A NESTING STUDY OF THE CATBIRD
(DUMETELLA CARQLENENSIS LINNAEUS)

[N SOUTHERN MICHIGAN

 

 

Thesis ‘or the Degree 0‘ M. S.
MECHIGAN STATE UNWERSETY

John L. Zimmerman

1959

 

u II in lung mum LII! Jfll 11an W m II

 

LIB R A R Y
Michigan State
n. L "

 

A TESTING STUDY OF THE
CATBIRD (DULETELLA CAROLIZIENSIS LINLIAEUS)
Ir SCUTZERN MICHIGAN

J 0H1! L. ZIM-IERI-‘LAN

AN ABS TI" AC T

Submitted to the College of Science and Arts
Michigan State University of Agriculture and
Apglied Science in partial fulfillment
of the requirements for the degree of

FRSTER OF SCIENCE

John Lester Zimmerman

During the sprin“ and summer of 1956 the nesting of

the Catbird (Dumetella carolinensis) was studied in Clin-
ton County, Michigan.

Male birds were first observed on May 6, and the fe-
males arrived not more than nine or ten days later.

Three songs of the male were discerned and some of
their uses determined. No females were heard to sing.

Four categories of call notes were variously used by both
sexes during the time of the study. The calls of the young
while in the nest were also recorded. The Wale begins to
sing shortly before sunrise and has been reported to sing
at night. Song cessation occurred during the first week of
August and no second song period was observed.

Territories were immediately proclaimed through sing-
ing by newly arrived males, and chase-singing clashes occur-
red between neighbors along the territory boundaries. The
male of an established territory exhibited both intraspe-
cific and interspecific defense through distinctly separable
behavior, and both sexes attacked non-avian intruders. The
territory was defended until completion of the second nest-
ing. The average size of 15 maximal territories was 3.1704
acres (0.315 pairs per acre). There was evidence of the
existence of a small reserve of unmated males.

The only courtship display observed was the chase be—
tween the male and female.

Both adults carried nest materials durina the early

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days of building, but the female apparently made the site

John Lester Zimmerman

selection and finished the construction. Locations, dimen-
sions, and heights were determined for 24 nests, and their
materials and manner of construction were analysed. Most
nests were in brushy uplands, with woodland edge containing
the next largest number.

The clutch averaged 3.27 eggs. Egg laying began the
day after the nest had been completed, and an egg was laid
each morning until the clutch was completed.

Only the female incubated. Incubation time was 14
days for the first egg and 13 days for all the rest in the
clutch. The incubation period was 13 days. Incubation did
not begin until at least the second egg was laid. Average
attentive and inattentive periods were determined and the
behavior of the adults around the nest was witnessed and
tabulated.

The female apparently contributed to the hatching of
the egg by pecking at the shell. Both adults rid the nest
of the egg shells by carrying them away or eating them.

The adults also ate the smaller bits of shell in the nest
and on the natal down of the nestlings.

On the day of hatching, the young weighed 8.45 per
cent of the adult weight and by fledging weighed 76.76 per
cent. Total length and the lengths of wing and tarsus were
taken daily.

The young spent an average of 10.47 days in the nest.
Brooding was done entirely by the female. She brooded

53.86 per cent of the observation time the first four days,

John Lester Zimmerman

26.80 per cent of the time the next four days, only 3.52
per cent the next two, and not at all on the last two days.
The drOp in brooding was a result of a decrease in the
length of each attentive period and the rate of these peri-
ods. Brooding fell into three periods during the day. The
behavior of the adults was studied closely throughout the
brooding period and tabulated.

Both sexes fed the young, but the female did not feed
more times than the male until the last two days of nest
life. The average interval between feedings was 10.04
minutes. The feeding rate generally increased during the
first eight days and then remained the same for the last
four.

Fecal sacs were either eaten or carried away. Not un-
til the ninth day, however,were the excreta carried away
more often than 1:;10 eaten. If no fecal sac was voided
after feeding, the adult substituted some other behavior
10.71 per cent of all post-feeding periods as compared to
leaving immediately 25.30 per cent of the time after feeding.

Only one brood was observed during normal departure;
all other broods exploded from the nest when disturbed.
Five days after fledging was the latest that the young were
found in the immediate vicinity of the nest.

Second nests followed both successful and unsuccessful
first nestings, but at a different average elapsed time.
There was a change in the size and shape of the terr tory

with the second nest.

John Lester Zimmerman

0f the 23 nests under observation, 60.87 per cent
fledged at least one young. Predation was the major factor
in nest failure. No cases of parasitism by the Cowbird
(Molothrus gtgg) were found.

The dispersal of the young during the days following
fledging was studied. Flocking of the young and adults was
observed on the study area after nesting, but fall departure

from the area was not observed.

A ICESTII‘IG STUDY OF TIE
CATBIRD (DUMETQLLA CAROLINENSIS LIINAEUS
IN SOUTHERK MICHIGAN

J OHN L. ZTI-I-TPJ-Llll

*n to tie College of Science and arts
hicbigai State Uni"e sity of Agriculture and
A;,lied "clones in _crtiel fulfill;ont
of the r~,uire ents for the degree of

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INTRODUCTION

Scepe and Purpose of the Study

This study is a descriptive investigation of the Cat-
bird (Dumetella carglinensis) in southern Michigan from its
arrival in the spring to a period just prior to its depar-
ture in the fall with special emphasis on its behavior dur-
ing the time of nesting.

The Catbird was chosen for study for three reasons:

(1) the writer's existing interest in the species, (2) few
life-history type studies are to be found in the literature
on the Catbird in spite of the fact that it is known to
almost any school child, and (3) because of its wide range
in North America, it was hoped that there would be an Oppor-
tunity to make some field studies on the species during a
tour of active duty with the United States Air Force that
was impending at the time the problem was chosen.

The approach is rather broad, but it is felt that such
an approach provided a variety of experiences which might
prove valuable upon pursuing further investigations in orni-
thology.

The field work upon which this thesis is based was

carried on during 1958 from March until late September.

Methods of Study
From the last week in March until the arrival of the
Catbird in May, reconnaissance trips to select a suitable

study area were made at least once a week to the general

{a}

area in which it was hOped the study could be conducted. A
total of 79 trips was made from May 1 to September 23 to the
study area and involved a total of 346 hours and 51 minutes
in the field. Of this time 127 hours and 21 minutes were
spent in blinds observing the activity around the nests.

Territories, those areas defended by the nesting pair,
were mapped out primarily by plotting the various song
perches of the male and then marking their location on a
map of the area. The presence of non-singing males and fe-
males and the movements of the birds were also indicated on
the map. Each territory was assigned a letter and each nest
was given a number according to the order in which it was
found.

Almost all the recorded activity at the nests was ob-
served from blinds placed close enough to allow observation
without bindeulars.

Since there is no obvious sexual dimorphism in this
Species, the identity of the sexes had to be determined by
behavior. Two assumptions were made to facilitate this
determination: that the male would be the individual sing—
ing the territory song, tkat the female would be the indi—
vidual incubating the eggs. Later in the study, after I

had become more familiar with the activities of the birds

'2

around the nest, the guarding activity of the male and the
use of separate routes to the nest by each of the pair aided
in the determination. After deciding the sex by behavior,

sometimes a particular aspect of the individual‘s plumage,

\J'

such as a missing or short feather or a color peculiarity,
could be used to separate the members of the pair thereafter.

The eggs were marked with dots of red fingernail polish
to indicate the order of laying. Weights of the young were
taken with a spring-operated platform scale that measured
to the nearest gram. ‘Whenever possibde weighing was done
at about the same time each day, usually between daylight
and 0800, and the over-all is.guh and the lengths of wing
and tarsus were taken in centimeters at the same time. The
nestlings were marked with red fingernail polish on their
claws so that individuals could be distinguished in the
nest. It was found to be necessary to repaint the young on
about the seventh day of nest life.

Nestlings were banded with U. S. Fish and Wildlife
Service aluminum bands just prior to-their departure from
the nest. All the members of a brood were painted with a
particular color of butyrate (airplane) depe on the tips of
the primaries to facilitate subsequent field indentifice-
tion. Red, yellow, white, green, and brown were the colors
used. The young were either painted with a single color on
the left or right primaries, or on the primaries of both
wings. The young of one brood were painted with one color
on the left primaries and a different color on the right
primaries. This method of marking the young was quite
satisfactory for identification of fledglings and Juveniles.
No attempt was made to determine whether the painting of the

young affected their survival by making them more apparent

to predators or by impeding their ability to fly.

Some adults were trapped and marked. Dripping water
as bait in a conventional government sparrow trap, the first
method used, was completely unsuccessful. The next method
tried was to place the young within the trap on the day of
their departure from the nest in hopes that the adults would
enter the trap to feed them. This was also unsuccessful,
since the adults were satisfied to try to feed the young
through the wire mesh of the trap. The third and finally
successful method was to place the nestlings at around
eight or nine days of age (before they were too active in
the nest) in an old nest within the sparrow trap. Since
the young did not move to the sides of the trap to be fed,
the adults found it necessary to enter to feed them. Once
trapped, the adults were also banded with government bands
and painted with butyrate dOpe. In the adults, however, the
dope was applied to their tails, either on the tips of the
rectrices or on the base of the tail and upper tail coverts.
Both adults of a particular nest were marked alike and no
distinction between the sexes was made.

Nest height was determined by a plumb line marked-off
in feet and inches and was measured from the rim of the nest
to a point on the ground directly below. Nest dimensions
were taken with a centimeter rule. The means of support
of the nest was determined and sketched, and the surround-
ing vegetation identified and mapped in relation to the nest.

The nest was then collected for a later analysis of con-

kn

struction materials.

Acknowledgments

It is with sincere thanks that I acknowledge all those
whose interest, help, and advice aided me in this investi-
gation. In particular I wish to thank Dr. George J. Wallace
for his willingness to talk over any aspect of this study,
for his advise, and for his constructive criticism during
the preparation of this manuscript. I am also indebted to
the other members of my committee, Dr. Phillip J. Clark and
Dr. Roland L. Fischer, for their advise and help in reading
and criticizing this thesis.

I am grateful to Dr. C. T. Black, Director of the Rose
Lake Wildlife Experiment Station of the Michigan Department
of Conservation, for his permission to conduct the field
work on the station grounds and for the use of an aerial
map of the study area. I likewise express my thanks to
Mr. and Mrs. Eber D. Keeney for permission to observe the
nests that occurred on their property and also for their
interest in this investigation.

I would like to acknowledge the correspondence re-
ceived from Mr. Walter P. Vickell of the Cranbrook Insti-
tute of Science, Bloomfield Hills, Michigan, concerning
the nest building activities of the Catbird.

I thank Mr. Roger M. Knutson of the Department of
Botany and Plant Pathology for his aid in the identifica-
tion of plant material collected on the study area.

I am also indebted to Dr. Robert 0. Ball of the

Department of Fisheries and Wildlife for the loaning of the
planimeter used to measure territory size.

Great credit is due to my wife. Her personnal sacri-
fice, help, and encouragement contributed greatly toward
the completion of this study and the preparation of this

manuscript.

DESCRIPTION or THE STUDY AREA

Location
The study area was centered in the northeast quarter
of section 24, Bath Township, Clinton County, Michigan,
about 12 miles northeast of Lansing on the Rose Lake Wild-
life Experiment Station and the adjacent property of Mr.
Eber D. Keeney. It covers approximately 306.78 acres

(0.479 square miles or 124.15 hectacres).

Vegetation

.
.

Vermilion Creek flows in a northerly direction throu,n

the western half of the study area. The vegetative cover
is approximately 1/4 deciduous woodland, l/h.woodland edge,
1/8 Cornus-Carex lowlands, and 3/8 uplands of fallow pas-
ture, brushy abandoned fields, and several cultivated plots.
There are three small stands of red pine (figggg resinosa)
and white pine (2; strobus) on the area. Figure l illus-
trates the distribution of these habitats.

The deciduous woodland is for the most part concen—
trated in the flood-plain of Vermilion Creek. The najor
co-dominants in the overstory stratum are American elm

(Ulmus americana), redznaple (Acer rubrum), and white ash

(Fraxinus americana). Shaghark hickory (Carya ovata),

 

swamp white oak (guercus bicolor), and basswood (Tilia
americana) also contribute to the overstory. The under-
story includes blue beech (Carpinus caroliniana) and wild

black cherry (Prunus scrotina) in addition to some small

-. ._ _—.- -.

PEACOLK ROAD

 

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MAJOR HABITAT DISTRIBUTiON

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specimens of those mentioned above. The shrub level was not
well develOped, silty dogwood (Cornus amomum) being a major
constituent. The herbaceous level was not particularly
noted except through the discomfort brought on by various
lettles and because of the striking color of the cardinal
flower (Lpbelia cardinalis) in late summer.

Smaller deciduous wooded areas on higher ground con-
tain red oak (Quercus rubra), black oak (Quercus velutina),
trembling aspen(P0pulus tremuloides), and black locust
(Robina pseudo-acacia).

Woodland edge is best develOped along the eastern bor—
der of the woodland along Vermilion Creek in the northfest
quarter of the study area. American elm is extremely abun-
dant with wild black cherry, black locust, box elder (éggg
negundo), pignut hickory (Carya glabra), and cottonwood
(Pogulus deltoides) also occurring. Shrubby growth is pri-
marily silky dngood, but multiflora rose (Eggg multiflora),
prickly ash (Xanthoxylum americanus), raspberries and black-
berry (Rubus Spp.), and shrubby St. John's wort (Hypericum
gpathglatum) also are present. Grape (Vitus sp.) is quite
common, often completely covering many small elms. Poison
ivy (Rhgg radicans) is also present in localized areas.

The herbaceous aspect is mainly of various grasses, vetch
(Vicia sp.), wild bergamot (Monarda fistulosa), white sweet
clover (Melilotus Elba), hawkweed (Hieracium sp.), common
milkweed (Asclgpias syriaca), and soapwort (Saponaria

officinalis).

10

The low area between Peacock Road :nd Ve rlnilion Creek
north of the service road was wet during the early part of
the summer but became drier toward late summer. Sedges
(Ccq rex spp.) are the dominant herbaceous plant, while silky
dogwood is the major woody plant. Willows (Salix spp. ) red-
osier dogwood (Cornus stolonifera), panicled dogwood (Cornus
racemosa), and white elder (Sambucus canadensis) are also .
present.

The low areas in the southern portion of the study area
are primarily stands of sedge with shrubby growths of willow,
panicled dogwood, and hawthorne (Crataegus sp.) along their
borders. These were qui 6 wet in the spring, but by late
summer were very dry except immediately along the channel
of the creek.

Some other scattered low areas also contained button-

oush (Cephalanthus occidentalis) and poison sumlc (Rhus

vernix).
The open fallow pastures are primarily h Hr :.ceous with
arious grasses predominating. Pussy-toes (Antennaria ep.)

 

common milkweed, various asters (gate; spp.), white sweet
clover, wild bergamot, dewberries (3393s sp.), soapwort,
goldenrods (Solidago spp.), common mullein (Verbascum
thapsus), and vetch are also present. The following trees
and shrubs characterize the brushier abandoned fields:
American elm, wild blte ck cherry, sass afras (Sassafras
albidum), wild crab (:yrus ioensis), stag—horned sumac

(Rhus tvnhina), honeysuckle (Lonicera ep.), silky dogwood,

11

and multiflora rose.
The cultivated area just north of the service road was
planted in corn, while the two narrow strips south of the

service road were planted w th an unidentified cereal grain.

Soil and TOpography

The study area is undulating to hilly with the highest
elevation in the fallow pasture just north of the corn field.
The land lepes down from this point in all directions,
drOpjing most rapidly toward the south. There is an abrupt
cliff-like drou down to the floodplain of Vermilion Creek
just within the east boundary of the woodland in the north-
west section. This becomes more gradual to the north and
disappears to the south just before the service road. The
uplands are well-drained Plainfield sand and Oshtemo sandy-
loam. The floodplain soils have a high proportion of muck

along with alluvial soils.

Uses of the Area

The area is used by the state conservation department
for game management studies, particularly as they relate to
farm conditions in southern Michigan. A field archery course
occupies the area along the east edge of the woodland along
Vermilion Creek, both north and south of the service road.
One of the author's blinds was set up a few feet to the
side of one of the archery targets and was used with some
anxiety when it wa‘ known that archers were on the Course.

There are also camping and picnicing facilities in the study

area

which

e re

used

EPOUPS during the as

b

1?

i
u

both Lay and overnight camping

"£11. 8 1” o

ARRIVAL IN THE STUDI AREA

Barrows (1912) states that the Catbird may arrive in
the southern counties of Michigan as early as April 1C, but
more often it is first observed between April 20 and the end
of the month. Wood (1951) gives the period of USL?1 arriva
as the last week or ten da's of April in the lower pennisula.
From the observations of Dr. J. W. Stack and Dr. George J.
Wallace, the Catbird can be expected in the East Lansing
area during the last week of April or the first week in May.

In the Spring of 1956 Catbirds were first observed in
the East Lansing area on the evening of May 1 and in the
Park lake area, agproximately three miles southwest of the
study area, on May 3. There were no Catbirds on the study

area on May 1, but they had arrived by the n xt visit to

the area on May 6. All of hese oirds were singing. ales.

q

Bent (1943) writes that he female arrives a few days a

“a

ter

5

the male, and Charles (1954) states that a geriod of eicht

v

ca ys elapsed from the first arrival until the sgecies be-

came plenti: ul, which could reflect the arrival of females
on her study area. Females were first observed in tie Earn
Lake area on May 13. None were observe: on the stud? are:

on May 3, but were ooserved 01 the next trip on May 15.

The female then does not arrive with the rcle but follows

by not more than nine or ten days.

From banding returns Gill (1934) has shown that the

older birds arrive back on the nestine area first - the

\‘v

'\ 0

older the bird, the sooner it returns in the sprir :.

SONGS ANL CALL NOTES

Songs
The song of the male is described by Saunders (1935)

to consist "of

Q)

great variety of phrases, with short causes
between them. The phrases ordinarily contain from two to
six notes each, but groups of notes within the :hrases are
not repeated." A series of ph ases say be up to ten minutes
in length with pauses of from 1 to 4 seconds every 5 to 30
seconds. The phrases are usually not repeated but occasion-
ally are. On two instances a particular phrase was repeated
numerous times, being very suggestive of the Mockingbird's
(Minus golyglottos) song pattern.

