have indicated the males far outnumber
the females, but this is probably due to the fact that the males
enter the traps more readily than the more retiring females, and
so are more often recorded. What is probably a more reliable
conclusion as to the actual sex ratio was found in the careful
studies of J. Fred Williams (1940). He states in his summary:
In a study of nestling Eastern Red-Wings made at Indian
Lake, Ohio, from June 18 to July 22 it was found that the young
could be sexed by dissection at any time after hatching. With the
age of nestlings known to the nearest day it proved possible to
distinguish between the sexes by means of weights after the fifth
day, and by means of tarsal lengths after the eighth day.
The following sex ratios were found:
Among 119 young, representing the full egg complements of 35
nests, 57 males, 62 females.
Among 94 young which were successfully fledged, 47 males, 47
females.
Among 21 young which died during the nesting period, 9 males,
12 females.
The apparent deviation of the first and third of these
ratios from the expected 50:50 could easily be due to random
variation in sampling.
To assume that the even 50:50 birth rate, or nearly that, is
the rule, does not agree with the well-known fact that the females
outnumber the males on the breeding grounds, unless we also assume
that the females begin to breed when less than one year old and
that the males, at least most of them, do not mate until they are
nearly 2 years old. This is true of the yellow-headed blackbird,
and probably also of the redwing. With the sexes as unbalanced as
they are in the breeding colonies, polygamy is likely to be quite
prevalent and promiscuity, or even polyandry, may occur, though
the latter is probably rare.
Dr. Charles W. Townsend (1920) gives the following excellent
account of the courtship display of the male:
The courtship of the Red-winged Blackbird centers as
distinctly about the display of the scarlet epaulettes as does the
courtship of the Peacock about the display of his train. The adult
male Red-wing when absorbed in feeding is a plain blackbird with a
pale yellow stripe on his shoulder or one with a narrow band of
red. The color may even be entirely covered up by the prevailing
blackness of his costume. When, however, his love passions are
excited he spreads his tail, slightly opens his wings, puffs out
all his feathers, and sings his 'quonk-quer-ee,' or his still more
watery and gurgling song, appropriate to an oozing bog, his 'ogle-oggle-yer.'
Now when he puffs out his body feathers he especially puffs out,
erects, and otherwise displays to their best advantage the
gorgeous scarlet epaulettes. These patches become actually
dazzling in their effect as he slowly flies toward the object of
his affections, for these beauty spots are most effective when
seen from in front.
While admiring the gorgeous display of scarlet and gold set in
its framework of glossy black, one is apt to overlook the awkward
posture of the bird; standing on some prominent perch, he leans
forward, pointing his bill toward his tail beneath the branch,
with his back hunched up, as if he were to become violently
nauseated, suggesting the ludicrous performance of the cowbird.
Allen (1914) mentions another form of courtship:
In addition to the ordinary display and erection of
feathers, a method of soaring is now indulged in. In comparison
with that of the Lark, it is rather crude, but undoubtedly it is
akin to it. Mounting in a rather irregular spiral, the male bird
attains a considerable height, where he hovers, oftentimes for
long periods, while his wings barely flutter. Song is not
generally indulged in. Eventually, with half-closed wings, the
bird drops down in a zigzag course to the marsh. A dozen or more
birds may frequently be seen in the air at once, as they perform
these evolutions. At this time, also, hovering at a much lower
height is frequently indulged in. With a few quick strokes of his
wings, the male vaults from his post into the air, and with
quivering wings and flaming shoulders, gives vent to his pent-up
passion in the "scolding song" described above.
Nesting.--Redwings build their
nests in a variety of situations, though usually in a marsh,
swamp, or wet meadow, where the nests are placed in cattails (Typhus),
dead or living, rushes (Scirpus), sedges (Carex),
tussocks of marsh grass, or such water-loving bushes as button
bushes (Cephalanthus), alders (Alnus), or willows (Salix).
Such associations in shallow ponds, or along the shores of lakes
or the banks of sluggish streams, afford suitable nesting sites.
Although the birds prefer the vicinity of water, their nests are
often found on dry uplands, sometimes at a considerable distance
from any water, in fields of tall grass, clover, and daisies,
where they must be built close to or even on the ground. Nests in
bushes and trees also have been reported by several observers.
A. D. DuBois has sent me the data for 42 nests found in four
northern states; 3 of these were in trees or bushes from 8 to 9
feet above the ground; 2 were in clumps of nettles on the margin
of a marsh, 2 feet above the dry ground. Of 24 nests reported to
me by T. E. McMullen, found in New Jersey, 6 were in bayberry
bushes near marshes and among sand dunes near the ocean; one was 9
inches up in a clump of goldenrod in a clover field; and another
was 8 inches up in a wild rose bush standing in 8 inches of water.
Alexander F. Skutch tells me that he found two nests in upland
alfalfa fields near Ithaca, N.Y. "The two were built in
exactly similar situations, in the midst of the stalks of an
alfalfa plant, with the bottom in each instance three inches above
the ground." Witmer Stone (1937) records redwings' nests in
privet hedges, marsh elders (Iva frutescens), and one in a
small cedar bush, in New Jersey. A. Sidney Hyde (1939) found a
nest in a clump of vetch (Vicia) and another in a wild
cherry shrub, in northern New York.
William Brewster (1937) says of the nesting habits of redwings
at Lake Umbagog, Maine: "Most of them breed on small,
floating islands moored not within areas permanently covered by
the lake but in bordering marshes which have every appearance of
thus belonging to it, whenever completely submerged. The islands
float only at such times but they keep ever level with the surface
of the water, however quickly it may rise or fall, yet seldom
shift otherwise than vertically, being too firmly anchored to
solid ground beneath by tough, flexible roots which proceed from
living bushes--and perhaps also medium sized trees--that
overspread what are essentially buoyant rafts of vegetable matter
for the most part long since dead."
