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forced to build in the willows bordering the sloughs, after the
manner of the Crackles and Red-wings. It is sometimes stated *
in accounts of the nesting of this bird that it places its nest among
wild rice {Zizania aqudtica), but this is rendered impossible by the
fact that the old rice stalks are weak and fall into the water in the
autumn, leaving only a low broken stubble; while the new growth
is usually only eight or ten inches high when the nesting season of
the Yellow-head is over.* It is true, however, that in rare instances



»J. W. Preston, Oftlogist. Vol. I. July, 1884, p. 36. Bendire. Life Hist. N.
Amer. Birds. 1805, p. 448 (quoting B. T. Gault).

2 Attention was called to this matter and a full explanation given by Ludwig
Kumlien of MUton College. Wis., in * The Osprey.' Vol. I, May, 1897, p. 117.



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374 Roberts, Colony of YeUow-headed Blackbirds, [^^^

stray nests are built among the low rice stubble, this bringing the
bottom of the nest almost to the water-level, a precarious position,
since a very little rise in the water in the slough would submerge
such nests.

The first day that the reed-clump selected was examined only
three nests were found, one about completed and two just begun.
During the next two days — May 14 and 15 — twenty-eight (28)
nests were tagged. Nest-building was then at its height and for
some days thereafter intense activity was dbplayed. New nests
were started almost daily until the end of May and one as late as
June 2. These later nests were probably, as will appear further
on, the work of unskillful birds that had failed in their earlier
attempts. In all, sixty-two (62) nests, counting unfinished attempts
as well as completed nests, were discovered, tagged, and subjected
to daily scrutiny in this one clump of reeds. Leaving the recital
of the detailed notes made during the thirty-two days to form an
addendum to this paper, a general summary of the findings may
here be presented as being of chief interest to the general reader.
For a clear understanding of how some of the observations were
obtained it should be stated that many hours were spent at various
times throughout the month in quietly w^atching, glass in hand, the
workings of the colony from a convenient distance.

It was never possible to tell just how many pairs of Yellow-heads
composed this colony; but probably thirty pairs is not far from the
correct number.

The females did all the work connected with the nest building,
the males taking no part whatever.

The females incubated the eggs without any assistance from the
males, except that occasionally the males brought food to their
sitting mates.

While the nests were being built and the eggs incubated the
males remained about the locality part of the time, perching on the
reed tops and occasionally showing some interest and concern,
especially if a hawk, bittern or other large bird appeared; but they
were more often absent ro^^ng about the neighboring upland in
little parties, foraging for food and amusing themselves. All the
birds, females as well as males, seemed to leave the nesting place to
feed and could be seen departing or returning in little straggling
bands, this being especially noticeable morning and evening.



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^°^9W ^^] Roberts, Colony of Yellow-headed Blackbirde. 375

The males assisted the females to a rather limited extent in
feeding the young. Observations in regard to the young were
unfortunately rather curtailed in this study for reasons that will
appear later. At other times the male bird has occasionally been
seen feeding the young both in the nest and after they had left the
nest and were perched about among the reed tops. 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 diflBculty.
On one occasion a female was seen carrying a large flat object,
squirming and curling about her bill, which was evidently a leech.

The nests were placed from two to three feet above the water.
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 com-
pact, 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 the 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. The details in the construction of the nest and
the considerable variation in the finish and size of different nests
are better shown in the accompanying illustrations than can be
presented by written description.

Of the sixty-two nests, twenty-eight were abandoned before
completion, being deserted in all stages of construction from the
first few strands to almost finished nests. Careful examination



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376 Roberts, Colony of Yellow-headed Blackbirds. [^^^

revealed the fact that in almost all, if not all cases, this was due
to faulty workmanship or poor judgment in selecting a site. Either
the material was not wet enough, making it impossible to handle it
satisfactorily and not affording suflScient shrinkage, or it was not
well placed, or the reeds forming the support were improperiy
situated so that as the nest dried it became distorted and unfit for
use. In one instance, it was positively determined that the same
bird built four imperfect nests before being able to construct one
that was habitable. She was closely watched for hours and as she
had chosen an open place in the edge of the clump it was easy to
observe her movements. After nearly completing one of the
faulty nests, this bird seemed suddenly to become aware that it was
a failure and in the savage manner in which she tore out the inside
and pulled to pieces the rim, displayed a degree of irritability and
temper that would have done justice to the average human artisan
under similar circumstances. To make matters worse, she began
at once the erection of another domicile some fifteen feet away,
using the nearly dry material pulled from the despoiled nest. This,
of course, she found impossible and although she tried later to carry
on the work with wet material this nest, also, was a failure.

