Social conformity affects experimental measurement of boldness in male but not female monk parakeets (Myiopsitta monachus)

in Behaviour
Restricted Access
Get Access to Full Text
Rent on DeepDyve

Have an Access Token?

Enter your access token to activate and access content online.

Please login and go to your personal user account to enter your access token.


Have Institutional Access?

Access content through your institution. Any other coaching guidance?



The standard approach for characterizing boldness rarely considers the influence of social environment on the expression of boldness in group-living animals. We studied a wild-caught, captive population of monk parakeets (Myiopsitta monachus) to investigate the impact of conspecific presence on boldness — a personality trait in monk parakeets — in a controlled environment. We quantified seven boldness metrics across three types of behavioural assay: novel object, emergence, and predator exposure tests in the presence of a companion pair of flock mates. Because of the high degree of sociality in this species, we hypothesized that the presence of companion birds would facilitate the focal individuals’ behavioural responses (i.e., increase the average boldness level). We found that behavioural response in a risky foraging context was inversely correlated between solitary and social condition in males, but not in females. Our results have implications for characterizing sex-specific differences of risk-taking behaviour in social animals.

Social conformity affects experimental measurement of boldness in male but not female monk parakeets (Myiopsitta monachus)

in Behaviour



AbdiH.WilliamsL.J. & ValentinD. (2013). Multiple factor analysis: principal component analysis for multitable and multiblock data sets. — Wiley Interdisciplinary Reviews: Computational Statistics 5: 149-179.

AplinL.M.FarineD.R.MannR.P. & SheldonB.C. (2014). Individual-level personality influences social foraging and collective behaviour in wild birds. — Proc. Roy. Soc. Lond. B: Biol. Sci. 281: 20141016.

AplinL.M.FarineD.R.Morand-FerronJ.CockburnA.ThorntonA. & SheldonB.C. (2015). Experimentally induced innovations lead to persistent culture via conformity in wild birds. — Nature 518: 538.

AveryM.TillmanE.KeacherK.ArnettJ. & LundyK. (2012). Biology of invasive monk parakeets in South Florida. — Wilson J. Ornithol. 124: 581-588.

BlumsteinD.T. (2003). Flight-initiation distance in birds is dependent on intruder starting distance. — J. Wildl. Manage. 67: 852-857.

BolandC.R. (2003). An experimental test of predator detection rates using groups of free-living emus. — Ethology 109: 209-222.

BrownJ.L. & BrownE.R. (1981). Extended family system in a communal bird. — Science 211: 959-960.

BucherE.H. & AramburúR.M. (2014). Land-use changes and monk parakeet expansion in the Pampas grasslands of Argentina. — J. Biogeogr. 41: 1160-1170.

CaparrozR.MiyakiC.Y. & BakerA.J. (2009). Contrasting phylogeographic patterns in mitochondrial DNA and microsatellites: evidence of female philopatry and male-biased gene flow among regional populations of the blue-and-yellow macaw (Psittaciformes: Ara ararauna) in Brazil. — Auk 126: 359-370.

CarereC. & MaestripieriD. (2013). Animal personalities: behavior physiology and evolution. — Chicago, IL.

CialdiniR.B. & GoldsteinN.J. (2004). Social influence: compliance and conformity. — Annu. Rev. Psychol. 55: 591-621.

ClarkeA.L.SaetherB.E. & RoskaftE. (1997). Sex biases in avian dispersal: a reappraisal. — Oikos 79: 429-438.

CollarN.J. (1997). Family Psittacidae (parrots). — In: Handbook of the birds of the world 4: family Psittacidae (parrots) (del HoyoJ.ElliottA. & SargatalJ. eds). Lynx EdicionsBarcelona p. 280-477.

CussenV.A. (2016). Psittacine cognition: individual differences and sources of variation. — Behav. Process. 134: 103-109.

Da SilvaA.G.EberhardJ.R.WrightT.F.AveryM.L. & RusselloM.A. (2010). Genetic evidence for high propagule pressure and long-distance dispersal in monk parakeet (Myiopsitta monachus) invasive populations. — Mol. Ecol. 19: 3336-3350.

DahlbomS.J.LagmanD.Lundstedt-EnkelK.SundströmL.F. & WinbergS. (2011). Boldness predicts social status in zebrafish (Danio rerio). — PLoS One 6: e23565.

DammhahnM. & AlmelingL. (2012). Is risk taking during foraging a personality trait? A field test for cross-context consistency in boldness. — Anim. Behav. 84: 1131-1139.