Althea R. Sherman (1932) refers thus to tree nesting in Iowa:
"It is 25 years since Red-winged Blackbirds began nesting in
the tops of our trees, which grow more than half way up the
hillside from a brook frequented by others of their species. Since
1907, when four females built nests at heights of 18 to 22 feet
from the ground in separate plum trees, there has been great
increase in growth of wild currant, wild gooseberry and elderberry
bushes in our house yard of about an acre in extent. In these
bushes more frequently than in the tops of plum trees do the
Red-wings nest."
C. J. Maynard (1883) adds the following: "I have found the
nests on an island in the marshes of Essex River, placed on trees
twenty feet from the ground! In one case, where the nest was
placed on a slender sapling fourteen feet high, that swayed with
the slightest breeze, the nest was constructed after the manner of
our Baltimore Orioles, prettily woven of the bleached sea-weed
called eel-grass. So well constructed was this nest, and so much
at variance with the usual style, that had it not been for the
female sitting on it, I should have taken it for a nest of I.
Baltimore. It was six inches deep."
Dr. George M. Sutton (1942) published a photograph of another
pensile nest, found by Malcom W. Rix in Oneida County, N.Y. It was
suspended "at the end of a grape-covered willow branch, about
three feet above water several feet deep. . . . The inside depth
of the nest was only slightly greater than that of the general
average of the species, and not comparable to that of a Baltimore
Oriole's nest. The color of the nest was distinctly that of a
Red-wing's, although the materials apparently were somewhat finer
than usual."
W. E. Clyde Todd (1940) mentions two Pennsylvania nests that
were more than 30 feet from the ground in willow trees, the
highest I have seen recorded. Brewster (1906) reports a nest in a
vertical fork of a small apple tree in an orchard not far from a
pond. Harold M. Holland (1923) found a redwing's egg and a
cowbird's egg in a Bell's vireo's nest; and later an egg of the
redwing and two cowbird's eggs, in another Bell's vireo's nest,
were so much like the eggs in the other nest that they appeared to
have been laid by the same interlopers.
Allen (1914) describes the progress of the nesting at Ithaca:
The first nests built are located in the dead stubs of the
cattails that have been burned over during the previous fall. At
first they are not sheltered by any vegetation of any kind, for
the new growth is barely above the water. . . . As the season
advances and the vegetation grows, green stalks are included in
the support. At first these are not sufficiently strong to serve
alone as a support, and consequently the nests are always attached
on one side to the dead stub. . . . This is true of most of the
nests constructed in early May, and it generally results in
disaster. So firmly are the nests fastened by the strands of
milkweed fiber, that the side attached to the green blades is
carried upward by their growth, while the other, attached to the
dead stubs, remains fixed. As a result, the one side is lifted at
the rate of almost an inch a day until the nest is inverted. The
birds continue to incubate until the last egg is rolled out. . . .
By the end of the third week in May, most of the vegetation in the
marsh is sufficiently strong to support a nest, and as a result,
nests built at this season are located rather indiscriminately in
cattail, sedge, burreed, water horsetail, dock, and arrow arum. By
the first of June the cattails and sedges are matured, and have
become very dense and harsh. The Redwings now desert them for the
softer vegetation, such as the dock and smartweed, which by this
time fill most of the small ponds.
The time required for building a complete nest is usually 6
days. Of this time, 3 days are spent on the outer basket and
"felting," and 3 days on the lining. Many of the later,
more poorly built nests require much less time for construction,
some of them being completed in as few as 3 days. . . . The
construction of the nest, in all cases observed at Ithaca, has
been entirely by the female. The male has never been seen with
nesting material in his bill. He is very attentive, however,
during the process.
. . .The adult birds commence building again, often before
the first young have left the nest. The second nest is located in
the immediate vicinity of the first, frequently within a distance
of 10 feet. This is true also when the first nest has been robbed
or destroyed. One pair, which was experimented upon, built 4 nests
within a radius of 25 feet between April 25 and May 18.
Nutall (1832) gives us the most complete description of the
nest of the redwing as follows:
Outwardly it is composed of a considerable quantity of the
long dry leaves of Sedge-grass (Carex), or other kinds
collected in wet situations, and occasionally the slender leaves
of the flag (Iris) carried round all the adjoining twigs of
the bush by way of support or suspension, and sometimes blended
with strips of the lint of the swamp Asclepias, or
silk-weed (Asclepias incarnata). The whole of this exterior
structure is also twisted in and out, and carried in loops from
one side of the nest to the other, pretty much in the manner of
the Orioles, but made of less flexible and handsome materials. The
large interstices that remain, as well as the bottom, are then
filled with rotten wood, marsh-grass roots, fibrous peat, or mud,
so as to form, when dry, a stout and substantial, though concealed
shell, the whole very well lined with fine dry stalks of grass or
with slender rushes (Scirpi). When the nest is in a
tussock, it is also tied to the adjoining stalks of herbage; but
when on the ground this precaution of fixity is laid aside.
Harold B. Wood sends me the following note: "A dissected
nest, which had been built around 18 burreed stalks, was composed
of 142 cattail leaves, up to 21 inches in length, and lined with
705 pieces of grasses. It also contained 34 strips of bark of
water willow, up to 34 inches in length, which made 273 laps
around the reeds, with only one making a complete loop around a
stalk. The tensile strength of the matting was tested by placing
in the nest increasing weights until a weight of four pounds was
held before the nest began to slip down the reeds. Eleven of 42
nests were completed and never used; no nest was ever used for a
second brood. Red-wings will not abandon eggs merely because they
are discovered, as will robins."
Eggs.--The eastern redwing lays from
three to five eggs in a set, usually four. Bendire (1895)
describes them as follows:
The eggs of the Red-winged Blackbird are mostly ovate in
shape; the shell is strong, finely granulated, and moderately
glossy. The ground color is usually pale bluish green, and this is
occasionally more or less clouded with a pale smoke-gray
suffusion. They are spotted, blotched, marbled, and streaked,
mostly about the larger end, with different shades of black,
brown, drab, and heliotrope purple, presenting great variation in
the amount, character, and style of markings. Occasionally an
entirely unspotted egg is found.