A skillful, industrious bird would build one of these large beauti-
fully 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. It never ceased to be a source of
astonishment how these bulky, well made structures could spring
up almost over night when it was considered that a single bird had
not only to collect but skillfully manipulate all this large mass of
material.

Thirty-six of the sixty-two nests begun were completed and
received eggs. In only twenty-six of the thirty-six was the whole
clutch laid. From one to five days was allowed to elapse after the
completion of the nest before egg-laying began. The eggs were
invariably deposited one each day. Of the twenty-six completed
sets, there were two sets of three each, twenty-two sets of four each,
and two sets of five each.* In one instance, a Cowbird's egg was

» The writer in a large experience has never found a set of six eggs, although this
number is sometimes given by authors. No detailed description of the eggs is
given here, as that formed no part of the present study.



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^*^*i9OT ^^] Roberts, Colony of YeUovyheaded Blackbirds, 377

deposited in a nest in which the Yellow-head had three eggs and
the latter laid no more eggs but incubated these four.

All the eggs of a set are colored alike but there is considerable
variation in different sets. Occasionally the appearance in a nest
of an egg differently marked from those already there, suggested
the possibility of a female now and then laying an egg in a neighbor's
nest.

In seventeen nests the period of incubation was completed; the
eggs in nine nests in which the full complement was laid being
destroyed before hatching. In these 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 in-
stance, 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.

In the seventeen nests in which incubation was completed all
the eggs hatched on the same day in only three nests; in three nests
one egg hatched each day; in two nests two eggs hatched the first
day and one egg each day thereafter; in four nests the eggs hatched
irregularly during three days; in two nests the four eggs in each
hatched during two days; in the set of five eggs one egg hatched
each day for three days, the remaining two on the fourth day.
In one instance it was two days after the first egg hatched before
the second hatched, this in a nest containing three eggs, one of
which was infertile. In each of three nests there was one infertile
egg. This irregularity in the time of hatching of the eggs is perhaps
due to individual variation in the time of beginning incubation, or
faithfulness to the duties of incubation on the part of different birds.

A brief rfeum^ of the foregoing exhibits the following facts in
regard to the nidification of the Yellow-headed Blackbird:

The nesting period in southern Minnesota is from the middle of
May to the latter part of June.

The female builds the nest and incubates the eggs without any
assistance from the male.

The male assists in the care of the young, but only to a limited
extent.

The body of the nest is constructed of wet material, the drying
and contracting of which fixes it securely in position.



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378 Roberts, Cdony of Yellow-headed Blackbirds, [^^

Among a number of birds there is a remarkable variation dis-
played in the nest-building ability, some individuals showing such
defective instinct In the selection of nesting sites and such a lack
of skill in workmanship that they are almost unable to construct
serviceable nests.

The usual full complement of eggs is four, sometimes three or five.

The usual period of incubation is ten days.

The eggs of a set rarely all hatch at the same time, usually a
period of two to four days being consumed.

The study of this colony of Yellow-headed Blackbirds met with
early interference and later was prematiu^ly terminated by an
annoying and unexpected series of events, a brief account of which
may be of some interest. Very early in the work it became evident
that eggs were disappearing from the nests and between this time
and the termination of the inspection June 13 every nest in the
colony, except one, was emptied of its contents — eggs and newly
hatched young — by some marauder or marauders, the identity of
which could not be determined. The one unrifled nest contained,
June 13, four nestUngs several days old and one infertile egg.
Assuming that these were also destroyed, which is almost a cer-
'tainty, there was not a single young bird reared by this colony of
Yellow-heads and all the season's effort went for naught. In all,
seventy-seven eggs and fifty-three young birds were taken. Nine-
teen of the thirty-six nests in which eggs were laid were emptied of
their contents before the full quota of eggs had been deposited.
Sometimes the eggs and young disappeared one or two at a time,
more commonly the nest was completely emptied between one visit
and the next. Usually the nests were not soiled or disarranged in
any way. In a few instances there were pieces of egg shells
clinging to the reeds or lying in the water below the nests, and once
or twice blood stains on the inside or rim of the nest. In one nest
there remained two tiny feet and some pieces of flesh, and in
another nest four feet, showing that in these instances at least the
young birds were dismembered and devoured piecemeal. Once
the dead body of a nestling that had fallen from the nest and been
drowned in the water below, disappeared during the same night
that its fellows in the nest above were disposed of.