I observed no instances of what I could consider nim-
icry, although some phrases were suggestive of the songs or
call notes of other species. The Catbird has been reported
by several authors to mimic many other species of birds and
also the call of the tree toad (gyla sp.); gigs: Bailey
(1912), Burns (1399), Forbush (1929), Russell (1929),
Saunders (1935), Townsend (1924), and Weydemeyer (1930).
Todd (1940) states that only occasionally will the Catbird
assume the role of mimic, but that it will sing "snatches"
of other songs.

This song described above, refered to in this caper as

‘

"the normal—volumed song" is used in territory proclamation
and defense and perhaps as an outlet for excess energy, as
suggested by Nice (1943) and others. The male continues

to sing this song throughout the nesting period, but it is

5-4
L)‘

used most frequently during territory formation, mating,
nest building, and the early days of incubation in the first
nesting. Apparently unmated males continue to sing this
territory song at a greater frequency throughout the nest-
ing season until general song cessation during the first
week of August. Males on territories that followed the
first nest with a second nesting increased their use of the
full length normal-volumed song soon after the young had
left the first nest and on into the early days of incubation
of the eggs of the second nest. As in the case with their
first nesting, this song was heard throughout the period of
their second nesting, but it was heard less frequently and
was often of shorter duration than the territory song of
spring.

There are two modifications of the normal-volumed song
used by the male. They differ from the territory song in
that they are shorter and of lower volume, but utilize the
same sound and pattern. One I have termed the "quiet-song"
which is sung with the bill barely open. It was first
heard on May 15 when I recorded the following notes regard-
ing it:

"Singing of a soft song by a Catbird one foot above

the ground in the aspens at road fork........began

quiet song again - bill barely Open, gular movement..

.......tail down, back and rump fluffed, tail flipping

slightly - really sort of a consistently vibrating

tail."
This song was used by the male as a signal song later in

the season as he approached the nest, although a short nor-

mal—volumed song was also used in this situation. The

quiet-song is also used in connection with territory def ns
when the male was in close proximity to the intruder.

The other subdued variation of the normal-volumed song
is the "whisper song", which is sung with the bill complete-
ly closed and is lower in volume than the quiet—song.
Saunders (1935) states that the whisper song is used after
the main season is over and is audible for only a few feet.
Bent (1948) reports that the whisper song is most often
heard in autumn but has been recorded throughout the year.
In this study it was most often heard being used by the

ale at his guard perch as the female approached the nest.
Some males, particularly the male of Territory J, also sang
a whiSper song immediately after feeding the young, right

after assuming the guard perch.

Call Notes
There are four catagories of call notes: the "mew",
the ”quirt", the "quitt", and the "ratchet-call".
The mew note shows the most variety in volume, tone,
and quality. This is the note from which the bird gets its
common name. The Chippewa Indians called the Catbird "Ma-
ma-dive-bi-ne-shi", meaning "the bird that cries with grief",

again referring to this particular call note. Herrick (1901)

described it as a "tshay", given as the observer set up his
blind. Herrick also heard this call note given during "cau-
tious explorations in the vicinity" by the bird. The mew

is included as a part of the territory son; of the male.

The male also gives a thin-sounding, wheezy variation prior

17

to the chase in intraspecific defense; perhaps this partic-
ular use is as a threat-call. The female often approaches
the nest giving soft or soft, wheezy mews; both male and
female also give the mew at normal volume and quality in
the vicinity of the nest. The mew is used almost to the
exclusion of any other songs or call notes around the nest
during the last two days before the young are fledged. Loud,
emphatic mews are used by both sexes in defense of the nest
from intruders. There are many other occasions when the
mew is used, to which I cannot attach any particular behavior.
The mew is the most used vocalization after song cessation
in the early fall.

The quirt is given by both sexes and is perhaps a
threat note. Bent (1948) describes it as "a low mellow
cluck, like the soft quack of a duck........giving the im-
pression of being uttered way back in the throat". He states
that it is a note of minor alarm. It was used whenever I
was in the vicinity of the nest or fledged young, and loud
:uirts were given when I was at the nest itself. Quirts
were also heard in the episode referred to later at nest
No. 15 while the adults were attacking a blue racer (Coluber
constrictor). Like the mew, however, it was often also
heard in situations for which I could not determine from
my observations the specific behavior correlated with it.

The quitt also is used by both sexes and was heard only
around the nest. It apparently is a communicat on call be-

tween the sexes, used ty both of them as one of the pair

'4

approaches the nest while the other is there. The male uses
it as a signal song, along with the quiet-song, as he ap-
proaches the nest, but there is considerable variation in
this usage. The male of nest No. 12 seldom used the quitt
call, but usually sang the quiet-song; wherea the axle o:

nest No. 19 seldom used the quiet-song but usually did use

the quitt call. As the male approached, the iemile usually

U

- - - or. '—. wv,— -.«'-E -, ——.- -'—,~ .' an.)-
to cuitt while SAG "as still a“ -ae “use.

be {318.11

Bicknell (1884) described what I call the ratchet-call
as "a short, crackling sound, like the snapping of small
faggots", and Bent (194C) mentions it as a ”harsh, sharply
enunciated chatter, rather wren-like". To me, however, it
sounded more like the sound made by a ratchet noise-maker
twirled in the hand by children at parties and adults on
New Year's Eve. This certainly is an alarm note. It is
given by the Catbird as it flies to cover, and was giaen
by several birds as I held them in my hand while banding
them. I also once recorded an adult to give this call when
the young gave an alarm note while being banded.

The only notes I heard given by the young while in the
nest were the food-begging calls. They are best described

as a series of "seep-seep”s or pssp"s. They are either

given in a series or singularly, end increase in volume with

the are of the nestlings. The young of nest No. 3, 12 days

8

(

since fledging, still gave this food-begging call, perhaps
now also serving as a location call note. Young at least

a week to a week and a half out of the nest were also hear

19

to give a loud metallic "tsip" note suggestive of the gall
note of the Indigo Bunting (Passerina cyanea); they also

could give a wheezy-sounding mew.

First Morning Song and Nié t Singing

The male Catbird begins to sing shortly before sunrise.
Allard (1930) found that the first morning song follows the
time of civil twilight quite closely, occurring both before
an“ after this time in May and early June and then usually
only after civil twilight in late June, July, and August.
There have been reports of the Catbird singing at night.
Bent (1948) records the observation of Francis H. Allen
that the song phrases are farther apart at night. Vaurie
(l94b) mentions a Catbird singing for over an hour in com-
plete darkness at 2100, and Pierce (1922) observed a bird
singing in the moonlight at midnight. The habit of night

singing is well known in the Mockingbird.

Singing by Female
At no time did I hear the female sing any song similar
to the normal-volumed, quiet-song, or whisper song. Whittle
(1923), however, reports a female singing the whisper song

while on the nest.

Song Cessation
The males arrive during late April or May in song and
continue to sing until the first week in August. Dates in
the literature for song cessation are July (Todd,1940),

laid-July (Trautman,1940), July 26 (Mehner,l952). August 3

(U

’

(Vaurie,194b), August 7 (Fry,l916), mid-August (Bicknell,
1:34), and also mid-August (Charles,l954). Both Vaurie and
Todd correlate this cessation of song with the onset of the
postnuptial molt. Eaton (1914) in New Ybrk and Charles
(1954) in South Carolina record a second song period occur-

ring in the fall. No second song period was observed in

this present study.

TERRITORY

Establishment

The territory provides the necessary cover for the nest
site and a certain amount of Space for the unhindered com-
pletion of nest-related activit ies. It also provides song
perches for the proclamation of the territory by the male.
Most of the food of the adults and the young is also gath-
ered within th teri itory , although on a few occasions dur-
ing the nestling stage adults were seen to collect food
outside of the territory. Most territories had no water
supply, so it is assumed that most adults must leave th
territory to drink and bathe. Figure 2 illustrates the
territories maintained on the study area during 1958.

Arriving in full song, the male itimediate ly proclaims
an area as his territory. Singing of the normal-volumed
song is the primary means of territory announcement. Males
sing from ex Y.DOSGd perches near the tops of the vegetation
or near the tips of branches. The heights of the song
perches range from one foot to 40 feet high; the median
height range is 15 to 20 feet above the ground. The males
were sometimes also observed to sing in flight while going
from one song perch to another, or to sing while moving
from branch to branch around a song perch. The territory

song continues from the time of arrival throng shout the

nesting cycle, but decreases in fre:uency during early in-

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LOCATION OF CATBIRD TERMTORlES

(a)

during early incubation of the second nest, and ceases con-

‘

pletely after the second brood is fledged.
Several workers have shown from banding studies that
some males are constant to approximately the same territory

from year to year and also that young f the grevious year

do return to the area of hatching. Gill (1940) records a

’5
to

Cateird bended as a fledgli one year returning to estab-

D

liSu a territory a Ten hundred set from ts place of
hatching and then returning to the same territory the next
year. Batezel (1959) also writes of an immature bird cand—
ed one year returning to the area of hatching the next year,

while the adults likewise returned to the same :rea. Gill

(1935) records an immature male banded during one seaeol

'_)

"O

returning to the vicinity o: the nest where it was hatched
for the next two breeding seasons. He also reports of an-
other male (Gill,l936b) that was constant to the same terri-
tory for six nestings over a period of four years. The
same male and female were trapped by Perkins (1929) on the
same territory for two years, the nest of one year being
within five feet of the two nests of the previous year.
Groskin (1945) recaptured a female for five consecutive
years in the same nesting area, and Wharton (1945) reports
of a female retaken in the same area three times over a
period soanning seven years.

Boundaries of the territories are rather indefinite

excep where territories are immediately adjacent to each

other. In these areas of contigency, neighboring males

did become involved in chases with one ano+her in uddition
to proclaiming territory by song. On May 15 in th area
Where territories N, M, and L come together, the followinc
excerpts are taken from my notes covering a period from
0850 to about 0915:

"Two birds now in a circular chase - sometimes sing-
ing short song enroute by at least one bird - very
seldom came into actual contact (just two or three
times during time of observation). Occasionally step
at a distance of 10 to 30 feet atart and sing. The
one bird chases the other, often to be chased in turn
by the other..............many soft quirt calls and
quiet singing......... The singing bird is flown at
by the other in most observed cases - the singing
bird leaves its perch and the other bird arrives in
chase after it from its perch almost immediately....
....... Area of chase seems to be out in about half
new.... Now they are both singing on Opposite sides
of the clearing......... After a step in the chase,
the birds have been observed to wipe their bill (a
few times), preen (once), or sing (most often)..."

A third Catbird became momentarily involved in the chase
described above, but then moved off to the west and sang.
A fourth male also came on the scene near the end of the
observation period and sang just to the south of the chase
area. In the Song Srarrow (Melospisa melodia) Nice (1937)
states that a series of chases ends in a fight on the
ground. Although occasionally the Catbirds described above
did come into contact while in the chase, no fighting was
observed either in this case or on any other simi ar
occasion during the study. The participants in a fight of
Soné ”narrow retire to "sing loud and long, answering each
other". In the greviously described territory encounter
the Catbirds, vhile not fiyhting, did stop their chasing

from time to time to sing from 10 to 30 feet apart before

renewing the chase.

On May 28, while nest No. 4 was being built, the mile

q

and female of Territory J were observed on their territory
with nest material in their bills when a thi‘d Catbird
cppeared nearby. The following was then observed:

"The male flew to the third bird in the multiflora
rose thicket, then one circular chase in the thicket
(chase with a radius of about five feet), then one on
the ground singing quietly w th body feathers fluffed,
wings drooped, and tail dragging at its tip; - moved
deliberately back and forth in front of the other bird
other bird did not sing, but moved slowly on ground or
in low branches. The female remained about ten feet
away in a low position in another shrub. Then the

two birds in a short flight up. Then all three were
lost from View."

Apparently this is an example of a threat or challenge dis-
play on the part of the defending male whose territory was
being trespassed.. Nice (1945) describes an erected-feather
threat posture given by the owner (or owner to be) of a

territory as a challenge nreceedin-

‘ k...

1‘- : fl 4.0 n
the 0119.38 (.OPVILOI’I OJ. Cl.

territory establishment encounter.

Defense

The male of an established territory continued to be
quite active in both intrasgecific and interspecifio defense
at least in the vicinity of the nest for I observed no
instances of territory defense at the periphery of the
territory after establishment.

In reaction to another Catbird, the male of the terri-
tory upon noticing the intruder moves toward the intruder

and usually gives a series of thin wheezy variations of the

V?

mew note. e then chases the intruder. The defending male

I“)
LI \

,.)

will continue to fly at and clase the intruding Catbird un-

til the intruder leaves the defender's territory. I never
observed an instance of this defense behavior where I knew
the intruder to be a female, but in many instances the sex
of the intruder was unknown. The female of the territory
was never observed to fly at or chase another intrudixg
Catbird.

Interspecific defense was also only observed in the

male. Nineteen instances were recorded involving eight

species. These were as follows: House Wren (Troglodytes

 

aedon),1; Cedar Wanting (Eombycilla cedrorum),4; Golden-

winged Warbler (Vermivora chrysoptera),2; Cowbird (Molothrus

 

333;),1; Rufous-sided Towhee (Pipilo erythrophthalmus),3;
Indigo Buntin5,2; Field Sparrow (Spizella pusilla),l; Song
Sparrow,2; and unidentified species, 3. Nice (1943) re-
cords no encounters between Song Sparrows and Catbirds that
were nesting commonly on Intercont. All these cases of
interspecific defense occurred in the inn diate vicinity

of the nest. It differed from intrascecific defense in that
no prior calls were given’by the defendin
bird flown at was never pursued, althcu h he niwht have
been flown at repeatedly. Not all non-Catbird intruders
were always attached. The male 3; Territory N was never
observed to chase other species, although several Oppor-
tunities for such behavior were available. Likewise the

male of Territory R, while chasing some intruders even as

c}-

‘ I . IQ.- .. 4-. . I. {a r- '1': u _ -' . 9‘ s x: ‘A
a Towhee, tolera (3' one 9130302108 .. CLv canals (aimlwiadeii‘.

 

ardinalis) which had nested within 13 feet of nest No. 12.
Orford (1929) reports a case of unsuccessful defense by a
pair of Catbirds against Cardinals. The Cardinals drove

the Catbirds awa from an almost completed nest and be an

‘<:

to build onto it. It was not known, however, if the Cardi-

nals actually took the nest over completely, since it was

4‘ "

ubsequentl: iound deserted and containing one Cowbi d e53.

Non—a vian in 1ude 3, if attacked, were attacaed by

I.

both se: (GS, although the male plaved a more vigorous part.

It

On the day the third egg was laid in nest No. 15, an inci-

H.)

dent involving a two and one half 'oot blue racer and the

adults of this nest was observed.

"The pair of birds behind the blind now, quirting.
Male sinaing short cuiet ;ohrases. Male still singing,
female in nest bush low down — 1054. Male jumped at
blue racer with wings upraised e.bove the shoulders -
fluttering - quirted and mewed. Didn't see it geek at
snake, I believe it umped at it with its feet — sing-
ing quietly. Snake was headed into the blind out I
moved a little, it paused, head and forepart of the
body off the ground, then moved to the west side of
the nest bush and coiled. Both birds there - quirting.
Male also singing quietly with wings occasionally
raised and tail spread...... Male now flew off, fe-
male still in branches above the snake. Fendle has
been quirting all this time, but did not behave as the
male did with wings and tail spread. Male now singing
quietly behind blind — 1106. Male now singing normal
volumed song from prickly ash thicket to ea st. “enale
still in nest bush ne r snake. Snak oegen nevi:

away at 1110 - female followed in branches of trees
and bushes about one to two feet aoove the 3r rund -
quirting..."

After the snake had moved 10 to 15 feet away fr m the nest
and apparently continuing on its way, the fa ale returned

to pez‘cn in the nest bush.

A similar disalay was observed in the vale of nest

i J

( )

No. 3, but the snake involve if there was a snake, was
not seen. In this particular instance the female did not
take part. he sale was on the ground, his fea hers erect-
ed, wings held up over his back, and his tail feathers
spread. He continued to cross back and forth over the same
spot, singine quietly most of the time. Then after ten

0

minutes the male flew away in a series of pouncin; flights,
perching on the taller weed stems. When about 29 feet asey
he returned to a tree just east of the nest bush.

Preston (1949) PGgOPtS an incident of a Catbird at-
taching a snake identified as either an immature black racer
(Coluber constrictor) or an imme ture pilot black n:he
(Ela he oosoleta ). The Catbird pulled the snake out of a
tree by its tail. Taube (1939) states that a Catbird peck-

. Q

ed a three foot water snake near its tail and that the bird
exhi sited "wings partly outspread and drooping to the ground”
when the snake stepped crawling. A black snake at a Catbird's
nest was driven away by four Catbirds, t IO Eastern Kin7birds
(Evrannus tyrannush a male oriole, and a wren as oesorib d

by Morris (1925).

Eastern chipmunk (Tamias striatus), thirteen-lined

groundsquirrel (Citellus tridecemlineatus), re; squ rrel

('3

T: min sciurus hudsonicus), and long-ta iled 1-:e::el (Hustalia

 

4" .,. 1- ,1 !.. 4.1 z a-.. “.4 :- --: 4., 34. J.-..—
irenzta) were obsezw-e .ul the laneelous vicinity 01 the
m

“4‘." £- '- - .«L‘ - ‘-~' : .. ‘ l ' , .— V. .L‘ ,1
W ’J( ,. . ’3 , ‘2 .. ’ « ~w‘.“ ‘ ~ x ~1 WV) _~ .f'] .5 ’ a
.11.! Us 0 wk. ' .-.Jue ’ U£-|J C ‘4. 13‘ LLA111: u-l‘ln; ) F (sli‘tLEJ’x‘LA L... L ‘vl h VJ. ‘1 v-17
1- 5L - W .1. ‘. . . ‘_ J. ‘ “ ' q .. cl‘a. - ‘ . -. .
‘rf‘ “ ' ' My ' w .,~~ '. » 37" ran» ‘1”: l *f- r} \ no ' '\
.- -.'i. u L l U01.) 930-».3’ --..LU..(:"-L:;;... U...e 1 us QuieuLiiO “No.4 .JL J¢-. .31). -...L«’
.' - ‘ l J. ‘ 1 .. 1.
z.) a 1 n, - .,.
it: It; s-.L‘J.a‘-L *Ll q'.e H‘ KD(;J 0 “VJ Cjnb L‘M‘mdo 41.4.. .' \
v

instances of defense against mamnals were observed, and in
both cases defense was by the 1em 1e Catbirv from on tie
nest. The female on nest No. 15 left and flew at a chip-
munk ten feet away. he other occasion involved a red

squirrel at nest No. 17. The squirrel was observed movin-~

through the trees northeast and uyhill from the nest. It
then came to the rim, flushing off the brooding female.

