SELECTED
DWIOHT
VOCALIZATIONS
OF
THE
COMMON
CROW
R. CHAMBERLAIN AND GEOROE W. CORNWELL
BIO-ACOUSTICS
has developedrapidly in the past decadeas a tool in
the study of communicativemechanismsin wild birds (Hinde, 1969).
The Common Crow (Corvus brachyrhynchos)is an ideal experimental
subjectfor this type of research.Johnston(1961: 15) remarkshow even
the casualobserverof crow behaviorcan detect changesin pitch and rate
of call delivery, an indicationof the communicativepotential and behavioralcomplexityof crow vocalizations.In a study of the functional
anatomyof the syrinx, Chamberlainet al. (1968) found the Common
Crow to be morphologically
capableof producinga significantvariety
of notes.
Bent (1946: 247-249) describesthe characteristic
vocalizations
of the
Eastern CommonCrow (C. b. brachyrhynchos),citing observationsby
Hoffman (1904), Knight (1908), Wright (1912), Allen (1919), Townsend (1923), and Forbush (1927). Allen (1919) relates crow notes to
time rhythms, triplets, and other periodic combinations.Good (1952)
discusses
the meaningsof a numbero.f crow vocalizationsincluding: the
rally call, given after sightingor hearinga crow predator; the squalling
cry, uttered by a crow capturedby a predator; and the scoldingcall,
given by adult crows during the nestingseasonwhen the young are
threatened.The alarm, assembly,ordinary cawings,and beggingcries
of the younghavebeentestedwith Americanand Frenchcrows,bothin
Franceand the easternUnited States(Fringset al., 1958). Theseauthors
tabulatedpositiveand negativephonotaxicresponses
to. calls; they also
tested crowswith the calls of other species,in many caseswithout observable effects on the crows' movements.
Davis (1958) made audiospectrographic
analyses.
of typical calls of
variousspeciesof North Americanand Mexicancrows,on the basisof
whichhe describedthe crowof Sinaloa,Mexico,as a new species,Corvus
sin.aloae.Chamberlain(1967) intensivelystudiedthe soundsproduced
by the CommonCrowand the environmental
and behavioralcontextin
which each call occursin the wild. An annotatedmagnetictape of the
vocalizatio.ns
discussed
in this paper is availablethroughinterlibrary loan
of the thesisand from the Laboratoryof Ornithologyat CornellUniversity.
Thompson(1969) showsthe cawingof CommonCrowsdisplaystwo
kinds of organization,structuredand unstructured.He has evidencethat
the rigid, idiosyncratic
structuredpattern identifiesthe individualcrow;
the unstructured
patternreflectsthe degreeof the individual'sexcitement.
On this basis,our paperdealsprimarilywith unstructured
vocalizations,
613
The Auk, 88: 613-634. July 1971
614
CIClA3/iBERLAIN
AIqDCORNWELL
[Auk, Vol. 88
and only includessix sounds(contactcall, announcement
call, duet notes,
mimicry,courtshipsounds,and immaturehungerand feedingcalls) that
may determineindividual recognition.We did not analyze crow vo.calizations for the stable and predictablecomponentsnecessaryfor species
recognitionand distinctiveness.
METItODS
We
recorded
selected
vocalizations
AND PROCEDURES
of
wild
and
tame
crows
and
noted
the
en-
vironmental context and behavior accompa.nyingeach. Decoy mounted crows and
Great Horned Owls (Bubo vlrginlanus) were used when appropriate to elicit calls
requiring their presence. Selected crow calls and the distresscalls of three sympatric
avian specieswere transcribed onto continuous loop tapes from the original field
tapes. Loop tape tests were made from an automobile using a Wollensak 1700 T
recorder with a 10-watt amplifier and a U.S. Army surplus cone speaker powered
by a 12-volt car battery. The speaker was mounted on a ski rack on top of the
automobile during field tests. Test tapes were broadcasted to crows in the field,
with the automobile and testing equipment hidden as well as conditions allowed
from direct sight of the crows.
Crow responses
to testswere classified,in part, by the following phonotaxicsystem
derived from that of Frings et al. (1958):
Class I:
Specific predicted responseof crows within the estimated hearing
range.
Class II:
Class III:
Class IV:
ClassV:
Only part (quantified as much as possibleby field observation)
of the crows within the estimated hearing range responded as
predicted,while the remainderdid not respondat all.
Only part of the crows within the estimated hearing range
responded as predicted, while the remainder reacted in other
than the predicted manner.
No responseamong crows within the estimated hearing range.
Unpredicted responsesby crows within the estimated hearing
range.