Watch and examine as closely as we could we were unable to



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Volj^VIj R0BERT8, Colony of YeUorv-headed BlackUrds, 379

determine what animal or animals it was that devoured these eggs
and birds. Presumably some small carnivorous manunal that
mounted the reed stalks from the water below, too nimble footed
and light bodied to leave any traces of its presence beyond the
despoiling of the contents of the nest. A pair of Least Bitterns
established themselves in the midst of the Yellow-head colony,
building their nest and laying their eggs, and from the unceasing
animosity displayed toward them by the Blackbirds, suspicion fell
on these birds. One of them was shot and its stomach examined
but it contained no traces of eggs or young birds. The dismember-
ment of the nestlings would also seem to exonerate the Bitterns for
they would certainly have swallowed them whole. The mystery
remained unsolved and I leave it for the speculation of those who
may be interested. It is but another of those tragedies constantly
occurring which seem to show how natural agencies operate to
destroy in great numbers birds and other animals, the too great
increase of which would seriously disturb the natural balance of
things.

TRANSCRIPT OF NOTES MADE DURING A DETAILED STUDY
OF A BREEDING COLONY OF YELLOW-HEADED BLACK-
BIRDS NEAR MINNEAPOLIS, MINN., IN 1901.

Nb8T I. May 13th. Completed, including lining; entirely dry. 14th.
Empty; pair keep close by. 16th to 17th inclusive. Empty. 18th. One
egg. 19th. Two eggs. 20th. Three eggs. Slst. Four eggs, ffwf to
30th inclusive. Four eggs. Slat. One young bird and three eggs. June
Ist. Two young birds and two eggs. 2d. Three young birds and one
egg. 3d. Four young birds. 4th. Four young birds, pin-feathers
showing plainly on two of them. Sth. Four young birds. 6th. Not
visited, severe wind-storm. 7th. Nest blown loose and fallen partly
over; one young bird dead in water below nest; other three have pin-
feathers one inch long. Sth. Empty; all three young birds gone, and
also the one that was drowned under the nest yesterday.

Nest II. May 13th. Just begun; a few strands; no shape or outline.
14th. Only one or two additional pieces added — these still wet. 15th.
First attempt abandoned and have begun new nest since yesterday eight
inches above beginnings of first one. A loosely constructed affair of finer
and dryer material than usual; about one-half of walls built; a few broad
leaves already in place but nest frail and not at all firmly placed. 16th.
Not visited. 17th. Much larger and firmer; now a bulky nest; upper
two inches and inside just added, very wet; two strips of broad dry lining



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380 Roberts, Colony of YeUow-headed Blackbirds, [q^

in place. 18th. Empty; a little wet material still being added to rim in
places; fine lining being put in. Female makes great ado, much worried
and utters rolling, squeaking and croaking notes. 19ih. Empty. f^)tk.
One egg. 2l8t. Two eggs. 22d. Three eggs. 23d. Four eggs, one much
lighter than others. 24th to June 3d inclusive. Four eggs. June J^.
Three young birds and one egg. 5th. Four young birds. Qth. Not
visited. 7ih and 8th. Four young birds. 9th. Empty; nest pulled
somewhat loose from fastenings.

Nest III. May 13th. Female working on nest. 14th. Walls incom-
plete; nearly dry; shallow and appears abandoned; no fresh material.
16th and 17th. Same condition. 18th. One or two damp strands lying
on nest but no repairs. 19th to 21 st. Abandoned and in ruin.

