生物学

ORIGINALARTICLEVocalisationsofwildcommonmarmosetsareinfluencedbydiurnalandontogeneticfactorsBrunaMartinsBezerraÆAntoniodaSilvaSoutoÆMariaAde´liaBorstelmanndeOliveiraÆLewisGeorgeHalseyReceived:23December2008/Accepted:23January2009/Publishedonline:18February2009
JapanMonkeyCentreandSpringer2009AbstractThevocalisationsofwildcommonmarmosets,Callithrixjacchus,wererecordedtoinvestigatewhethercallratebyindividualsisaffectedbytimeofday,age,sexordominancerankwithinagroup.Wealsoinvestigatedhowvocalisationpitchwasaffectedbyage,focussingonasinglecommoncall,thetrillcall.Adultsvocalisedmorethanjuvenilesorinfantsduringthemajorityofdaylighthours.Onlythecallrateofjuvenilesvariedsignificantlyovertheday.Nodifferenceswerefoundbetweeneithersexordominancerankwithrespecttorateofvocalisations.Thetrillcallsemittedbyyoungwildcommonmarmosetswereofahigherpitchthanthoseemittedbyadults.Weconcludethattheauditorycommunicationofwildcommonmarmo-setsisrelatedtotheageoftheanimals,bothintermsofcallrateandthephysicalcharacteristicsoftheirvocalisations.KeywordsAge-relatedvariations
Rateofvocalisations
Dailytimevariation
Callcharacteristics
VocalcommunicationIntroductionAnimalcommunicationplaysavitalroleinmanyanimalinteractionsincludingaggression,predation,feeding,playingandmating(e.g.Marler1961;Shettleworth1998).Thewayprimatescommunicatewilldependontherestrictionsimposedbytheirhabitsandhabitats(e.g.GautierandGautier1977),withvocalsignalsplayinganimportantroleforcommunicationinarboreal,socialpri-mates,duetothepoorvisibilitywithintheirhabitats(e.g.Altmann1967).Also,thesocialstructure,includinggroupsizeanddominancerankofindividuals,affectsmanyaspectsofmonkeycommunication(Klopfer1977);forexample,thesefactorsestablishhowmanyindividualswillinteractwitheachotherandhowcontactismadebetweenparticularindividuals(Klopfer1977).Thephysicalstruc-tureofcertainvocalisationscanencodeinformationaboutthecallerincludingsex,ageandthebehaviouralandsocialcontextofthecall(e.g.Jonesetal.1993;NorcrossandNewman1993;SchraderandTodt1993).However,certainstudiessuggestthatcallsencodeonlyverylimitedinfor-mation(e.g.OwrenandRendall2001).Atleastinsomespeciesofprimate,timeofdayisrelatedtovariationsinvocalrates,e.g.intheblackhowler(Alouattapigra),thebrownhowler(A.guariba),theredhowler(A.seniculus)andBarbarymacaques(Macacasylvanus)(HorwichandGebhard1983;Hammerschmidtetal.1994;CornickandMarkowitz2002).Thesevaria-tionsarelikelytoberelated,forinstance,toatmosphericconditionsinfluencingthepropagationofcallsatdifferenttimesoftheday(seeMartenetal.1977;Laronetal.1997)andalsotochangesinbehaviouralactivity(e.g.CornickandMarkowitz2002).Commonmarmosets(Callithrixjacchus)aresmall,diurnalprimates,livingingroupsofupto15individuals,B.M.Bezerra(&)BatEcologyandBioacousticsLaboratory,SchoolofBiologicalSciences,UniversityofBristol,WoodlandRoad,BS81UGBristol,UKe-mail:[e-mail];[e-mail]
A.daSilvaSoutoDepartamentodeZoologia,UniversidadeFederaldePernambuco,Recife,BrazilM.A.B.deOliveiraA´readeFisiologia,UniversidadeFederalRuraldePernambuco,Recife,BrazilL.G.HalseySchoolofHumanandLifeSciences,RoehamptonUniversity,London,UK123Primates(2009)50:231–237DOI10.1007/s10329-009-0132-7usuallyinhabitingawell-definedhomerange(e.g.Hershkovitz1977;StevensonandRylands1988).Thesegroupsvaryinsocialstructure,butalwaysincludeadominantreproductivepair(e.g.StevensonandRylands1988).Thepoorvisibilityprovidedbythearborealenvironmentinwhichcommonmarmosetslive(Altmann1967;Yamamoto1991)makesvocalsignallingextremelyimportantforcoordinatingtheirsocialactivitiesandbehaviours(GeissandSchrader1996;Hook-CostiganandRogers1998).MembersofthegenusCallithrixareactive,displayingawiderangeofbehavioursfor10–12hbetweensunriseandsunset(e.g.Yamamoto1991;KanthaandSuzuki2006),andtheyarethoughttoberelativelyinactiveduringthenight.Timeofdayinfluencesthebehaviouraltimebudgetofcommonmarmosets,forinstanceintermsofvisitingdifferentareaswithinthehomerange(MendesPontesandMonteirodaCruz1995),ratesofforagingactivity(AlonsoandLangguth1989)andratesofscent-marking(Nogueiraetal.2001).Vocalactivityratecouldpossiblybeinfluencedbysim-ilarfactors.However,thereislimitedinformationonthevariationsinvocalratesofcommonmarmosetsandthereasonsforthosevariations.Inthepresentstudywecharacterisethedailyvocalactivitypatternofwildcommonmarmosets.Welookathowratesofallcallsvarywithrespecttotimeofday,gender,rankandageincommonmarmosets.Weconsiderexplanationsforthesefindingsintermsofvariationsinbehaviourknowntoberelatedtothesefourfactors.Fur-thermore,weinvestigatetheeffectofageonthephysicalcharacteristicsofaquietcalltypicallyusedbycommonmarmosetstocontactconspecificsatshortdistances(Bezerra,pers.observ.),thetrillcall(Fig.1).MethodsStudysiteThestudywascarriedoutina32-hafragmentofAtlanticRainForest,inPernambuco,NortheastBrazil(75609700S,35102300W;Soutoetal.2007).SubjectsWeobservedwildindividualsfromthreesocialgroups.Initially,thenumberofanimalsinthegroupswas7,12and10.Thesenumbersvariedthroughoutthestudyduetobirths,deathsandindividualschanginggroupalli