DavidM.CezillyF. & GiraldeauL.A. (2011). Personality affects zebra finch feeding success in a producer-scrounger game. — Anim. Behav. 82: 61-67.

DavidM.PinxtenR.MartensT. & EensM. (2015). Exploration behavior and parental effort in wild great tits: partners matter. — Behav. Ecol. Sociobiol. 69: 1085-1095.

DayR.L.MacDonaldT.BrownC.LalandK.N. & ReaderS.M. (2001). Interactions between shoal size and conformity in guppy social foraging. — Anim. Behav. 62: 917-925.

DindoM.WhitenA. & de WaalF.B. (2009). In-group conformity sustains different foraging traditions in capuchin monkeys (Cebus apella). — PLoS One. 4: e7858.

DingemanseN.J. & de GoedeP. (2004). The relation between dominance and exploratory behavior is context-dependent in wild great tits. — Behav. Ecol. 5: 1023-1030.

DingemanseN.J.BouwmanK.M.Van De PolM.van OverveldT.PatrickS.C.MatthysenE. & QuinnJ.L. (2012). Variation in personality and behavioural plasticity across four populations of the great tit Parus major. — J. Anim. Ecol. 81: 116-126.

EberhardJ.R. (1998). Breeding biology of the monk parakeet. — Wilson Bull. 110: 463-473.

EdelaarP.RoquesS.HobsonE.A.Gonçalves da SilvaA.AveryM.L.RusselloM.A.SenarJ.C.WrightT.F.CaretteM. & TellaJ.L. (2015). Shared genetic diversity across the global invasive range of the monk parakeet suggests a common restricted geographic origin and the possibility of convergent selection. — Mol. Ecol. 24: 2164-2176.

EslamiA.El MostafaQ.S.B.SanchezG.BougeardS. & EslamiM.A. (2015). Package ‘multigroup’. — CRAN Comprehensive R Archive Network for the R programming language.

EvansJ.BoudreauK. & HymanJ. (2010). Behavioural syndromes in urban and rural populations of song sparrows. — Ethology 116: 588-595.

FarineD.R.MontiglioP.O. & SpiegelO. (2015). From individuals to groups and back: the evolutionary implications of group phenotypic composition. — Trends. Ecol. Evol. 30: 609-621.

FavatiA.ZidarJ.ThorpeH.JensenP. & LøvlieH. (2015). The ontogeny of personality traits in the red junglefowl, Gallus gallus. — Behav. Ecol. 27: 484-493.

FoxR.A.LadageL.D.Roth IIT.C. & PravosudovV.V. (2009). Behavioural profile predicts dominance status in mountain chickadees, Poecile gambeli. — Anim. Behav. 77: 1441-1448.

GalefB.G. & WhiskinE.E. (2008). ‘Conformity’ in Norway rats? — Anim. Behav. 75: 2035-2039.

GillF.B. & DonskerD. (2014). IOC World Bird List (v 4.3). Available online at

GriffinA.S.LermiteF.PereaM. & GuezD. (2013). To innovate or not: contrasting effects of social groupings on safe and risky foraging in Indian mynahs. — Anim. Behav. 86: 1291-1300.

GrigorP.N.HughesB.O. & ApplebyM.C. (1995). Social inhibition of movement in domestic hens. — Anim. Behav. 49: 1381-1388.

GyurisE.FeroO. & BartaZ. (2012). Personality traits across ontogeny in firebugs, Pyrrhocoris apterus. — Anim. Behav. 84: 103-109.

HarelR.DuriezO.SpiegelO.FluhrJ.HorvitzN.GetzW.M.BoutenW.SarrazinF.HatzofeO. & NathanR. (2016). Decision-making by a soaring bird: time, energy and risk considerations at different spatio-temporal scales. — Philos. Trans. Roy. Soc. B: Biol. Sci. 371: 20150397.

HellströmG.HeynenM.OostenJ.BorcherdingJ. & MagnhagenC. (2011). The effect of group size on risk taking and social conformity in Eurasian perch. — Ecol. Freshw. Fish. 20: 499-502.

HobsonE.A.AveryM.L. & WrightT.F. (2012). An analytical framework for quantifying and testing patterns of temporal dynamics in social networks. — Anim. Behav. 85: 83-96.

HobsonE.A.AveryM.L. & WrightT.F. (2014). The socioecology of monk parakeets: insights into parrot social complexity. — Auk 131: 756-775.

