A REVIEW
OF SOME ASPECTS OF AVIAN
ROBERT W. FICKEN AND MILLICENT
FIELD
ETHOLOGY 1
S. FICKEN
T•E last 30 yearshaveseenthe development
of a newapproachto the
study of behavior, which has increasinglyinterestedornithologistsas
they have attemptedto understandavian biologyfully. This new approachis now known as ethology. Both amateurand professionalornithologists
have contributedto its progressfrom the beginning.
A basictenetof ethologyis that all behaviorof animalscan eventually
be understood.The ethologistattemptsto explainbehaviorfunctionally
(what doesit do for the animal?), causally(what are the internal and
externalfactorsresponsible
for eachgiven behavior?),and evolutionarily
(what is the probablephylogenyof the behavior,how doesit contribute
to th'esurvivalof the species,and what are the selectivepressures
acting
uponit?) (seeTinbergen,1951, 1959; Hinde, 1959b).
Somebasicprocedures
are essentialin an ethologicalstudy (Hinde,
1959b: 564). The first step is to describeand classifyall the behavior
of an animal, at the same time, if possible,dividing the behavior into
logicalunitswhichcanbe dealt with furtherin otherdisciplines--particularly physiologyand ecology(see Russellet al., 1954). Althoughstudies
often beginqualitatively,they eventuallyshouldbe quantified. Generalizations,which are to be valid for many species,must be basedon work
using closelyrelated speciesfirst, and more distantly related ones later.
The animal is studied as an integratedwhole. Some workers, notably
Konrad Lorenz, keep and breed animalsin captivity under closescrutiny.
Most of this paper dealswith communicationof birds. We have stressed
particularly the analysisof displays,their evolution,and their relation to
taxonomy--topicsof great interest to systematicornithologistsas well as
to ethologists.In addition,we discusscertain maintenanceactivities.
LITERATURE
OF ET•OLOC¾
Much of the early ethologicalliteratureappearedin Europeanpublications,but it
is now also appearingin this country frequently. The principal journalsare: Animal
Behavioar (formerly British Journal of Animal Behaviour), Symposiumof the
ZoologicalSocietyof London,Journalof Comparativeand Physiological
Psychology,
Zeitschrlftfiir Tierpsychologie,
and Behaviour(with monographs
appearingas supplements in the last two). Papers on avian ethologyalso appear frequently in the
major ornithological
journals. Standardreferencebookson ethologyare The study
of instinct (Tinbergen,1951), Learningand instinctin animals (Thorpe, 1963), and
Socialbehaviorand organizationamong vertebrates(Etkin, 1964).
Recentmonographson individualspeciesincludethoseby Marler (1956a) on the
Chaffinch (Fringilla coelebs);Hinde (1952), Great Tit (Parus major); Tinbergen
• Written at the request of the A.O.U. Committee on Research.
637
The Auk, 83: 637-661. October, 1966
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(1953), Herring Gull (Larus argentatus); Moynihan (1955b), Black-headed Gull
(L. ridibundus); Curio (1959a), Pied Flycatcher (Muscicapa hypoleuca); Simmons
(1955), Great Crested Grebe (Podiceps cristatus); and Immelmann (1959), Zebra
Finch ( Taeniopygia castanotis).
Some outstanding examples of comparative ethological studies are those by Lorenz
(1952) on dabbling ducks, Meyerriecks (1960) on herons, Tinbergen (1959) and
Moynihan (1955b, 1956, 1958a, b, 1959, 1962) on gulls, Andrew (1957a, b) on emberizine finches and (1961a) other passerines,Itinde (1955-1956) on carduelines,
Dilger (1960) on parrots (Agapornis), McKinney (1961) on eiders (Somateria),
Curio (1959b) on flycatchers (Muscicapa), and L•ihrl (1960-1961) on nuthatches
( Sitta) .
ETHOLOGICAL
CONCEPTS
Sincethere are severalrecentreviewsof ethology (Emlen, 1955; Thorpe,
1963; Hinde, 1959b,1961; Eibl-Eibesfeldtand Kramer, 1958), we shall
discussonly a few critical conceptsand terms of particular interest to
field students.Many of the theoreticalconceptsare still controversial
and
will undoubtedlybe modified substantiallyin the future. The glosseries
of Verplanck(1957) and ThOrpe (1951) containmany definitionsof
ethologicalterms.
Someactionsof animalsare variable, othersmore stereotyped,and the
two kinds often occur togetherin a behavioralsequence."The variable
introductoryphaseof an instinctivebehaviourpattern or sequence"
is
calledappetitivebehaviorand the act terminatinga behaviorpattern or
sequenceis the consummatory
act (Thorpe, 1951). Tinbergen (1951:
106) givesan exampleof a sequencein which a PeregrineFalcon (Falco
peregrinus)searchingfor food beginsby randomlyroamingover its hunting territory. This appetitivebehaviorcontinuesuntil a stimulussituation
is encountered(e.g., a flock of teal executing fligh't maneuvers). Such
situations may cause the falcon to abandon its random searching,but
what follows is still appetitive behavior of a more specializedkind--the
flock of teal may releasesham attacks by the falcon, resulting in the isolation of a member of the flock. The final stoop, capture, kill, plucking,
and eating form a relatively simpleand stereotyped"chain of consummatory acts."
Stereotypedmovements,many of which serve as consummatory
acts,
have been termedfixed patternsor fixed action patterns (Thorpe, 1956).
Investigationof suchpatterns led to the modern conceptsof instinctual
behavior. Instinct as exemplifiedby these actionsis a stereotypedpattern of behaviorwhich is inheritedand specific(Hinde, 1959b).
In addition, instinctualbehaviormay be characterizedby the accumulation of reaction specificenergy (now often referred to as specificaction
potential or S.A.P.) which is defined by Thorpe (1951) as "the state of
the animalresponsible
for its readinessto performthe behaviourpatterns
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of oneinstinctin preference
to all otherbehaviour
patterns."He points
out that this specificreadiness
"diminishes
or disappears
whenthe consummatoryact of the chargedinstincth'asbeenperformed."However,
if the actionis not released,the S.A.P. accumulates.
The thresholdfor
releaseof the particularact is then loweredand the action may occur
without any externalstimulus.Such action is often called a vacuum
activity,overflowactivity,or "Leerlaufreaktion"
(Lorenz,1950; Thorpe,
1956). Lorenzobserved
this in a captiveStarling(Sturnusvulgaris)
whichrepeatedly
performed
all the behaviorpatternsof insecthunting,
catching,
killing,andswallowing,
withoutany discernible
stimulus(Tinbergen,1951:61). Lorenzpostulated
a mechanism
whichwouldprevent
the occurrenceof an act before the animal encounteredthe specific environmental stimuli. This "block" has been termed the innate releasing
mechanism
(I.R.M. or, morerecently,R.M.) (Lorenz, 1950; Thorpe,
1956). The I.R.M. is "selectively
responsive
to a specialstimulussituation"(Tinbergen
andPerdeck,
1951:2). Thisconcept
wasintroduced
to
accountfor the factsthat animalsoften respondto a particularstimulus
situationwith specific
responses
eventhoughtheyhaveneverencountered
the situation
before,andthat,in suchcases,
theanimaloftenresponds
to
only a very limited part of the total stimulussituation.
Releasers are structures or actions that emanate sign stimuli which
are perceivedby an animal. Releasersoften reach a high degreeof
specialization,
and their evolutionmay parallel that of the associated
specificresponse(Lorenz, 1935). Tinbergen (1953: 197), using models,
showedthat in Herring Gulls the red spot on the parent's bill is the
primary releaser of the pecking responseof the chick. Neither the back-
groundcolor of the bill or head color are releasers;in fact, the presence
of the head is not even necessary. Although most of the examplesof
releasersand their sign stimuli are derived from experimentalstudiesof
visual stimuli, the conceptsare also applicableto olfactory, auditory, and
tactile ones (see Lorenz, 1950). Supernormalsti•nuli are those that are
even more effective than the natural stimuli; for example, Tinbergen
(1951: 43) foundthat oystercatchers
prefer a clutchof five eggsto a
natural clutch of three and an abnormally large egg to one of their own.
Drive has been defined by Thorpe (1951) as "the complexof internal
and external statesand stimuli leading to a given behaviour." Thus, this
term may includethe stimuli, specificaction potential, and innate releas-
ing mechanisms
involvedin a given behavioralact. Becauseof the difficulties of determining internal states without experimentation,the term
tendencyhasbeenusedrecentlyto indicate"the readiness
to showa particular type of behaviouras observedundernatural conditions"(Hinde,
1955-1956,as givenby Marler, 1956a: 5). Causalfactorsincludeboth
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externaland internalstimulileadingto a givenbehavior(Tinbergen, 1959:
29) and thus causationis approximatelysynonymous
with the term drive
or motivation.
Displacementactivity has been used in two ways. It sometimesmeans
behaviorwhich is thought to have been activatedby one or more drives
which are not the drives normally associatedwith it. In other use it
refers to the performanceof a behaviorpattern out of the contextof
behavior with which it is normally related (Thorpe, 1951). The first
definitionis highly controversial(seelersel and Bol, 1958; Rowell, 1961;
Sevenster,1961); the secondis more useful for the field observer.One
exampleof displacement
activity is that of fighting Great Tits which
"may suddenlystart to peck at a bud or pick up leavesand then throw
them over their shoulders--activitiesnormally used in feeding" (Hinde,
1959b). Somedisplacement
activities,however,are not entirely irrelevant.