The average measurement of 380 eggs in the United States
National Museum collection is 24.80 by 17.55 millimeters, or about
0.98 by 0.69 inch. The largest egg in the series measures 27.94 by
19.05 millimeters, or 1.10 by 0.75 inches; the smallest, 20.57 by
15.75 millimeters, or 0.81 by 0.62 inch.
Young.--Allen (1914) has this to say
about the incubation of the eggs:
"During the days when the eggs are being deposited,
frequently both birds continue their excursions to the uplands.
With the laying of the third egg, incubation begins, and
thenceforth both birds remain in the marsh. Incubation, so far as
observed, is performed entirely by the female. In one instance the
first egg hatched in ten days, and frequently one or more of the
eggs requires twelve, but the usual period is eleven days."
Of the development of the young, he writes:
At hatching the young are blind and helpless. The skin is
scarlet, with but a scant covering of buffy or grayish down along
the principal feather tracts. They are at first exceedingly
helpless, scarcely able to raise their heads for food, but they
gain strength rapidly after the first feeding. During the first
day there is considerable increase in size. On the second
day feather sheaths of the primaries and secondaries show
distinctly. By the third day these feather sheaths appear
distinctly along all of the tracts. On the fourth and fifth
days there is a great increase in the size of the body and in the
length of the quills. On the sixth the feather sheaths of
the wing break open. On the seventh the wing feathers have
grown considerably, and those of the other tracts begin to break.
On the eighth all of the sheaths have broken, and the wing
feathers have attained considerable length. On the ninth
the feathers have grown still further, but do not yet cover all of
the bare spaces. The young can fly short distances, however, and
cannot be kept in the nest if once frightened or removed. If the
nest has become polluted, as frequently occurs when it has become
greatly compressed by the growing vegetation, they may leave of
their own accord on this day. On the tenth the stronger of
the young leave and climb to nearby supports. If the nest is
approached, all leave, but otherwise the weaker remain until the eleventh
day, when all scatter to the vegetation in the immediate vicinity.
They all remain in this neighborhood for at least ten days, even
after the parents have ceased caring for them and have started a
second brood.
He quotes from F. H. Herrick as follows: "In the space of
four hours on the first day. . .fifty-four visits were made and
the young were fed forty times. The female brooded her young over
an hour, fed them twenty-nine times, and cleaned the nest thirteen
times. The male made eleven visits, attending to sanitary matters
but twice. . . . On the following day. . .in the course of nearly
three and one-half hours, 55 visits were made, and the young were
fed collectively or singly 43 times. . . . The male bird served
food eleven times and attended to sanitary matters once. In the
course of forty-two minutes the first young bird to leave the nest
was fed eight times, seven times by the mother and once by the
father."
Allen continues: "The principal insects eaten are May
flies, caddis flies, and lepidopterous larvae. Generally three or
four insects are brought each time, and one delivered to each
young. This is not always the case, however, for sometimes the
entire mass is given to one bird. There seems to be no order in
this distribution, the young bird with the longest neck and widest
mouth always getting fed first. The food is delivered well down
into the throat of the young, and if not immediately swallowed is
removed and given to another."
Ira N. Gabrielson (1914) listed the following items given to a
brood of young redwings during 51 feedings: 12 unidentified items,
11 wireworms, 1 cricket, 3 beetles, 2 May flies, 3 other flies, 4
green worms, 20 grasshoppers, 3 moths, 1 spider, 4 tomato worms,
and 1 measuring worm.
Wood says in his notes: "Of the 37 nests which were
followed through the season, 16 had successful broods; 23
contained 73 eggs, of which 53 hatched (72 percent). From these 73
eggs only 35 full-grown young birds left the nests, a productivity
of 48 percent. Two out of 94 eggs were infertile." In his
published paper (1938), he writes: "The ability of a nestling
redwing to take care of himself was tested. A nestling less than
two or three days old would be apt to drown if it should tumble
out of the nest. As they grow older they become more able to save
themselves. Placed in water, the half-grown nestling will float
and can swim, but in a very excited manner. They will swim to the
reeds and hold on, calling for their parents. When well covered
with feathers, but yet a few days before being ready to vacate the
nest, they readily swim, but excitedly, and can climb up the
cattails to the nest. They are not combative and cannot protect
themselves against enemies."
Probably two broods are normally raised in a season, and
perhaps often three.
Plumages.--The early nestling
plumages are described above. Dwight (1900) describes the juvenal
plumage of the young male as follows: "Above, including sides
of head, wings, tail, and lesser coverts (i.e., the so called
'shoulders') dull brownish black (no red at this stage), the
feathers edged with buff, palest and narrowest on primaries,
rectrices, head and rump, and richest on scapulars and secondaries.
Below pinkish buff, ochraceous on the chin, thickly streaked
(except on the chin) with brownish black. Obscure superciliary
line ochraceous-buff."
A complete postjuvenal molt, beginning in August, the time
varying for the earlier and later broods, produces the first
winter plumage of the male, in which the "entire plumage,
including wings and tail," is "greenish black much
veiled with buffy and ferruginous edgings, palest below and faint
or absent on primaries and rectrices. Lesser wing coverts
('shoulders') dull orpiment-orange, each feather with subterminal
bars or spots of black. Median coverts rich ochraceous buff
usually mottled with black subterminal areas chiefly on the inner
webs, the shafts usually black."
The first nuptial plumage is "acquired by wear, which is
considerable, birds becoming a dull brownish black by loss of the
feather edgings and by fading. The mottled 'shoulder patches' are
characteristic of young birds, the amount of orange varying
greatly. The wings and tail show marked wear."
A complete postnuptial molt occurs in August, at which young
and old become practically indistinguishable. Dwight describes
this adult winter plumage of the male as "lustrous greenish
black, feathers of head and back, greater wing coverts and
tertiaries edged more or less (according to the individual) with
buff and ferruginous brown. Below, the edgings are paler or
absent. The bright scarlet-vermilion 'shoulders' are acquired
together with the rich ochraceous buff median coverts."