The felale immediately flew at the squirrel, mewin“

L;

loudly

and with much wine ”

C.‘ "

luttering. The squirrel left without

.
I

taking the single youn: in the nest and moved a i to the

L—
south. The female continued to fly at it with wins flut-
terings and loud mews, but she did not continue the Chase

after the squirrel was from 10 to 15 feet away from the

nest. On two occasions dOgs passed directly under females
on the nest, but the females gave no reaction to their

wresence that I could observe. Gabrielson (1913) mentions

n

that his Catbirds chased a chipmunk away and that the female
‘became uneasy in the nest at the approach of a cat or dog.
My presence at the nest, eitLer to check the eggs or

Ifeigh.the yetng, elicited a rGSponse by the adult similar
‘t<> that for other non-avian intruders. If both nenbers of
the gair were there, the mole was the more ar'rrressive.
E3crth birds would mew loudly and eu'rt and would go into
13319 alsfid.wing, tail Spread, erected feether attitude;

£3111; the male did this for ntre than the female. U2131ly

. 'Q- - ‘1 1- .W ‘ ".v" r 3 ~ '~' -L' 1]. ' ,~ . -'» . 7-: :7 a -..‘-
DL‘EB male would anyOmCJ anfl his t-il soresd ens nib we”?

3.
r)
(:3
r.
(J
(4

.+.. . - 4.1.: '. J- -- . a. a . -..-.« -- .‘*-. .
there erected, out J13 winks held leuubl a 7~

\ . ,
v n x
U ‘

L ‘

his sides; then upon getting :ithin two or three feet, he
would go into the raised win; attitude. The male w uld also
occasionally sing quietly while in this dngluy. Berger
(1954) describes a similar intimidation display after the
incubating Cot bird was flu shed from the nest. The bird
moves off "a short sistgnce gray from tie nest before ad-
vancing with outstretche; wings towers the observer :Wivin
the typical loud alarm note repeatedly” and ' ould apjroech
to within two or three feet. The males of some nests were
more aggressive than others; sone birds would regularly
fly at and strike my h9nd in the nest. Once the male of
nest No. 7 flow at me from behind, strikint me on the
sho.lder, similar to eXQeriences I have had w: n nestin:
Mockingbirds. On seversl occasions adults remained sway

q

from the nest while I was there, but could be he re nearby

quirting
This raised-wing attitude in defense an: inst n‘:n—evisn

9%

intruders is the only observed occurrence durinc the entire

(0
(1.
m
m
o
*5
'. J.
G’
a)
r.

.study that might be considered wing-flashing :
Sutton (1946) for the Mockingbird. He describes ring-

fTLeshing as the reniges beind spread und lift ed arch-an tel

S—

"en instinctive

Ikishion" over the body. He feels this is
~:Kasture indicatind udriness, susgicion, distrust" and con-
tLieiues that it is "occasionally, but more or less accident-
Cildly, associated with the capture of food", an idea that

115155 been sometimes gresezted. chrie (1997 ) in his dis-

‘3lléssion of the Western Red-legged Tin ush (Lirzociehl

g3

plumbea) mentions that it wing flashes like the Moxinétird
and states that he has also observed this behav;or in the
Catbird. He writes that as with this thrush, the wing
flashing in the Catbird takes place only during the court-

Ship performance.

Injury-feigning

No examples of injury—feigning by Catbirds were ob-
served during the study. Berger (1954) states that F. V.
Hebard mentioned such an incident to him occurring on Fay
50, 1949. A bird was flushed from a nest and flew to a
gravel road a few feet away and gave a modified broken
wing display, fluttering its wings moderately fast as it
moved slowly along the ground away from the nest.

Upon being attacked by a Blue Jay (gianocitta cgistata),

1

air

an

Freeman (1949) describes a Catbird imitating a young
as a defense behaviorism for escape. He states that the
'bird equalled and flew from the tree with half Opened,
:feebly fluttering wings, sinking ragidly and almost touch-

‘

iaag the ground, then rising up to another tree. The oird

tdaen shook itself, looked around, and flew off normally"

txoward its nest.

Mobbing
No cases of mobbing by the Catbird were observed by
naea, bmt Friedmann (1929) states that two Catbirds joined a
EiCDloin (gurdus migratorius), three Yellow Warblers (Dendroica

liSLIflacnia),and one Blackpoll Warbler (Dendroica striata) in

it)

chasing a fe ale Cowbird from a Robin's nest. Hamerstrom
(1957) observed Catbirds to initiate mobbing of a Red-tailed
Hawk (Buteo jamaicensis), and Belles (1890) found Catbirds

and threshers to be "coarsely abusive" to a pet Barred Owl

(Strix varia).

Length of Maintenance of the Territory

The male at least was observed to continue the defense

\ O

of the territory a ter the young had left the first nest

.LJ.
and were being fed by the adults. Charles (1954) states
that the Catbird holds its territory throughout the lest-

inn season regardless of how many nests are built. n ter

.n‘.-”

the completion of the second nesting, however, there is no

more territory defense, Clthough the adults will continue

*” give duirts and loud mews at my presence while the newly

\J 'v'

.‘r
1'.

LI)

- M ,3 - a" C. \ 1 h . ‘ J- ‘v'. ' fly
so yo*nu are nearby. In 38 instances Inere there a

.9 ,‘
A. 10 “LL

no second nesting after the com;letion of the first, the

(F

territory was discontinued soon after he first brood had
left the nest. Singing of any type ends during the first
tieek of August, which corresgonds with the general com-
;;letion of the second nesting period. Nest No. 23 was just

1J3 the incubation period then, but the male was never heard

uC> sing after this time.

Size of Territory
Odum and Kuenzler (1955) define two types of territo-
r‘iAas, the maximal and the utilized territory. The former

j-E5 “toot area that is contained within the outermost points

. ‘su- §

of observed territory activity, while the latter refers to
that area within the maximal territory that is most used -
ncluding the nest location, most frequently utilized song
perches, and regular feeding areas. Only the maximal ter-
ritory was determined in this study, although it was appar—
ent that a somewhat smaller utilized territory did exist.
On territories where a second nesting took place, the
utilized portion did shift its location within the maximal
territory in relation to the new nest site. The plotting

of ma imal area was made during the period of territory

N

formation and through the incubation period of the first
nest. During the nestling stage, the maximal territory

was not as easily discernible and with the beginning of the
second nest was not as vigorously maintained as during the
early days of the first nesting. The areas of these maximal
territories were measured with a planimeter ind are listed
in Table 1. They ranged from 1.47 acres to 5.169 acres
'with an average of 3.1704 (standard deviation - 0.9023
ilcres). This meal gives 0.515 pairs per acre. In southern

Illinois, Brewer (1955) had two pairs of Catoirds with home

Iaanges equalling 0.15 and 0.56 acres which are decidedly

‘

CLifferent from those determined in the oresent study an‘
w"ere areas that were not necessarily congletely defen=ed.

bfcning (1949) found a gair density of 2.2 per acre in

1"- ‘ 1 0 fi "'
"3.sennsin wnion gives an average territory size 01 0.455
av<‘-=1.'*es. Young's study likewise reflects a much higher

<30noentratien of birds than my Rose Lake population.

TABLE 1
SIZE OF TqfifilTORIES ON THE STUDY AREA

Territory Area
A not determined
3 2.5845 acres

C 2.2/26
D 5.5479
E 4.2611
F 3.0241
G 3.3c92
H 3.2186
I 3.5789
J 2.7859
K 2.7550
L 1.4700
M 5.1690
N 2.2122
0 not determined
P not determined
Q not determined
.. 5.4156
3 3.5337
T not determined
U not determined
V not determined
mean 3.1704 acres

0

stand. dev. .902? acres

number ‘ 15

Unmated Males
There were four males that maintained song perches or
the study area for various lengths of time but never at-
tracted mates. The location of their singing areas is

indicated in Figure 2. Rice (1937) also mentions a small

reserve of unmatcd birds in her Song Sparrow pepulation.

COURTSHIP AND MATING

No obs rvation of courtship and mating was recognized

L

as such prior to the :irst nesting. Apparently mated yai

C‘
-.)

flfi mm

5-4)

would move about the territory together while
never ge‘ting far apart. In fact, since this type of pair-
ed behavior was observed on May 15, the first day females
were noted in the study area, selection of mates Lust take
place Quite soon after the arrival of the females.

The only observation of this tyge or behavior durin;
the entire study €38 with the pair of territory m two days
after the first brood had left nest No. 3 and were still
in the immediate vicinity being fed by the adults. This

“' vrd female were seen in a hort chase from branch to

I

‘ J.

branch Within the DQSU thicket, both mewing.
Bent (1948) describes the courtship as a chase in and
out of the underbrush, the male often stopping to sing with

7

the disglay as one of strutting with the sings lowered in;

J

'the tail high and erect, displaying the chestnut under-

a

'tail eoverts. Charles (1954) describes another display.

'“kw states that in the courtship cistlay the male puffs

L1) to twice its normal size with the neck and tail stretch-
Ci in line with the body and clambers around the female

ea
3111 this posture. If the female flies away from the male's

<1fi.sglay, he either flies after her or sits and gives the

IZZB'TS AID BEST BUILDING

Nest Building

L3

Both adults were seen carryinr nesting :cteria l-os

arly as 10 days prior to the day when the first ego c; the
first nesting was laid. Latham (193t) records the build-

ing of dummy or trio 1 nests before the final nest UU oe
used is co.pleted. According to Letiam, these are oyen,
bulky affairs built in an exaosed loce tion. Wa ter E.
Nickell, naturalist at Cranbrook Institute of Science,
writes me that he had observed clumps of ti :iLs near zany
finished Catbird nests, but it was several ears oefo re he

had the epaortrnity to witness the male's role in regard

to these dummy nests. Mr. Nickell summarizes this behavior

A

as follows: "The male carries a twig or even in one case a
piece of cellOphane which someone had folded up into a nar-
row strip about five or six inches in length. He flies
ahead of the female, sing 115 e} :citedly and 5oes to on us-
rig? fork in the shrubbery where he, at the approach of

l

)- I)
(D
'2
f)
H.
0
If
U)
f)
(1.)

L;

the female deposit his burden. If the a?
,

U)

C\

Iasually does, flies away, he is media tely grasps the W‘i
(Dr‘other object and flies away after her, in a short time

ineturning to the sane glace, followed by the femile. This
to on for sometime. Obviously, in the total grocess,

Eie male gathers up to ten or t'elve twigs depositing them
j—TI the crotch he las chosen and not always caiiying the,
*~>-€3v ““0 n so that what eventually results is the clump of

.
‘9‘ s..- - - 5-;

4b . >~ ‘
“V*J4“s, Which is either used as a foundation cy tae female

or if she chooses another site, she will build the nest

entirely." I did not observe an; dummy nests under con—

a,
U

struction, but I did find incomplete nests varyin; from
collections of twigs placed in s crotch or fork to nes**al-

4‘

most complete except ior the lining.
Whittle (1923) gives evidence of the dominant role

played by the female in construction. He regorts that if.

I'
O
.3
)J

the male brought material While the fv..le was at the nest,
he would give it to her to place in the nest. Also if the
female brought material while the male was there, he would
get out of her way.

Bent (1943) gives five to s x devs as the time neces-
sary to complete the nest, while Herrick (1935) gives eight
days. Three 6178 prior to the laying of the first eg3.is
the earliest that I found 3 nest under construction. By
that time the foundation and cup formation hid been almost
completed, and the middle bark or leaf lever was just be-

0 he laid down.

c?-

ginning
In the building of the nest for the second brood, there

syperently is no grolonged period of site selection. Nickell

O

’1
I 317'
\

J orres;ondence)likewise concurs with this observation.

The male is usually involved with the feedinf of the young

K—

of the first nesting, and in the fer inst nces observed

A
‘

the nest building at this time was done entirely hv the

female.

Descriytion and Flecement

- n ~ _ .A- r . . . pt." "
The nest is oi the c 3-sh25ed stetant tyye. Tiole h

o
n
.-

gives the diznensions for all nests C11 thieh mes sure e1ts
were taken. It is interestin:; to note that the inside di-
ameter has the m:llest ste ndard deviation. The reduced
vrr :tion of this dimension night ;ossible reflect the

de ndence of the inside diameter of the cup on the size
of the bird rather than en the 3’r rticulte r confi“t1ration of
the nest Site.

Of the 24 nests described, eight were sugported from
beneeth on ugright crotches, seven on horiz ent 31 forks,
five on single horizontal b anches or two or more parallel
branches, and three on twigs :reu;-t to the nest oy th
oirds to grovide such swgyort in a too dee; nest site;
one nest had no one: suggort. Todd (1940) reports a nest
that was located on the top rail of a fen c azd Colton
(1759) writes of a nest built in a natural cavity of a
dead apgle tree wliicli tile ”irds he.d filled to a deyth of
nine inches so that the tn :3 stue“ out of the ogening.

All the nests had some lateral supgort provided hv the
ren01es or twigs of the nest tree or shrub or of fin ad—

jacent tree or shrub.

1'")

The nests were placed rom 2 feet, 5 inches to 5 feet,

11 inches above he Sound; the average for 24 nests was
53.33 inches (5 feet, 3.3: inches). Most nest heights re-
ported in the lite1ature fell bett een two and ten feet
above the ground (Beerg,1931; Bent ,1948; Berger,l95lb;
Brackbill,l950; Burleigh,l927; Cherles,l954; Davis,1942;

Gabrielson,1913; Howell,1932; Latham,1936; tallory,1915

 

 

 

 

 

 

 

TABLE 2
NEST DIMEHE OHS
Inside Outside Inside Outside
Diameter Diameter Bepth Detth
number 20 2O 20 19
mean 2.075 cm. 11.65 cm. 5.715 cm. C.447 on.
range 7.5-9 cm. 10-14 cm. 2.6-5 cm. 6-10.5 en.
st. dev. 0.4034 cm. 1.001 cm. 5.165 cm. 1.349 cm.

 

 

41

Morse,1923; Todd,l940). There are several other recorded
heights outside this range. Pearson, Brimley, and Brimlev
(1942) give the commonest range as between 3 and 15 feet,
but they also mention records of SO and 50 feet. Baerg,
Mallory, and Morris (1923) all report nests 20 feet above
the ground. Todd found a nest built 25 feet up, as did

also Latham. etham also reported the observation of a nest
built one feet above the ground, and Trautxuin (1940) found
two nests built on the ground.

Table 3 gives the type of vegetation in which the nests
were built. The 24 nests were located in 14 different
species of trees and shrubs with no one species being used
with outstandingly greater frequen y than any other. Of
these nesting locations, five had grape vine (Vitus 3;.)
as a part of the nest substrate. All but two were located
at a site where grape vine was immediatel" adjacent or
quite close by. With these two, grape vines did occur
frithin the territory but were at least 100 feet away from

'the nest in one instance.

Nesting Habitats
Most nests were located in the brushy uplands. Wood-

-' "‘ con J-‘,— H v f‘ > - n"- . h"! (
—~cznd edre was the second JuSt freiuent nest site haiitat,

exrrd the least number of nests were located in the Cornus-

 

SLEEESE lowlands. No nests were placed within the woodlands
CDT‘ associated with the ogen plands. Table 4 lists the
I"HE-‘Sts on known territories for the five habitat tyges

V!

‘J‘ “ _- Q L ‘
._tu1in the study area.

TABLE 3

NESTIHG VEGETATICN

)

Plant Species Number of fleets

K

American elm (Ulmus americana)

\

Honeysuckle (Lonicera so.) 3

Lilac (fiyringa vulgaris)

\Jl

Multiflora rose (Rosa multiflora)

 

\3!

Silky dogwood (Cornus amomum)

 

Alder (Alnus rugosa)

 

Beautybush (Kolkwitzia amabilis)

Black locust (Robina pseudo-acacia)

 

Choke cherry (Prunus Virginians)

 

Elderberry (Sambucus canadensis)

 

Forsythia (Forsythia sp.)

 

Mock orange (Philadelphus Sp.)

 

Wild crab (Eyrus ioensis)

 

+4 54 F’ FJ +4 :4 F’ +4 r4

Tfild crab and multiflora rose

TABLE 4

NEST HABITATS

 

 

 

 

Habitat Nests Found Territory Known, Total
One Rest Presumed

Brushy uplands l4 0 14
Edge 3 l 9
Cornus-Carex

lowlands 2 5 7
Deciduous woods 0 O 0
Open uplands O O C
Totals 24 e 30

 

 

 

 

Nest Structure and laterials
The nest is essentially a three-layered structure.
The first is the foundation layer; the second, the cup-

forming layer; and the third, the lining. The foundation

U2

layer was moderately to well develOQed in 15 of the 21 no ts

analysed for their materials. In all but one of these nests
it was primarily composed of woody twigs. In this one

pa ticular nest the foundatio: was formed from dried her-
baceous weed stems. The twigs used were of kinds that in-
dicated that they were mostly gathered close by. Herbaceous
weed stems, straw, bark, paper, and leaves were also found
in this first layer. The cup-forming layer, which usually
formed the bulk of the nest, can be further divided into
three sub-layers - a transition sub~layer next to the
foundation, the main cup-forming sub—layer, and a transi-
tion sub—layer next to the lining. The main cup-forming
sub-layer was usually the test developed of the three. It
was almost entirely of bark in 14 nests, primarily of leaves
in three nests, mostly of herbaceous weed stems in two
nests, and of about equal portions of bark, leaves, and
weed stems in two others. Grape was the most frequently
used bark, but that of the ninebark (Physocarpus ouulifolius)
and of the beautybush (Kolkwitzia amabilis) was used as

the major type in several nests. The transition sub-layer
next to the foundation was better develoted than the main
cup-forming sub-layer in four nests and in these cases

was increased D! the addition of large amounts of herbaceous

7
U

weed stems. The transition sub-layer next to the lining
was never very thick, being ,rimarily an area of merger
between the main cup-forming sub-layer and the lining.