This ranking scheme was used for field classification of behavioral responsesto
broadcastsof five crow vocalizations (Table 1). The expected responsewas predicted
prior to broadcast. Actual responseswere compared to the predictions as a further
confirmation
of the context
in which
the vocalizations
were
recorded
and
tested.
Vocalizations failing to elicit a responsewere tested repeatedly to establish the specific
context under which they were given.
The reactions to field tested vocalizationswere also classifiedas "positive" (q-)
or "negative" (-) phonotaxis and "other" responses. "Positive" phonotaxis was
recordedwhen crows respondedby flying directly to the broadcastsource. "Negative"
phonotaxis was recorded when the responsewas a direct flight away from the broadcast source. The balance of responseswere tabulated under "other" (see tabular
documentation in Chamberlain, 1967). Sounds that caused overt responsesamong
crows were classified"primary" and nonresponsesoundswere designatedas "other."
Three tape recorderswere used in the field to record Common Crow vocalizations:
A Wollensak model 1700 T with a built-in converter and a Wollensak hi-impedance,
omnidirectional, crystal microphone (50-8,000 c.p.s.) along with a Turner model 58,
omnidirectional,hi-impedancemicrophone; a battery operated Kudelski Nagra III
July 1971]
Common Crow Vocalizations
TABLE
615
1
CLASSIFICATION
OF CROW I•.ES?ONSES
TO CROW VOCALIZATIO]gS
TESTEDAND I•.ANKED
1
Class of response
Crow vocalization
Prediction
I
Assemblycall
Aggregationto
sound source
Simplescoldingcall
Aggregationto
12
sound source
80%
Dispersalcall
Dispersalfrom
27
91%
8
sound source
67%
Squallingcall
Aggregationto
sound source
22
88%
Moribund call
Aggregation to
5
soundsource
25%
II
2
6%
III
1
3%
3
20%
2
-
IV
V
Total
tests
-
-
30
-
-
15
-
-
1
-
3'0
8%
-
25%
3
12%
-
-
25
2
7
20
4
10% 20%
12
10% 35%
Extensive tabular documentationof crow responsesin Chamberlain (1967).
One test included 21 Fish Crows.
with a Nagra III omnidirectional microphone; and a Hitachi transistorizedportable
model TRQ-370 with a Hitachi model TRQ-370 unidirectional microphone was used
for short range recording. A 39-inch parabolic reflector was used to pick up distant
crow vocalizationsand a 26-inch snow coaster disc to tape those nearby. Missilgrams
made on a Missilyzer manufactured by the Kay Electric Company were used to
illustrate
call differences.
PRIlVrARY VOCALIZATIONS
As SElVrBLY CALL
The assemblycall is an intenseand raucousmobbingcall containing
long notes (wide band width of individual call notes) (Figure 1A), and
is given when.crows see or hear nearby crow predators, e.g., the Great
Horned Owl, Red-tailed Hawk (Buteo jamaicensis),or red fox (Vulpes
]ulva). The assemblycall has the apparent function of calling together
a group.of crowsto drive predatorsaway from placesthe crowsfrequent,
suchas nesting,roosting,or feedingareas. The CommonCrow assembly
call attracts to. the sound sourceCommonand Fish Crows (Corvus ossi]ragus) within hearingrange (Table 1).
Assemblycalls are given throughout the year. Field tests and/or
observationswere made during all months o.f the year. Six night visits
to Virginia crow roostsrevealedthat CommonCrows give assemblycalls
at night. These night observationsare the basisfor all followingreferences
to night vocalizations.
When giving the assemblycall from a perchedand erectposition,the
Common Crow holds the contour and wing feathers close to the body.
The tail is retainedapproximately1 inch below the body plane, and the
616
CI-•A1VXBEIRLAIl•
AI•TD
CORIffVq'ELL
[Auk,Vol.88
Figure1. A, assembly
call; B, simplescolding
call; C, modified
scolding
call;
D, alertcall.(Certain
vocalizations
areillustrated
morethanonce
to show
variation.)
July 1971]
Common Crow Vocalizations
617
rectricesspreadlaterally about 2 inchesbeyondthe tail's closedposition.
The tail flicks up and down below the body plane during the call, and
the wings move rapidly up and over and back and down to a closed
position.Crowsemittingassembly
callswhiledivingat an aerialpredator
have a dihedralwing angle,and often extendthe legswith clawsopenin
the mannerof a raptor closelypursuingprey. Crowsrespondingpositively
to the assemblycall fly with rapid flappingwings.