The full brilliancy of the spring plumage is produced by wear,
the buff and brown edgings disappearing; the wings and tails of
the adults show less wear than in the young birds.
Of the plumages of the female, Dwight (1900) writes: "In
natal down and juvenal plumage females differ little from males,
the juvenal dress averaging browner above with less buff below and
the chin narrowly streaked. The first winter plumage is acquired
by a complete postjuvenal moult as in the male, from which the
female now differs widely, being brown and boldly streaked. The
first winter plumage is hardly distinguishable from the adult
winter and passes into the first nuptial by wear, which produces a
black and white streaked bird, brown above. A pinkish or salmon
tinge is often found in females in any of these plumages,
especially about the chin and head, and an orange or crimson tinge
may show on the 'shoulders' of the older birds."
Food.--Beal (1900) prepared an
extensive report on the food of the redwing, based on an
examination of 1,083 stomachs collected during every month in the
year from most of its range in the United States and Canada. In
spite of the prevailing impression that redwings are very
injurious to the farmer's interests, his diagram shows no very
decided fondness for grain, as most of the birds' food consisted
of weed seeds and insects. Unfortunately, no stomachs were
examined from the rice-growing region during sowing and harvesting
of this crop, where considerable damage is claimed. "The food
of the year was found to consist of 73.4 percent of vegetable
matter and 26.6 percent of animal." His table shows the
following average percentages for the 12 months: animal
food--predaceous beetles 2.5, snout-beetles 4.1, other beetles
3.5, caterpillars 5.9, grasshoppers 4.7, other insects 4.1,
spiders and myriapods 1.3, other animal food 0.5, total 26.6
percent; vegetable food--fruit 0.6, corn 4.6, oats 6.3, wheat 2.2,
other grain 0.8, weed seeds 54.6, other vegetable food 4.3, total
73.4 percent. The consumption of weed seeds amounts to 97 percent
in November.
Another table shows the frequency with which certain vegetable
foods were taken. Among the larger items, oats were found in 190
stomachs and corn in 117. Weed seeds of some kind were apparently
found in all the stomachs, panic grass in 168, bear grass in 271,
ragweed in 189, and smartweed in 200. Small fruits were seldom
eaten, blackberries being found in 7 stomachs, blueberries in 2,
and gooseberries, strawberries and currants were found in only one
stomach each.
Of 84 specimens examined by F. H. King in Wisconsin, 37 had
eaten corn and weed seeds, 31 only seeds, 7 only corn, 3 rye, 2
oats, 8 wheat, and 2 tender herbage; five had eaten 7 beetles,
four 7 grasshoppers, one a moth, and one a caterpillar; eight had
eaten small mollusks. Bendire (1895) includes small mollusks and
newts in the food. Forbush (1907) writes: "They forage about
the fields and meadows when they first come north in the spring.
Later, they follow the plow, picking up grubs, worms, and
caterpillars; and should there be an outbreak of cankerworms in
the orchard, the Blackbirds will fly at least half a mile to get
cankerworms for their young. Wilson estimated that the Red-wings
of the United States would in four months destroy sixteen
thousand, two hundred million larvae."
During the nesting season, much of the redwings' food is
obtained in the marshes, but they resort regularly to the uplands
to glean insects, grain, and seeds in the plowed fields,
cultivated lands, and recently cut hay fields. They even resort to
trees at times. DuBois says in his notes: "From an upstairs
window I watched a female redwing, as she searched the foliage of
the nearby basswood for the small, smooth, green caterpillars
which infest these trees. Her method was similar to that of the
vireos, though she lacked some of their skill and grace. She
hopped from twig to twig, eating the caterpillars from the leaves;
and once she made a little flight to take a caterpillar from the
under side of a leaf while hovering in the air. I had seen a
female redwing at the same business in this tree before."
Francis H. Allen writes to me: "In October the redwings
feed on the seeds of a white ash behind my house. They come there
day after day, sometimes for a week at a time. I notice the manner
of feeding of a small flock composed of both sexes. After reaching
up and picking off a samara, the bird held it against the twig on
which it perched and in this way evidently detached the wing, or
perhaps shelled the seed. They seemed to be unable to cut off the
wing with the bill alone without a solid twig to aid them. My
neighbor, Mr. John S. Codman, has seen redwings eating seeds from
white pine cones in the tops of the trees, perching on the cones
as they picked them out."
Southerners have complained that redwings pull up the long-leaf
pine seedlings and eat the seeds. But they are useful in
destroying the cotton boll weevil in the south and the alfalfa
weevil, two of our most destructive weevils. They also eat the
larvae of the gypsy moth and the tent caterpillar.
Economic Status.--On its northern
breeding grounds the eastern redwing is almost wholly beneficial,
and comparatively few complaints are made of serious damage to
crops. Its food while here consists almost entirely of insects,
very few of which are useful species, and weed seeds, which form
by far the largest proportion of its food. The young are fed
almost exclusively on insects. It does some damage to sprouting
grain in the spring, and to sweet corn in the summer, while the
kernels are soft and milky, by tearing off the husks and ruining
the ears for the market. Other grains are also attacked to a
limited extent, but much of the grain eaten is waste grain picked
up from the ground.
In the Middle West, where the redwings are much more abundant
and where the cereal crops are more extensively cultivated, these
and other blackbirds, in late summer and fall, swoop down in vast
hordes on the grain fields and do an immense amount of damage to
the grain both while it is ripening and while it is being
harvested. Even there, the redwing has some good points in its
favor. Lawrence Bruner (1896) writes from Nebraska: "Even
when it visits our corn fields it more than pays for the corn it
eats by the destruction of worms that lurk under the husks of a
large percent of the ears in every field. Several years ago the
beet fields in the vicinity of Grand Island were threatened great
injury by a certain caterpillar that had nearly defoliated all the
beets growing in many of them. At about this time large flocks of
this bird appeared and after a week's sojourn the caterpillar
plague had vanished, it having been converted into bird
tissue."