They are seen frequently when an animal seeminglyhas tendenciesto
behavein two different ways or when one strong tendencyis prevented
from expression.For example,songin birds whichhave just escapeda
dangeroussituationis probablya manifestationof attack-escape
motivation (seeMoynihan, 1965a: 242).
Redirectionoccursin contextssimilar to thoseof displacement,but is
fundamentallydifferent in causationaccordingto Moynihan (1955a: 242)
who has defined redirection
as "autochthonous
activities
of a drive di-
rected toward an object or animal other than the one releasingand usually
directingthem (althoughthe releasingobjector animalremainsavailable,
or partly available,as a potentialgoal at the time)." Both redirected
attack (Moynihan, 1955a) and redirectedsexualbehavior(Ficken and
Dilger, 1960) have been noted in birds. Young (1949) describeda male
Robin (Turdus migratorius) which tried to copulatewith a female but
shethreatenedhim each time; the male then "copulated"with a moundof
earth and a crumplednewspaperbefore the female respondedsexually.
Animals sometimesstart to perform a movementbut do not complete
it. Heinroth termed theseintention movementsbecausethey indicate to
the observerwhat the animal is going to do (Marler, 1956a: 4). Such
acts often occur when an animal is in a situation
in which two tendencies
are in conflict, and they are consideredto indicate ambivalence.
M^rNTF•N^NCE
ACTrv•X•F•S
Maintenance activities are those "concerned with locomotion and the
generalhealth and efficiencyof the body, mostly occurringthroughout
the year" (Marler, 1956a: 8). Of these,motor patterns involved in the
care of the body surface have been called comfort movementsor toilet
behavior.
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Maintenanceactivitiesare ofteneasilyobserved,
yet they remainvirtually unrecorded
for somefamilies. Theseactivitiesare describedfor various
species,particularly by Nice (1943), Andrew (1956), Heinroth and
Heinroth (1958), Wicklet (1961b), Ficken (1962b), Meyerriecks(1960),
Coutlee (1963), and McKinney (1965).
The study of maintenanceactivitiesis important,aside from the fact
that th'eyare necessary
for the survivalof the animal. Sincesuchmovementsoften evolveinto components
of display (seep. 647), knowledge
about themis essentialto an understanding
of the evolutionof bird displays. Further, they are usually stereotypedand of potential value in
taxonomy,particularly at the ordinal and familial levels (see Table 1, below). We shall describebriefly someof the more significant movements
with the hope of encouragingfurther observations.
Stretchingmovementsof two types occur in all carinate birds (Nice,
1943). One involvesthe stretchingdownof onewing and the corresponding leg, typicallyalsowith a spreadingof the tail. However,Kilham
(1959) notesthat woodpeckers
do not stretch'the corresponding
leg. The
otheris a stretchingof the wings(closedor perhapssomewhatextended)
over the back. During this latter, somespeciesspreadtheir tails symmetricallyat the sametime (Heinroth and Heinroth,1958: 112). Some,
suchas herons,stretchtheir neck forwardduringboth typesof stretching
(Meyerriecks,1960: 11). The stretchingdownwardof both wingswhich
occursin some young passerines,has also been reported in some adult
parrots (Nice, 1943) and in adult emberizines(Andrew, 1956). The
straighteningof both legswhile the bird is standing(usuallywithout involvementof the wings)occursin youngbirdsbut lessfrequentlyin adults
(Nice, 1943; Ficken,1962b: 159). Comparative
studiesof thesemove-
ments,givingthe finerdetailsof form,sequence
(seeFicken,1962b),and
ontogeny,may be of taxonomicvalue.
Preeninginvolvesmanipulatingfeatherswith the bill. Preeningof the
tarsi (Whitaker, 1957a)hasalsobeennotedin severalspeciesof passerines.
Preeningmovements
and sequences
are unknownin mostbirds, but they
may be of taxonomicvalue. For instance,oscinesand anatidsdistribute
oil over the plumagein different ways. Oscinestake oil from the uropygial
gland with the tip of the bill, then scratch,first touchingthe tip of the
bill with the claw of the secondtoe and subsequentlyrubbing the claw
all over the top of the head. Anatids bite their oil gland and pressoil into
the feathersgrowingon or about the gland; they then rotate the head
against thesefeathers (Lorenz, 1956).
Antingwas described
by Whitaker (1957b: 195) as "the applicationof
foreignsubstances
to the plumageand possiblyto the skin." Ants are
typicallyused,but a varietyof otherobjectsmay stimulatethe behavior.
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Simmons(1959) distinguishedtwo types: direct (the bird annointing
itself) which occursin over 100 speciesfrom many passerinefamilies,
and indirect or passiveanting (the ants swarmover the bird) which occurs
in certain larger birds suchas corvids, turdids, grallinids, and cracticids.
Recent reviews include those by Whitaker (1957b), Simmons (1957a,
1959), and Poulsen (1956). Recently Kelso and Nice (1963) reviewed
the experimentalevidenceof Dubinin (1951-1956) that anting functions
to destroy external parasites.
Bathing movements
are describedby Nice (1943). Morris (1955) describedthe variationsin the form and sequenceof bathing and drying
movementsin severalbirds. Recordsof specieswhich bathe in water, dew,
snow, and dust are scanty.
In body shaking,the contourfeathersare first evenly and slowlyruffled.
The shaking begins with the torso, and then usually involves the neck
and head. In owls, this progressionis reversed (Heinroth and Heinroth,
1958).
Sunbathinginvolvesa ruffling of the body feathers,spreadingthe wings
and tail, and often leaningto one side,as describedfor many speciesby
Hauser (1957) and Gibb (1947). The stimulus for this behavior is not
known, although Hauser suggeststhat humidity is more important than
high air temperatureand Lanyon (1958) thinks that a suddenwarming
of the bird's immediate environment may initiate it. Its function is uncertain.
In head-scratching,
birdsscratchin one of two distinctiveways. Some
lower one wing and bring the corresponding
leg over the shoulder(indirectlyor "over the wing"). Othersbring the foot directlyto the head,
with no wing lowering (directly or "under the wing") (Heinroth and
Heinroth, 1958; Simmons,1957b, 1961). Head-scratchingprobably functions in arranging and oiling the feathersof the head, and possiblyin
relieving irritating stimuli (Simmons, 1961).
Observations
on the methodof head-scratching
of many commonspecies
remain unpublished.Since the type of head-scratchingis almost always
consistent
within a species,it is usefulas a taxonomiccharacter(Table 1).
Somenonpasserine
familiesscratchindirectly, others directly; most passerines scratch indirectly. In a few cases there is variation within a
family, e.g., Psittacidae (Simmons, 1957b; Brereton and Immelmann,
1962). There is also occasionalvariation within a genus,as in Seiurus
(Ficken and Ficken, 1958).
In a few known casesthere is a changewith' age. For example,some
waterthrushes(Seiurus) scratchdirectly for a few dayswhen the behavior
first appearsand then switchto the indirect method (Ficken and Ficken,
1958). The reverseof this processis unknown (Wicklet, 1961b).
Oct.
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In sleepingsomebirds (e.g., passetines)placethe bill underthe scapulars while many others (e.g., pigeons)draw their heads betweentheir
shoulders.Diversesleepingposturesare found in other groups,someof
them apparentadaptationsto peculiaranatomicalfeatures. For example,
heronsplace the bill betweenthe bend of the wing and the body (Heinroth and Heinroth, 1958). The hangingparakeets(Loriculus) sleephanging upsidedown, and the related Agapornispullaria also sometimessleep
in this position(Dilger, 1960).
Locomotionobviouslyincludesseveraltypesof movement.Sinceflight
is sooften modifiedin displays,a knowledgeof the normal form of flight
in a speciesis particularlyimportant. Flight patternsare often diagnostic
of groups and may separate superficially similar groups such as swifts
and swallows.
The legsare usedfor locomotionin walking,running,hopping,sidling,
and swimming. Although there are many exceptions,walking and running
are characteristicof groundforagingbirds. Somespecies,suchas the Song
Sparrow(Melospizamelodia),employboth, dependingon the environmental conditions.Many specieswhich walk as adults, hop when they first
leave the nest (Nice, 1943). The only bird known to do the oppositeis
the Wheatear (Oenantheoenanthe) (Neal Smith, pets. comm.). There is
variation even within a genus; all speciesof Carduelishop, except C.
flavirostris,a tundra dwellerwhichwalks. Walking and hoppingare thus
rather plasticbehaviorsand vary accordingto habitat (seeWicklet, 1961b).
The motor patterns of feeding for even a single species,are poorly
known although they are obviouslyof great importance. A few feeding
patternswhich showinterestingtaxonomicdistributionsare discussedhere.
A prying movement (sometimescalled gaping or "Zirkeln") occursin at
least eight passefinefamilies. The birds stick their bills into the ground,
a soft substance,or a crack, and then open them with considerableforce.
Some ground foraging birds scratch the vegetational substrate, but
othersapparentlynever do (e.g., the Ovenbird,Seiurusaurocapillus,uses
its bill in moving leavesaside). Two different scratchingprocedureshave
evolved.