SIMPLE
SCOLDING CALL
The primary function of the simplescoldingcall (Figure lB) is to
announcethe presenceand location of a crow predator. Good (1952)
describesthis call. One of the three mobbingcalls the CommonCrow uses,
the simplescoldingcall is more sharplystaccatoand continuousand not
so raucousas the longer-notedassemblycall, althoughraucousnotesare
commonto both calls. The simple scoldingcall is given when a crow
hears an unseenpredator, and also while approachinga distant predator
it can see. At close range the scolding vocalization is abandoned for
assemblycalls,whichare moreeffectivein driving away a crowpredator.
Simple scoldingcalls are deliveredat various degreesof intensity
dependingon the type of predator,its distancefrom the crow, its movements, and the seasonof the year. For example, Common Crows give
intenseand rapid scoldingcallswhenthey hear hootsof the Great Horned
Owl, but less rapid and intensecalls when they hear the clucksof the
Sharp-shinnedHawk (Accipiter striatus). Apparently this variation in
calling occursbecausethe Great Horned Owl is a crow predator in winter
roostsand springnestinggrounds,whereasthe Sharp-shinned
Hawk rarely
preys
upon
crows.
Given throughoutthe year, day or night, CommonCrow simplescolding
callsattra.ctboth Commonand Fish Crowsto the soundsource(Table 1).
Crows do not remain near the test sourceof the simple scoldingcall for
as long a time as with the assemblycall. They dispersed
beforethe field
testsendedin 5 of 15 broadcasts.Somebirds continuedto.repeat simple
scoldingcallsup to 10 minutesafter field testsstopped.
When giving the simplescoldingcall perchedand erect, the Common
Crow movesthe head up and down and forward and backward. When
the headmovestowardthe tail andup, the wingsflick up and away from
the body. The beak closeswhen the head movesforward and down and
openswhen the headmovesback and up.
Crows used alternate flapping and gliding flight when approaching
simplescoldingcalls during 4 and rapid flapping flight in 11 of 15 field
tests.
618
MODIFIED
C•^•r^•
^•
Co•wtnn
[Auk, Vol. 88
SCOLDING CALL
The modifiedscoldingcall is a mobbingcall and is functionallysimilar
to the simplescoldingcall, whichit closelyresembles,
but all its notesare
infiected(Figure 1C). It is utteredthroughoutthe year, day or night,
in responseto the vocalizationor distant sightingof crow predators.
Posturesaccompanying
this call are nearlyidenticalto thoseof the simple
scoldingcall. In five testscrowsdid not approachso rapidly or remain
near the soundsourceso long as in response
to.the simplescoldingcall.
ALERT CALL
The conversational
alert call expresses
the crow'sawareness
of danger
perceivedby auditory or visual means. Alert signalsvary in intensity,
frequency,duration and number of notes (Figures 1D, 2A), and also
vary in delivery accordingto. the immediacyand type of danger. For
example,alert notesgiven by a ground-feedingcrow surprisedby a predator are sharp, intense,and rapid. Those uttered by a crow that seesa
hunter approachingat a distanceare lesssharp,lessintense,and spaced
at greaterintervals. The distinctivefeature that separatesthe alert call
from simplescoldingis the numberof notesper call. The simplescolding
call hasan unlimitednumberof notesper series,whereasthe alert sequence
rarely has more than sevennotes, and generally six or less. The alert
call is often deliveredmore rapidly than the scoldingcall. Alert calls did
not provokea dispersalresponseamongcrowstested.
Some birds indicate the type of predator with their alert calls, and
some have specificcalls to. distinguishaerial from ground predators.
Collias and Joos (1953) note that the hawk call of the Domestic Fowl
(Gallus domesticus)is an intense,harsh scream,but that for a dog or
man is a cackling sound. Catbird (Dumetella carolinensis) alert calls
changeabruptly from short notes to protracted catlike "meows" as an
intruder approachesthe nest (Collias, 1960': 369). We found no such
differencesin crow alert calls, and 12 tests suggestthat the number of
notesper crow alert seriesdoesnot conveyshadesof meaningor degree
of danger.
The function of the alert call is to warn crowsof nearby or distant
danger.Crowsrespondto thissignalby emittingalert, assembly,modified
or simplescoldingcalls,flying up into treesif on the ground,and flying
away from and back to an arborealperch. Also, perchedcrowsshow
nervousmovementssuch as rapid wing and tail flicking and frequent
defecation. The posturesassociatedwith the alert call are similar to
thosefor the simplescoldingcall. In 12 of 17 tests,crowsresponded
positivelyto the alert call by givingassembly
and simplescoldingcalls
whileapparentlysearching
for the nonexistent
predator.