In the southern states, it does great damage to the rice crop
by pulling up the seedling rice plants in the spring and by eating
the soft grain as it ripens. In this respect the redwing is almost
as bad as the bobolink. It does some good, however, by destroying
the seeds of the so-called "volunteer" rice, which, if
allowed to grow, would injure the value of the crop.
S. D. Judd (1901) says that on the fall migration, bobolinks
and redwings converge and swarm into the limited area of the rice
districts so as to destroy annually $2 million worth of the crop.
And B. H. Warren (1890) quotes T. S. Wilkinson as saying:
"The rice crop in Louisiana, from the time the rice is in the
milk till harvest time and during harvesting, is much damaged by
birds, principally the Red-shouldered Blackbird. Shooting is the
only remedy thus far resorted to which is at all effective, and it
is only partially so. I have known rice crops to be destroyed to
the extent of over 50 percent, which is a loss of say $13 per
acre. While this is an extreme case, a damage and expense of from
$5 to $10 per acre is very common."
Beal (1900) says in conclusion: "In summing up the
economic status of the redwing the principal point to attract
attention is the small percentage of grain in the year's food,
seemingly so much at variance with the complaints of the bird's
destructive habits. Judged by the contents of the stomach alone,
the redwing is most decidedly a useful bird. The service rendered
by the destruction of noxious insects and weed seeds far outweighs
the damage due to its consumption of grain. The destruction that
it sometimes causes must be attributed entirely to its too great
abundance in some localities."
Behavior.--On the ground the
redwing walks deliberately, or runs, or hops rapidly when trying
to keep up with a feeding flock. In late summer or early fall, one
may occasionally see immense flocks of redwings mixed with
grackles, cowbirds, and starlings feeding in the open fields. Such
flocks sometimes contain hundreds or even thousands of birds. I
have seen flocks that covered as much as an acre or more or a
broad expanse of meadow or pasture land, densely spread over the
ground like a great black mantle. The flock moves along steadily
as it feeds, all moving in the same direction; at intervals those
in the rear rise, fly over the main flock, and settle in front of
the advancing horde, to resume their feeding; this happens again
and again, giving the impression of a vast rolling cloud of black
birds. When the edge of the field is reached the whole mass rises
in a body, to rest in the treetops for a time, or to swoop down
into another field.
In the air the flight of the redwing is characteristic; it
flies with bursts of rapid wing beats, between which are slight
intermittent pauses, producing a somewhat wavy motion. The flocks
are in orderly formation, wheeling and turning in unison, but the
individual birds in the flock are constantly changing their
positions, rising and falling more or less independently. The vast
flocks that travel through the southern states in fall and winter
are most impressive. Pearson (1925) writes: "At this time
they may be seen in flocks numbering tens of thousands, and they
present a marvelous spectacle as they fly with all the precision
of perfectly trained soldiers. I have seen fully thirty thousand
of them while in full flight suddenly turn to the right or the
left or at the same instant swoop downward as if they were all
driven by common impulse. They perform many wonderful feats of
flight when on the wing. Sometimes a long billow of moving birds
will pass across the fields, the ends of the flying regiment
alternately sinking and rising, or even appearing to tumble about
like a sheet of paper in a high wind."
Wilson (1832) says: "Sometimes they appeared driving about
like an enormous black cloud carried before the wind, varying its
shape every moment; sometimes suddenly rising from the fields
around me with a noise like thunder, while the glittering of
innumerable wings of the brightest vermillion amid the black cloud
they formed, produced on these occasions a very striking and
splendid effect."
Redwings are very aggressive in driving away any large bird
that approaches their nesting places; crows, hawks, and even
ospreys are vigorously attacked and pursued sometimes far beyond
the boundaries of the territories; even the bittern is driven to
cover in the marsh. Francis Allen tells me that he once saw a
redwing "riding on a crow's back for an appreciable length of
time."
If a man approaches a nesting colony, even within a hundred
feet, the male redwing rises from his lookout perch and flies out
to meet him with loud cries of alarm or harsh chacks,
hovering over his head and threatening to attack him, but seldom
actually striking him. Alexander F. Skutch says in his notes:
"As I crossed one large meadow where several redwings
apparently had nests, I had an escort of guardian males all the
way; for as soon as I passed beyond the bounds of the domain of
one of them and he dropped behind, another vigilant bird would
take over, hover over me, and shriek down imprecations."
DuBois writes to me of a most pugnacious redwing, saying:
"He would hover directly over my head, where I could not see
him, and from that advantageous position would strike the top of
my head, pecking so hard through a thin summer cap that the blows
were quite stinging. After he had struck repeatedly, I hoisted a
bamboo staff that I was carrying, directly under him, thus forcing
him upward; but he alighted on top of the staff and sat there,
temporarily, looking down at me. Three days later, when I had
stooped over, near his nest, he struck me on the back and on the
arm, and even alighted for an instant on my back. He attacked the
camera, also, when I left it standing on its tripod covered with a
focussing cloth."
The great fall and winter roosts of redwings and other
blackbirds are well know, but few have noted the early summer
roosts of the males alone while the females are busy with their
nesting. Dr. A. K. Fisher (1896) has told us about this as
observed in southern New York in June: "The red-winged
blackbird is another species which appears to leave its mate and
family to spend the night in company with other males. While
watching in this marsh during the early summer evenings the writer
has seen flocks composed wholly of males flying in, from an hour
before sunset until dusk. Some of these bands contained a hundred
or more noisy fellows, while others were made up of only eight or
ten individuals. It is probable that all of the males of a given
inland marsh band together toward sunset and come to the great
rendezvous to spend the night."