Gallinaceous birds scratch backward
first with one foot and then
the other,while othergroups(e.g., someemberizines,
thrushes,timaliids)
useboth feet at once(Wicklet, 1961b: 323). There is no apparentrelationshipbetweentypeof locomotion
on the groundand typeof scratching,
althoughWicklet (1961b) suggested
that scratchingarosefrom an existing
locomotorytype.
The practiceof holdingfood with one or both feet showsa spotty distribution in both nonpasserines
and passetines.For example,amongnineprimaried oscinesit occursin at least some icterids and carduelinesbut is
absentin emberizinesand parulids (except for the Yellow-breastedChat,
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Icteria virens[Neal Smith,pers.comm.]). Wickler (1961b) discusses
the
peculiardistributionof thismotorpatternand suggests
it is at leastpartly
related
to tarsal
structure.
COMMUNICATION
Communication,which occurs"wheneverthe activities of one animal
influencethe activities of another animal" (Alexander, 1960: 38), is a
major field of research.Birds are an especiallyfavorablegroup for study
becauseof the similarity of their sensorysystemsto our own and the
consequentpredominanceo[ signalsinvolving color vision and hearing.
Communicationis characteristicof all birds and is mostly by display,
that is, "those peculiarly standardizedand often exaggeratedperformances, includingall vocalizationsand many movementsand postures,
whichhavebecomespecialized
and modifiedas socialsignalsor releasers"
(Moynihan, 1955a: 240). Displaysusuallyare fixed actionpatterns (see
p. 638).
The processof ritualization resultsin inter- and intra-specificsignals
or displays. The evolutionof displaysystemsinvolvessimultaneous
modification of the motor patterns and releasersof the actorsand the patterns
of responseand readinessto respondof the reactors. However, certain
movementsof birds may communicateinformationwithout being peculiarly standardizedor exaggeratedto serve a communicatoryfunction-for instance,the coordinatedflight of birds in a flock. In somecasesit is
difficult to differentiate between ritualized and non-ritualized movements,
e.g., some pre-flight movements.The analysis of displayshas been of
primary concernto ethologists,perhapseven to the neglectof other areas.
Causation.--Recent studies have indicated that displays are produced
by dual or multiplemotivationalfactors(seeTinbergen,1959). Agonistic
displays (the term "h'ostile"was formerly used) are those where presumablyboth attack and escapetendencies
are primarily involved. Courtshipdisplaysusuallyinvolvesexual,attack,and escapetendencies
(Morris, 1956), thusanalysisof motivationin thesecasesis especially
difficult.
There are as yet no ideal studieswhich can be used as models for the
analysis of causationand it is obvious that many attempts at causal
analysisare neededbefore the best methodologycan be established.
Threecloselyrelatedapproaches
to theanalysisof causation
haveoften
been used (see Tinbergen, 1959).
First, the specific social and environmentalsituations evoking certain
behaviorsare often determined. For example, in territorial species,the
bird usually exhibits "pure" attack to an intruder within his territory,
while the intruder exhibits"pure" escape.Most displaysoccurat or near
Oct.]
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645
territorialboundaries,
whereit mightbe expected
that escape
andattack
tendencies are in conflict.
Second,
studyof the separateelementsof a complexdisplaymay suggestwhattendencies
are involved.Tinbergen(1959: 11) hasshownthat
in the"Upright"displayof gulls,whichoccurs
in agonistic
situations,
the
attacktendency
is indicated
by theraisingof thecarpaljointsandstretching of the neckwith the bill pointeddownward.Thesemovements
are
characteristically
foundin intentionmovements
of two typesof attack,
i.e., deliveringwing beatswith the foldedwing and peckingat an opponentfromabove.However,othercomponents
of the Uprightdisplayare
indicativeof the escapetendency.The relatedGreatSkua (Stercorarius
skua)doesnotraiseth'ecarpals
in a similardisplay,a factcorrelated
with
the absenceof wing beating in fights.
Stokes'study (1962) of the agonisticbehaviorof the Blue Tit (Parus
caeruleus),
however,somewhat
contradicts
the ideathat differentelements
of a displayindicatedifferenttendencies.
He foundthat a givenelement
rarelyled to a highlypredictable
subsequent
behavior,sinceindividual
elements
oftensimultaneously
represented
tendencies
to attack,stay,and
escape.Alsothe relationship
between
elements
of the displayandsubsequent behaviorchangedseasonally.
Finally, the useof "time scores"involvesanalyzingthe sequentialpatterningof behavioractsover time. This yieldsquantitativeinformation
on the relative strengthsof the tendenciesinvolvedsincethey represent
"the relativeproportion
of observed
attacksandwithdrawals
linkedwith
eachdisplay"(Tinbergen,
1959:33). Thismethodis properlyusedwhen
behavioral
patternsalternatein quicksuccession.
An animalin an unchanging
environment
usuallydoesnot have rapid motivational
shifts.
Thus if a displayalternatesrapidly and consistently
with other movements,it may be concludedthat the display and these movementshave
roughly the samemotivationalstate. This methodis difficult to employ
in field studiesbecauseof the interactionbetweenthe displayingbird and
the reactor(s). This difficulty can be overcomeby analyzingonly those
caseswhere the recipient's behavior is relatively constant. Models or
mountedspecimens
are sometimesusefulas "constantstimuli" (Tinbergen,
1959: 32-33).
Althoughthe precedingexamplesof causalanalysishave dealt with
visualdisplays,the motivationunderlying
vocalizations
canbe determined
in muchthe samemanner. Examplesof suchstudiesare thoseby Andrew
(1961b) on the Blackbird(Turdusmerula)and Ficken(1962a) on the
AmericanRedstart ( Setophagaruticilla).
Function.--Displays
arereleasers
andtheir functions
or "signalvalues"
are determined
by observing
the reactionof the recipientof the display.
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The reactionsmay be covert, overt, or both. Covert reactionsare usually
more gradual physiologicalchanges,e.g., stimulation of ovulation in
budgerigarsby the calls of males (Vaugien, 1951; Ficken et al., 1960;
Brockway,1966). Overt responses
usually occur immediatelyafter the
communicated
signalis received. For example,observations
by Tinbergen
(1959: 23) and his co-workersshowedthat a femaleBlack-headedGull
approached
a hiddenmaleimmediatelyafter an "Oblique-cum-Long-Call"
in 13 out of 16 cases;when she failed to do so she was engagedin
squabbles
with anotherbird. The femaledid not approachthe malewhen
he was not calling. Thus one can concludethat the functionof the call
is to inducethe femaleto approach.Assessing
functionis often difficult
and large numbersof examplesare needed(e.g., Stokes,1962), and some
displays, such as "song," may have more than one function. Marler
(1956b) discusses
in detail the functionsof the vocalizationof the Chaffinch.
Tinbergen (1959: 24) has, from the functionalstandpoint,classified
displaysinvolved in agonisticinteractionsand pair formation into two
groups:spacingout, or distance-increasing,
and distance-reducing
displays.
The first groupincludesthreat displayswhich tend to make the opponent
retreat or cease advancing (Tinbergen, 1959; Moynihan, 1955c). In
most speciesseveralthreat displayshave evolvedwith slightly different
functions--someare more offensive,somedefensive,some for long-range
signalling(e.g., song), and othersfor short-rangesignalling(Tinbergen,
1959: 25).
Distance-reducing
displaysare also widespreadin birds. Appeasement
or submissive
displaysinhibit aggression
by the opponent.Many of these
displaysare composed
of "reversedmovements"of attack, i.e., opposite
movementsfrom those indicatinga strong attack tendency (see Marler,
1956a). For example,many passerines
adopt a fluffed submissive
posture
which is very unlike the postureof an attackingbird, which'sleeksits
feathers and directs its head toward the opponent. Distance-reducing
displaysare particularly important in promoting social bonds between
membersof a pair, youngand parent, etc.
Origin o/ displays.--Displaycomponents
seemto be "derived" activi-
ties,havingultimatelyevolvedfrom precursors
whichdid not havesignal
value (Tinbergen,1952). The originof vocalizations
is very poorlyunderstood,but Spurwayand Haldane (1953) suggestthat they are derived
frombreathingmovements.
Moynihan(1955a) hasgivenfour sources
of
visualdisplays.First, displacement
activitiesare oftenincorporated
into
displays.An exampleis the mock preeningof theeMallard (Anas
platyrhynchos)--asimilar displayalso occursin many other ducks•in
which the male, while courtingthe female,reacheshis bill behind his
Oct.]
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FICKEN^•) F•CX•N,Avian Field Ethology
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slightlylifted wing,movingthe bill over the underside
producinga "Rrr"
sound. In somespeciesspeciallymodifiedfeathersare exhibitedduring
thisdisplay(Lorenz,1951-53). Mock preeningseemsclearlyderivedfrom
real preening,which, in a courtshipsituation,is "out of context."
Displays may also be derived from redirectedactivities,but examples
are rarer. Moynihan (1955a: 243) and Tinbergen (1959) suggestthat
the peckinginto the groundand pullingof vegetationin somegull displays
duringterritorial clashesprobablyhad their originin redirectedaggression.
Third, intentionmovementsare commonlyritualized into display components;Daanje (1950) givesmany examples.Both sexualand agonistic
displaysmay have componentsderived from the loweringof the breast
and the wing and tail movements
whichprecedejumpingup or flying.