Nest IV. May 14th. Nearly ready for lining; still building upper part
of walls; upper one-third wet; a few large flat pieces of reed leaves forming
bottom inside as though for foundation of lining. 16th. About same in
morning; at 6 p. m. a few wet strips added to rim on west side, woven
around stems and hanging down into nest almost to bottom. 16th. Not
visited. 17th. Appears deserted. 18th. Abandoned and going to ruin.
2l8t. Same.

Nest V. May 14ih. Ready for lining, a little of which has been placed;
wet nearly throughout, but this nest is among thickly standing reeds so
that it is protected from sun and wind and would not dry as rapidly as
more exposed nests. 16th. Completely lined, fine reed-tops around upper
edge; nest still damp and soggy but lining dry. 16th. Not visited. 17th.
Empty; dry and firm. 18ih. Empty; in good condition; female close
by with bit of reed in bill. 19th. One egg; fine lining at rim has been
added since yesterday. 20th. Two eggs. 21st. Three eggs. 22d.
Four eggs. 23d to 31 st inclusive. Four eggs. June 1st. One young bird,
three eggs. 2d. Three young birds, one egg. 3d. Three young birds,
one egg. 41h. Three young birds, one egg; pin-feathers starting on one
bird. 6th. Three young birds, one egg. 6th. Not visited. 7th. Empty;
no soiling or disarrangement of nest.

Nest VI. May 14th. Still in early stage of construction, little more
than framework; wall open to bottom on two sides, built up about three-
fourths way around. 16th. Wall completed and first coarse bottom-
lining and one or two strands of fine lining placed; female in nest when
approached. 16th. Not visited. 17th. Completed and quite dry
around top; body still damp and soft. A nicely lined nest, the edge thick
and well built of reed-plimies. 18th. One egg. 19th. Two eggs. 20th.
Three eggs. 21 st. Four eggs, female on nest. 22d to 30th inclusive.
Four eggs; female found on nest 27th and 30th. 31st. Two young birds
and two eggs ; female on nest. June 1st. Three young birds and one egg.
2d. Four young birds; female on nest; she made a great hue and cry and
called the neighbors around till the reeds were full of them — mostly
females. 3d. Four young birds. 4ih. Empty; inside of nest spotted
with blood.



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Vol^^VIj Roberts, Colony of YeUovyheaded BlackHrds. 381

Nest VII. May 14th. Nearly ready for lining, a little coarse material
already placed. 15th. Coarse lining all in, no fine top-lining. 16th,
Not visited. 17th. Empty, in good condition. 18th. One egg. 19th.
Two eggs. 20th. Three eggs; coarse lining.much disarranged and partly
covering eggs. £l8t. Four eggs. £M. Four eggs. iS3d. Five eggs.
£4th. Four eggs; nest loosened from its hold on reeds and has slipped
down about two feet, now within one foot of water, which is six inches
deep; scattered strands left hanging all up and down reeds where nest
had slipped. 26th. Four eggs; nest torn and frayed out on one side.
iSOth. Four eggs, warm. B7th to 31 st inclusive. Four eggs. June Ist.
Two young birds, two eggs. Sd. Three young birds, one egg. 3d.
Empty; nest clean.

Nest VIII. May 101. Completed; still wet at top in places, protected
from sun and wind by thick reeds. 15th. Empty. 16th. Not visited.
17th. Empty, bottom lining a little disarranged. 18th. Empty, more
disarranged. 19th to 21 st. Abandoned.

Nest IX. May 14th. Completed and entirely dry, exposed to sun and
air. 15th. Empty; adding fine lining around rim. 16th. Not visited.
17th. Empty. 18th to eist. Abandoned.

Nest X. May 14th. Body finished but still wet nearly throughout
owing to protection from sun and wind ; large pieces of reed leaves forming
bottom of lining already in; first strands of fine lining just placed. 15th.
About complete, still damp and soft. 16th. Not visited. 17th. One
egg; nest dry and firm. 18th. One egg. 19th. Two eggs. 20th
Three eggs. 21 st. Four eggs. 22d. Five eggs. 23d to 30th inclusive.
Five eggs. 31 st. One egg hatched. June let. Two eggs hatched.
2d. Three eggs hatched. 3d. Five eggs hatched. 4th. Empty, except
two feet of young birds and several small pieces of flesh left in nest.