Experiments were conducted by Reginald D. Manwell (1941), at
Syracuse, N.Y., in April and May, to determine the strength of the
homing instinct of the redwing. He released 133 males at distances
varying from 2 to 210 miles from the place of capture; of these,
47 birds were recaptured after their return. "The proportion
of birds recaught after any given liberation did not exceed 50
percent and was generally not over 33 percent." Some others
may have returned, but were not captured. Most of them returned
within a week or two, but some did not appear until the following
spring.
Voice.--Aretas A. Saunders
contributes the following full account of song: "The song of
the red-wing, well known to bird lovers as conqueree, is
actually much more variable than this simple rendition. It
generally consists of from 1 to 6 short notes, followed by a
somewhat longer trill. The quality is pleasing, and the presence
of prominent liquid and explosive consonant sounds give it a
gurgling sound.
"The conqueree song, to my ear more like ko-klareeee,
is by far the commonest form, the first note being lowest in
pitch, the second medium, and the trill highest. Of 102 records of
red-wing songs, 46 have 2 notes followed by a trill, and 19 are as
described above. A good many songs of different individuals are
apparently just alike, beginning on A'', the second note on C''',
and the trill on E'''. On one occasion I listened to 8 birds
singing in chorus: 6 of them sang this song, another ended with
the trill on D''', and the other began on C''' and ended on G''',
but all sang the simple 2 notes and a trill.
"Of my records, 10 have only 1 note before the trill, 29
have 3 notes, 9 have 4 notes, 1 has 5, and 1 has 6; 6 other
records do not end in a trill but follow the trill by a
low-pitched terminal note ko klareeee tup. While it is
common for the trill to be the highest pitch of the song, I have
14 records in which the note before the trill is about 1 tone
higher than the trill. A peculiar variation, of which I have 9
records, has the trill made up of notes slow enough to be heard
separately and counted. In such cases the number of notes in the
trill varies from 5 to 7. Such songs usually have but 1 note
before the trill, so that such a song sounds like ka-lililililip.
"Red-wing songs are short, varying from 4/5 to 1 3/5
seconds. The range of pitch, however, is great, from A' to G'''.
Individual songs are very variable in range of pitch, from half a
tone to 8 1/2 tones. The commonest range, and about the average is
3 1/2 tones; 20 of my records have this range; 10 other records
range the 6 tones of a full octave, and 10 more range over an
octave. Songs with the greater ranges have 4 to 6 notes before the
trill.
"When a male red-wing sings, it commonly spreads the tail,
half-spreads the wings, ruffles up the feathers on its back, and
lifts the red feathers on its 'shoulders,' so that they flash
brilliantly with the coming of the conqueree. At times it
sings in flight, and often, when flying from one perch to another,
hovers a foot or so above the contemplated perch and sings just
before alighting. In the spring migration one may find a flock of
male red-wings in the tree tops, nearly every one singing at short
intervals, so that the result is a loud continuous chorus. In May,
in the nesting season, in a cattail marsh well populated with
red-wings, there is a chorus of song just as daylight is
beginning. Each male sings his song two or three times a minute,
and each female continuously emits a high-pitched, sharp call. I
do not remember to have heard this call at any other time.
"The common call of the red-wing, usually written chack,
often sounds to me more like tsack. An alarm note, used
when one nears the nest, is a downward slurred peeah, and
another, less frequently heard, is a mournful sounding downward
slide, like peeiiaoh.
"The season of song begins with the first arrival in
spring, which in Connecticut is March or sometimes late February.
It terminates in late July or early August. The average of 17
years is July 25, the earliest July 16, 1917, in Connecticut, and
the latest August 5, 1940, in Cattaraugus County, New York.
Ordinarily red-wings do not sing at all in the fall, but once,
October 31, 1937, I found a small flock of males, several of them
singing."
DuBois writes to me: "On April 28 and 29, 1930, I heard a
thrush-like song suggestive of the veery coming from somewhere
beyond a house; and on May 2, I definitely saw a female red-wing
singing this song at the edge of the marsh by the road." I
can find no other mention of a female song.
Witmer Stone (1937) gives his impression of the voices of the
pair when their breeding ground is invaded as follows:
As one approaches the nesting site the male launches into
the air and begins to call 'sheep; sheep; sheep; sheep,' each call
separated from the next by an interval. Then as the excitement
increases there is a long drawn 'zeeet' interpolated irregularly
thus: 'sheep; sheep; sheep; sheep; zeeet; sheep; sheep; sheep;
zeeet; sheep; sheep; zeeet,' etc., the bird all the while poised
on rapidly beating wings directly overhead, and now and then
swooping down still closer. The female, arising from her perch on
a cattail, has a similar note but less harsh than the 'sheep' of
the male, and she also utters a much more rapid and differently
pitched series of notes; 'chip-chip-chip-chip;
chip-chip-chip-chip-chip,' etc., then both birds alight on a
bayberry bush and call together, the female seeming to relieve the
male entirely from the first part of his cry and to her repeated
'chip-chip-chip-chip,' etc., he contributes only the long drawn 'zeeet'
at regular intervals so that the combination is almost like his
opening effort.
In recording the vibration frequencies of passerine song,
Albert R. Brand (1938) found that the highest note in the song of
the eastern redwing had a frequency of 4,375 vibrations per
second, the lowest note 1,450, with an approximate mean of 2,925
vibrations per second.
Enemies.--Probably more redwings
have been killed by man than by any other one agency, for when
they swoop down in clouds on the corn fields, grain fields, and
rice plantations they have been slaughtered in multitudes to
protect the crops. Wilson (1932) gives the following graphic
account of how they used to be killed in great numbers, while
roosting at night in the marshes. In some places--
when the reeds become dry, advantage is taken of this
circumstance, to destroy these birds, by a party secretly
approaching the place, under cover of a dark night, setting fire
to the reeds in several places at once, which being soon enveloped
in one general flame, the uproar among the Blackbirds becomes
universal; and, by the light of the conflagration, they are shot
down in vast numbers, while hovering and screaming over the place.