Finally, higher intensity movementscharacteristicof the tendencies
producingthe display may becomeritualized. Moynihan (1955a: 241)
cites examplesof the "Swoop" and "Soar" displaysof the Black-headed
Gull which include attack and escape elements of greater "vigor and
elaboration" than intention movementswhich are low intensity movements.
Sincemany displaysare composed
of morethan one postureor movement, often with differentevolutionaryhistories,it is necessaryto consider each componentseparately.In many casesthe same component
occursin more than one displayand this often facilitatesanalysis. Determiningthe derivationof components
may be relativelysimplewhen
theyare similarto an unritualized
behaviorpattern(seeDaanje,1950;
Marler, 1956a; Tinbergen,1959). However,in other cases,e.g., the
complex
courtship
displays
of manakins(Pipridae)(Sick,1959) andbirds
of paradise(Paradiseidae)
(Armstrong,
1942), themovements
haveundergone so much elaborationthat their precursorsare unrecognizable.In
thesecasescomparativestudiesof a group of related species,someof
whichpossess
the movement
in questionin a lessritualizedform,provide
many usefulcluesto derivation.The studyof the ontogenyof displays
is an important but seldomused method of obtaining evidenceabout
derivation and th'e developmentalintegration of form and function
(Moynihan, 1959).
The types of changesinvolved in the ritualization of a movementhave
beendiscussed
by Daanje (1950), Morris (1957), Blest (1961), and
Hinde and Tinbergen(1958). We mentionherea few of the moreobvious
changeswhich occur. Conspicuousstructureswhich are correlatedwith a
movementoften are developed.As Hinde and Tinbergen(1958: 258)
point out, "there hasprobablyalwaysbeena parallel elaborationof structure and movement."For example,warblerswhichhabituallyspreadtheir
648
FICKEN
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tails havestrikingtail markingswhile thosethat wag or flick their tails
do not (Ficken and Ficken, 1962a).
Changesin the nature of the movement,suchas exaggeration(Lorenz,
1952: 7; Daanje, 1950), and changesin speedof performanceas comparedwith the precursor(Blest, 1961) alsooccur. Rhythmicrepetition
maydevelop,
asin the"dancing"
movements
of estrildine
finches(Morris,
1957). There are alsooften changesin coordination(Daanje, 1950) as,
for example,the simultaneousoccurrenceof a componentof the first
phaseof take-off (crouching)and one from the second(tail lowering).
In ritualization
a variable behavior often becomes more constant in
form. Wide ranges in the strengthsof the eliciting factors are accompaniedby slight changesin form of the display, giving it a typical intensity (Morris, 1957; Hinde and Tinbergen,1958). The courtshipdisplay of the male CutthroatFinch (Amadinafasciata) remainssimilarin
form despitemotivationalshifts (Morris, 1957). In contrast,graded
displaysare oneswhereslightmotivational
shiftsare reflectedin display
movements(Marler, 1961a: 107).
Emancipationoccurswhen ritualizedresponses
becomefreed from the
causal factors of their precursors. There are few examplesof this phenomenonand it may not be as widespreadas once thought (Hinde and
Tinbergen,1958: 259). Blest (1961) discusses
the topicat length.
Naming displaysand the problemof homology.--Displays
shouldbe
givendescriptivenames,not onesthat suggesttheir causationor function,
particularlybecause
concepts
aboutthesemay change(Tinbergen,1959;
Dilger, 1962: 85). Displaysare usuallynamedfor their mostobvious
component
or combination
of components
(Tinbergen,1959). Namesof
displaysare usuallycapitalized
to distinguish'
themfromnamesof other
behaviors.
Behavioralhomology,as with morphological
homology,impliescommon
phylogeneticdescent. However, homologiesare rarely known with certainty. Tinbergen(1959: 7) suggeststhat similarity in form, wide and
continuousdistributionthroughthe group,and similar motivations,functions,and derivations,are indicativeof homology.Difficulties arise when
the same name is applied to similar displays in two speciessince this
implies hornology. The number of descriptiveterms to use for a given
type of displayis limited, however. It may be best at this time to use
the most useful descriptivewords and to state that no homologiesare
implied with behaviorpatterns,of other species,that might bear the
same
name.
Oct.]
1966 J
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649
EVO•.UT•O•
Intraspecificand interspecificvariation in behavior.--The evolutionof
behaviorat the intraspecificlevel has attracted attention only relatively
recently. In a few casesthe selectivepressures
responsible
for geographic
variation are known. Curio (1961: 47) demonstratednumerousdifferencesbetweentwo subspecies
of Pied Flycatchers;thesewere manifested
mainlyin changes
of threshold
and motivation.One differencewhichhas
obvioussurvivalvalue is that the northernsubspecies
mobbeda predator,
the Red-backedShrike (Lanius collurio), strongly,while the southern
subspecies,
whichis outsidethe rangeof shrikes,did somuchmoreweakly.
Adaptive geographicvariation is also shownin the beggingnotes of
nestlingSnowBuntings(Plectrophenax
nivalis). On Bylot Island nests
are accessible
to weaselsand the nestlingsare usuallysilent (Drury, 1961).
However,in Greenlandthere are no weaselsand the younghave loud
and frequent beggingcalls (Tinbergen, 1939).
In addition to extensiveindividual differencesin song (Weeden and
Falls, 1959; Marler, 1961b), there is also geographicvariation in some
cases(e.g., Mayr, 1942; Benson,1948; Lanyonand Fish, 1958; Thorpe,
1961; Borror, 1961). In many casessong"dialects"(interpopulational
differences)are phenotypicrather than genotypic differences. Local
dialectsmay be signsof incipientspeciation
(Marler and Tamura,1962).
Behaviormay also be remarkablysimilar betweenisolatedpopulations
of the same species.Dilger (1960) found that the four subspeciesof
Agapornispersonataare very much alike in such features as courtship
feeding,precopulatory
displays,the mannerof carryingnestmaterial,and
nestbuilding,althoughthey differ distinctlyin color. In somebirds the
songsof two isolatedsubspecies
are remarkablysimilar,e.g., the songsof
the British and Tenerife Island forms of both the Corn Bunting (Emberizacalandra)and Blackbird(Marler, 1960).
Polymorphismin behavior has been infrequently described. A well
studiedcaseis that of the White-throatedSparrow(Zonotrichiaalbicollis).
Someindividualshave a white median stripe on the crown and othersa
tan stripe; matingsare usually of birds of oppositemorphs (Lowther,
1961). White-stripedfemalessing a nearly normal songand react to
song playback, but tan-striped femalesdo neither. White-striped males
react to playback longer and stronger than do tan-striped males. The
assortativemating is probably a result of these behavioral differences
(Lowther, 1962). Huxley (1955) cites examplesof behavioral polymorphism in birds in host preference,vocalizations,nest-construction,
and breeding season.
Sexualdimorphismin behavioris commonand is often associatedwith
dimorphismin color pattern. In the Common Grackle (Quiscalusquis-
650
Fxc•:ExA2•DFXC•:EX,Avian Field Ethology
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cula) both sexesgive all but one of the displaysof the other, but differencesoccur in the relative frequencywith which they give these (R.
Ficken, 1963: 70). Suchdifferencesbetweenthe sexesare probably due
to differencesin threshold,as are somedifferencesin the frequencyof
homologous
displaysamongrelated species(Hinde, 1959a: 94) and among
populationsof the samespecies(Curio, 1961: 47). Thresholddifferences
also may be responsiblefor individual variation and the rare occurrence
of a behavior.For example,a displaycommonin onespecies
of Agapornis
wasseenonly twicein anotherspecies
despiteyearsof observation(Dilger,
1960: 682). Threshold changesare a convenientway of retaining the
potential for possiblerapid shifts of behavior in responseto changing
selectivepressures(R. Ficken, 1963: 70).
Displays and associatedreleasers,suchas color patterns, are often involved in maintainingreproductiveisolationamong closelyrelated sympatric species.Thus, there often is selectionfor differencesin behavior
patterns,particularlythoseinvolvedin pair formationand courtship.
In birds with a long period betweenpair formationand copulation,
displaysprecedingcopulationneednot be as specificas thosein birdsin
which copulationoccursat theeinitial meeting (e.g., Marler, 1957: 28;
Hinde, 1959a: 89-90). In most speciesmales are more active in courtship than femalesand their displaysare more speciestypical.
Hinde (1959a) discusses
at length the nature of speciesdifferencesin
courtship.These includedifferencesin the actual and relative strengths
of the tendencies
to attack,escape,and behavesexuallytowardthe mate.
For example,Chaffinchand Bullfinch (Pyrrhula pyrrhula) malesare less
aggressive
towardtheir matesthan are the Goldfinch(Cardueliscarduelis)
and Canary (Serinus canarius). The Chaffinch and Bullfinch are also
strongly sexually dimorphic in color pattern, while the Goldfinch and
Canary are not (Hinde, 1959a: 93-94). The femalesof non-dimorphic
speciesmay releasemore aggressionbecauseof their plumage color (see
also Hamilton, 1961).
In somecloselyrelated sympatricspeciescolorsand patterns are more
divergentthan the display movements(Hinde, 1959a: 96; Ficken and
Ficken, 1962a).