HombergerD.G.Enkerlin-HoeflichE.C.SnyderN.F.WileyJ.W.MunnC.A.GrahamJ.WrightT.F.DoolingR.J.KorbelR.SeibertL.M. & MatsonK.D. (2008). Manual of parrot behavior. — BlackwellOxford.

HuaF.YongD.L.JanraM.N.FitriL.M.PrawiradilagaD. & SievingK.E. (2016). Functional traits determine heterospecific use of risk-related social information in forest birds of tropical south-east Asia. — Ecol. Evol. 6: 8485-8494.

HuangP.KermanK.SievingK.E. & St MaryC.M.S. (2016). Evaluating the novel-environment test for measurement of exploration by bird species. — J. Ethol. 4: 45-51.

HuberL.RechbergerS. & TaborskyM. (2001). Social learning affects object exploration and manipulation in keas, Nestor notabilis. — Anim. Behav. 62: 945-954.

JacksonA.L.RuxtonG.D. & HoustonD.C. (2008). The effect of social facilitation on foraging success in vultures: a modelling study. — Biol. Lett. 4: 311-313.

JetzW. & RubensteinD.R. (2011). Environmental uncertainty and the global biogeography of cooperative breeding in birds. — Curr. Biol. 21: 72-78. VisserL. & van den BosR. (2011). Male Wistar rats show individual differences in an animal model of conformity. — Anim. Cogn. 14: 769.

JollesJ.W.BenjaminA.T. & ManicaA. (2016). Recent social conditions affect boldness repeatability in individual sticklebacks. — Anim. Behav. 112: 139-145.

KaiserH.F. (1960). The application of electronic computers to factor analysis. — Educ. Psychol. Meas. 20: 141-151.

KermanK.MillerL. & SewallK. (2018). The effect of social context on measures of boldness: Zebra finches (Taeniopygia guttata) are bolder when housed individually. — Behav. Process. 157: 18-23.

KermanK.SievingK.E.St MaryC. & AveryM.L. (2016). Evaluation of boldness assays and associated behavioral measures in a social parrot, monk parakeet (Myiopsitta monachus). — Behaviour 153: 1817-1838.

KingA.J.WilliamsL.J. & Mettke-HofmannC. (2015). The effects of social conformity on Gouldian finch personality. — Anim. Behav. 99: 25-31.

KrauseE.T. & NaguibM. (2011). Compensatory growth affects exploratory behaviour in zebra finches, Taeniopygia guttata. — Anim. Behav. 81: 1295-1300.

KrzanowskiW.J. (1979). Between-groups comparison of principal components. — J. Am. Stat. Ass. 74: 703-707.

KurversR.H.J.M.EijkelenkampB.van OersK.van LithB.van WierenS.E.YdenbergR.C. & PrinsH.H.T. (2009). Personality differences explain leadership in barnacle geese. — Anim. Behav. 78: 447-453.

KurversR.H.J.M.AdamczykV.M.A.P.van WierenS.E. & PrinsH.H.T. (2011). The effect of boldness on decision-making in barnacle geese is group-size-dependent. — Proc. Roy. Soc. Lond. B: Biol. Sci. 278: 2018-2024.

KurversR.H.J.M.NoletB.A.PrinsH.H.T.YdenbergR.C. & van OersK. (2012). Boldness affects foraging decisions in barnacle geese: an experimental approach. — Behav. Ecol. 23: 1155-1161.

LaDageL.D.RothI.I.TimothyC.FoxR.A. & PravosudovV.V. (2009). Effects of captivity and memory-based experiences on the hippocampus in mountain chickadees. — Behav. Neurosci. 123: 284.

LapiedraO.ChejanovskiZ. & KolbeJ.J. (2017). Urbanization and biological invasion shape animal personalities. — Global Change Biol. 23: 592-603.

LazarusJ. (1979). Flock size and behaviour in captive red-billed weaverbirds (Quelea quelea): implications for social facilitation and the functions of flocking. — Behaviour 71: 127-144.

LopesA.R.S.RochaM.S.JuniorM.G.J.MesquitaW.U.SilvaG.G.G.R.VilelaD.A.R. & AzevedoC.S. (2017). The influence of anti-predator training, personality and sex in the behavior, dispersion and survival rates of translocated captive-raised parrots. — Glob. Ecol. Conserv. 11: 146-157.

MainwaringM.C.BealJ.L. & HartleyI.R. (2011). Zebra finches are bolder in an asocial, rather than social, context. — Behav. Processes. 87: 171-175.

MartellaM.B. & BucherE.H. (1984). Nesting of the spot-winged falconet in monk parakeet’s nests. — Auk 101: 614-615.