Sometimes straw is used for the same purpose, being previously
strewed near the reeds and alder bushes, where they are known to
roost, which being instantly set on fire, the consternation and
havoc is prodigious; and the party return by day to pick up the
slaughtered game.
Before it was made illegal to sell game in the market, redwings
were killed in large numbers in the fall and sold in markets as
"reed-birds"; when fattened on grain or rice, their
little bodies served as delicious morsels for the gourmand's
table; few could distinguish them from bobolinks.
The high mortality rate in the nestlings has been mentioned
above; probably 50 percent of the eggs laid fail to produce young
large enough to leave the nest. The large nesting colonies are
fruitful hunting grounds for furred and feathered predators. Crows
and grackles eat the eggs, and even the small nestlings, if they
are left unguarded. Dr. Allen (1914) accuses the long-billed marsh
wren as being accountable for the greatest devastation, which is
rather strange since they live so close together in the marshes.
He says:
While I was standing near a nest containing two eggs, I
noticed a peculiarly acting Marsh Wren about 30 feet away. The
vivacious notes so characteristic of the species were not uttered.
It made its way through the vegetation directly toward the nest
until within about 10 feet of me, when it began to circle. After I
had retired to a distance of about 15 feet, the Wren went without
hesitation straight to the nest, hopped upon the rim, and, bending
forward, delivered several sharp blows with its beak upon one of
the eggs. It then began to drink the contents much as a bird
drinks water. After a few sips, it grasped the eggshell in its
beak and flew off into the marsh, where it continued its feast. .
. . That cases are not isolated is shown by the fact that of 51
nests of the Redwing observed in a limited area, the eggs of 14
were destroyed in this or in a similar way, and it is not at all
uncommon to find one or more of the eggs of a nest with neat,
circular holes in one side, such as would be made by the small,
sharp beak of a Wren.
J. A. Weber (1912), of Palisades Park, N.J., tells of seeing a
bronzed grackle causing a great commotion in a colony of redwings.
He shot the grackle and found a young redwing in its bill; the
skull of the young bird, which was large enough to have been out
of the nest for about a week, had been crushed. An investigation
of the nests in the vicinity showed them to contain only one or
two young in each, indicating that the grackles may have robbed
them. Usually the grackles take only the eggs or the very small
nestlings.
The reactions in a redwing colony to the presence of hawks and
other large birds show that they are regarded as potential
enemies; great horned owls could do considerable damage to the
adults and also to the larger young, as could marsh,
sharp-shinned, and Cooper's hawks; even the apparently inoffensive
bittern might not object to eating a tender nestling. Minks,
foxes, and weasels, and in the drier spots squirrels, could easily
climb to the nests and destroy the eggs of young. Wood says in his
notes that "water snakes, Natrix sipedon, seen in the
swamp, gave evidence of having destroyed some nests." The
damage done to nests, eggs, and young by predators is, however,
not always a total loss to the productive capacity of the colony,
for the redwings will continue to build new nests and make
repeated attempts to raise their broods until well into midsummer,
when their reproductive urge wanes.
Friedmann (1929) calls the redwing "a fairly common but
rather local victim" of the cowbird. At Ithaca, Allen (1914)
found hundreds of nests but never any cowbirds' eggs. On the other
hand, Walter A. Goelitz (1916), of Ravina, Ill., writes:
"Until this year I have never found the eggs of this bird in
Red-wing nests, but in a little colony of some twenty-five pairs
of Red-wing Blackbirds, I destroyed eleven Cowbird eggs on June
17th and six on June 27th of the present season."
Robert H. Wolcott (1899) never saw a cowbird's egg in a
redwing's nest during his collecting in Michigan, but found it not
unusual in Nebraska. He says: "The owners of the nest, in
case eggs of their own have already been deposited, apparently
peck holes in all, including that of the intruder, and desert the
nest. But in one instance a nest was found where the single, still
fresh Cowbird's eggs which it contained had been almost entirely
buried beneath a new floor, and above this were four Blackbird's
eggs."
Out of hundreds of nests, found at Buckeye Lake, Ohio, by
Milton B. Trautman (1940), "a Cowbird's egg was found in each
of 4 nests. These nests were isolated. Apparently, it was
sometimes possible for a Cowbird to lay its egg in a solitary nest
without discovery, whereas if it attempted to lay an egg in a nest
in a colony, it was driven away. Once eggs were in the nests the
Cowbird was not tolerated about the nesting colonies."
Redwings are afflicted with a number of external and internal
parasites; Allen (1914) lists four species of Acarina and
three of Mallophaga; and Harold S. Peters (1936) names
three species of lice, one fly, three mites, and two ticks that
infest the eastern redwing.
In spite of their many enemies, some redwings seem to live for
a reasonable number of years. From his study of banding records on
Cape Cod, Mass., Packard (1937) has this to say about longevity:
"Averages compiled from the 266 returns show that 16 percent
of the total number of Red-wings banded survived one year, 7
percent two years, 4 percent three years, 2 percent four years,
and 0.3 percent five years after banding." This takes no
account of any survivors that did not return to the traps; and the
ages of banded birds is not always known. He continues: "The
oldest males in the records are two banded as adults in April
1931, and taken yearly through 1936. As it requires at least two
years to attain to adult plumage, these birds were hatched in
1929, or earlier, thus being at least seven years old. Several
females lived five years after banding." Banding records
published by May Thacher Cooke (1937) show that 6 redwings lived
for 5 years after banding; 2 for 6 years and 1 for 8 years; only 2
of the 5-year-old birds were banded as young birds, so that some
of the others may have been 2 years older than the records
indicate.