A goodexampleof modificationof courtship,as a result of selectionon
some other feature, occursamong the Ploceinae (Crook, 1959). The
nest of primitive membersis globularand malesdisplay just below the
entrance,which'is near the top. In other speciesthe nest is modifiedand
the entrance is underneath; the birds display with the same orientation
to the entrance,but hang upsidedown.
Behavior and speciation.--The role of behavior patterns as isolating
mechanismsbetween two sympatric populations has recently been re-
19•6t•
]
Fm•E•
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Avian
Field
EthoIogy
651
viewedby Hinde (1959a), Spieth (1958), and Mayr (1963). Although
thereare severalothertypesof mechanisms
reducingthe probabilityof
interspecific
crosses
(prematingmechanisms)
or of their success
(postmatingmechanisms),
behavioral
isolatingmechanisms
are probablythe
mostimportant(Mayr, 1963:95). Vocalizations
andvisualbehaviorare
effective in various combinations
in reducingmixed pairings (Dilger,
1956a;Stein,1958,1963;Lanyon,1960a;andHinde,1959a,givemanyex-
amples).It hasbeensuggested
that learnedbehavior
maybe important
as an isolatingmechanism
(seeCushing,1941), but Hinde (1959a: 100)
suggests
that this is improbable
althoughhe statesthat "learnedmating
preferences
couldtide the species
over a periodin whichthe courtship
displays
hadalteredsomewhat
buttherehadbeennocorresponding
genetic
changein responsiveness
to thesedisplays
by otherindividuals."In some
casesalthoughthe signalsthemselves
may be innate,the response
to them
may be learned (Marler, 1961a: 116).
Habitat preferenceand feedingbehavior differencesmay reducecompetition and enable reproductively isolated populationsto coexist sympatrically (Hinde, 1959a; Dixon, 1961, gives examplesin Parus). Although there are often morphologicaldifferenceswhich supplementthese
behavioraldifferences,MacArthur (1958) found that in five speciesof
sympatricDendroica,whichdid not differ appreciablyin body lengthor
bill size,behavioraldifferencesin the methodof feedingwere of prime
importancein allowingcoexistence
in the samehabitat.
Brown and Wilson (1956) give examplesof characterdisplacementin
bird behaviorincludingfeedinghabits,habitat preference,and song.
Actions of selectivepressureson behavior.--Single environmentalfactors
may producea multiplicity of effects on behavior. This has been well
demonstratedby Cullen (1957) in her study of the adaptationsof the
Black-leggedKittiwake (Rissa tridactyla) to cliff nesting. Such nesting
situations,when comparedwith the open ground nestingof most gulls,
result in relaxation of predator pressureand restrictionsimposedby the
limited area and dangerto the youngof falling off the cliff. Both factors
have producednumerouschangesin behavior; the alarm call is rare, and
the submissive
displayis exaggerated,
thus obviatingfalling.
Most often many forcesshapea singlebehaviorpattern. For example,
if song (and certain call notes) has the primary functionsof attracting
conspecificfemales and repelling rival males, there are many variables
which would influenceits evolution. Songswith propertieswhich promote
ease of location by conspecificswould be advantageousbut, at theesame
time, would render the singingindividual more vulnerable to predation.
Furthermore,individualrecognitionby conspecifics
of the songof males
on neighboring
territoriesreducesaggression
(Weedenand Falls, 1959).
652
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TABLE
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1
EXAMPLES OF TI•IE USE OF BEI•IAVIORAL CItARACTERS 12• TAXOIgOlVIY
Activity
Method
of head
Level used
Familial
scratching
Subfamilial
Holding food with
Familial
the foot
Dust bathing
Subfamilial
Water bathing
Familial
method
Method of oiling
feathers
Visual agonistic
displays
Song
Taxonomicdiscrimination
Recurvirostra, Himantopus, and Haematopus related
to charadriids rather than scolopacids (Simmons,
1957b)
SuggestPsittacinae may be polyphyletic (Brereton
and Immelmann, 1962)
SeparatesIcteria virens from Parulidae (Fieken and
Fieken, 1962b)
Supports relationship of Passer to ploceids (Mayr,
et al., 1953: 120)
Separatestimaliids from most other passerines(Sim-
mons,1963)
Familial
Separatestimaliids from most other passerines(Simmons, 1963)
Generic
Splits Hylocichla mustelinafrom Catharus spp. (Dilger, 1956b)
Generic
Often useful at this level in Anatidae (JohnsBard,
1961)
Tribal
Useful at this level in estrildine finches (Delacour,
1943)
Intergeneric Shows relationship of Setophaga ruticilla and Dendroica (Fieken and Fieken, 1962a)
Intrageneric Shows close affinities of Vermivora pinuc and V.
chrysopteraand of V. peregrinaand V. ruficapilla
(Saunders, 1951)
Suggest relationship of Fringilla and carduelines
(Marler, 1957)
Length of pair bond Subfamilial Separatesestrildinesfrom ploceids (Steiner, 1955 in
Mayr, 1958)
Sub familial
Separates Anatinae from some other subfamilies
(JohnsBard,1961)
Bower construction
Subfamilial Subdivides Ptilonorhychidae into two subfamilies
and familial and places cat-birds in a separate family (Ailuroedidae) (Marshall, 1954: 183)
Subfamilial Shows affinity between Frlngilla and carduelines
Form of courtship
(Andrew and Hinde, 1956)
display
Interfamilial Presenceof tail quivering suggestspossiblerelationship among corvids, estrildines,and ploceids (Andrew, 1961a: 561)
Nest construction
Ordinal
Evidence for relationship between hummingbirds
and swifts (Pearson, 1953; Amadon, 1959)
Intergeneric Indicates close relationship between Hirundo and
Ptyonoprogne (Mayr and Bond, 1943)
Familial
Separates Peucedramus from Parulidae (George,
Flight call notes
Subfamilial
Time of initiation
of incubation
Subfamilial
Participation of
sexesin parental
Subfamilial
1962)
Feeding of nestlings Sub familial
Nest sanitation
Familial
Separates estrildines from ploceids (Steiner, 1955
in Mayr, 1958)
Separates Anserariassemipalmata from other Anatidae (JohnsBard,1961)
Separates estrildines from ploceids (Steiner, 1955
in Mayr, 1958)
Separates Peucedramus from Parulidae (George,
1962)
Oct.]
1966 J
F•cxEN ANDF•CXEN,Avian Field E•hology
653
However,thisadvantage
is counterbalanced
by the stereotypy
neededfor
species
recognition
(Marler, 1957,1960). Localdialectsmayhelpinduce
the return of malesand femalesto their birthplaces(see Marlet and
Tamura,1962: 375) wheretheymaybe bestableto survive.The physical characteristics
of the habitatmay haveimportanteffectson the form
of song.Th'us,limitedvisibilitywithindensehabitatsmay resultin a
highdegree
of dependence
onvocalsignals(Dilger,1956b:350) andcan
favorthedevelopment
of lowfrequency
songs
whichcarryfarther(Ficken
and Ficken, 1962a). Speciesspecificityis stronglyselectedfor in areas
with rich avifaunaswhere.eachsongmust standout conspicuously
from
the general backgroundof sound (Marler, 1960: 350).
Other factorsmay influencethe evolutionof bird vocalization.Certain
distantlyrelated,but ecologically
competing,
species
have developed
similar threatcalls(Dilger, 1956a: 196; Dixon, 1961: 199-200) whichcould
result in someincreasein spacing. Socialstructureis also influential.
Dueting (antiphonalsingingor calling) is associated
with long-termor
closecontactbetweenmembersof a pair and occursin sometropicaland
temperatezonespecies
whichremainmatedthroughthe year and alsoin a
few migratorybut colonialspecies(seeArmstrong,1942: 156-159). Songs
of estrildinefinchesare of low volumeand specificity,qualitiescorrelated
with their useonly as closerangesexualsignals;in thesebirds pair formation occursin the flock so the femaleseesa potential mate beforeshehears
him and malesdo not singin territorial defense(Hall, 1962). The whole
subjectof "song" is further complicatedby the wide range of differences
among speciesin the degreeto which a song is modified by learning
(Lanyon, 1960b; Thorpe, 1961; Marler et al., 1962) and also by the
difficulty of definingit.
Convergence.--Behavioral
convergenceis widespread,probably as a
result of various factors. One is the limited number of possibilitiesavailable, a fact seemingto accountfor the similarity of appeasementpostures
of distantlyrelated species(Tinbergen,1959: 61). Functionalnecessity
may alsolead to similarity, as with the female solicitingdisplay, most of
the components
of which are functionalin facilitatingcopulation(Marlet,
1956a: 116-117). Similarity in habitats is often associatedwith convergence.Thus,scratching
the groundby hoppingbackwardshasappeared
in eight passerinefamilies (Wickler, 1961b: 323) and flycatchingin at
least five (Hinde and Tinbergen, 1958: 262). Hole-nestingbirds of different families may exhibit similarities which are adaptive to this mode
of life, e.g., gapingof the youngat the darkeningof the nest hole as occurs
when the parents arrive (Haartman, 1957: 341), loud begging calls
(Heinroth in Tinbergen, 1939: 35-36), and notesresemblingthe hissing
of a snake (Sibley, 1955). Similar precursorsof two behaviorsmay lead
654
Fxci•rA>m
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to convergence,
as in courtshipfeedingdisplaysof different specieswhich
are derivedfrom similarjuvenilebeggingdisplays(Andrew, 1961a: 562).