July 1971]
DISPERSAL
Common Crow Vocalizations
619
CALL
The dispersalcall (Figures 2B, 2C) is the extremedegreeof the alert
call. Its notesare generallysharper(thinner band width), and they are
deliveredclosertogetherthan alert notes. The first note is often infiected
(Figure 2B). The variability in soundintensity betweenalert and dispersalsignalswas not measured,
althoughwe suspectthat dispersalcalls
are deliveredwith greater volume than alert calls. The. dispersalcall
made CommonCrows fly directly away from the test area during eight
broadcasts.In three testsCommonCrowscameto the call giving mobbing
callsand apparentlylookingfor a predator (Table 1).
Dispersalcalls are given by crowsthat senseimmediatedanger,such
as a hunter'ssuddenappearancenearby. Crowsin roostscommonlygive
oneafter sightingdanger,say a Great HornedOwl. The numberof notes
in a dispersalcall doesnot appearto conveydifferent degreesof danger
to responding
crows.We believethis is the vocalizationFringsand Frings
(1957) refer to as the alarm call consisting
of "four short notes." We
foundthe dispersalcall to vary in notenumber. In eight testsof dispersal
calls scoresof crows rose out of trees and flew high in the air, massing
in a circlingflock and giving simplescoldingand assemblycalls.
Frings and Frings (1964: 58) state, "If a crow suddenlyflies away
from the group without making any sound,the. others usually follow.
It has spreadan alarm--the fastestand safestway." Chamberlainmade
a supposed"sentry" perchedabove a flock of ground-feedingcrows fly
on four different occasionsduring this study without giving a dispersal
call. In each case the flock remained on the ground until Chamberlain
camewithin their sight.
SQUALLING CALL
Squallingca]Isare givenby crowsstrugglingto.escapefrom a predator
suchas a hawk or fox, and can be producedby holdingan immatureor
adult crowupsidedownby its legsand shakingit (Figures2D, 3A). It
variesin intensity•frequency,tempo,and durationwith the gravity of
the situation. For example,a crow that is shakenvigorouslydelivers
squallingnotesmore intensive]y,sharp]y,and rapidly than one shaken
slowly. Squallingca]Isare generallyhigherpitchedand have more of a
wailingquality thanothercrowvoca]izations.
Common and Fish Crows respond to immature and adult Common
Crow squallingca]Isby gatheringrapidly to the soundsource(Table 1).
At night CommonCrowswi]] fly to squallingca]Is near a roost. One
Januarynight in westernVirginia, crowsgaveassemblyand simplescolding ca]Is over the soundsourcebefore settlingback into coniferssome
620
CI•A1VZBERLAIN
A•D CORNWELL
0.5
LO
TIME
IN
05
IN
L5
•
SECONDS
I0
TIME
[Auk, VoL 88
15
20
SECONDS
c
10
TIME
iN
SECONDS
TIME
IN
SECONDS
t5
20
1,5
20
i
D
I0
Figure 2. A, alert call; B, dispersalcall; C, dispersalcall; D, squa111ng
call.
July 1971]
CommonCrow Vocallzatlons
621
A
015
LO
TIME
0.5
I•
go
I•i
gO
IN
•
LO
c
Figure3. A, squallingcall; B, squallingcall broadcasted
in reverseat the speed
originallyrecorded; C, moribundcall; D, threat call.
622
CHA1V•BERLAIN
ALOUD
CORNWELL
[Auk, Vol. 88
200 yards from thoseoccupiedbeforethe test. Broadcasting
distresscalls
of the EuropeanJackdaw(Corvusmonedula)eliciteda negativeresponse
at night in Frenchcrowroosts,causingbirds of severalspeciesto desert
the roostspermanently(Fringset al., 1958).
Crows respondto squallingnotes with assembly,modified, and simple
scoldingcalls. They apparentlyapproachedthe soundsourceintending
to mob the crow predator. We broadcasted adult squalling calls in a
crow roost in westernVirginia in January with the tape reversed. The
crows respondedby aggregatingto the sound sourcein spite of tape
reversal (Figure 3B).
MORIBUND CALL
The moribund call (Figure 3C) is the extreme squallingcall of the
CommonCrow and is emitted by a dying crow. Moribund calls are not
deliveredas rapidly or loudly, but are more raucousand gurglingthan
squallingnotes. Becauseof its weakenedconditionwhile giving this call,
a crow doesnot struggleor fight off a predator. The moribundcall is a
definite communicationproducedby the dying bird and not a sound
producedmechanicallyor incidentallyin the processof dying.
Crows showed variable responsesto the moribund call tested in the
field. In 20 tests, crows exhibitedpositive phonotaxisin 5, negative
phonotaxis
in 7, and made8 other responses
(Table 1).