MartellaM.B. & BucherE.H. (1990). Vocalizations of the monk parakeet. — Bird. Behav. 8: 101-110.

MartinL.B. & FitzgeraldL. (2005). A taste for novelty in invading house sparrows, Passer domesticus. — Behav. Ecol. 8: 702-707.

MartínL.F. & BucherE.H. (1993). Natal dispersal and first breeding age in monk parakeets. — Auk 110: 930-933.

MoretzJ.A.MartinsE.P. & RobinsonB.D. (2007). Behavioral syndromes and the evolution of correlated behavior in zebrafish. — Behav. Ecol. 18: 556-562.

PatrickS.C.CharmantierA. & WeimerskirchH. (2013). Differences in boldness are repeatable and heritable in a long-lived marine predator. — Ecol. Evol. 3: 4291-4299.

PeckH.L.PringleH.E.MarshallH.H.OwensI.P.F. & LordA.M. (2014). Experimental evidence of impacts of an invasive parakeet on foraging behavior of native birds. — Behav. Ecol. 25: 582-590.

PepperbergI. & ShiveH. (2001). Simultaneous development of vocal and physical object combinations by a grey parrot (Psittacus erithacus): bottle caps, lids, and labels. — J. Comp. Psychol. 115: 376-384.

R Team (2002). The R stats package. — R Foundation for Statistical ComputingViennaavailable online at

ReaneyL.T. & BackwellP.R.Y. (2007). Risk-taking behavior predicts aggression and mating success in a fiddler crab. — Behav. Ecol. 18: 521-525.

ReneveyN.BsharyR. & van de WaalE. (2013). Philopatric vervet monkey females are the focus of social attention rather independently of rank. — Behaviour 150: 599-615.

RusselloM.A.AveryM.L. & WrightT.F. (2008). Genetic evidence links invasive monk parakeet populations in the United States to the international pet trade. — BMC Evol. Biol. 8: 217.

SchuettW. & DallS.R. (2009). Sex differences, social context and personality in zebra finches, Taeniopygia guttata. — Anim. Behav. 77: 1041-1050.

SchuettW.TregenzaT. & DallS.R. (2010). Sexual selection and animal personality. — Biol. Rev. 85: 217-246.

SchuettW.DallS.R. & RoyleN.J. (2011). Pairs of zebra finches with similar ‘personalities’ make better parents. — Anim. Behav. 81: 609-618.

SewallK.B. (2015). Social complexity as a driver of communication and cognition. — Integr. Comp. Biol. 55: 384-395.

ShortK.H. & PetrenK. (2008). Boldness underlies foraging success of invasive Lepidodactylus lugubris geckos in the human landscape. — Anim. Behav. 76: 429-437.

SievingK.E.ContrerasT.A. & MauteK.L. (2004). Heterospecific facilitation of forest-boundary crossing by mobbing understory birds in north-central Florida. — Auk 121: 738-751.

SomaM. & HasegawaT. (2004). The effect of social facilitation and social dominance on foraging success of budgerigars in an unfamiliar environment. — Behaviour 141: 1121-1134.

SouthJ.M. & Pruett-JonesS. (2000). Patterns of flock size, diet, and vigilance of naturalized monk parakeets in Hyde Park, Chicago. — Condor 102: 848-854.

StevensJ. (1992). Applied multivariate statistics for the social sciences. — Lawrence Erlbaum AssociatesHillsdale, NJ.

StoweM.BugnyarT.LorettoM.C.SchloeglC.RangeF. & KotrschalK. (2006). Novel object exploration in ravens (Corvus corax): effects of social relationships. — Behav. Process. 73: 68-75.

StrubbeD. & MatthysenE. (2009). Establishment success of invasive ring-necked and monk parakeets in Europe. — J. Biogeogr. 36: 2264-2278.

TallentB.R.LawL.M.RoweR.K. & LifshitzJ. (2018). Partial cage division significantly reduces aggressive behavior in male laboratory mice. — Lab. Anim. 52: 384-393.

ThorpeR.S. (1988). Multiple group principal component analysis and population differentiation. — J. Zool. 216: 37-40.

ToscanoB.J.GownarisN.J.HeerhartzS.M. & MonacoC.J. (2016). Personality, foraging behavior and specialization: integrating behavioral and food web ecology at the individual level. — Oecologia 182: 55-69.

TraisnelG. & PichegruL. (2018). Does it always pay to defend one’s nest? A case study in African penguin. — Ethology 124: 74-83.