Behavior and taxonomy.--A taxonomiccharacter is "any attribute of
an organismor of a groupof organisms
by whichit differsfrom an organism
belongingto a different taxonomiccategoryor resemblesan organismbelonging to the same category" (Mayr et al., 1953: 105). Tinbergen
(1959), Hinde and Tinbergen(1958), Mayr (1958), Amadon(1959),
and Wickler (1961a, b) reviewthe subjectof the useof ethologicalcharactersin taxonomy.
Examples of the use of behavioral charactersin taxonomy are listed
in Table 1. This table is by no meanscomprehensive
but is designedto
give an idea of the variety of typesof behaviorwhichhave beenusedand
the taxonomiclevelsat which they have provento be useful. In many of
thesecasesmorphologicalcharacterssubstantiateconclusions
drawn from
behavior.
The use of behaviorpatternsas taxonomicch'aracters
presentsmany
of the sameproblems(suchas convergence)
encountered
in usingmorphologicalonesaswell assomeadditionaldifficulties(e.g.,modificationthrough
experience). Some patterns, such as call notes, visual displays, and
maintenanceactivities,developnearly identicallyunder a wide range of
conditions.Others, such as songand reactionsto environmentalstimuli
(Mayr, 1958), are often easilymodified(see Tinbergen,1959: 4).
The functionalsignificanceof behaviorsmust be known if they are to
be usefultaxonomically.For example,displaysand morphological
features
servingas releasers,
whichhavebeenselectedfor specificdistinctiveness,
will be of little use abovethe specieslevel (Marler, 1957). In casesin
which there is interspecificcommunication,
as often occurswith certain
mobbingcalls, there is often little specificdistinctiveness
and the calls
may evenbe convergent(Marler, 1957: 25), thusof little taxonomicuse.
Behaviorcharactersare sometimesmore useful than others since they
may be more conservative(Mayr et al., 1953: 119) or permit finer dis-
criminations(Mayr, 1958). In morphologically
similargroupsthey are
particularly
importantsinceeventheslightest
cluesmustbe used(Mayr,
1958: 348). Behaviorhasbeenof greatvaluein detectingsiblingspecies.
Thus, Empidonaxbrewsteriwas first detectedas beingdifferentfrom a
sibling(E. trallii) by its song(Stein, 1963).
Behaviorpatternsare generallyusefulas taxonomiccharactersin direct
proportionto their improbability. Improbabilityincreases
with complexity.
However,beh'aviorpatternswhichare performedin oneof twoways,neither
seemingto be more advantageous,
are often useful taxonomiccharacters.
This is true of the form of the vertical componentin tail movementsand
type of headscratchingmovement.
Oct.]
1966 •
Fm•cE•r^•rt)FrancEs,,
Avian Field Ethology
655
Comparisonof "likes" betweenspeciesmust be donewhen individuals
are similarly motivated. Thus, only the highestintensitiesof particular
behaviorpatternsshouldbe comparedand the behaviorsshouldbe studied
in similar contexts.Comparisons
should,of course,be made during the
samestagesof the life cycle.
The useoJ behavioralcluesin reconstructing
evolution.--Theretention
of characteristics
whichseemto be primitivemay give cluesto the origin
of a group. For example,somewoodwarblersnestlow (but feedhigher),
singflight songsin the forest,and have distractiondisplays.Thesebehavioralpatternsare characteristic
of ground-adapted
species
and suggest
that parulidsmay haveoriginatedfrom sucha group (Ficken and Ficken,
1962a). Retention of apparently "useless"charactersmay indicate the
recencyof an adaptation; for example, the eggs of the h01e-nesting
ProthonotaryWarbler (Protonotariacitrea) are heavily spotted.
Within a speciesthere are two types of rare behavior. Someare found
in all or almostall individualsbut occuronly with unusualor supernormal
stimulussituations. Othersare found in only a small part of the popula-
tion but are not dependenton unusualstimuli. If they are commonin
closelyrelatedspeciesit is highly probablethat they were alsoat one time
of more frequent occurrencein the speciesin question. Likewise, if a
particular rare display is complex,it is also very likely that it was once
more common. It is usually impossibleto know whether such behaviors
are beingselectedfor or against,but they conceivablycould be important
to the future evolutionof the group.
ACKNOWLEDGMENTS
We wish to thank the A.O.U. Committee on Research for inviting us to write
this paper and for guidance during its preparation. In addition, we wish to thank
Robert Beck, Walter Bock, Carl Carlson, William C. Dilger, Lester L. Short, Francis
G. Scheider, George Watson, and Richard Zusi for their criticisms. This work was
supported by National Salerice Foundation Grants GB 891 and GB 3226.
LITERATURE CITED
An•XA•mER,R.D.
1960. Sound communication in Orthoptera and Cicadidae. Pp.
38-92 in Animal soundsand communication(W. Lanyon and W. Tavolga, eds.).
A.I.B.S. Publication No. 7. Washington, D.C.
A•At)O•, D. 1959. Behavior and classification: some reflections. Naturforschenden
Gesellschaftin Zijrich, 104: 73-78.
A•rtm•w, R. J. 1956. Normal and irrelevant toilet behaviour in Emberiza spp.
Brit. J. Anim. Behav.,4: 85-91.
Am)R•W, R.J.
1957a. The aggressiveand courtship behaviour of certain emberizines.
Behaviour,10: 255-308.
A•mR•W, R.J. 1957b. A comparativestudy of the callsof Emberiza spp. (buntings).
Ibis, t)O: 27-42.
656
FICKEN
AND
FICKEN,
Avian
Field
Ethology
[ Vol.Auk
83
A•DREW,R.J. 1961a. The displaysgiven by passerines
in courtshipand reproductive
fighting: a review. Ibis, 103a: 315-348, 549-579.
ANDPa•W,R. J. 1961b. The motivational organisation controlling the mobbing calls
of the Blackbird (Turdus merula). I. Effects of flight on mobbing calls. II.
The quantitative analysis of changesin the motivation of calling. III. Changes
in the intensity of calling due to changes in the effect of the owl or to the
progressive waning of mobbing. IV. A general discussion of the calls of the
Blackbird and certain other passerines. Behaviour, 17: 224-246, 288-321;
18-. 25-43, 161-176.
A•REW, R. J., ^• R. A. I-I•E.
1956. The systematic position of Fringilla•
someethologicalevidence.J. f. Orn., 97: 263-273.
Am•sT•o•G, E. A. 1942. Bird display and behaviour. New York, Oxford Univ.
Press.
BE•so>r, C.W.
1948. Geographic voice-variation in African birds. Ibis, 90: 48-71.
B•;•sT, A.D. 1961. The conceptof "ritualisation." Pp. 102-124 in Current problems
in animal behaviour (W. H. Thorpe and O. L. Zangwill, eds.). Cambridge,
Cambridge Univ. Press.
BorRow, D. J. 1961. Intraspecific variation in passerinebird songs. Wilson Bull.,
73:
BR•E•O•,
57-78.
J., ^•
K. I•rM•L•^•r.
1962. Head-scratching in the Psittaciformes.
Ibis, 104: 169-175.
B•oc•cw^¾, B. F. 1965. Stimulation of ovarian development and egg laying by
male courtship vocalization in Budgerigars (Melopsittacus undulatus). Anim.
Behav., 13: 575-578.
B•ow•, W. L., ^•D E. O. WinsoN. 1956. Character displacement. Syst. Zool., 5:
49-64.
Cotr•]•,
75:
E.
1963. Maintenance behavior of the American Goldfinch. Wilson Bull.,
342-357.
C•oox, J.H.
1959. Behaviour study and the classificationof west African weaver
birds. Proc. Linn. Soc. London, 170 Section, 1957-58, pt. 2: 147-153.
Ctrn•;•, E. 1957. Adaptations in the kittiwake to cliff-nesting. Ibis, 99: 275-302.
Ctrmo, E. 1959a. Verhaltensstudien am Trauerschn•ipper. Zeits. f. Tierpsych., 3:
1-188.
Ctrmo, E. 1959b. Beobachtungen am I-Ialbringschniipper, Ficedula sernitorquata,
im mazedonischenBrutgebiet. J. f. Orn., 1OO: 176-209.
Ctr•o, E. 1961. Zur geographischen
Variation von Verhaltensweisen.Die Vogelwelt,
82:
33-48.
CtrsRr•G, J. E.
1941. Non-genetic mating preferenceas a factor in evolution.
Condor, 43: 233-236.
D^^•J•, A. 1950. On locomotory movements in birds and the intention movements
derived from them. Behaviour, 3: 48-98.
D•;^cotr•, J. 1943. A revision of the subfamily Estrildinae of the family Ploceidae.
Zoologica,gS: 69-86.
Dn•½E•, W. C. 1956a. Adaptive modifications and ecologicalisolating mechanisms
in the thrush genera Catharus and Hylocichla. Wilson Bull., 68: 171-199.
Dn;c.E•, W. C. 1956b. Hostile behavior and reproductive isolating mechanismsin
the avian genera Catharus and Hylocichla. Auk, 73.' 313-353.
Dma•,
W. C. 1960. The comparative ethology of the African parrot genus
Agapornis. Zeits. f. Tierpsych., 17: 649-685.