THREAT
CALL
The threat call (Figure 3D) is the mostvariableof the CommonCrow's
vocalizations.Threat calls are often given as screams,cackles,staccato
and rattling notes,coos,and a variety of other sounds. They occur in
a highly variablecontextand are often indescribable.A crow may utter
one when under attack or threat, or when attacking or threateninga
predator or another crow. Crows respondedto five field tests in an
unpredictable manner.
Threat calls are the commonestnotes heard among roosting Common
Crows. The birds compete with one another for roosting perches. In-
comingcrowstry to.dislodgethosealreadyroosting,and both the attackers
and those attacked utter threat calls. The apparent function of these
signalsis to make the opponentretreat.
Good (1952) describesgrowlcalls givenby CommonCrowsdiving or
pursuinga wingedpredatorat closerange. Prior to diving at a flying
predator,a crow will first hover on beatingwings,then start an erratic
descentwith wingsclosedin a dihedralover the rump. In sevenobservations the legs were extended with open claws, and a type of threat
July 1971]
Common Crow Vocalizations
623
ID
Figure 4. A, growl call; B, immature hunger and feeding call; C, contact call;
D, announcement call.
624
CItAMBERLAIiN
^•) COR•WE•
[Auk, Vol. 88
vocalization (or growl call) was emitted when the crow passedclose to
the predator (Figure 4A). Crows while mobbing a flying or perched
raptor give assembly,simpleand modifiedscoldingcalls, but supplant
them with threat calls when close to or within striking distance of a
raptor. One April Chamberlainheard an adult CommonCrow emit threat
signalswhen diving upona Turkey Vulture (Carthartesaura) that came
near its nest containingthree fledglingsin west central Florida.
During threat vocalizationwhile perched,the neck, nape, throat, and
head feathersare erect and appear ruffled. The wings move back and
up when the bird rears back while under attack of when threatened.
The wingsmay be droopedand spread,and the headloweredbetweenthe
legsprior to attackingor beingattacked.
IMMATURE
HUNGER
AND FEEDING CALLS
Immature CommonCrowsgapeand give thesecalls (Figure 4B) when
stimulatedby hunger or the sight of food, by seeingor hearing objects
associated
with food,or by a combinationof any or all of these. Hunger
calls elicit variable responsesamong crows in the field. Frings et al.
(1958) statesthat "beggingcriesof youngnestlings"had no observable
effect
on the movements
of crows when
field
tested.
In
31 tests we
obtained 14 positive,9 negative,and 13 other responses
to hunger calls
broadcastedin the field (8 tests showedtwo classesof responses).
The hungercall resembles.
squallingnotes,but its individual notesare
no.tso protractedand wailing. The feedingcall containsa numberof rapid
but clearly distinguishable
notesdeliveredby the youngwhile swallowing
food after uttering hunger notes while gaping. Hunger calls are subject
to differentdegreesof delivery,dependenton the amountand proximity
of food in relation to the calling bird. The stronger the stimulus, the
fasterand moreintensethe delivery of the high-pitchednotes.
Muir (1954) noted that unfed young Tawny Owls (Strix aluco) call
more often than fed ones,thereby expressingtheir degreeof hunger; he
suggests
this behaviormay bring about a more even food apportionment
amongthe youngby adult owls. We notedthis samephenomenon
in both
tame and wild CommonCrows. Immature hunger calls also function as
locationnotes,helpingparent crowsreestablishcontactwith their young.
Pet crows often associate food with a human voice when talking ac-
companieshand feeding; these.birds stop their insistent hunger calls
when the ownersare concealedand quiet, but promptly resumegaping
and the accompanying
vocalizations
whenthey seeor hear their owner.
Many bird speciesare known to have food calls given by the adult
that stimulatefeedingresponses
in the young,suchas the YellowWarbler
July 1971]
Common Crow Vocalizations
625
(Dendroica petechia) and Least Flycatcher (Empidonax minimus)
(Collias, 1960: 369). We detectedno specificvocalizationgivenby parent
crowsto their young that could be interpretedas a food call. Nestling
crows respondwith hunger calls to virtually all vocalizationsof adults
near the nest,includingthe assembly,simplescolding,alert, and dispersal
calls.
While giving hungercalls in or out of the nest when perched,immature
CommonCrows move their wings rapidly up and down away from the
body. The tail alsomovesup and down during begging. The bright-red
mouth is evidentduring the period of open-mouthedfood begging.
CONTACT CALL
The componentsof group movementsby CommonCrows are assembly,
preparationfor movement,initiation, liaison while moving, and cessation.