ValeG.L.DavisS.J.van de WaalE.SchapiroS.J.LambethS.P. & WhitenA. (2017). Lack of conformity to new local dietary preferences in migrating captive chimpanzees. — Anim. Behav. 124: 135-144.

van de WaalE.ReneveyN.FavreC.M. & BsharyR. (2010). Selective attention to philopatric models causes directed social learning in wild vervet monkeys. — Proc. Roy. Soc. Lond. B: Biol. Sci. 277: 2105-2111.

van de WaalE.BorgeaudC. & WhitenA. (2013). Potent social learning and conformity shape a wild primate’s foraging decisions. — Science 340: 483-485.

van den BrinkV.DolivoV.FalourdX.DreissA.N. & RoulinA. (2012). Melanic color-dependent antipredator behavioral strategies in barn owl nestlings. — Behav. Ecol. 23: 473-480.

van HorikJ.O.LangleyE.J.WhitesideM.A. & MaddenJ.R. (2017). Differential participation in cognitive tests is driven by personality, sex, body condition and experience. — Behav. Process. 134: 22-30.

van OersK.KlunderM. & DrentP.J. (2005). Context dependence of personalities: risk-taking behavior in a social and a nonsocial situation. — Behav. Ecol. 16: 716-723.

Vander WalE.Festa-BianchetM.RéaleD.ColtmanD.W. & PelletierF. (2015). Sex-based differences in the adaptive value of social behavior contrasted against morphology and environment. — Ecology 96: 631-641.

WebsterM.M. & WardA.J.W. (2011). Personality and social context. — Biol. Rev. 86: 759-773.

WebsterM.M. & LalandK.N. (2012). Social information, conformity and the opportunity costs paid by foraging fish. — Behav. Ecol. Sociobiol. 6: 797-809.

WhiteC.M.MarksJ.S. & KirwanG.M. (2018). Sharp-shinned hawk (Accipiter striatus). — In: Handbook of the birds of the world alive (del HoyoJ.ElliottA.SargatalJ.ChristieD.A. & de JuanaE. eds). Lynx EdicionsBarcelonaavailable online at (accessed 28 July 2018).

WhitenA.HornerV. & De WaalF.B.M. (2005). Conformity to cultural norms of tool use in chimpanzees. — Nature 437: 737.

WickhamH.ChangW. & WickhamM.H. (2013). Package ‘ggplot2’. — CRAN Comprehensive R Archive Network for the R programming language.

WilsonA.D.M. & GodinJ.-G.J. (2010). Boldness and intermittent locomotion in the bluegill sunfish, Lepomis macrochirus. — Behav. Ecol. 21: 57-62.

WilsonD.S.ClarkA.B.ColemanK. & DearstyneT. (1994). Shyness and boldness in humans and other animals. — Trends Ecol. Evol. 9: 442-446.

ZouF.JonesH.JiangD.LeeT.M.MartínezA.SievingK.ZhangM.ZhangQ. & GoodaleE. (2018). The conservation implications of mixed-species flocking in terrestrial birds, a globally-distributed species interaction network. — Biol. Cons. 224: 267-276.


  • View in gallery

    A diagram of the novel object arena. Thick lines represent branches and twigs inside the cage.

  • View in gallery

    List of behavioural measures used, and the experimental setting within which the measures were captured (adapted from Kerman et al., 2016).

  • View in gallery

    A diagram of the emergence and predator exposure arena. Thick lines represent branches and twigs inside the cage. The side coloured in dark grey depicts the opaque cover behind which the observer stands.

  • View in gallery

    Summary statistics of seven behavioural metrics used in solitary and social treatments (mean ± SD), and component loadings from the group-level principal component analysis (mgPCA) of the solitary and social groups, with Varimax rotation.

  • View in gallery

    Wilcoxon signed-rank test of the effect of companions on five behavioural metrics loaded on PC1 and PC2.

  • View in gallery

    Spearman rank-order correlation analysis on PC1 and PC2 scores for all individuals, as well as for each sex.

  • View in gallery

    The linear relationship of PC1 scores between solitary and social contexts in (A) males and (B) females. The regression lines and the amount of variation explained by each regression model are presented in the figures.

  • View in gallery

    Sex differences in behavioural metrics captured in the social treatment.


Content Metrics

Content Metrics

All Time Past Year Past 30 Days
Abstract Views 74 74 37
Full Text Views 31 31 18
PDF Downloads 8 8 1
EPUB Downloads 0 0 0