The third layer, the lining, was in every case composed of
rootlets. In 13 nests there were also small bits of ‘ark,
small twigs, leaves, and herbaceous material in addition

to the rootlets. Dark brown to black and light brown to
yellow-brown rootlets were found with about equal frequency
in the nest linings. Red-brown rootlets occurred much less
frequently and a ways in combination with other colors of
rootlets.

After dismantling the nest, an analysis of the materi-
als was accomplished by making a sight judgement of the
preportions according to the bulk of the various materials.
Considering the nests together, herbaceous materials were
the commonest, forming 27.2 per cent of the average nest;
woody twigs formed 23.1 per cent, bark formed 23.5 per cent,
rootlets formed 14.2 per cent, leaves formed 7.7 per cent,
paper formed 0.7 per cent, and twine formed 0.4 per cent.
Table 5 gives the grogortion of different materials com-
prising the nests that were analysed. Bent (1943) mentions
that some nests in the Mid-west are lined with horsehair.
McAtee (1940) regorts the presence of lumps of dirt in the
foundation of one nest, and Turle (1930) includes rags as

occurring in Catbird nests.

T

A
11L

B

E}

E.
.4

PROPORTION OF MATERIALS IN NESTS

 

 

 

 

 

 

 

 

 

 

 

 

Nest Twigs Herb. Bark Leaves Paper Twine Rootlets
No. Mat.
1 .056 ‘.333 .500 0 0 0 .111
3 .250 .500 .125 X 0 0 .125
4 .500 .167 .167 0 O 0 .167
5 .167 .333 X .333 X 0 .167
6 .200 .200 .300 0 .050 .050 .200
7 .300 .100 .400 .010 .050 .040 .100
8 .417 .033 . C3 .333 X 0 .083
9 .220 .220 .220 .220 O 0 .110
10 .250 .525 .125 i 0 0 .100
11 .222 .333 .333 X 0 0 .111
12 .333 .333 .167 X X 0 .167
14 .421 .316 .053 .053 .053 0 .105
15 .273 .132 .364 .090 0 0 .091
17 .167 .353 .250 .167 0 0 .0€3
18 .250 .250 .250 X X X .250
19 .333 .167 .333 0 0 0 .167
20 .333 .111 .333 .167 0 0 .056
21 .0625 .375 .0625 .250 0 0 .250
22 .167 .167 .500 0 X 0 .15:
23 .125 .500 .125 X 0 0 .2 0
24 .43; .137 .250 X X 0 .125 #
mean .261 .272 .235 .077 .007 .004 .142
Nests 2, 13, and 16 were destroyed before they could be

collected for analysis. The mark, X, indicates presence,
but in a quantity too small to evaluate.

EGGS 333 3G a LAYING
Noffleld study of the e5 5s was attempted. Bent (194 3)
describes the e55s as bei;5 deep 5105s; Creenish-hlue or
oluish-5 een, much deeper toned than the e55s of tie Robin
Wood Thrush (Hylocichla mustelina). They are usually
without spots, but Sage et2£L.(l9l3) regorts Catbird e55s
spotted with red. Bent 5ives the size from a sample of 50
3558 in the National Museum as 23.3 mm. X 17.5 mm.

The numoer of e: m; BOT clutch ranged from two to four.

UV ~

ED

Thexe were ten nests with four e558, ei5ht with three e55

H‘
l

(and four :ith two e558. This 5ives a mode of four, a med
51n.of three, and a mesh v:1ue of 3.2 e553 per nest. Bent
(21943) gives the ran5e as from two to five as does also
Ekar5er (1951b). Harlow (1918) reports the ran5e as from
tfiree to five, and Young (1949) gives an avera5e of 3.1
eggs per nest. Trautman (1940) reports a nest containing,
:11): e555. Table 6 5ives the number of e55s per clutch
euzcmbrdin5 to the time of Wiestin . In both this tabulation
amni in the determination of the clutch figures aoove, nest
NC>- 21 has been omitted, since it failed durin5 e55 1ayin5
bef'ore the clutch was complete. or the ten nests that were
firwst; nestings, seven had four e553, two had three eggs,
and. Guns had two e55s. This 5ives a median and mode both
equ;;1_ to four and a mean of 3.6 @553 per nest. There were
foul‘ fleets that were considered as either late first nest-
ingms <31“ second attempts after the failure of the first nest-

ln“, - . . , .
b Jun this cate5ory the median and moae each equalled

M"? "‘ C
i.L.3L¢. 0

NUMBER OF EGGS PER CLUTCH

 

 

Time of Nestin5

 

 

First nestings
Second attempts
or late first

nestin5s
Second nestin5s

Total nests

 

 

 

 

 

 

 

HLLLEUG 1" Of :59 S fig 12;:- :3“
4 3 2 Mode Median Mean
Eees Sees 3553
7 2 1 4 3 . f
3 3 3:4 5 3.125
10 8 4

 

FREQUENCY OF EGG LAYING DURING MORNIHG

FIGURE 3

 

Rhinfber of
eggs laid 4'
during the

intervening 33
time periods

 

 

0700 0200 0900 1000

1

Clock hours

'3‘.

three with a mean of 2.75 eggs per clutch. Second nestincs

had a bimodal number of eggs at three and four with the

N

median at three and the mean equallinU 3.125 eggs.
Nests No. 19 and No. 25 were the only ones that were
under daily observation while being built. In both nests

the first egg was laid the day after each nest was completed.

Bent (194s and Shufeldt (1893) also give this as the elapsed
time until the first e55, but Herrick (1935) reports a iest
in which the first egg was not laid until three days after

the completion of the nest, and Berger (1951b) gives three,

four, and five days as the elapsed time between the com-
;gletion of the nest and the laying of the first 655.
athem (1936) states that the first egg of three laid was

éhaposited in the nest the day the nest was finished and that

tdie last was not laid until seven days later.

The eggs are always laid in the morning. Figure 3
slicnvs the frequency of laying of 14 eggs. One egg was laid
Eur (3700, another by 0730, two more by 0300,Ittree more by
0900, four more by 1000, and three more by 1100. There is
SCHnea evidence that certain females laid consistently in the
eaJFng part oi the morning, while other females laid con-
sisstmently in the late morning; but the number of definite-
lY'<DIDServed instances of this are too few to make any
Serfl3rhllization. Herrick (1935) and Shufeldt (1T93) place
the most

the time of egg laying between 0900 and l200 with

f ' J. 1 a
PeilLbelit occurrence between the hours of 0900 and 1100.

Dav143 (1942) found all four eggs of one nest to be laid:

one egg daily for four day , at 0300.

In all nests under observation a single egg was laid

each day until the clutch was complete.

I 1-D\ III-r. » .I\II.\.‘I{.I\..K(I|(|’&
‘ .1. . \‘ I. ...

51

INCUBATION
Only the female was observed to incubate the eggs.
The only instance recorded in the literature of a male in-
cubating is by Forbush (1929), who states that the male
does incubate sometimes, occasionally singing while on the

nest. He gives no further details.

Length of Incubation

The incubation time in this study is defined as the
elapsed time from the laying of an egg to its hatching.
The term incubation period refers to the supposed time the
eggs are actually being effectively incubated and is count-
ed from the day the last egg is laid until the day the last
egg hatches. The incubation times of five eggs are known
rather accurately. Egg No. 2 and egg No. 3 of nest No. 18
both.hatched after 13 days. Egg No. 4 of nest No. 17
hatched after not more than 13 days, 2 hours. Egg No. 3
of nest No. 17 had an incubation time of not more than
13 days, 5 hours. Egg No. l of nest No. 18 hatched after
14 days. Along with the times of 12 other eggs, it appears
'that.the first egg laid hatches on the 14th day after lay-
ing, while all the other eggs in a clutch hatch after 13
days. The incubation period is 13 days and is equal to
the incubation time of the last egg laid. Mrs. F. W.
commons as reported by Roberts (1932) gives the following
ixunibations times for five eggs in one nest: the first
gégg hatched after 15 days, the second after 14 days, the
third after 13 days, the fourth after 14 days, and the

fifth after 13 days. Bent (1948) and Gabrielson (1913)
give from 12 to 13 days as the incubation period. Herrick
(1955) and Kendeigh (1952) give 13 days as the average.
Burns (1915) reports the range of the incubation period
from 12 to 14 days. Berger (1951b) states that the periods
ranged from 13 to 15 days. Davis (1942) writes that each
of four eggs was laid in a Catbird nest daily from June 15th
to June 18th, and that they all hatched on July lst. This
gives an incubation period of 13 days.

The eggs in nest No. 23 were incubated through the
23rd day since the first one was laid; on the 24th day the
nest was deserted although the eggs were still there and
apparently not disturbed. Latham (1936) had a second nest-
ing that went to 22 days of incubation before the nest was

abandoned.

Attentiveness and Inattentivenees
Only the female of the nest No. 18 was observed in-

cubating the day the first egg was laid; and it seems quite
probable, considering the incubation times of the eggs, that
incubation does not begin regularly until at least the se-
cond egg is laid. Females were observed to incubate on the,
day the second egg was laid, but not for long periods. '
Bent (1948) mentions that the female does not begin incu-
bating regularly until a few days after the set has been
completed. Schufeldt (1893) states that the female sat at
.irregular intervals during the first few days, and Herrick

(1935) writes that the Catbird did not begin to incubate

"with earnest" until after the third egg was laid.

The average attentive period was 20.53 minutes for 47
periods of known length, and the average inattentive period
for 47 periods of known length.was 12.03 minutes. From
these values it is determined that 63.97% of the female's
observed activity was in incubating. Kendeigh (1952) gives
figures for the Catbird of 22.7 minutes for the average
attentive period and 7.0 minutes for the average inatten-
tive period. He gives an average of 33 attentive periods
a day, with the female spending 75.9% of her daytime activi-
ty in incubation. Davis (1954), from data supplied by
Kendeigh, states that the female spent 65.9% of the observ-
ed time in incubation. Counting also periods of unknown
length, the attentiveness in my study ranged from 0.5 min-
utes to 120 plus minutes, while the inattentiveness ranged
from 0.5 to 78 plus minutes. There were 1.7 attentive
periods per hour and 1.6 inattentive periods per hour.
Table 7 tabulates these data.

No day to day trend in the lengths of the inattentive
and attentive periods as incubation proceeded was apparent
in the data. Kendeigh.u952) found that the only daily
variation in the attentiveness was due to the temperature.
At 69 degrees F. the attentive periods were the longest
and came at the least frequent intervals. Above and below
this temperature the periods of attentiveness were shorter

and alternated more frequently with inattentive periods.

a— ‘
I

‘7.“

1:11:

LE

7

ma

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A. ATTENTIVE PERIODS IN HINUTES ACCORDING 10
THE DAYS SINCE THE FIRST 3 "‘ WAS LAID
O 1 2 j 4 5 6 7 6 9 10 11 12 13 14 l5 16 17
- l 14 - 49 l - - - 9 29 51 70 ’5 5' 13 9
2 11 .5 6 17 17.5 59 3 19 14
1 11.5 15 22 ll 3 75 l
.5 10 7 5.5 .5 8
l 7 45.5 16 C
12 28 9
25 7.5
11
B.. INATTENTIVE PERIODS IN MINUTES ACCORDING
TO THE DAYS SINCE THE FIRST EGG WAS LAID
O 1 2 3 4 5 6 7 C 9 10 11 12 13 14 15 16 17
- - 11 - 19 7 - 15 - 6 6 24 4 5.5 55 14.5 7 16
5 12 7.5 6 4.5 5.5 17 12 2 15
7.5 4 18 9 19.5 26 16 5
29 6 8 2 27 19.5
5 .5 12
8 35 3.5
14 7
22 7.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C.

TABLE 7—Continued

NUMBER OF ATTENTIVE AND INATTENTIVE
PERIODS PER OBSERVATION PERIOD

 

Time

Period

Attentive
Periods

Inattentive
Periods

 

Total

2+34
1+5}
2+38
l+22
l+00
1+48
1+45
1+47
1+29
2+3?
1+32
1+56
2+05
2+45
2+OO
1+30
3+11
l+ll
2+1l
2+14
2+57

mwmm-h-HHHmwm-rz-uk-P-qwmoom-h-

QNMH-P‘OOOHMOML‘KH ##NHONKOKNW

 

 

42+25

 

K3
[0

 

Ch
(I)

 

Behavior during Incubation

The female came to the nest usually by the same route
to perch on the same rim; however, she might come with a
good bit of hesitancy, Often making several approaches up
to the rim only to retreat. Other times she came directly
over her usual route to the nest rim to immediately settle
on the nest. Most females were quite constant in the posi-
tion they faced on the nest, but I have not seen any cor-
relation with ccver, sunlight, compass direction, or lepe
that would be the same for all nests. I would imagine that
the position on the nest is merely a function of the ap-
proach route which did seem to be determined by the avail-
ability of cover and suitable perches. The female may
settle on the nest with a side to side motion, or more often
without any such motions. The female would sometimes ap-
proach the nest giving soft, quiet or soft, wheezy mews,
and she would occasionally continue to mew after settling
on the nest. The female of nest No. 17 was twice observed
to come to the nest with food in her bill although there
was only a single unhatched egg in the nest at the time.
Both these instances occurred, however, the day following
the hatching of one of the eggs, but the newly hatched
bird had disappeared by the next morning. In both cases
the female ate the food immediately after settling down
on the nest.

While the female was at the nest, the male would often

sing from a regular song perch, usually at normal volume,

57

either the long territory song or more often a shortened
variation of this song of only a few phrases. When not
singing the male has been observed to perch quietly, preen,
or move off to feed in the area. Davis (1942) states that
while the female was on the nest, the male perched nearby
or fed. Concerning the singing of the male during incuba-
tion he further writes, "the male sings in the usual loud
manner occasionally but frequently sings a weak warbling
song. .These notes are very similar to the usual song but
the volume is greatly diminished. One must be near to
hear the song". He did not mention during what activities
these songs were used, but the weak song referred to per-
haps is the whisper song used by some males in this study
at the guard perch.

The female was observed to leave the nest under three
different circumstances: when disturbed, in response to the
male's signal, and for unknown reasons. Of all the observ—
ed departures 12.5% were when disturbed, either being
flushed off the nest or purposely leaving to fly at an
intruder. ‘When flushed, she would leave the nest quickly
and quietly, dropping low, and moving rapidly through the
‘underbrush away from the nest. The female left the nest
148.2 per cent of the time in reaponse to the male‘s signal,
'which.was usually the quiet song, although a short normal-
'volumed song was also used, and the male of nest No. 19
vnould generally only give the quitt call. In almost half
(44w4 per cent) of all signaled departures the female also

\fl
CD

gave one to several quitts when leaving the nest.. On
several occasions she would begin to quitt on the nest prior
to the vocal signal of the male, having apparently realized
his presence by some other means. The female of nest No.
12 delayed leaving for several minutes 20 per cent of the
times the male signaled. The female of nest No. 17 failed
to leave 71.4 per cent of the times the male signalled; she
would, however, quitt a number of times and become quite
restless. No other females delayed or refused to depart
when signalled by the male. After leaving the nest, the
female would most often fly away from the immediate area.
Occasionally she would fly in the direction of the male;
both birds would then perch near each other, quitting.
During the 13th day of incubation of next No. 12 the male
fed the female after she left the nest.
"Female to perch southeast of nest at 1324 - moved
down and then back up to perch. Moved to east rim and
then onto nest facing west at 1325. Bird mewed to
northeast of nest. Male singing short phrases to
north at 1330. Male quitting east at 1334 — female
left nest then to east. Male flew to perch in honey-
suckle north of nest. Female flew to him. Male fed
female. Then female flew northeast; male perched
Just north of nest, wing fluttering."
No other instance of the male feeding the female during
incubation was observed. avis (1942) observed the male
and female to perch near each other while she was off the
nest and touch or rub bills. Table 8 illustrates the de-
jparturss of females from the four nests under observation

ciuring the incubation stage.

During the periods while the female was off the nest,

A f‘
TABLE (1

FIQIALES' DEPARTURES FROM THE NEST WHILE INCUBATIKG

 

 

 

Nest )9 Left Left Without Left With geignsis, 79
No. the Nest c?“s Signal J's Sig. QQuitt Delays
15 10 disturb. 3 (30%) 3 (30%) 3 (100%) 0
unknown 4 (40%

12 28 disturb. 1 (3.6%; 15(53.6%) 2(13.3%) 3
unknwn. 12(42.9%

17 15 disturb. 3 20%) 6 (40%) 6 (100%) 0
unknown 6 4053)

19 3 0 3(100%) 1(33.3%) 0

Total 56 disturb. 7 12.5%) 27(48.2%) 12(44.4%) 3

unknwn. 22 39.2%)

 

 

 

 

 

 

the male was observed to assume the guard position on 77.6
per cent of these inattentive periods. The two samples of
the duration of unguarded inattentive periods were 4.4 and
3.8333 minutes. The three smaples of duration of guarded
inattentive periods were 7.6842, 14.4286, and 19.0 minutes.
The mean of the unguarded period samples equalled 4.1167
minutes, while the mean of the guarded period samples equal-
led 13.7043 minutes. Although these two means are not
significantly different from each other at the 5 per cent
level of significance, there is the possibility that there
still is an actual difference in the lengths of unguarded
and guarded inattentive periods (t22.2614, with df=3,
0.10(P(0.20). The femal apparently stays away longer
when she has seen the male come to a guard perch as she
left, and she returns sooner on occasions when the male

did not come to guard. The male used several regular
perches varying from one to eight feet from the nest, most
often moving three or four times between perches during a
single guarding period. Occasionally he would come to the
nest, perching quite close by or on the rim, and then move
off to one of his other guard perches or back to the one
from which he came. The male was usually silent during
the guarding period, but at nest No. 17 he used the whisper
song at least once during about three out of four periods,
and the male of nest No. 12 sang the quiet-song at least .
once about one out of four periods. The mtle would wing

.flutter for a period following his arrival at a perch,

31

then step and remain quiet. Often he would preen momen-
tarily while perched. mmediately before moving again the
male would begin to wing flutter and would usually wing
flutter while moving about. Wing fluttering referred to
here and mentioned elsewhere was observed in both the male
and female, but was observed much more frequently in the
male. The wings are held out away from the body approxi-
mately 30 degrees to the longitudinal axis and fluttered
or quivered rapidly and stiffly. It is not continuous,
but is interrupted by pauses. As the activity wanes, the
pauses between successive flutters become longer. Davis
(1942) also observed this wing fluttering in male and fe-
male Catbirds and mentions that it "occurred when the birds
appeared to be excited, as, for example, after I had dis-
turbed the nest or when the female returned after feeding".
This wing fluttering should not be confused with.wing
flashing as described by Sutton (1946) and Vaurie (1957)
and mentioned before under territory defense. The male
averaged 9.14 minutes on guard out of an average period of
11.25 minutes during which the female was off andpgone
from the immediate vicinity. The male was actually guard-
ing, therefore, 81.2 per cent of the time the nest was
unattended by the female. Davis reported that the male
always guarded during the inattentive periods at a perch
a few feet away.