Land birds that travel in flocksappearto placeheavy relianceon contact
notes betweenindividuals. Marshall (1964) lists a "seep note" by the
Brown Towhee (Pipilo fuscus)that mated birds use to maintaincontact
with each other when they are a short distance apart but hidden from
eachother. Odum (1942) notesthat the "chick-a-dee-dee-dee"
call of the
Black-cappedChickadee(Parus atricapillus) is usedto maintain contact
when the flock is scattered. Contact notesthat function to keep the flocks
togetherare commonin migrating crows (Figure 4C). This call char-
acteristicallycontainsthree, four, or more notes;but, commonlya fournoted sequenceis uttered by one crow in note pairs. CommonCrows
maintaingroupcohesion
by answeringeachotherwith identicalor similar
contactnotes,particularlyin roostsand in migratingflockswhen pairs
become separated.
Crows emit contact calls while in flight or perched. When perching,
the associatedposturesare similar to thoseusedin simple scoldingcalls.
ANNOUNCEMENT
CALL
Announcementcalls (Figure 4D) are used by individualsflying to
join an aggregationof CommonCrows, such as those at feeding grounds
or roostsand functionas a form of recognitionand contact. These calls
are extremelyvariable in quality of delivery, and often closelyresemble
simplescoldingand assemblycalls,but are usuallymuchshorter. Common
Crowsgive thesecalls when in gliding or flapping flight. During gliding
flight the bird descendsat approximately45 degreeswith wings held in
a dihedral position,the tail level with the body or angled dorsally. On
five instances,
an answerwasreceivedfrom a flockmember(s)
beforethe
bird resumednoisy,flappingflight.
626
DUET
C•^:•BERL^• * AI•IDCORNWELL
[Auk, Vol. 88
NOTES
These notes (Figure 5A) were heard betweentwo tame, caged adult
CommonCrowsseparatedby an opaquepartition. Both birds appeared
to be males. These two crowsdevelopedfour recognizableduet combinations including rattling notes and cawing variations that they used to
establishmutual recognitionwhen out of each other's sight. Apparently
paired wild crowsalso use these duets for individual recognitionand
contactin roostsor largefeedingflocks.
Many bird speciespractice duetting,generallybetweenpairs (Thorpe
and North, 1965). CommonCrows are no exception: one crow emits a
certain
vocalization
that
stimulates
another
crow
to answer
in kind.
Five duetswere heard betweenfive different pairs of wild crowsin roosts
during this study.
COURTSHIP
VOCALIZATIONS
The observation and recording of vocalizations associatedwith pre-
copulatorybehavior in the Common Crow were too limited to justify
reportinghere. Bent (1946: 227-229) describes
the behaviorand vocalizationsaccompanyingCommonCrow mating.
OTHER VOCALIZATIONS
Juvenile notes.--Immature crows in their first year have a variety of
juvenile notesthat are apparentlypracticedwhile gainingexperienceprior
to actual use (Figure 5B). An immature Common Crow Chamberlain
heard in July emitted juvenile.notes resemblingassemblycalls. In west
central Florida we recordedan immature Common Crow in April trying
to give the screamspeculiar to the Florida population of the Common
Crow (C. b. pascuus) (see below). Juvenile notes are given with the
head loweredand beak open. The wings flick up and away from the body
and down to a closedposition.
Contentment no.tes.--Five tame crows in southwesternVirginia gave
contentmentnoteswhen they had fed to capacity,were having their throat
feathers stroked, or were otherwiseapparently content. These notes are
soft and plaintive to the ear (Figure 5C). While emitting them the bird
sits low on a perch in contrast to the erect position during the alert call.
Rattling notes.--Rattling notes are heard within crow roosts as well
as from flocksof feedingand migratingcrows(Figure 5D). This vocalization generallycontains5-20 sharply delivered,staccatonotesin a single
utterance, somewhat like a rapid woodpeckertapping. Rattling notes
are given by apparently paired crowswhen diving near each other, while
descending
into a roost,or whenenteringa diurnal feedingflock. Clucking
July 1971]
Common Crow Vocalizations
627
A
B
c
0.5
I:O
L5
?•0!
Figure 5, A, duet notes; B, juvenile notes; C, contentmentnotes; D, rattling
notes.
628
Ca^•BERL^•S ^•m CORNWEL•
[Auk, Vol. 88
sounds,intermediatebetweenrattling and threat notes,are utteredwithin
feedingand migratingflocks. In July in southwestern
Virginia, a juvenile
crowgavehungercallswhile approaching
an adult crowin a tree, to which
the adult respondedwith rattling notes..Given by both male and female
CommonCrowsin captivity, rattling noteselicitedno observableresponses
from wild crows when field tested.