Dn•½ER,W. C. 1962. Methods and objectives of ethology. Living Bird, 1: 83-92.
Drxo•, K.L.
1961. Habitat distribution and niche relationshipsin North American
Oct.
1966 ]
F•CXEN
^ND
F•CX•N,
Avian
Field
Ethology
657
species
of Parus'.Pp. 179-216in Vertebratespeciation(W. F. Blair, ed.). Austin,
Univ.
of Texas Press.
DRUR¾,W.H. 1961. Studiesof the breedingbiologyof Horned Lark, Water Pipit,
Lapland Longspur,and Snow Bunting on Bylot Island, NorthwestTerritories,
Canada. Bird-Banding, 32: 1-46.
D•JmNn%V. B. 1951-56. Fauna, USSR. Paukoobrasnye (Arachnida). 1951. Vol.
6, no. 5. Feather mites (Amalgesoidea).Ch. I. An introduction to their study.
Acad. of Sciences,USSR, Moscow-Leningrad:363 pp. 1953. Ibid., vol. 6, no. 6.
Ch. II. Families Epidermoptidae and Freyanidae. 1956. Ibid., vol. 6, no. 7.
Ch. III. Family Pterdichidae. 814 pp.
E•BL-EmEs•LDr, I., ^t,m S. KR^•r•R. 1958. Ethology, the comparative study of
animal behavior. Quart. Rev. Biol., 33: 181-211.
E•rL•N, J.T.
1955. The study of behavior in birds. Pp. 105-153 in Recent studies
in avian biology (A. Wolfson, ed.). Urbana, Univ. of Illinois Press.
ErKr•, W. (ed.). 1964. Social behavior and organization among vertebrates.
Chicago, Univ. of Chicago Press.
FmK•N, M. S. 1962a. Agonistic behavior and territory in the American Redstart.
Auk, 79: 607-632.
Fmx•N, M. S. 1962b. Maintenance activities of the American Redstart. Wilson
Bull., 74o: 153-165.
FmXEN, M. S., ^N• W. C. D•R.
1960. Comments on redirection with examples
of arian copulationswith substitute objects. Anim. Behar., 8: 219-222.
F•cK•, M. S., ^N• R. W. F•cK•m 1962a. The comparative ethology of the wood
warblers: areview. Living Bird, 1: 103-122.
FmK•N, M. S., ^N• R. W. F•CKEN. 1962b. Someaberrant charactersof the Yellowbreasted Chat, lcteria virens. Auk, 79: 718-719.
F•cK•, R. W. 1963. Courtship and agonisticbehavior of the Common Grackle,
Quiscalusquiscula. Auk, 8'0: 52-72.
F•CK•N, R. W., ^N• M. S. F•cK•.
1958. Head-scratchingin Seiurus (Parulidae)
and other passerines.Ibis, 100: 277-278.
FICKEN,R. W., A. V^NTIENHOVEN,
M. S. FICEEN,ANDF. C. SIBLEY. 1960. Effect
of visual and vocal stimuli on breeding in the Budgerigar (Melopsittacus
undulatuy). Anita. Behav., 8: 104-106.
GEORGE,
W.G.
1962. The classification
of the OliveWarbler,Peucedramus
taeniatus.
Amer. Mus. Novit., no. 2103: 1-41.
GraB,J. 1947. Sunbathingby birds. Brit. Birds,4,0: 172-174.
H^^RTM^N,L. VON. 1957. Adaptation in hole-nestingbirds. Evolution, 11: 339-347.
H^LL, F. 1962. Evolutionary aspectsof courtshipsongin estrildinefinches (abstract).
Anita. Behav., 10: 178.
H•LTON,
T. H. 1961. On the functions and causes of sexual dimorphism in
breeding plumage characters of North American speciesof warblers and orioles.
Amer. Nat., 95: 121-123.
H^•JSER,D. 1957. Some observationson sun-bathing in birds. Wilson Bull., 69:
78-90.
HmNROra, O., ^ND K. HmNROta. 1958. The birds. Ann Arbor, Univ. of Michigan
Press.
H•N•, R.A.
1952. The behaviour of the Great Tit (Parus major) and some related species.Behaviour Suppl., 2.
Hr•E, R. A. 1955-56. A comparativestudy of the courtship of certain finches
(Fringillidae). Ibis, 97: 706-745; 98: 1-23.
658
FICKEN
AND
FICKEN,
Avian
FieldEthology
[ Vol.Auk
83
I-I•n•, R.A.
1959a. Behaviour and speciationin birds and lower vertebrates. Biol.
Rev., 34: 85-128.
I-I•n•, R.A.
1959b. Some recent trends in ethology. Pp. 561-610 in Psychology,
a study of a science. Study I, vol. 2 (S. Koch, ed.). New York, McGraw-Hill.
I-I•ng, R.A. 1961. Behavior.Pp. 373-411 in Biology and comparativephysiology
of birds, Vol. 2 (A. J. Marshall, ed.). New York, Academic Press.
I-I•n•, R. A., A•O N. T•B•C•.
1958. The comparativestudy of species-specific
behavior. Pp. 251-268 in Behavior and evolution (A. Roe and G. G. Simpson,
eds.). New Haven, Yale Univ. Press.
I-IuxLg¾, J.S. 1955. Morphism in birds. Acta XI Int. Orn. Congr., Basel: 309-328.
I•asgn, J. J. A. VAN,ANDA. C. A. BoL. 1958. Preeningof two tern species.A study
on displacementactivities. Behaviour, 13: 1-88.
I•r•Z•rA•,K.
1959. Experimentelle Untersuchungeniiber die biologischeBedeutung
artspezifischer Merkmale beim Zebrafinken (Taeniopygia castanotis Gould).
ZoologischeJahrbiicher,116: 437-592.
JoabscAmp,P. 1961. The taxonomy of the Anatidae--a behavioural analysis. Ibis,
103a:
71-85.
Kgzso, L., Am) M. M. Nm•.
1963. A Russian contribution to anting and feather
mites. Wilson Bull., 75: 23-26.
K•L•A•r, L. 1959. Head-scratchingand wing-stretchingof woodpeckers.Auk, 76:
527-528.
LArynx, W. E. 1958. The motivation of sun-bathingin birds. Wilson Bull., 70:
280.
L.a•vo•, W. E. 1960a. The Middle Americanpopulationof the CrestedFlycatcher
Myiarchus tyrannulus. Condor, 62: 341-350.
LArYnx, W. E.
1960b. The ontogeny of vocalizationsin birds. Pp. 321-347 in
Animal soundsand communication (W. Lanyon and W. Tavolga, eds.). A.I.B.S.
Publ. No. 7. Washington, D.C.
LANYON,W. E., ANDW. R. F•s}t. 1958. Geographicalvariation in the vocalizations
of the WesternMeadowlark. Condor, 60: 339-341.
LSar•L, H. 1960-61. Vergleichende Studien iiber Brutbiologie und Verhalten der
Kleiber Sitta whiteheadiSharpeund Sitta canadem{sL. J. f. Orn., 101: 245-264;
102:
LORENZ,
K.
111-132.
1935. Der Kumpan in der Urnwelt desVogels. J. f. Orn., 83: 137-213,
289-413.
Lom•NZ, K. 1950. The comparative method of studying innate behaviour patterns.
Pp. 221-268 in Physiologicalmechanismsin animal behaviour. Soc. Exp. Biol.
Sympos.4, Cambridge.
Loa•NZ, K. 1951-53. Comparative studies on the behaviour of the Anatinae. Avic.
Mag., 57: 157-182; 58: 8-17, 61-72, 86-94, 172-184; 59: 24-34, 80-91.
Lom•NZ,K. 1956. The objectivistictheory of instinct. Pp. 51-76 in L'instinct dans
le comportementdes animaux et de l'homme. Paris, Masson et Cie.
LOWT•Ea, J. K. 1961. Polymorphism in the White-throated Sparrow Zonotrichia
albicollis (Gmelin). Canadian J. Zool., 39: 281-292.
LOWT•Ea,J.K. 1962. Behaviorin relation to polymorphicvariation in the Whitethroated Sparrow, Zonotrlchia albicollis. Abstracts, 13th Intern. Orn. Cong.,
Ithaca, New York.
MAcAa•ua, R. H. 1958. Population ecology of some warblers of northeastern
coniferousforests. Ecology, 39: 599-619.
M^an•a, P. 1956a. Behaviourof the Chaffinch,Fringilla coelebs.Behav. Suppl.,5.
Oct.
1966 ]
FIc•c•^•I)FIC•CE•,
Avian
Field
l•thology
659
M^RLER, P. 1956b. The voice of the Chaffinch and its function as a language.
Ibis, 98: 231-261.
M^RL•a, P. 1957. Specific distinctivenessin the communication signals of birds.
Behaviour, 11.- 13-39.
M^aLER, P. 1960. Bird songs and mate selection. Pp. 348-367 in Animal sounds
and communication (W. Lanyon and W. Tavolga, eds.). A.I.B.S. Publ. No. 7,
Washington, D.C.
M^a•a, P. 1961a. The evolution of visual communication.Pp. 96-121 in Vertebrate
speciation (W. F. Blair, ed.). Austin, Univ. of Texas Press.
M^R•a, P. 1961b. The logical analysisof animal communication.J. Theoret. Biol.,
1:
295-317.