In the Song Sparrow, Nice (1937) found that the male

guarded for only a few minutes and then left to Join the

female, often escorting her back to the nest. Table 9
presents the guarding activity of the male at the four
nests observed during incubation.

When the female returns to the vicinity of the nest
while the male is at his guard perch, the male would eith-
er sing or remain silent. For the four nests observed dur-
ing incubation, Table 10 gives the activity of the male on
the return of the female. The female was observed to re-
turn to the vicinity of the nest 44 times while the male
was guarding. He sang some’sort of a song or call note
on 59.1 per cent of these instances. The male of nest No.
12 most often sang the quiet song; the male of nest No. 17
used the whisper song or the quitt call with about equal
frequency and the male of nest No. 19 only used the quitt.
Mews and short normal-volumed songs were used much less
frequently. The male would always depart soon after the
arrival of the female. On 18 occasions(4l per cent) he
would perch momentarily near the female or the female would
fly to perch near the male, after which the male would
leave and the female would approach the nest. After she
was on the nest, the male was heard to sing a quiet song
or short nowmal-volumed song 43.1 per cent of the time
from a perch nearby.

On two separate days when the temperature was in the
high eighties, the female gaped while incubating. She
would open the bill about 20 to 30 degrees and then close

it slowly or with a series of quick snaps. The female

TABLE 9

ACTIVITY OF THE MALE WHILE THE FEMALE IS
OFF THE NEST, THE GUARD PERCH

 

 

 

 

Nest ,Porr, form", No. of Perches Guarding; Length
No. anot tron. Used During a Off and Gone of non-
guarding guard Si le Period (in min.) guarded
l 2 3 4 5 periods
15 6 1 l - Ol, 09,
02, 06,
04 min.
12 6 21 1 1 s 7 4 118 03, 08,
145 03, O4,
02, 03,
min.
17 1 19 2 2 3 3 3 165 -
§O2
19 O 4 4 56 -
57
Total 15 45 6 4 11 10 7 22% 45 min.
0

 

 

 

 

 

 

 

 

 

 

’1
'VIT

TABLE 10

ACTIVITY 0}? MALE UPON THE RETURN OF' THE
FEMALE WHILE TEE MALE IS GUAFDING

 

 

 

 

 

 

 

 

 

 

Nest 3 Did 5‘ Did If 6‘ Sang (3' leaves (Tsang

No. Not Sing Sing 1 g- ”'52) if" :1; direct to near after,9
" '3; 3° 3" 5 ,9 on nest

g i 3 em 2; e

15 1 l

12 13 12 2 - 6 1 3 15 IO 16

17 4 11 - 5 l 1 4 7 E 2

19 O 3 - - - - 3 3 O 1

Tota 18 26 26 18- l9__

 

 

 

 

 

 

 

C\
U)

always reOpened it slowly. The bill was usually held open
between 30 seconds and one minute, then closed for a few
seconds, and then reOpened. The female did not gape all
the time she was on the nest, but separated a series of
gapes by periods of several minutes. There was no gular

movement associated with this gaping.

HATCHING

The eggs are pipped the day before hatching, or some-
times just a few hours before hatching. Two eggs in nest
No. 10, however, were pipped five days ahead of hatching.
The female has been observed to poke at the eggs while in-
cubating during the days prior to hatching; she apparent-
ly contributes to the pipping of the eggs by this activity.
Some eggs, such as those in nest No. 10, were noticeably
pipped from the outside rather than from the inside as
seen in other eggs. The pipping appears a little beyond
the center of the egg toward the larger end. One of the
eggs in nest No. 12 broke with a crack audible eight to
ten feet away.

I was present at the hatching of three eggs, and the
following notes were written at these times:

"Nest No. 12, July 9, 1958. Male now left to south
at 1011 as female came from southeast and wing flut-
tering, then female to east rim and then onto nest
facing southwest - did not feed, gave a single quirt,
1012........ Female quirting on nest and poking
under body. Heard a crack and female immediately
carried egg shell away to the south at 1015. Checked
nest immediately - other egg has hatched, half of egg
shell still in nest. Female back to nest from south-
east at 1018, facing west on nest........when female
returned, she paused slightly on east rim but did not
poke in nest........Male singing north at 1029. Fe-
male began to quitt on nest, left to southeast with

a few quitts...........Female came in from southeast,
male left to south. Female to east rim with food,
quirted, fed one young, picked up the other half of
egg shell and flew with it to north."

"Nest No. 17, July 22, 1958........then male flew up
to north rim of nest and bent over with head in nest
for about 15 seconds at which time the female flew
up to Just north of nest in nest tree, and male flew
south to perch, wing fluttering there momentarily.
Female moved onto nest to incubate after a slight

 

6?

hesitation on north rim - 1156..........I left blind -
at 1200, flushed female to check eggs. Egg No. 3 is
hatching right now, egg almost completely Open. No.
4 is still pipped about the same, and No. 2 not pip—
ped at all. Female came to north rim at 1204, hesi-
tated awhile, looking and poking in nest, then onto
nest facing southeast........... Female poking and
looking in nest........Female stood up several times
to look and poke in nest - l218.......... At 1221
female stood up, poked in nest, and picked up one
half of egg shell and ate it, then poked in nest and
picked up other half of egg shell, leaving with it
to north at 1222. At 1223 perched on south rim ap-
parently eating bits of shell then settled on nest
facing north......... At 1224 repeated eating of
shell bits..... At 1225 stood up and poked in nest
Just momentarily....... Again at 1226, up on south
rim poking into nest and again apparently eating
something - can hear bill snapping. Not back down
on nest until 1228, facing north again."

"Nest No. 17, July 23, 1958. At 1139 male up on north
rim, moved around to east rim, picked up egg shell
half and left immediately with it to the northeast.
Male then back with food, perched Just north, wing-
fluttering. Then to nest on north rim - did not

feed, but flew to Just southeast, quitting...........
At 1144 male flew up to east rim, poking in nest,
quirted a number of times and apparently eating egg
shell bits. Left then to southeast.......... I
checked nest - young bird still in larger piece of
shell (the small end), removed young from shell break—
ing the allantois. Young weighed 2.25 g. (average of
three weighings). Replaced young in shell and put
back in nest. No bits of shell were on exposed por-
tion of young - 1200......Vale came from north to
perch Just south.with food.....flew to nest at 1215,
east rim; hesitated, apparently did not feed, left
immediately with the other half of egg shell to south-
east. Back again Just to south, whisper sang, up on
vine bridge, wing fluttering, without food - 1216"

Both.sexes were observed to rid the nest of the egg_shell
halves. In the first instance above the female left with
half of the shell immediately aft r it hatched, then re-

turned within three minutes and settled down on tae nest.

Then she left the nest after being on for 11 minutes and

returned with food in six minutes, fed one of the newly

II)

Ox
2

hatched young and then left with the other half of the
shell. She returned within half a minute and settled on
the nest to brood. In the second case the young apparent-
ly began hatching while neither bird was at the nest. The
male came to the nest but did not take the egg shell and
left as the female arrived and settled down to brood. She
stood up several times and poked in the nest but always
settled back down. At approximately 26 minutes after the
egg had hatched, the female stood up on the rim of the nest
and ate one half of the shell, then picked up the other
half and left with it. She was back at the nest within a
minute. The third instance observed was an egg that broke
Open while neither adult was at the nest. In this case,
however, the male took the smaller half and left with it.
He immediately returned to the nest with food but did not
feed, then left. After four minutes, he came back to poke
in the nest, then left again. Neither adult came to the
nest for the next 30 minutes; then the male returned with
food. He did not feed, but he picked up the other half
of the egg shell and left with it. Gabrielson (1913) ob—
served the female Catbirds to peck at pipped eggs prior to
Inatching and also to remove the smaller bits of shell from
the nest.

The natal down of the newly hatched young is damp and
xnatted and covered with small bits of shell. The adults
jpick off and eat these shell bits in addition to some bits
of shell within the nest. The adults must not carry the

K.
(“9

egg shell halves very far from the nest site, since they
are usually back to the nest within a minute.

One young at nest No. 10 had the allantois still at-
tached to its abdomen. It remained dried, shrivelled, and
attached for several days. This particular nestling show-
ed a noticeable retarded development and never was success-

fully fledged.

70

DEVELOPMENT OF NESTLINGS

Table 11 gives the average measurements of weight,
wing length, tarsal length, and overall length of all nest-
lings upon which these measurements were taken. Figure 4
illustrates these data graphically. Table 12 gives the
percentages of the average adult weight attained by the
nestlings for each day of nest life. Since no adult
weights were taken in this study, the average weight was
determined from weights given for a total of 162 individu-
als measured in other studies (Baldwin and Kendeigh, 1938;
Blake, 1958; Hartman, 1955; Nice, 1938; Norris and Johnson,
1958; Stegeman, 1955; Wetherbee, 1934). These are tabur
lated in Table 13. Nice (1943), discussing the weights of
passerine nestlings, states that a newly-hatched bird weighs
six to eight per cent of the adult; and after the first ten
days, the weight increases to 60 to 80 per cent. Young Cat-
birds in this study weighedBJiE per cent of the average adult
weight on the day of hatching, and at ten days they weigh-
ed 72.4 per cent. On leaving the nest at 11 days, the
young had attained 76.76 per cent of their adult weight.
Data given by Baldwin and Kendeigh (1938) and Wetherbee
' (1934) on a total of 83 immatures indicated that these
birds weigh an average of Just 0.38 grams more than the
average adult.

Nice (1943) reports data collected by W. E. Schantz
on the develOpment of activities in Catbirds which had been

raised from eggs. The various activities and the days

TABLE 11

DAILX AVERAGE OF WING LENGTH, TARSAL LENGTH,
TOTAL LENGTH, AND WEIGHT 0F NESTLINGS

 

 

 

 

Day Wing Length Tarsal Length Total Length Weight
n a in cm. n i in cm. n i in cm. n I in g.
0 0.76 5 0.51 4.14 13 3.06
l 17 0.92 17 0.63 17 4.60 19 4.63
2 19 1.10 19 0.72 19 5.22 19 6.95
3 17 1.38 17 0.93 17 5.35 18 10.44
4 15 1.30 15 1.13 15 6.39 19 13.34
5 16 2.52 16 1.45 16 7.17 18 17.56
6 15 2.92 15 1.60 15 7.62 15 20.47
7 14 3.64 14 1.82 14 8.02 13 23.46
S 21 3.95 21 1.95 21 8.30 19 25.66
9 17 4.59 17 2.00 17 8.67 17 26.70
10 13 4.90 13 2.12 13 8.77 13 26._3
11 8 5.39 8 2.14 8 9.25 8 27.:1

 

 

 

 

 

 

 

 

 

 

 

72

 

 

 

AVERAGE HEASVREHEN‘I’S 0F NE3‘L\NGS T
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I
.’ s ’
‘ l 5“ .‘v—‘O
I. ‘< 6 /O. ’2.0
CI 0
. ,' / '
'4 - 'l' . 45
II.
I! .
a " .
’9': / bl.°
c/. 4
‘Dmis fitmfc ihkiaHzQG‘ ' '0 fi . : i i '1 3' 5 y' " \‘0 "9-5
omrs smci tunes-MN?-

TABLE 12

DAILX PERCENTAGES OF AVERAGE ADULT
WEIGHT 0F NESTLINGS

 

 

 

Day Average Weight Per Cent of Adult Weight
Taken as 36.23 Grams__
0 3.06 gms. 8.45 %
l 4.63 12.78
2 6.95 19.19
3 10.44 28.82
4 13.34 36.°2
5 17.86 49.30
6 20.47 56.50
7 23.46 64.75
C 25.68 70.88
9 26.76 73.96
10 26 23 73.40
11 27.8 76.76

 

 

 

TABLE 13

ADULT WEIGHTS REPORTED IN THE LITERATURE

 

 

 

 

 

Source Number Sex Mean Freq. X Mean
Baldwin and 23 J 34.1 5;. 784.3 g.
Kendeigh (1938) 23 (f 33.4 768.2

34 ,p 36.5 1241.0

30 x0 35.5 1065.0
Blake (1958) 1 - 37.0 37.0
Hartman (1955) 8 ,p N 38.9 311.2

9 or 37.7 339.3
Stegeman (1955) 5 c? 45.3 226.5

3 ,9 40.8 122.4
Nice (1938) 13 - 35.9 423.5
Norris and 1 o" 40.0 40.0
Johnson (1955‘) l o” 44.0 44.0
Wetherbee (1934) 11 - 38.5 423.5
Total 162 A 5869.1 5.
Mean Adult Weight 36.23 g.

 

 

 

 

74

75

after hatching of appearance of these activities were as

follows:
Gaping and defecating at hatching
Preening 6 days
Cowering 6 days
Stretching legs up 7 days
Stretching wings up 7 days
Stretching sideways 7 days
Scratching head 7 days
Stretching both.wings down 7-8 days
Yawning 8 days
Shaking self 8 days
Fluttering wings in begging 9 days
Packing at objects 9 days
Fanning wings (flight maturation) 11 days
Leaving nest 11-12 days
Landing on other young 11-12 days
Bathing 13 days
Drinking 13-14 days
Antagonism note 13-14 days
Fighting 13-14 days
Singing 60 days

I found young Catbirds giving the first seep-seep

begging call at three to five days. On the earliest oc-

casions the young beg only when the adult is on the nest
rim. A few days later they begin to beg while the adult
is still perched nearby. At four days they were observed
to Open their bills and give the begging call when no adult
was near the nest. By the ninth day in the nest the young
are quite active. They seep loudly and stretch their necks
'with open bills.and wing-flutter while begging. Young
birds were first observed to preen at the age of ten days.
tip until the age of four to six days the young would not
defecate when being handled. From this age on, however,
they always defecated when taken from the nest to be

we ighed .

76

CARE OF THE YOUNG

Brooding
Only the female was observed to brood the nestlings,
and I found no records in the literature of a male brood-

ing.

Length of nestling stage

he time in the nest for 15 young was exactly deter-
mined. One of them left at 8 days, two at 9 days, four at
10 days, and sight at 11 days. It appears also that at
least one young in nest N0. 2 and one in nest No. 3 re-
mained until the 12th day. The range, than is from 8 to
12 days with a mean of 10.47 days and median of 11 days.
Kendeigh (1952) reports two early departures at 7 and 8
days, but the majority of the young, 8 out of 14, left at
10 days. Herrick (1901) had a young bird leave the nest,
perhaps prematurely, at 10 days. Schufeldt (1893) describes
the departure of young birds that had been in the nest 10
to 11 days. Davis (1942) felt that the young of one nest
left one day early at 11 days, and he had another brood
leave at 12 days. Kendeigh reported another nestling that

did not fledge until 15 days after hatching.

Attentiveness and inattentiveness

Table 14 tabulates the prOportion of the total obser-
vation time spent in brooding for each day of nest life at
five nests watched during the brooding stage. The percent-

age of observation time the female Spends in brooding

TABLE 14

PROPORTION OF THE TOTAL OBSERVATION
TIME SPENT IN BROODING

 

 

 

Day of Total Total Time Percentages of
Nest Observation Spent in Total Time Spent
Life Time Brooding in Brooding

0 354 min. 183.0 min. 51.70 %
l 399 244.5 61.28
2 439 170.5 38.84
3 312 193.5 63.62
4 412 93.5 22.69
5 643 213-0 33.13
6 236 62.5 26.48
7 480 119.5 24.90
8 31: 10.0 3.15
9 425 16.5 3.3g
10 240 none 0.0
11 220 none 0.0

 

 

 

 

ranges from 51.70 per cent on the day of hatching to a high
of 63.62 per cent on the third day, to 3.88 per cent on the
ninth day, and to a low of zero per cent on the tenth and
eleventh days. Grouping the days into four periods, the
percentage of time spent in brooding is 53.86 per cent for
days zero through 3, 26.80 per cent for days 4 through 7,
3.52 per cent for days 8 and 9, and zero per cent for the
last two days. Gabrielson (1913) determined the average
brooding time to be 50.8 per cent. At the beginning of
brooding the female spent 77.58 per cent of the observation
time on the nest, and he found that this time decreased each
day to about 30 per cent as the young became older. Ken-
deigh (1952) reported that brooding decreased from 62.1

per cent of the daytime hours on the day of hatching to
51.7 per cent on the first day and to 20.9 per cent on the
second day.

Considering all the days of brooding together gives
an average of 1.5 attentive and 1.6 inattentive periods
per hour. Table 15 lists the number of attentive and in-
attentive periods and their hourly rate for each day of
nest life.