Rattling notesmay be oneof the male courtshipcallsaddressed
to.the
femaleprior to matingin the spring. The femaleanswerswith submissive
vocalizations
similar to thoseimmatureCommonCrowsgive when begging
for food (Townsend,1927). Townsendstatesthat rattling notesmay also
be emittedby malescominginto sexualmaturity for the first time in their
secondfall while aerially pursuing females. One Septemberin western
Virginia, Chamberlainwatchedat least 14 CommonCrows of unknown
sex and age erratically pursuingand diving upon each other while constantly givingrattling and threat calls.
Wow-wow notes.--•Vow-wownotes (Figure 6A) were given repeatedly
by three adult tame crowsbut were never heard from crowsin the wild.
This sequencesoundslike a dog yelping, but was not believed to be
mimicry becauseit was heard from birds in New York and Virginia. No
function could be associated with this vocalization.
While giving wow-wownotes,the head is moved up and down as if
bowing,thebeakis opened
andclosed,
thetail feathersarespreadlaterally,
the wingsmoveup and away from the body and downto a closedposition,
the nictitatingmembranecoversthe cornea,and the bellyshakesnoticeably.
Carr-carr notes.--Carr-carr notes are protracted caws (Figure 6B).
These were recordedin Septemberat a crow roost in western Virginia.
We saw no responseto them by roostingcrows. We twice heard threesyllabledcarr-carr notes uttered near an active crow nest by an adult
crowin May, and onceby an adult crowin a flock of eight crowsperched
in elm trees in September,both in western Virginia. No responseor
particularcontextwasnotedin eitherinstance.
Whisper notes.--•Vhisper notes, as implied, are muted. We recorded
an adult crow giving whisper notes (Figure 6C) resemblingalert calls
in March in western Virginia. Staccato whisper notes also were heard
in a crow roost one February in southwesternVirginia. No responsewas
noted in either
instance.
Coo notes.--In Myakka River State Park, Florida, Chamberlainwalked
near a family group of CommonCrowsin April. The two adults uttered
assemblyand simplescoldingcalls,and one adult gave a two-notedhigh
pitched "coo-coo" (Figure 6D) between these mobbing calls. Nearby
crows made no. apparent response. A coo note was again heard in the
July 1971]
Com•non Crow Vocalizations
629
A
B
D
Figure 6. A, wow-wow notes; B, carr-carr notes; C, whisper notes; D, coo
notes.
630
C•^•B•L^X• A•D CO•t•WEL•
[Auk, Vol. 88
s' A
0,5
0,5
Figure7. A, organnotes(delineated
by arrowsnext to a scoldingnote); B•
wah-oo notes; C. C. b. pasctatsscreams.
samelocale,givenby an adultcrowpriorto an alertcall directedat the
observer.Coonotesmay be associated
with danger.Similarsounds
have
beenheardfrom tame crowswhenseeingstrangepeople,dogs,etc. Townsend(1927) describes
apparentlysimilarcoonotesas one of the male
precopulatoryvocalizations.
Organnotes.--Chamberlain
useda crowcallto lurecrowsto a mounted
Great Horned Owl in westernVirginia in March. The crowsgavesimple
scolding
andassembly
callswhilemobbing
thedecoy.Duringthemobbing•
July 1971]
Common Crow Vocalizations
631
one crow with a flock perchedin a clusterof conifersuttered at least 10
high-pitched
organnotes(Figure 7A). No particularresponse
by individual
crowsperchednear the crow uttering organ noteswas seen. Organ notes
may be similarto coonotesin that they are associated
with danger.
Wah-oo note.--In southwesternVirginia a crow was recordedgiving
a singlewah-oo note in a roost in February approximately10 minutes
before sundown (Figure 7B). On 12 occasionsduring the study,
crepuscularcrow sounds similar to wah-oo notes were heard, but not
taped. Roostingcrows emit many soundsnot encounteredelsewhere,
includingsoundsassociatedwith threat. For example,one adult crow in
a flock of crowsflying into a roostin westernNew York uttered highpitched,four-syllabledchippingnotes.
C. b. pascuusscreams.--Individualsin the Florida population of the
CommonCrow commonlyproduceintense,raucousscreams(Figure 7C).
Crows near the sound source make no apparent response.
Bent (1946: 262) statesthat severalobservers
havereporteda vocalization peculiar to the Florida Crow. Mortimer (1890) heard soundslike
the criesof a cuckoo(Coccyzussp.). These may have been similar to
the crow screamswe heard in Myakka River State Park, Florida.
Mimicry.--Common Crows often mimic other birds and mammals.
Forbush(1927) hearda crowgive an excellentimitationof the whine of
a dog. He also heard crows emit a varied assortment of notes, some of
which were imitations,suchas the cry of a child, the squawk of a hen,
and the crow of a youngrooster.