M^a•a,
P., M. Ka•Ta,
^>;DM. T^•rum.
Oregon Juncos. Auk, 79:
1962. Song developmentin hand-raised
12-30.
M^•,•a, P., ^•D M. T^•ruR^. 1962. Song "dialects"in three populationsof Whitecrowned Sparrows. Condor, 64: 368-377.
M^as•-•L, A. J. 1954. Bower-birds. Oxford, Clarendon Press.
M^¾a, E. 1942. Systematicsand the origin of species.New York, Columbia Univ.
Press.
M^¾a, E. 1958. Behavior and systematics. Pp. 341-362 in Behavior and evolution
(A. Roe and G. G. Simpson,eds.). New Haven, Yale Univ. Press.
M^¾a, E. 1963. Animal speciesand evolution. Cambridge, Harvard Univ. Press.
M^¾a, E. ^•D J. Bo•.
1943. Notes on the classification of the swallows,
Hirundinidae. Ibis, 85: 334-341.
M^¾a, E., E.G. L•s•¾,
^•D R. L. Us•c•R.
1953. Methods and principles of
systematiczoology. New York, McGraw-Hill.
McK•¾,
F. 1961. An analysis of the displays of the European eider Somateria
mollissima mollissima (Linnaeus) and the Pacific eider Somateria mollissima v.
nigra Bonaparte. Behaviour Suppl. 7.
McK•>;>;•¾,F. 1965. The comfortmovementsof Anatidae. Behaviour,25: 120-220.
M•¾•aaI•CXS, A.J. 1960. Comparative breedingbehavior of four speciesof North
American herons. Publ. Nuttall Orn. Club, 2: 1-158.
Moams, D. 1955. Birds' cleaningbehaviour. Cage Birds, 108: 257, 415, 418.
Mom•Is, D. 1956. The function and causationof courtshipceremonies.Pp. 261286 in L'instinct dansle comportementdesanimauxet de l'homme. Paris, Masson
et Cie.
Moams,D. 1957. "Typicalintensity"andits relationto the problemof ritualisation.
Behaviour, 11:
MoYmm•, M.
1-12.
1955a. Remarks on the original sourcesof displays. Auk, 72:
240-246.
MoYma^•, M. 1955b. Some aspectsof reproductive behavior in the Black-headed
Gull (Larus ridibundusridibundusL.) and related species.Behaviour Suppl. 4.
Moyma^•, M. 1955c. Types of hostile display. Auk, 72: 247-259.
MoYma^•, M. 1956. Notes on the behavior of some North American gulls. I.
Aerial hostile behavior. Behaviour, 10: 126-178.
MoYma^•, M. 1958a. Notes on the behavior of some North American gulls. II.
Non-aerial hostile behavior of adults. Behaviour, 12: 95-182.
Mo¾•a^•, M. 1958b. Notes on the behavior of someNorth American gulls. III.
Pairing behavior. Behaviour, 12: 112-130.
Mo•im•,
M. 1959. Notes on the behavior of some North American gulls. IV.
The ontogenyof hostile behavior and display patterns. Behaviour, 14: 214-239.
660
FICIrEN
AND
FICIrEN,
Avian
Field
Ethology
MoYm>r^•, M.
[ Vol.Auk
83
1962. Hostile and sexualbehavior patternsof South Americanand
Pacific Laridae. Behaviour Suppl., 8.
NicE, M.M.
1943. Studiesin the life history of the Song Sparrow II. Trans. Linn.
Soc. New York, 6: 1-329.
PE^RSO•,O. P. 1953. Use of caves by hummingbirds and other speciesat high
altitudes in Peru. Condor, $$: 17-20.
Po•JLsE•,H. 1956. A study of anting behaviour in birds. Dansk Orn. Foren. Tids.,
$0:
267-298.
ROWELS,C. H. F.
9:
1961. Displacementgrooming in the Chaffinch. Anim. Behav.,
38-63.
R•JSS•LL,W. M. S., A. P. M•^•), ^m) J. S. H^¾•s. 1954. A basis for the quantitative
study of the structure of behaviour. Behaviour, 6: 153-205.
SA•J•)•}•s, A. A. 1951. A guide to bird songs. New York, Doubleday and Co.
Sew•sTe•, P. 1961. A causal analysis of a displacement activity (fanning in
GasterosteusaculeatusL.). Behaviour Suppl., 9.
Sm•e¾, C. G. 1955. Behavioral mimicry in the titmice (Paridae) and certain other
birds. Wilson Bull., 67: 128-132.
SIcx, H. 1959. Die Balz der Schmuckv6gel(Pipridae). J. f. Orn. 100: 269-302.
Sru•ro•s, K. E.L.
1955. Studieson Great CrestedGrebes.Avic. Mag., 61.' 3-13,
93-146, 181-253,294-316.
S•M•O•S, K. E. L. 1957a. A review of the anting-behaviour of passerinebirds.
Brit. Birds, $0: 401-424.
S•r•ro•s, K. E. L. 1957b. The taxonomic significance of the head-scratching
methodsof birds. Ibis, 99: 178-181.
S•M•O•S, K. E.L.
1959. Anting movements and their relationship to certain other
behaviourpatterns. Ibis, 101: 368-373.
S•M•O•S, K. E.L. 1961. Problemsof head-scratching
in birds. Ibis, 103a: 37-49.
Stupors, K. E. L. 1963. Some behaviourcharactersof the babblers(Timaliidae).
Avic. Mag. 69: 183-193.
SPI•:r>r, H. T. 1958. Behavior and isolating mechanisms. Pp. 363-389 in Behavior
and evolution (A. Roe and G. G. Simpson, eds.). New Haven, Yale Univ. Press.
SPm•w^v, H., ^m) J. B. S. H^•.•)^•.
1953. The comparative ethology of vertebrate
breathing. Behaviour, 6: 8-34.
S:r•,
R. C. 1958. The behavioral, ecological, and morphological characteristics
of two populationsof the Alder FlycatcherEmpidonax traillii (Audubon). New
York State Mus. and Sci. Serv., Bull. 371.
S•m•, R.C. 1963. Isolatingmechanismbetweenpopulationsof Traill's Flycatchers.
Proc. Am. Philosoph.Soc., 107: 21-50.
S:r•m•, H. 1955. Das Brutverhaltender Prachtfinken,Spermestidae,als Ausdruck
ihres selbsfiindigen
Familiencharakters.Acta XI Congr. Internat. Ornithol., Basel:
350-355.
S•roxEs,A. W.
1962. Agonistic behaviour among Blue Tits at a winter feeding
station. Behaviour, 19:
118-138.
Tao•E, W. 1951. The definition of terms used in animal behaviour studies. Bull.
Anim. Behav., 9.' 34-40.
T>rol•e•, W. H. 1956. Learning and instinct in animals. London, Methuen.
T>rol•e•, W. H. 1961. Bird-song. Cambridge, Cambridge Univ. Press.
Tao•es, W. H. 1963. Learning and instinct in animals. London, Methuen.
T•m•lm•, N. 1939. The behavior of the Snow Bunting in spring. Trans. Linn.
Soc. New York, $: 1-95.
Oct.]
1966
Fm•:E•
Am)F•½•:EN,
Avian
FieldEthology
661
TIl•BERGEIg,
N. 1951. The study of instinct. Oxford, Clarendon Press.
T•BEROEN,N. 1952. Derived activities,their causation,biologicalsignificance,origin
and emancipation during evolution. Quart. Rev. Biol., 27: 1-32.
TIIqBEROEIq,
N. 1953. The Herring Gull's world. London, Collins.
TIIgBERGEIg,
N. 1959. Comparative studies of the behaviour of gulls (Laridae):
a progressreport. Behaviour, 15: 1-70.
TINBERGEIg,
N., AIgDA. C. PERDECK.1951. On the stimulus situation releasingthe
begging responsein the newly hatched Herring Gull chick (Larus argentatus
argentatusPont.). Behaviour,3: 1-39.
VAUO•E•r,L. 1951. Ponte induite chez la perrucheondul6emaintenue/t l'obscurit6
et dans l'ambiance des voli•res. Comp. Rend. Acad. Sci., 232: 1706-1708.
VERI'LAIqCIr,
W. S. 1957. A glossaryof some terms used in the objectivescience
of behavior. Amer. Psychol. Assn., Washington, D.C.
WEEDE•, J. S., AIqDJ. B. FALLS. 1959. Differential responsesof male Ovenbirds to
recordedsongsof neighboring
and more distantindividuals.Auk, 76: 343-351.
WH•TA•:Ea,L.M. 1957a. Lark Sparrowoilingits tarsi. Wilson Bull., 69: 179-180.
WHITAKER,L. •f. 1957b. A r6sum6of anting, with particular referenceto a captive
OrchardOriole. Wilson Bull., 69: 195-262.
WlCKLER,W. 1961a. 0kologie und Stammesgeschichte
yon Verhaltenweisen.Fort.
der Zool., 13: 303-365.
Wm•LEa, W. 1961b. t•ber die Stammesgeschichte
und den taxonomischen
Wert
einiger Verhaltensweisender ViSgel. Zeit. f. Tierpsych., 18:
Youno, It.
320-342.
1949. Atypicalcopulatorybehaviorof a Robin. Auk, 66: 94.
Departmentof Zoology,Universityof Maryland,CollegePark,Maryland.