Table 16 shows the attentive periods and Table 17
gives the inattentive periods observed during this study.
From the day of hatching through the third day, the atten-
tive periods are longer than the inattentive ones. After
the third day, the inattentive periods are longer. These

periods are based only on intervals of known length. The

TABLE 15

HOURLY RATE OF ATTENTIVENESS AND INATTENTIVENESS
FOR EACH DAY OF NEST LIFE

El
\C)

 

 

 

 

 

 

Day of Total “Total No. No. Att. Total No. No. Inatt.
Nest Observ. Att. Per./Hr. Inatt. Per./Hr.
Life Time Periods Periods

0 354 min. 11 1.86 10 1.69
1 599 20 3.00 20 3.00
2 439 9 1.23 9 1.23
3 312 9 1.73 a 1.54
4 412 9 1.31 10 1.46
5 643 17 1.59 16 1.49
6 236 5 1.27 6 1.53
7 480 17 2.13 19 2.38
3 318 0.19 3 ‘ 0.57
9 425 4 0.56 8 1.13
10 240 0 - all -

11 220 0 — all -

Total 4018 102 109
'i 1.5 1.6

 

 

 

 

 

 

TABLE 16

ATTENTIVE PERIODS IN MINUTES FOR
76 PERIODS 0F KNOWN LENGTH

 

 

 

 

 

 

 

 

 

 

Day
or Nest o l 2 3 4 5 6 7 8 9 10 11
Life 1..-
33 14 23 30 6 11 3 9.5 10'4 o o
6 6 3 25 33 7 25 9 7
5 3 12.5 21 6 11 5.5 9 2.5
3 8.5 8 28 15 10 4 12 2
11 8.5 27 27.5 24.5 8 6.5 2
5.5 6 14 25.5 6 16.5
3 6 65 14 5
l: 0.5 22 2
7.5 2
10 13
5 5
2 15
13 1
47 15
13 1
19.5
42
Sum 84.5 211.5152.5 157 84.5 89 37.5121.5 1017.5 0 0
Number 8 17 7 6 5 8 4 15 1 5 o 0
Mean 0.56 2.44 21.7926.l716.911.lj9.3: 8.1 1 3.5 o o

 

 

 

 

 

 

 

 

 

 

TABLE 17

INATTENTIVE PERIODS IN MINUTES FOR 75 PERIODS
0F KNOWN LENGTH AND Two ADDITIONAL
PERIODS 0F UNKNOWN LENGTH

 

 

 

 

 

 

 

Day
Of Nest 0 1 2 3 4 5 6 7 8 9 10 11
__Life I
10.5 22.5 8. 12 ll 14 93 8 163 9.5all all
3 5 10 13 52 9 12 25 115 9
18 1 8 6 10 19 8 19 47
10 7 13 10 37 9 41.5 20 41
3 5 16 13.5 64.5 29.5 12.5
7.5 4 25 22.5 17.5 14
1 9 15 3 8 7
7 5 23 12
1 3.; 59 23
12. 7
1.5 17.5
3 9.5
14 34
l
11
19.5
8
Sum 61.0132.595.5 109 174.5188.5154.5208.527e 06.5
Number 9 l7 7 7 5 1 9 4 l3 2 4
Mean 6.777.79 13.64 557 34.920.94 8.63 6.04 3924.93

 

 

 

 

 

 

 

 

 

 

 

 

*Period of unknown length

[0

average inattentive period of the eighth day, however, is
an exception; this figure is based on two periods of un-
known length. .

The data on attentiveness and inattentiveness, rate
of these periods, and the per cent of Observation time
spent in brooding are grouped in Table 18 according to the
four periods mentioned above. Both the length of each at-
tentive period and its rate function tOgether to result in
the successive drOp in the percentage of observation time
spent in brooding for each of the four periods.

Both Gabrielson (1913) and Kendeigh (1952) agree that
the brooding activity in a normal day fell into three pe-
riods. The first was from 0430 to 0730 during the coolness
of the morning. The second lasted from 1030 to 1400 while
the sun was more directly on the nest. The third was from
1830 until dark during the evening coolness. Figure 5
illustrates the relative amounts of brooding observed dur-
ing this study. As can be seen, brooding did fall into
three major groups but with their limits differing some-
what from those determined by Gabrielson and Kendeigh.

The first and most active brooding period began around day-
light and continued to around 1045. The second period be-
gan about 1130 and continued until 1400. The third began
at approximately 1700 and lasted until dark. It should be
pointed out that the determination of such periods of rel-
ative brooding activity are biased by what time of day

most of the observation.was done. N0 pre-planned attempt

TABLE 13

BROODING ACTIVITY DURING THE FOUR PERIODS

 

 

 

OF THE NESTLING STAGE

Length Length Per Cent of
Periods Att. Att./Hr. Inatt. Inatt./Hr. Observation
in Days Feriod Period Time in

in Min. in Min. Brooding
4 - 7 11.33 1.55 27.63 1.72 26.”0
S - 9 6.75 0.38 81.97 0.35 3.52
10 - 11 none - all - 0.0

 

 

 

 

 

 

000 N

capr.

m wraiu

.20 wd4¢w74 2‘ 023,90 JZ_DOO¢Q UO FZDOZ<

mdDoI Xuoau 2. we»;

3. 02.. so... can: act. 03 . can. ow: coo. 02.0 bow. core 93. com.

 

 

FREQUE NL‘! 0F BROODtNG

“‘6“

Lou

in

was made to equalize the periods of observation throughout
the day, but an attempt was made to study the nest at least
some through all hours of daylight. Just how large a fac-
tor such bias was is not known; however, it is felt that
the apparent high activity of the first period and the
relatively lower activity of the third period might have

been in part a reflection of such bias.

Behavior during brooding

When approaching the nest, the female utilizes the
same routes she established during incubation. As in in-
cubation, she sometimes comes to the nest with great hesi-
tancy. On one occasion the female of nest No. 12 made
seven approaches and subsequent retreats before coming to
the nest on the eighth try. The female may come quietly,
but particularly if the male remains nearby, she approaches
with soft or soft, wheezy mews, or more often with quitts.
0n 72.04 per cent of all instances where the female came
to the nest to brood, she fed at least one young before
brooding. The remaining times she did not feed, although
occasionally she still had food in her bill. Sometimes
the female would come to the nest to feed and then remain
perched on the rim for as long as from 12 to 21 minutes
before leaving or from 14 to 15 minutes before broodinr.
Up through the seventh day after hatching, the female
broods more often than she leaves; on the eighth and ninth'
days she leaves more often than she broods; and from the

tenth day on, she always leaves after feeding.' As was

observed at times during incubation, the female will some-
times be heard to mew on the nest.

During a 30-minute th nderstorm, the female of nest
No. 19 showed no special behavior while brooding the young
for the entirety of the period. The female of nest No. 12
_1eft the nest during a short early morning shower.

abrielson (1913) writes that on days of steady rain of
several hours duration, the young were brooded most of the
time. Both‘Whittle (1923) and Bailey (1933) observed that
the female shaded the young with wideSpread wings when the
nest was exposed to direct sunlight. No female vas ob-
served in this study in such a protective posture, but no
nest under close observation during brooding was located
where it was exposed to the direct rays of the sun. Bailey
also describes the female assuming a widespread-wing pos-
ture "with feathers drawn close, bill pointed straight up
and eyes shut" during a hailstorm.

While the female is brooding, the male still sings
normal-volumed phrases. Occasionally it is a long terri-
tory-type song, but more often Just a short phrase is sung.
Davis (1942) also states that the male sang occasionally
during the brooding period.

Females were observed to leave the nest in five dif-
ferent situations. As in incubation, the female left the
nest after an approaching male gave a vocal signal, and
these cases composed 77.27 per cent of all observed de-

jpartures. The remaining four situations made up 22.72 per

cent of all departures and included 10.23 per cent after
,the unsignalled arrival of the male, 2.27 per cent due to
the female's leaving the nest with egg shells, 2.27 per
cent due to the female's being flushed by or deliberately
flying at an intruder, and 7.95 per cent due to unknown
causes. The most frequent signals were the quiet song,
which comprised 33.23 per cent of all signals heard; and
the quitt call, which made up 44.12 per cent. he male of
nest No. 12 used the quiet song most frequently while the
male of nests No.'s 3 and 19 and the male of nests No.'s
4 and 17 used the quitt call the most. Out of the 77 times
the male arrived, with or without a prior signal, the fe-
male gave a quitt or mew when leaving the nest 47 times
(61.04 per cent). Quite often the female of nest No. 19,
upon the signalled approach of the male, did not leave but
moved only up on the rim. These were not counted as de-
partures, except in three cases when she subsequently left
the nest. This failure to depart completely occurred 14
times at this nest or 45 per cent of the times the male
signalled. These data on the females' departures at the
five nests observed closely during brooding are in Table
19. Whether departing immediately or after some delay,
the female usually leaves over the same route each time.
As the male comes to the nest, he usually uses the
same route for every approach, and his is separate from
that regularly used by the female. He usually gives a

'vooal signal whether the female is at the nest or not.

TABE l9

ACTIVITY ASSOCIATED WITH TIE DEPARTURE OF THE

 

 

 

 

 

 

FEMALE 717.72: T313 2333? BURIETG ERGO-DING
Times female a 8 Type of Simal Used ,PQuitts or
Nest ,9 No After L” -;—r News After
No. baaves Signal Signal "E? 3: i g. 3 3‘3 Signal
bye? bya‘ 3.3, 33 g. f: g or s Arr.
3 l O l 1
C- D - l 2 l 1 1
M - 2
U - 3
12 52 D - O 41 25 7 9 32
M - 5
E - l
U - 5
17 6 D - 1 4 4 3
E - 1
19 21 M - 1 20 l 19 11
Total 88 D - 2 68 26 1 30 10 1 47
M - 9
E - 2
U - 7
Per
Cent 22.72 77.27

 

 

 

 

 

 

 

 

 

 

D - disturbed, M - unsignaled approach of Male, E - egg
shell removal, U - unknown.

59

Sometimes the female does not leave as the male comes to

the nest with food, as in this case at nest No. 12;
"Male singing quietly to south at 0231 - one phrase.
Male perched in honeysuckle with food at 0832, wing
fluttering. Female with food flew from west past the
male to the east and then to the southeast perch. Fed
young from the southeast rim and then onto the nest
to brood at 0834. Male then came to perch Just north,
then just above nest, still with food. Female quirt-
ing on nest. Male moving about with food, wing flut-
tering and quitting........Male to perch Just north..
....female gave a quirt....male flew to honeysuckle..
..male returned twice to perch just north, then to
Just above nest.....female reached out and grabbed
some food from male, than male fed remaining part to
her. Male left immediately".

On several occasions the male and female came to the nest
simultaneously with food, perching on different sides of
the rim. Both adults fed the young, then the male left
immediately. The female remains, removes the fecal sac if
there is one, then leaves or settles down on the nest to
brood.

The male was observed to feed 177 times while the fe-
male was 22$ at the nest. Following these feedings, he
leaves the vicinity of the nest 37.29 per cent of the time
or assumes the guard perch 62.71 per cent of the time.
Sometimes the male would remain on the nest rim as long as
11 minutes before leaving. He is usually silent as he goes
to one of his guard perches, the same ones used during in-
cubation; but 25 per cent of these times he gave some sort
of vocalization immediately. The male of nest No.'s 4
and 17 and the male of neat No. 12 occasionally went to the
nest, did not feed, but assumed the guarding position. It

lfllS noted that guarding activity wanes during the last two

(x

0“) J

o1

q

(16

l
&

days of the brooding “eriod. Table 20 contains data on t
activity of the male immediately after feeding.

The male‘s guardinr activity continues to be similar
to that during incubation. The male may remain quiet at
one perch or move about between several guard perches.
The males were observed to gape, preen, quirt, and whisper-
sing during the guarding periods. The male also w'ng flut-

L

ters in similar circumstances as in the incubation stage.
Davis (1942) mentions that he observed the wing-fluttering
behavior to continue during brooding. A new activity,
however, is food gathering. The male does not guard as
tenaciously as he did during incubation, but leaves the
guard perch to collect food in the immediate vicinity of
the nest. He then goes to the nest and feeds, and then
reassumes the guarding activity.

As the female pproaches the nest while the male is
in the guard position, he sings or gives a call note 80.34
per cent of the time. The most frequently used vocaliza-
tions were the quiet song and the quitt call note. After the
arrival of the female in the vicinity of the nest, the
male leaves directly from the nest area, usually with a
quitt, 81.20 per cent of the time. On the other occasions
he flies near the female or she flies near him, and they
remain close to one another for a few minutes before she
goes to the nest. The male of nest No. 12 was the only
one that was occasionally heard to sing, most often the

quiet song, after the female had settled down to brood the

TABLE 20

ACTIVITY OF THE MALE IMMEDIATELY.AFTER FEEDING
(FEMALE NOT PRESENT) - THE GUARDING POSITION

 

 

 

 

Nest Times aFed After Feedinrr (5' Sang O“ to Nest

No. andgp Not FEEE?E§"T6‘§G§?EJImm. After Did Not Feed,
at Nest at Guard but to Guard

3 57 32 5 5 0
4 l4 4 10 10 2

12 50 9 41 O 10

17 6 l 5 5 3

l9 70 20 50 8 0

Total 177 66 111 28 15

Per 37.29 62.71

Cent

 

 

 

 

 

 

 

young. Table 21 gives the activity of the male at the
guard perch upon the arrival of the female at the five

nests studied closely during brooding.

Feeding and Food

Feeding activities

Both the female and the male feed the young in the
nest. In 403 observed feeding operations in which the sex
of the adult was known, the male fed 221 times and the fe-
male fed 182 times. Table 22 gives the breakdown of these
feedings according to the age of the young. There is only
a general relationship between the differences of the num-
ber of times the male and female fed and the amount of time
spent by the female in brooding (See Table 18). From the
day of hatching through the third day, the male fed an aver-
age of 5.5 times more than the female. In the second peri-
of of brooding, although the female is now brooding only
26.80 per cent of the observation time as compared to 53.36
per cent in the first period, the average difference re-
mains about the same, 6.5 times in favor of the male. In
the third period during the eighdland ninth days, when the
female is spending only 3.52 per cent of the observation
time in brooding, the difference drops to an average of
2.0. Not until the tenth and eleventh days, during which
time the female was not observed to brood at all, did the
female feed the young more times than the male (6.5 more
times).

Herrick (1901) states that the male rarely came to the

TABLE 21

ACTIVITY OF TIL-3 MALE UPON THE ARRIVAL OF THE
FEMALE WHILE THE MALE IS GUARDING '

\0
\JJ

 

 

 

 

 

 

 

 

 

 

 

me If Sang, Used a Leaves d‘Sang
Nest Did Jr Direct To Near After
No. ~Iot Sing Sang 3 g... 4- .. g; 4- on Nest
"’ 3'5 ’25 *3 '5'
E 3“ 3M 3> a? A”
3 0 6 5 1 6
4 3 5 5 e
l2 14 43 7 20 10 6 49 8 13
17 2 6 2 4 4
l9 4 34 5 3 l 21 28 10
Total 23 94 5 15 33 12 29 95 22 13
Per , n n
Cent 1 19.06 ~0.34 81.20 3.0

 

 

 

 

 

 

 

 

 

 

 

 

Day
Male
Female
Difference

Average

 

 

 

TABLE 22
NUMBER OF FEEDINGS BY ADULTS DURING

THE DAYS OF NEST LIFE
0 1 2 3 4 5 6 7 8 9 10 11
3 10 15 15 28 31 13 29 5 25 10 16
O 9 7 5 18 22 7 2S 3 24 2O 19
3 l G IO 10 9 6 l 5 l 10 3

5.5 6.5 2 5.5

Difference
For Each
Period

 

 

 

 

 

nest, but that When he did he would pass the food on to the
female who in turn fed the young. As has been shown above,
the male is quite a regular and active visitor to the nest
during the brooding stage both during the guarding activity
and to feed the nestlings; but I did witness the male feed-
ing the female who in turn fed the young on numerous oc-
casions at several nests. It is more a case, however, of
the female taking the food from the male rather than the
male feeding her. The following notes were taken at nest
No. 19 on July 29, 1958, and are representative of this
behavior.
"At 0821 female came from southeast quitting. Male
quitting - male flew to southeast, quitting as female
came to perch Just southeast, then to Just north, to
north rim, hesitated Just a moment. Did not feed,
had no food as far as I could see, and settled down
on nest facing east at 0822. Male Just south at
0825 with food, quitting. Then to Just north, to
north rim. Female up on west rim and took some of the
food from the male. Male fed what was left and fe-
male also fed young. Male left over west rim. Fe-
male remained on west rim momentarily, then back down
onto nest to brood at 0826.“
I observed such behavior by the female at the nest 28 times
- twice at nest No. 12, twice at nest No. 17, and 24 times
at nest No. 19. It was never observed at nests No.'s 3 or
1+, the other two of the five nests under close observation
during the nestling stage. At nest No. 19 the male and
the female were both there at the same time on 27 instances.
On.24 of these the female got at least some of the food
:from the male. Sometimes this passing of food to the fa-

xnale does not take place right at the nest. On one occa-

ggion.at nest No. 19 when the young were four days old, the

".
9v

fem male was off but nearby the nest as the male came with
food. The male fed the female, who then went to the nest
to feed the nestlings. Again when thes young were 10 days
old she had just fed them as the male came to a perch near
the nest with food. The female left the nest to perch
near the male, took the food from him, and returned to

feed the young again. On another day the male c ame to the
nest while the female we 3 on the rim, but he successfully
dodged her thrust and fed the young himself. The female,
however, took the food out of the bill of the young he had
just fed and refed it to the same or a d erent nestling.
Another time, in attempting to dodge the female's thrust
at the food he was carrying, the male drOpped it into the
nestwhereupon the female immediately retrieved it and fed
the young. And yet on another occasion th male success-
fully fed one young, but as he irau ht his head out of the
nest With the remn ining food in preparation to feed a
second, the female grabbed what u 3 left and fed it horse l.

Wh n the nestlings apparently did not open their bills
at the approach of an adult, the latter gave the quirt call
repeatedly until the young usually Opened their bills to
receive the food.

If the female came to the nest with food, but aid not
feed; she settled down to brood W th the food still in her
bill. he usually still had the food in her bill when she
left, but twice she ate it while on the nest. Another

time, after settin'

(
v-.
V

n the nest with food in her bill, the

young began to ”seep" after she had been on the nest 7.5
minutes. She stood up, quirted, fed the young, and then
tsettled back down. Only once,when the female did not feed
the young,did she eat the food before settling on the nest
to brood. The male was observed to fail to feed two times.
Both times he ate the food before leaving the nest area.