In captivity, crowslearn to mimic the human voice, as Chamberlain
noted in eight tame crows studied. One adult male crow in western
Virginia, couldsay "oh my God, oh Lord" very clearly. An adult male
crowin westernNew York couldsay "hello" loudly and clearly. One in
Florida announced"I'm Jim Crow." The myth regarding splitting a
crow'stonguebeforeit will "talk" is probablyattributable to the natural
split at the tip of the tongue.
One of the functionsof mimicry may be to establishand strengthen
the individualpair bond (Thorpe and North, 1965). This is particularly
so in those specieswhere territorial aggressiveness
is not very marked,
as the Common Crow (Good, 1952). In certain species,this ability
enables each bird to learn the vocal contribution
of its mate as well as
its own (Thorpe and North, 1965). Crowsmay usethis trait in maintaining contactwith a mate. If so, the extremeof this unusualimitative
ability of birdsin parrots(Psittacidae),Starlings(Sturnusvulgaris),and
crowsis plausiblyexplained. PerhapsCommonCrows in the wild use
thesepowersto imitate the idiosyncrasiesand inflectionsin the vocalizationsof their mates,or othermembersof a flock.
632
Ct:IA3.•BERLAIN
AND CORNWELL
[Auk, Vol. 88
Interspecificresponseto distresscalls.--CommonCrowswere testedby
distresscalls of the Starling, Bluejay (Cyanocitta cristata), and the
CommonGrackle (Quiscalusquiscula). They gatheredto the Bluejay
calls in 5 of 10 tests,showedno responseto the CommonGracklecalls
in 5 of 6 tests,and were unpredictablein responseto the Starlingcalls.
Fish Crowsrespondedpositivelyin all testsof the Starling call.
ACKNOWLEDG2V[ENTS
Release 68-1 of the Virginia Cooperative •Vildlife Research Unit, Virginia Commission of Game and Inland Fisheries,Virgina Polytechnic Institute, Wildlife Management Institute, and U.S. Fish and Wildlife Service,cooperating.This investigationwas
financed by the Frank M. Chapman Memorial Fund and The Virginia Commission
of Game and Inland
Fisheries.
The authors thank S. A. Cable for technical assistance
and equipment maintenance and for permitting use of the electronic equipment in
the V.P.I. Radio and Motion Picture Studio. Appreciation goes to Lee Wilkins of
Deerfield, Virginia, for encouragement, maintenance of electronic equipment, and
helpful technical advice. We especially thank Peter Paul Kellogg, Miss L. V.
Engelhard, and the staff of the Library of Natural Sounds, Cornell University for
the use of the Missilyzer and other electronicequipment. We are most grateful to
Mrs.
Sadie Wolvin
and to the others who let us record the vocalizations
of their
tame
crows. We thank the staff of the Myakka River State Park, Florida for allowing us
to record crows on the premises. We are indebted to Mrs. Anne Tatlow IV, Gary
Sale, Robert Oster, Gary Howard, Glenn R. Dudderar and the V.P.I. Graduate
students who aided in the field testing of crow calls during this study.
SUMMARY
This study documents23 of the vocalizationsof the CommonCrow, and
describesthe appropriateenvironmentaland behavioralcontext for each.
Ten
calls were tested in the field
to further
substantiate
and
define
predictedcrow responses
to thesesignals. Crows respondedto nine of
these field-testedcalls. Crow vocalizationsdescribedare: assemblycall,
simple scoldingcall, modified scolding call, alert call, dispersal call,
squallingcall, moribund call, threat call, immature hunger and feeding
calls,contactcall, announcement
call, duet notes,juvenilenotes,contentment notes,rattling notes,wow-wownotes,carr-carrnotes,whispernotes,
coonotes,organnotes,wah-oonotes,C. b. pascuusscreams,and mimicry.
Crowresponses
to interspecific
distresscallsare noted. Thesevocalizations
are not all the sounds of the Common
Crow known
to the authors
or
other workers. The vocal repertoireof CommonCrowsshowsconsiderable
diversificationand specializationin relation to behavior patterns concernedwith flockingandwith predators.
An investigation to determine which sounds are innate, learned, or
combinationsof both shouldfollow the completedocumentationof Common
Crow vocalizations.Indeed, the study of sound variation in passefine
July 1971]
Common Crow Vocalizations
633
populationsis important for the analysisof developmental,
genetic,and
comparativeaspectsof vocalizationas a biologicalphenomenon.
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Department o• Zoology, University o7 Maryland, CollegePark, Maryland 20742, and Schoolof Forestry, University of Florida, Gainesville,
Florida 32601. Accepted30 May 1970.