Nest XI. May 14th. Ready for lining; one wide dry leaf in place;
upper part of sides and interior of nest still wet. 15th. Coarse lining
nearly complete, no fine lining; a very large and deep nest. 16th. Not
visited. 17th. Same as on 15th. ; no fine lining. 18th. Empty, no fine
lining at rim. 19th. One egg. 20th. Two eggs. 21 st. Three eggs.
22d. Four eggs. 23d to 3l8t inclusive. Four eggs. June let. One
young bird, three eggs. 2d. Three yoimg birds, one egg. 3d. Four
young birds. 4ih. Four young birds; pin-feathers just starting on two
of them. 5th. Four young birds; pin-feathers on two about one-half
inch long. 6th. Not visited. 7th. Four young birds; pin-feathers one
inch long on three and one-half inch long on the fourth. 8th. Four young
birds; tips of brown feathers beginning to show, giving a general brownish
hue to the nestlings. 9th. Empty; blood on inside of nest.

Nest XII. May 14th. A completed and entirely dry nest; bottom
lining of large pieces of reed-leaves three-fourths inch wide. 15th. Lining
torn out and disarranged; some of the fine reed-tops and broad bottom
lining lying across top of nest. 17th. Badly disarranged and plainly
deserted.



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382 Roberts, Colony of YeUow-headed Blackbirds. [^^*^

Nest XIII. May 14ih, Upper sides being built, nest wet and soggy
throughout; sides incomplete and with holes; a few pieces of wide reed-
leaves (dry) already in bottom. 16th. Coarse lining complete, very
little fine lining; nest at thjs stage not contracted at rim. 16ih. Not
visited. 17th. Empty; in good condition. 18th. Missed. 19th. Two
eggs. 20th. Three eggs. 21 st Four eggs. 22d to SOth inclusive.
Four .eggs. 31 st. One young bird, three eggs. June let. Three young
birds, one egg. 2d. Four young birds. 3d. Foiu- young birds. 4^.
Four young birds ; one downy, one with pin-feathers just starting, one with
pin-feathers about one-fourth inch long and the other with pin-feathers
about one-half inch long. Sth. Four young birds. 6th. Not visited,
severe storm. 7th. Nest evidently blown loose in high wind yesterday;
it slipped down about six inches and turned over so that all foiu- young
birds fell out; they were all in the water under the nest, dead, evidently
drowned; not killed by any animal; later they disappeared.

Nest XIV. May 14th, Framework nearly complete, wet throughout;
no dry leaves inside; upper edge of walls incomplete. 15th. Walls
complete and part of coarse lining placed; two pieces of latter lying across
top of nest ready to be placed in position. 16th. Not visited. 17th.
Complete and dry; a pretty nest. 18th. Same. I9th. One egg. 20th.
Two eggs. 21 8t. Three eggs. 22d. Four eggs. 23d to 31 st inclusive.
Four eggs. June 1st. One young bird, three eggs. 2d. Three young
birds, one egg. 3d, 4th and Sth. Four young birds. 6th. Not visited.
7th. Empty; foiu- feet of young birds left in nest.

Nest XV. May 14th. Ready for lining; black, wet and soggy throu^-
out. ISth. Part of coarse, and few strands of fine, lining placed; drying
out and much lighter colored; this nest was built of very wet and black
material so that it was at first very conspicuous. 16th. Not visited.
17th. Dry and light colored. 18th, Empty; two snails in bottom of
nest. 19th, One egg. 20th. Two eggs. 21st. Three eggs. 22d to
31st inclusive. Three eggs. June Isl. One young bird, two eggs. 2d.
Three young birds. 3d. Three young birds. 4^- Empty; blood spots
on inside of nest.

Nest XVI. May 14th. Finished; well lined; still wet in walls and
bottom and soft on pressure. 15th. Empty; becoming dry; no coarse
broad reed leaves in bottom lining as usual, strips of fine grass instead.
16th. Not visited. 17th. Same as on 15th. 18th. One egg. 19ih.
Two eggs. Several large pieces of reed-tops form a fringe three inches
high on one side of the nest due to their being loosely woven in the rim,



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