The average interval between feedings by the adults
is 10.04 minutes. Table 23 lists the average interval be-
tween successive feedings according to the day of nest
life. The longest average interval was 19 minutes and oc-
curred on the second day. The shortest interval, 6.02
minutes, was recorded on both the eighth and eleventh days.
Considering the rate of feeding as indicated by the in-
terval between feedi rs and according to the four periods
of brooding, it can be seen that the rate generally in-
creases through the first two periods, days zero through
seven, and then levels off at an interval of 6.33 to 7.17
minutes during the last two periods, days eight through
eleven. Herrick (1901) reports the rate of feeding to be
about once every 3.5 minutes. Kendeigh (1952) states that
the rate remains uniform from day to day, being the lowest
during the hottest hours of th day. Gabrielson (1913),
however, also believes that the daily number of visits
does tend to increase with the age of the nestlings.

In food gathering, adults have been observed to cross
neighboring territories. Moapfood, however, was collected

within the territory in the near vicinity of the nest.

TABLE 23

AVERAGE LENGTH IN MINUTES OF THE INTERVALS
BETWEEN FEEDING ACCORDIN TO THE
DAYS OF NEST LIFE

 

 

Day
Of Nest O 1 2 3 4 5
Life

CA

 

 

Average 7.5 l914.2111.67 1010.3511.39:.3 3.027.638.326.02
Interval

 

 

 

 

 

 

 

 

 

Number

of Obsrv. 1 16 19 18 42 44 8 52 43 43 28 33
Intervals

Average

Interval 13.10 10.02 6.83 7.17

For Each
Period

 

 

 

 

 

Food

Numerous studies have been made on the food of nest-
lings and of adults. Judd (1900) examined the stomachs
of 14 nestlings and found their food to be 4 per cent
vegetable and 96 per cent animal material, the latter pri-
marily of ants, beetles, caterpillars, spiders, and grass-
hOppers. Gabrielson (1913) gives a detailed list of foods
he observed being fed to the young. Although some food
that was fed the young in this study was recorded in my
field notes, I made no real effort to determine the exact
nature of the food given the nestlings. The food of the
adults is Split about equally between insects and fruit.
Table 24 tabulates food studies reported by Beal (1397).
Judd (1897,1900), and Purdum (1902). Barrows (1912) reports
after Forbes that the fruit content of the food increases
more and more as the season progresses. In May the food
is 100 per cent insectivorous, then in June insects com—
prise only 64 per cent, and by July the insect portion is
down to 15 per cent. There are two reports of the Catbird
eating bees (Grant, 1945; Wood, 1930), and Phillips (1927)
recorded a Catbird observed to wade into shallow water at

a fish hatchery and catch 1% inch trout fry.

Nest Sanitation
If a fecal sac was voided after feeding, it was either
carried away or eaten. The carrying away of a fecal sac,
however, was not observed until the fifth day of nest life.

On the eighth day the sac was carried away about as often

FOOD OF THE ADULT IN OTHER STUDIES

(*1 ". 1‘ T“ ", ’
;..L1DL'J I; ‘7‘

."\ 1".
V x.‘

 

Number of

 

Source Stomachs Animal Vegetable
Examined
3/4-ants,beetles,
caterpillars,& l/3-cultivat-
grasshOppers ed fruit
Beal 213
(1397) l/4-bugs,miscell. 2/3-wild
insects, and fruit
Spiders
Judd 200 all insects all fruits
(1397)
Judd 11 9% unspecified all fruits
(1900)
124fl-beetles r
lOfl-ants lCfi-cultiv.
S%—catermillars fruit
Purdum 192 4fl-grassh03pers 435fl-wild
(1902) 4%e87iders and fruit

 

,J
2p-bugs

 

 

myriapods

k Sfi-miscellaneous

 

 

 

 

*Furdum also counted 1% as mixed mineral matter

 

101

as it was eaten. From the ninth day on, it was more often
carried away than eaten, but eating of the excreta was ob-
served on every day except the tenth. Gabrielson (1913)
states that up to the sixth day the fecal sac was devoured;
from the sixth day on, however, some were eaten while others
were carried away. The proportion carried away increased
toward the end of nest life. He found the fecal sac to be
removed 19 times and eaten 54 times, or 2.84 times as often.
I observed the fecal sac to be carried away 35 times and
eaten 122 times or 3.49 times as often.
If the young do not void after feeding, the adult may
perform some other action such as poking in the nest,
merely waiting or leaving immediately. Rand (1942) believes
that fecal sac removal is a complimentary action to feed-
ing, and the adult will substitute some other activity
such as pecking the young or poking in the nest if no sac
is voided by the young. My observations do not support
Rand's belief. In 411 feeding Operations that were ob-
served at the nest, the following subsequent behavior
was noted:
If a fecal sac was voided -
ate fecal sac 122 times ..................29.2€%
carried sac away 55 times................. 8.52%
If a fecal sac was not voided -
substituted some other behavior 44 times..10.71%
poked or peeked in nest 33 times...€.03fl

brooded lO times...................2.43%
left with egg shell 1 time.........0.25fl

'- A(-‘

1 1.. ,.J. ,‘ , ; 1 J. V ,1, AJ- 11 .. J. “’7
[1831 0-1qu 01" ‘u ’1... ‘0'.) d 53; JJ v-1 0 tone {188 0 1U}
;.

timggccooooooooooooooo0.000000000000000.ooi-JO¥'\‘

left immediately 104 times ...............25.fo

 

Not known if sac was voided or not............. 0.73%

After only 10.71 per cent of all feedings did the adults
substitute some other behavior, while 25.06 per cent of the
time they merely wa ted,and 25.30 per cent of the time they
left immediately. Table 25 tabulates these data for each
day of the brooding stage.. On two occasions when both the
male and female fed at the nest tOgether, only one sac was

voided. The mule tried to get the excreta, but both times

the female got it. The male then left immediately.

Nest Helpers

I have no observations of other individuals of the
same or different species helping the adults with their
nesting activities. There are several instances, however,
reported in the literature. Weatherbee (1930) reports a
situation where a Robin nested a few feet from a Cathird's
nest. The Robin was found incubating on the Catbird nest
numerous times; and after the young Catbird's eggs hatched,
the young fere regularly brooded find fed by the adult Robin.
After the female Cardinal had disappeared, Brooks (1922)
observed a Catbird feeding the Cardinal's young until they
were able to fend for themselves. In this instance the

male Cardinal tried unsuccessfully to drive the atoird

' J

:7

1‘ )

H

H)
l

away. Hayward (1937) reports a Catbird feeding
grown Flicker (Colaates auratus).

Sometimes other Catbirds came to the vicinity of the
nest to join the adults in alarm calls as I checked the

young. In only one instance out of the seven where a

TABLE 25

NEST SANITATION ACTIVITY FOR E£CH DAY OF NEST LIFE

 

 

 

 

Day Times Ate Took Poked Breaded Took Hesit— Left Unkx-In.
Fed Sac Sac Shell ated Imzz.
0 4 1 l 1 1
1 19 12 6 1
2 24 6 1 3 10 4
3 23 ll 2 7 3
4 50 2‘3 6 15 6
S 54 18 2 5 22 7
C 21 8 1 3 6 3
7 60 30 2 2 16 7 3
t 52 9 8 2 33
9 50 l2 14 14 6
10 W 30 2 4 22+
11 24 1 8 5 10
Totl 411 22 35 33 10 1 103 104 3

 

 

 

 

 

 

 

 

 

 

 

Catbird trespassed onto the territory of another in this
type of situation did the male of the territory drive off
the intruding bird. On three occasions at two different
nests a Brown Thrasher (Toxostoma rufum) that was nesting
nearby came to the nest, giving a call similar to that of
the quirt of the Cattdrd,while I was checking the Catbird's
nest. In another instance at nest No. 20 an Ovenbird
(Seiurus agrocaoillus) was attracted by the fuss of the
adults around the nest while I weighed the nestlings. The

Ovenbird gave loud chips.

FLEDGING
Only at nest No. 19 was the normal departure of the
young observed. In every other case the young exploded
from the nest on my morning weighing rounds. In these ex-
plosive departures the young fly off in all directions to
perch near or on the ground. Some scurry under some kind
of cover in the ground litter, and others remain perched

V

in the Open under the nesting thicket. If the young can
be found, they are easily caught and brought back to the
nest. Some young, when placed in the nest again, would
remain there; others immediately left the nest again. In

all cases where the young stayed in the nest after being

replaced, they were gone from the nest by the end of th

In the two days proceeding the departure, the young
are 1uite active in the nest, movii: about and fluttering
their wings. In deyarting from the nest the young move
up on the rim and then out onto the nearby branches. They
move about very little and flutter their wings to help
maintain tteir balance. The adults continue to come to
feed them at their perches near the nest. Five days after
fledging was the latest that fledglings were found in the

immediate vicinity of the nest.

I )

yr»

RENESTING

Of the seven pairs that were successful for a first
nestin5, five renested. Only nest No. 7 and nest No. 10
were not followed by a second nesting. The adults in these
two cases were 5one from the territory soon after fled5in5
of the first brood. The time between broods was counted
from the day of fledging of the first brood to the laying
of the first e55 in the second nest. The distance between
the firs t and second nest was ,aced off in a straiglt-line
direction. The five second nestin5s were as follows:

No. 12 followed No.

No. 19 followed No.

No. 13 followed No.

No. 13 followed No.
No. 14 followed No.

by ll days and was 30 feet away.
by 14 days and was 315 feet away.
by 10 days e.nd wa 60 feet away.
by 11 days and was 65 feet aiay.
by 8 days nd was 150 feet away.

(‘3 Chm \31 N

The second nest then followed the first by an ave ra5e of

3...:
O
(‘3
C:

ays and was located an aver ~5e f 124 feet awa‘
Both Latham (1936) and Mousley (1917) give an elapsed time
of 11o mxys whicha rees with this study. Mousley, however,
states that the second nest was 25? yards from the first;
and Black (1929), reporting on three successive nests of
a single pair in one season, stated that each nest was only
a "few inches" from the previous one. The second nest in
these five instances was built in the area in which the
young of the first nes st were bein5 fed.

I have no direct evidence tha the fairs in the first
nestin5s remain mated for the second. As has been stated,
the male does continue to defend the territory while the

first brood is being fed. It as also observed that

-J

F’"
'-

of the adults feed the young in the days following fled5in5.
The male of territory M continued to feed th youn; in the
area in which the female was building the second nest.

The male of territory D fed an immature bird near the se-
cond nest while the female was incubating. Forbush (1929)
writes that the male feeds the first brood, since the

second nest is be5un almost immediately.after they leave

the nest. I feel quite certain, in view of these observa-
tions, that the male is the same for both nestin5s; but

I cannot say anythin5 in this regard about the female.

There were no third nestin5s, and Barrows (1912)
states that two broods are usual for Michigan. In South
Carolina Charles (1954) reports three broods occurring
and Forbush (1929) also mentions that three broods had been
reported in Massachusetts.

Three instances of renestin5 followin5 the failure of
the first nest occurred. In one case,in territory J, the
male involved was a partial albino so that his identity in
connection with the two nests was certain. In the other
two cases th territory of each was closely observed, and
the males remained on their territories and sang regularly
durin5 the elapsed time. As in the case with the other
second nestin5s, it is not known if the female of these
renestings was the same. These renestin5s were as follows;

No. l was last in use the day the second egg was

laid. The second nest, No. 22, received its first

e55 42 days later and was located 208 feet away.

No. 4 was last in use on the ei5ht day after the
young were hatched. It was followed 14 days later

by No. 17, located 135 feet away.

No. 9 was last in use during incubation (exact day

unknown). The first egg was laid in No. 23, 43 days

later. This second nest was 60 feet from the first.
There is then an average of 33 days before the first egg
in the second nest is laid, and this nest is located an
average of 134.33 feet away. Charles (1954) writes that
only seven days passed before the first egg in the second
nest was laid after a snake ate the young of the first
nest.

There is a change in the shape and size of the terri-
tory fer the second nest, perhaps because the center of
activity shifts. For example, in territory M, nest No. 19
was located on the opposite side of the territory from No.
3. With this change in the nesting site, the area around
No. 3 which bordered territory K was relinquished to the
male of that territory. Of the five normal second nest-
ings and the three renestings after the initial nest
failed, only in territory R, where the second nest was
close to the first, was there no apparent shift in the

size and shape of the territory.

NESTING SUCCESS

Nesting Results

Of the 23 nests under observation, 14 or 60.37 per
cent fledged at least one young. Tables 26 and 27 tab-
ulate these nesting results. Batts (1958) found 43 to 47
per cent of 53 nests successful, and Berger (1951b) had
62.5 per cent of 40 nests fledge at least one bird. In a
total of 169 nests, Kendeigh (1942) reported that 70 per
cent were successful. Young (1949) writes that out of
22 nests, 55 per cent were successful.

In these 23 nests 74 eggs were laid. A total of 27
:eggs did not hatch as a result of the following causes:

".

c - either infertile or died as embryos

l7 - predation

2 - desertion
The 47 eggs hatching were 63.51 per cent of those laid. A
comparable figure of 65 per cent is given by Young (1949),
but Berger (1951h) found tlat in 21 nests studied, 93 per
cent of the eggs hatched.

Of the eggs that did hatch, 36 or 76.60 per cent of
the young were fledged. 0f the 11 young lost two fell
from the nest, one died from xposure and the other from
xposure or predation, and the remrining nine died as a
result of gradation. Young (1949) reports a similar figure
of 79 per cent, while Kendeigh (1942) found 55 yer cent
of the hatched young finally fledged.

Comgarin: the number of

D'OLInf‘, fled “QC: to .1"qu 130130.].

eggs laid, 43.65 per cent of the eggs :roduced fledglings.

TABLE 26

NESTING ZESULTS IN 23 CATBIRD NESTS

 

 

 

 

 

Period Nest Eggs Eggs Young
No. Laid hatched Fledged
First 1 2 o -
2 4 4 4
3 4 4 4
4 4 '5 o
5 4 4 4
6 4 2 2
7 3 2 l
8 4 4 3
9 2 o _
10 3 3 2
11 4 3 0
Second 12 2 2 2
13 4 O -
l4 3 o -
15 4 O -
l6 2 2 2
17 4 2 O
18 3 3 3
19 3 3 3
20 3 3 3
21 2 l l
22 3 2 2
23 3 o -
Total 74 47 36

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE 27
CAUSES FOR LOSS OF EGGS AND NESTLINGS
Nest] Infertile [ 7 _ [Exposure
No. or Deserted Predation.EXposure or
Embryo Died Predation
- Bees 7
l 2
4 l
6 2
7 l
9 2
11 l
13 4
l4 2 1
l5 4
l7 2
2l 1
22 l
23 3
Total 8 2 l7
Nestlings 7‘—
4 2 1 ‘
7 l
8 l
10 1
11 3
17 2
Total 9 l 1

 

 

 

 

 

 

 

a.‘
ll”

Berger (1951b), in 23 nests, reported that 65 young (T2 Ler
cent) were fledged from 79 eggs laid. Kendeigh (1942)
found th t 55 per cent of the e gs laid develoned fledg-
lings. Young (1949) reported that 51 per cent 01‘ the eggs
eventually resulted in fledged young.

Nesting activity can be grouped into two periods ac-
cording to the time of nesting, and their reSpective suc-
ces determined. In the first period from May 18 to July
3, composed entirely of first attempts, 30.56 per cent of
the 33 eggs laid hatched. Six eggs were lost to p=edation,
and ‘aree were either infertile or coxmt ined dead embryos.
Of the 29 young hatched, 68.97 were fledged. Seven nest-
lings were lost to predators and two died from exposure
and/or predation. The second period from June 19 to
August 25 was made up of :r sable la te first nestings or

arly second att empts and second nestings following a
successful or unsuccessful first nest. In these nests
only 50 per cent of the 36 egg hatched, but of the 18
nestlings only two were lost, both tresuma 31y throurh are-
dation in nest No. 17. This gives a fledging success of
CF.C9 yer cent. In summary then, the success of the two

nesting periods was as follows:

Hatching Pledging
First Period 30. 36% 63.97%
Second Period 50.00% 76.89%

First nesting s suffer their greatest loss from the fail-

ure of the hatched young to fledge, while later nest are

~ 1..
.... ,
..

unsuccessful due to the failure of the eggs to hatch.

Predation

As has been shown predation is the major factor in
the loss of both eggs and nestlings. Both Young (1949)
and Batts (1956) also found this to be true. No actual in-
stances of predation, however, were observed during the
study. A red squirrel did come to nest No. 17 While the
female was brooding the single remaining young, but the
squirrel was driven away by the fenale before the nest
was plundered. The young that fell out of nest No. 4 was
last seen on the litter in the shallow gully under the
nest with an eight-inch Milk Snake (Lamprgneltis doliata)
a few feet away. Apparently the snake had been attracted
by the presence of *he young and was perhaps anticipating
a meal. I had to leave the study area before the outcome
could be observed. One young of nest No. 11 was found
dead in the nest early one morning with its head bitten
off. Perhaps this was due to predation by owls. Both
Barred Owls and Screech Owls (QEE§_§§;Q) had been observed
in the area during the study.

The only evidence of egg predation was the finding
of broken egg shells under or near the nest. Often when
eggs were missing from the nest there was no sign of them
at all, the eggs apparently having been carried off.

On the day of the departure of their nest mates two
young were found directly under their nests with most of

the parietal and frontal areas of their skulls jacked away.

Both young killed were the runts if their broods. In one
case, at nest No. C, the young bird probably could fly,

but of the four young, it had the shortest wing measure-
ment. At nest No. 10 the nestling was the second of the

9
118

('I'

three hatched, but was so retarded that the barbs of
wing feathers had not broken through the she:‘ th, and it
grobably could not fly a ‘all. It might be that both
these young were killed by the adults, either accidentally
or inten ir>n 1h, when they failed to leave the nest, though
this is purely conjecture. No such instances are recorded
in the literature.