Field marks.--The male redwing,
with his gaudy epaulets, is unmistakable; but the female, with her
brown back and streaked breast, is much less conspicuous. At a
distance redwings in any plumage can often be recognized by their
flight and flock formations, as described above. ***
Fall.--After the young of the second
brood are strong on the wing, sometime in July, the females and
young gather in flocks and feed on the uplands during the day,
returning to the marshes to roost at night. The adult males form
separate flocks and follow the same plan. But early in August, all
the redwings seem to disappear, during the molting period, and are
not much in evidence until the middle of September or later, all
in fresh plumage and ready to migrate. Allen (1914) explains this
disappearance as follows:
The adult males, which begin molting about two weeks earlier
than the females or young, are the first to go, and shortly they
are followed by the females and young. To the ordinary observer
they have completely disappeared. No longer are they seen leaving
the marsh in the morning or returning at evening. Along the ponds,
streams, and lake shore there are none to be seen. They are
apparently gone from the neighborhood. If at this time, however,
one penetrates into the heart of the marsh, where the flags wave
four and five feet over his head, he may hear a rush of wings
ahead of him as a flock of birds breaks from cover and drops again
into the flags a short distance beyond. He may hear this again and
again, and yet never see a bird, so impenetrable is the thicket of
flags. A few vigorous "squeaks," however, such as
frequently draw birds from cover, and the secret is disclosed. A
flock of tailless, short-winged birds hover above his head for a
moment, and then is off again into the tangle. If specimens are
collected, the disappearance of the Red-wings is no longer
mysterious. Aside from the loss of the tail, which is obvious, one
finds that the outer primary feathers are but just breaking their
sheaths. With such handicaps, it is no wonder that the long
flights to the uplands are not attempted, and that they seek
protection in the effectual shelter of the marsh.
About the middle of September, the males appear again on the
uplands, 2 weeks ahead of the females and young. Says Allen
(1914):
Well defined migration begins about the middle of October.
At that time all loitering ceases, and the evening and morning
flights in and about the marsh are very regular, scarcely a bird
lingering during the day. Beginning about three-fourths of an hour
before, and continuing about half an hour after the sun has
disappeared behind the hills, they can be seen in flocks of from
ten to a thousand continually dropping into the marsh. . . . The
form of the flock is rather irregular, but always with the long
axis at right angles to the direction of flight, thus differing
from the characteristic form of the flocks of Grackles which
sometimes extend for over a mile in length, although only a few
rods wide. The maximum flight occurs at sundown. The morning
flight is not so regular as that in the evening, and it extends
over a shorter period. Beginning a few minutes before sunrise,
flocks are continually in sight for about thirty minutes. Their
formation is open and they vary in numbers from a few to over ten
thousand birds, the largest flocks extending to the east and to
the west as far as the eye can see, but generally not more than a
hundred birds deep. . . . The method of segregation of these birds
in the morning flight is interesting. A single male or a small
group of males, finding themselves in a flock of females, drop out
of the ranks and await the appearance of a flock of their own sex,
or until their own numbers are sufficiently augmented to form a
flock of some size, when they are again up and away. . . . The
fall migration continues until about the middle of November. The
last birds seen are generally scattered flocks of females."
The southward migration from Cape Cod, and perhaps from other
localities in southern New England, apparently starts much earlier
than from Ithaca, N.Y., as described above, due to different
conditions in the marshes. Fred M. Packard (1936) writes:
"The swamps of Cape Cod differ considerably from those about
Ithaca. Cattails are few at the station, and the marsh plants
rarely grow taller than four feet, affording but little shelter. .
. . While the marsh studied by Dr. Allen is an ideal place for
birds to remain undisturbed during the molting period, the swamps
of Cape Cod seem poorly suited for such a purpose." From
"the almost complete absence of Red-wings in September and
later at the station," and from the dates and localities of
recoveries of birds banded at the station, he concludes that they
"begin the southward migration in July and August before the
summer molt is started, and that they probably complete the molt
in swamps after their migration has begun. Unlike the swamps of
Cape Cod, many of the marshes on the flight route, such as those
found near Newark and Salem, New Jersey, afford suitable
protection for molting, comparable to that provided by the marsh
at Ithaca."
His map, showing fall and winter recoveries of banded birds,
indicates that the flight route from Cape Cod follows along the
north shore of Long Island Sound to northern New Jersey, across
that state to the Delaware River, avoiding the seacoast of New
Jersey, and then along the coastal marshes to South Carolina. All
but 1 of his 18 recoveries came from these marshes.
Milton B. Trautman (1940) has this to say about the migration
of redwings at Buckeye Lake, Ohio: "During fall the species
was more numerous than it was at any other season, and many
thousands were present daily. On September 10, 1927, Edward S.
Thomas took a picture of a small part of a flying flock. There
were more than 400 birds in the picture, and we estimated that
there were at least 10,000 in the flock. Undoubtedly, there were
days during each fall when 20,000 to 50,000 were present."
Winter.--The winter range of the
eastern redwing includes much of its breeding range in the
southeastern and southern states. Most of the birds spend the
winter south of the Ohio and Delaware rivers, and from northern
Florida to northern Louisiana and northeastern Texas. But some few
are to be found occasionally in winter considerably north of these
limits, even as far north and east as southeastern Massachusetts,
locally and chiefly along the coast.
Their winter habits are much like those of the fall months,
when they travel about in large mixed flocks with cowbirds, rusty
blackbirds, grackles, and starlings. Milton P. Skinner (1928) says
that, in North Carolina in winter, they show a tendency to join
with meadowlarks and pipits. He says further: "During the
winter from Christmas until March 1927, there was a flock of 200
Red-winged Blackbirds almost constantly with the Cowbirds about
the Pinehurst stockyards. Although they were usually on the
ground, they often alighted on low oaks, sapling pines and even on
tall gums, clustering close together on the very top in compact
flocks. Occasionally flocks of Red-winged Blackbirds were seen
elsewhere, particularly about old cowpea fields. Early in the
winter, and again after the winter was over, I found these
blackbirds about old cornfields, freshly planted oat fields, and
swampy places, but I did not see them there during the
winter."
Red-winged Blackbird*
Agelaius phoeniceus [Eastern
Redwing]
*Original Source: Bent,
Arthur Cleveland. 1958. Smithsonian Institution United States
National Museum Bulletin 211: 123-150. United States Government
Printing Office
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