The following predators were found on the study area:

Reptilia: Milk Snake (Lamoroneltis doliata)
Blue Racer Coluber constrictor)
Garter Snake (Thamnoohis sh)

Aves: Marsh Hawk (Circus c‘aneus)
Screech Owl (Otus fig}
Barred Owl (Strix varia)
Blue Jay (Cyrnocitta cristata)
Common Crow (Corvus brachyrhynchos)
House Wren (Troglodytes aedon)

Common Crackle (guiscalus guiscula)

Mammalia: Ec astern Chipmunk (Tamias striatus)
Red Se uirrel (Tc miasciurus hudsonicus)
Long-tailed Weasel (Mustela frenata)

 

Table 28 lists the various Species reported in the litera-

ture as proven predators on Catbird nests.

Desertion
In the study by Youn; (1949),13.C4 per cent of his
22 nests were lost through desertion. I had only one case
of nest desertion (4.35 per cent of all nests); and it

mi: :ht have been th d rect result of gredation, since of

Source I

Batts (1958)
Charles (1954)

Errington (1935)

William and
Br. Alshonsus (1917)

 

[‘55
dd.

E

r". \ "x
1.1;:

CATBIRD NEST PREDATORS REPORTED IN THE LITERATUE; -7

 

Species

Mammalia

#J

Gray Squirrel (Sciurus carolinensis)

Rat (Rattus norvegicus), Cat (Felis
domestics), and Wmischevous boys

Red Fox (Vulnes fulva)

Cat (Felis domestics)

 

Aves

 

Batts (1956)

Bent from Breckenridge
(1941*)

Bent from Trine (1948)

Charles (1954)

Hamerstrom and
Hamerstrom (1951)

Howell (1951)

Lee (1927)

Morse (1923)

Nauman (1916)

Phillips (1951)

 

Finder (1923)
Warren (1890) '

Young (1949)

[Crackle (guiscalus quiscula)

House Wren (Troglodytes aedgn),
probable

Marsh Hawk (Circus cyaneus)

Grackle (guiscalus quiscula)

Crackle (guiscalus guiscula), Blue
Jay (Cyanocitta cristata)

Cooger's Hawk (Accipiter cooperii)

+1

Duck hawk (Falco geregrinus anatum)

 

House Wren (Trqglodytes‘agggg)
Long-eared Owl (Asio otus)
Blue Jay (Cyanocitta cristata)
Barn Owl (g:§g_g;§g)

Screech Owl (gigg‘agig)

Crow (Corvus brachyrhynchos)

TABLE 28 Continued

 

 

Source_

1

Species.

Reptilia

 

Batts (195C
Clarke (1915)
Laske y (1946)

Spencer (192”)

 

Common Garter Snake (Thamnoghis 5;.)
Milk Snake (Lampropelti§_doliata)
Pilot Black Snake (Elaohe s3.

Black racer (Coluber constrictor)

 

thethree eggs laid th third egg had dissapgeared over the
night grior to findinr the nest deserted. One cannot rule
out the gossitility that the female also might have fallen
trey. No adults of other nests under observation were

‘

known to have disagreared.

Cowbird ParaSitism

H

tism by the Cowhird.

”d

I observed no instances of garas
Friedmann (1929) lists the Catbird as a very uncommon vic-
tim, stating that "the Cowbird has never been definetly
reported to be successful with this bird". He also writes
that the atbird refuses to tolerate the Cowbird's eggs,

throwing them out of the nest. Todd (1940) also refers to

O
F!)

this activity throwing the foreign eggs out of the nest.

Norris (1947) found one nest out of 47 (2.1 per cent)
paaasitised by a single Cowbird egg which did not hatch.
In a total of 71 nests, Berger (1951a) found only one nest
parasitised (1.41 per cent). This nest contained two Cow-
bird eggs and four eggs of the host, but the Cowbird @538

q

isacgeared two days a ;er they were discovered. Berger
slanted an egg of the Cowbird in a Catbird nest, and an
dult removed this egg within three minutes, flying off

with it in its bill. He suggests that the Catoird may be

L)

g

a common host Species; but since the Cowoird lays very
early in the morning, the Catbird has already removed the
egg before the nest is observed. Trautman (1940) 1a no
eggs or the young of the Cowbird in 35 nests, but reported

two occasions where Catbirds were feeding Cowbird fledglings

3.4
',_1

out of the nest. Nickell (1953) discovered only 0.27 yer
cent of 3,000 Catbird nests in southern Michiga pa asi-
tised by the Covbird. These Cowbird eggs disappeared from
most nests in less than a day, and he also believes that
they are probably taken out by the Catbirds. In several
nests Cowbird eggs were found partially covered by the
lining material or buried two inches deep in the nest
foundations. One nest, however, had two 6 to 7 day old
.Catbirds and one almost-fledged Cowbird.

Bent (1948) reports that the eggs of the Yellow-billed
Cuckoo (Coccyzus americanus) have been found in Catbird
nests, but there are no reports of a case of successful

parasitism by this species.

External Nest Parasites

No study of nest parasites was made, but mosquitoes

P.

were observed to feed on the partially feathered nestl ngs.

Turle (1930) found lice on newly fledged voung, and Leakey

(1944) reported heavy infestation of the nest and nest-

lings with mites, Malloghaga, and ticks.

;.J
L-J

Dispersal of the Young

After fledging, the young remain in the immediate
vicinity of the nest for five to eight days. Depending
on the cover, they may remain in the nest thicket, as at
nest No. 3, where the young stayed within the confines of
the isolated nesting thicket up to the fifth day, or they
may be found from 40 to 60 feet away. After this period,
the young, accompanied by the adults, move farther away.

I have recorded them at distances from 150 to 350 feet
away from the nest. The young were still being fed by the
adults at this distance on the twelfth to fifteenth day.
With first broods this overlaped with nest-building and
egg-laying activity of the female, and in cases where the
sex of the adult was known, only the male was feeding the
young by this time.

I have only three records of young birds any great
length of time out of the nest. Two are observations of
the single young of nest No. 21 seen approximately 1550
feet from the nest n the 30th and 4lst day after fledging.
Both times this bird was in a small group of other Catbirds
(3 one time, 5 the other). The other record is of one
young from nest No. 19, 350 feet from the nest on the 37th
day after fledging. It was accompanied by two other un-

marked young (all the young of that brood were marked).

Flocking

After the nesting activity ceases and tie male no
longer is singing any song, the territory is abandoned.

The latest observation of an adult on its now defunct
territory was twelve days after he fledging of the second
brood. I found no immatures on what had been the nesting
territory after the fifteenth day. Laskey (1946) states
that from her banding records it appears the immatures
remain on the territory after fledging, but she gives no
time. Both adults and young birds congregate in low areas,
such as along Vermilion Greek or in brushy, marshy flats or
hollows. Although I have insufficient evidence, census
figures of these loose flocks, while not discerning
individuals, suggest that a particular flock is stationary,
remaining in one general locality. Gill (1936a) believes

these small,loose flocks are family groups, composed of

DJ

t e female and young and occasionally the male. The young

of nest No. 21 may have been with its parents when seen
again, but it was also accompanied by non-related Catbirds,
and the one immature of nest No. 19 was with two other

juveniles that were not nest mates. Perhaps these flocks

are not always family groups as Gill suggests.

Fall Departure
Since my last day in the field was September 23, I
do not know when the Catbirds left the study area. Barrows
1912) gives September and October and occasionally Novem-

.1.

ber as the months of departure in Michigan. Wood (1951)

1T1

1 3.

places the usual departure time durin; the first and second

weeks of October in southern Michigan.

SULELXRY

The nesting of the Catbird was studied in Clinton
County, Michigan, during the Spring and summer of 195? on
a 306.78 acre area with a vegetative cover of approximate-
ly 1/4 deciduous woodland, 1/4 woodland edge, l/d Cornus-
Carex lowlands, and 3/5 uplands of fallow pasture, brushy
abandoned fields, and several cultivated plots.

Male birds were first observed on the study area on
IMay 6, although they had been seen in the East Lansing
area five days earlier.. The females arrived no more tha.
nine or ten days later. *

Three songs of the male were discerned: the normal-
volumed song used most often in territory proclamation,
the quiet-song used as a signal song and in territory de-
fense, and the whisper song which was also used as a sig-
nal song. There are four categories of call notes: the
mew, quirt, quitt, 9nd ratchet—call. They are variously
used by both sexes in territory defense, in nest-related
activities, in communication between the ,air, find in alarm
situations.

The young were heard to give a food-begging and loca-
tion call, a loud metallic "ts p", and a wheezy-sounding
mew .

The male began to sing shortly before sunrise and has
been repor ed by others to sin a night.
No females were heard to sin

Song cessation was comtleted by the first week of

q 3..

‘b

J

August and no second son; geriod occurred.

Territories were immediately proclaimed throuyh sin;-
ing by newly arrived males, and chase—singing clashes oc-
curred between neighbors along the territory boundaries.
The male of an established territory defended it against

other Catbirds with in advance accomganied with a wheezy

H

i

mew, an attack, and a cause. Intersreeific defense dif-
fered in that no wheezy mew was given prior to the attack
and there was no chase. Both sexes attacked non-avian
intruders with a raised-wing, tail-spread, feathers-erect—
ed display. The male sang the quiet song and both sexes
mewed loudly and quirted. The diSplay of the female,
however, is less vigorous. The territory was defended un-
til comgletion of the second nesting. The average size
1.1704 acres giving 0.315

'1

of 15 maximal territories was
gairs ger acre. There was evidence of the xistence of
a small reserve of unmated males.

The only courtship display observed wa the chase
between the male and female.

Both adults arried nest materials during the early
days of building, but the female apparently made the site
selection and finished the construction. There was no
prolonged yeriod of site selection for the second nest.
Measurements were taken on 24 nests and their average
height was 63.3? inches above the ground. These nests

were located in 14 different sgeoies of trees and shrubs,

r-a . -- J n ' \q I I5 '\ '- q-r“'\ ’
wnd {race vines fo-med a ,art of the case or were

y uh

immediately adjacent in all but two nests. Most were in
brushy uplands, with woodland edge containing the next
largest number:* The nest is a three-layered structure with
herbaceous materials, woody twigs, and bark a the most
.abundant constituents. It was always found lined with
rootlets.

The number of eggs yer clutch averaged 3.27. Oviposi-
tion beman the day after the nest was completed and a ways

occurred in the mornine most often between 0900 and 1000.

‘U’

An egg was laid each da;

vv
0

until the clutch was com,lcte.

Only the female incubated. Incubation time was 14
eye for the first egg and 13 days for the other eggs in
the clutch. he incubation period was 13 days. The eggs
in one nest were incubated through the 23rd day before the
nest was abandoned. Incubation did not begin until at
leas‘ the second egg was laid. The average inattentive
geriod was 12.0? minutes, while the average attentive
period was 20.53 minutes. There was no daily variation
in attentiveness.

The female usually used the same route in coming to
the nest to incubate, often givin; mew calls as she ap-
proached. The male 0 ntinued to sing the normal-volumed

song during incubation. The female left the nest almost

half-the tim

(D

in res;onse to the male's signal. The mile

‘
‘

u the

*5

was seen to fe emale once after she had left the

(D

J V

nest. During tie inattentive period LAO male assumed

Lu

.. . , _,~ 9 f _‘ ‘ ‘ “a; _.--‘ '4 .‘ q 7‘ __ o. , . I,
one Luard fiBPCd 77.0 ier cent 0. the time and m intained

it for 31.2 yer cent of the unattended period. During
guarding the male whisper-sang, :reened, and wing-flutter-
ed. Females were also observed to wing-flutter at other
times. When the female returned,the male
of vocalization 59.1 per cent of L16 time before leaving
and was also heard to sing 43.1 per cent of the time after
the female was on the nest. The female was observed to
gape while incubating on hot days.

The female apparently contributed to the hatching of
the egg by peeking at the shell. Both adults rid the nest
of the egg shells by carrying them awa‘. Once, however,
the female ate onzhalf of a shell. The adults also at
the smaller bits of shell in the nest and on t
down of the nestlings.

0n the day of hatching, the young weighed 0.45 per
cent of the adult weight and by the day of fledgin; weigh-
ed 76.75 her cent. Total length and the lengths of the
wing and tarsus were taken daily. The nestlings were first
heard to give the food—begging call at three to five days.

The young spent an average of 10.47 days in the nest..
Brooding was done entirely by the female. She brooded

WI, T
.1; J

'5 oer cent of the observed time the first four .ays,

‘

25.80 per cent of the time the next four,only 3.52 per cent

(’l'

the next two, and no at all on the last two days. The

drOp in brooding was a result of a decrease in the length

of each attentive period 'nd a decrease in the rate of

these geriods. Brooding fell into three jeriods during

a fig

the day. The female used the same routes she established
during incuoation. While the female was brooding, the male
still sang the normal-volumed song but usually Just

short phrase. The fem 1e left the nest after the male's

signal 77.27 per cent of the time. The most frequent sig—

41

nals were the quiet-song and the :uitt. He came to one
nest over a route that is different from that used by the
female, and he usually signalled whether the female was
there or not. Sometimes the female did not leave as the
male came to feed. On these occasions she almost always

‘

took some of his food to feed t do n °stlings herself. When

J

the female was not at the nest, the nele assumed the

gerch 62.71 per cent of the time. He was observed to Cape,

Q

preen, quirt, and whis oe r-sing at the guard 3081t101 ind

to interrupt guarding with food gathering in the immediate
vicinit 3r of the nest. He signalled again $0.34 per cent
of the time the fentle returned.

Both adults fed the young, but the female did not
feed no; e often than the male until the last two days
of the nest life. If the nestlings did not cgen their
bills immediately, the adults ;uirted. The average inter-
val bet een feedings wa s 10.04 minutes. The feedini rate
generally ncreased during the first eight days and then

reUL‘ .ined about the same for the lost our. A review of

of the literature ga.ve the progortion of the various kinds
of food eaten by immatures find Ldults.

The fecal sac was seen to be eaten by the adults on

..J
:o
~1

every day of nest life except the tenth. Beginnin; on the
fifth day and continuin’: until fled :ging, the excreta were
also carried away. From the ninth day on they were carried
away more often than eaten. If there was no fecal sac
voided after feedin;, the adults substituted some othe°
behavior 10.71 Der cent of all post-feeding periods as con—
gared to leaving the nest immediately 25.30 per cent of

the time after feedin~

92'

Only one brood was observed during norm 1 departure;
all other broods exploded from the nest as I came on my
morning weighing rounds. Five days after fled; in; was
the la tes t that the young were found in the immediate
vicinity of the nest.

Second nestin 5s followed 10.? avs after the fledging
of the first brood and were located an average of 124 feet
atay. Renestings following the fai.lure of the first nests
averaged 33 days later and were built 1? 4.;3 feet a'e.y.

There was a change in size and sh :pe of the territory

A

(L‘
0

with the second n ‘t.

Of h 23 nests under observation, 60.?7 per cent
fledged at least one young. Although no eceual cases of

('5

predation were observed, it was the major factor in both

m
Sn.

PJ—

the loss of eggs and nestlings. No cases of parasit
by the C wbird were found.

The fledglings remained in the area of the nest for
five to ei; ht dcys. After this they were found 150 to 350

feet away in an area in which they remained until they were

5"'

no longer fed by the :dults. juver ile wss found 550
feet from its nest on the 30th a11d at Mn on the 41st day

afte A fled in“. Another wa found 350 feet awe; on the
37th day. Smell, loose flocks of adults and young formed
in the lower portions of the study area and 1erhags re-
mained in the san1e general location. There was no evidence
to suggest that these floc he were composed of family
groups. Fall de varture from the study a ea was not ob-

served.

a.)

y-)

LITERATURE CITE

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Bailey, Florence Merriam
1933. Cave Life of Kentucky. Amer. Mid. Naturalist,

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191?. Mimicry in the Song of the Catbird. Auk, 29:
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Ada/v0 .

Baldwin, S. Prentiss and 8. Charles Kendeigh
1933. Variations in the Weight of Birds. Auk, 55:
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1939. Results of Catbird Banding in Camden, New
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195”. The Distribution and Po;ulation of Easting
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Beal, F. E. L.
139 . Some Common Birds in Their Relaticn to Agri-
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36111-4, [to C o
194‘. Life Histories of North American Nuthatches,
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1951b. Notes on the Nesting Season of the CAtbira.
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1954. Injury-feigning by the C third. Wilson Bulle"
f g- _ ”fl

0 : v.1.

}..J

Bicknell Eugene P.
1934. A Study of the Singing of Our Birds. Auk,

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195:. Respiration Rates. Bird Banding, 29: 37-40.

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1890. Barred Owls in Captivity. Auk, 7: 101-114.

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1950. Successive Nest Sites of Individual Birds of
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1955. Size of Home Range in Eight Bird Species in a
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Brooks, Earl
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Burleigh, Thos. D.
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1954. Breeding Habits of the Catbird. Chat, 18: 3-
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1942. Descrigtive Notes on a Catbird Nest. Bird
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1954. A Simple Method for Obtaining Attentive Data.
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()

Errington, Paul L.

1935. Food Habits of Ilid-west Po: :es. Jour. g;
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1929

 

 

Freeman J.

h)

1949F Catbird's Defense Behaviorism. Auk, 65: 29

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Fry,

1929. The Cowhirds. Charles C. Thomas, Springfield,
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Henery J.
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1913. Nest Life of the Catbird, Dumetella carolinen-
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Gill Geoffrey

1934. A Migration Study of Catbirds from 1929 to
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1935. The Constancy of Catbirds to Mates and to
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0.

1936b. Further Notes on the Constancy of Catbirds to
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1940. An Analysis of Catbird Returns Over a Ten Year
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‘ l
P)

in:

V

Hamer: on, Franc:
1 7 2
l

o 1-1.. 1.. I 2". '7 a---
an a 4"." ~ . 3A - ta -
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s

\OH‘

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I..JI
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O

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’

 

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“'1”

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f‘J

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L
H

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(L)

'\
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Pindgr, L. Otley

 

 

mam U - v-1 -- '2' '- '34". .
y;,. Son A stellaneous hLCUJ on ,ires. .ii 0A
~. . .. .. " [/1
Ducht-Lan.’ J5 .L,9-lv"1' 0
w—. .L \ Ila "
.‘LI‘CS ULLIP .L' o N o
"‘ J.‘ 1 ,3 ‘ .1... a r
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1932. The 3 res cf Iinnesota Vol. II. Univ. of

 

 

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n—--;

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*5
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OCT 13 .7960 99

FEB 15 tum W

 

 

 

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