Mixed Bird Flocks

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Mixed bird flocks: patterns of activity and speciescomposition in a region of the Central Andes of Colombia

Bandadas mixtas de aves: patrones de actividad y composicinde especies en una regin de la Cordillera Central de los Andes

de Colombia

Enrique Arbele!"Cort#s$%&'% (ernando A) *odr+gue!"Correa$%,and Manuela*estrepo"Chica$

1Semillero de Investigacin en Aves. Programa de Licenciatura en Biologa yEducacin Ambiental. Facultad de Educacin. Universidad del uindo.!ra 1"# !ll 1$%# Armenia# uindo. !olombia.&!orres'ondent([email protected]

$)useo de *oologa. +e'artamento de Biologa Evolutiva. Facultad de !iencias.Universidad %acional Autnoma de ),-ico. A'artado 'ostal /022#/3"1/# ),-ico+.F.# ),-ico.

!entro de Investigaciones en Ecosistemas. Universidad %acional Autnoma de),-ico. Antigua carretera a P4t5cuaro %6m. 7/1. !ol. San 8os, dela 9uerta# "712/)orelia# )ic:oac4n# ),-ico.

Recibido: 15 abril 2010Aceptado: 09 septiembre 2010

Abstract

Mixed bird loc!s are groups o indi"iduals rom dierent species t#at tra"el and oragetoget#er. $uc# groups are common in se"eral bird communities around t#e %orld. &epresent species composition and acti"it' patterns o mixed bird loc!s in a region o t#e(entral Andes o (olombia. &e compared t#e number o species per loc!) as %ell ast#e number o loc!s among * dierent #abitats. &e tested #'pot#eses concerning t#eloc!s dail' acti"it' and t#e co+occurrences o species %it#in t#em. &e recorded ,5species) and t#e species number per loc! "aried rom - to 21. ur data suggest t#at#abitat aects t#e number o loc!s but not t#eir species number) and t#at t#e acti"it'o loc!s is similar t#roug#out t#e da'. /n addition) t#e association o birds in loc!s isaected b' interspeciic acilitation) %it# some species co+occurrences ound moretimes t#an expected b' c#ance. &e #'pot#esize t#at some tanager species could #a"ea role in loc! co#esion. &e %itnessed 2 predator attac!s upon loc!s) a number o
mailto:[email protected]:[email protected]


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agonistic interactions among loc! members) and squirrels ollo%ing bird loc!s. urresults meet some general patterns described or mixed bird loc!s.

-ey .ords:a atasola atural Reser"e) montane orest) 3uind4o) species ric#ness)$out# America.

*esumen

as bandadas mixtas de a"es son grupos de indi"iduos de dierentes especies que"iaan ' orraean untos) ' son comunes en "arias comunidades de a"es alrededor delmundo. resentamos la composici6n de especies ' los patrones de acti"idad de lasbandadas mixtas de a"es en una regi6n de la (ordillera (entral de los Andes(olombianos. (omparamos el n7mero de especies por bandada ' el n7mero debandadas en * #8bitats distintos. "aluamos #ip6tesis relacionadas con la acti"idad delas bandadas durante el d4a ' la presencia simult8nea de especies en estos grupos.bser"amos ,5 especies) ' el n7mero de especies por bandada "ari6 entre - ' 21.

uestros datos indican que el #8bitat parece aectar el n7mero de bandadas pero nosu n7mero de especies ' que la acti"idad de las bandadas es similar durante el d4a. aasociaci6n de especies en bandadas parece estar inluida por acilitaci6n intraespec4ica' algunas especies se presentan simult8neamente m8s de lo esperado por azar.ipotetizamos que algunas tangaras pueden tener un papel en la co#esi6n de lasbandadas. bser"amos 2 ataques de depredadores) as4 como "arias interacciones#ostiles entre miembros de las bandadas ' la participaci6n de ardillas. uestrosresultados se austan a ciertos patrones descritos para las bandadas mixtas.

/alabras clave:Reser"a atural a atasola) bosque montano) 3uind4o) riqueza deespecies) $udam;rica.

0ntroduction

eterospeciic groups) deined as %ild groups o animals made up o indi"iduals odierent species tra"eling and eeding toget#er) are a common p#enomenon indierent #abitats around t#e %orld.


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into groups according to t#eir role in t#e co#esion o t#e loc! =e.g.) Mo'ni#an) 19,9>Munn and o%ell) 19?5> $rid#ar et al.) 2009. /n general) t#esespecies groups are depicted as leadersGollo%ers or nuclearGsatellites) and t#eir speciesseem to obtain dierent beneits in t#eir association %it# MCDs =$rid#ar et al.) 2009.

Bullien and (lobert)2000> $rid#ar et al.) 2009. ino) 2000> oodale and Hotagama) 200F> $rid#ar et al.) 2009.

Altoget#er) MCDs in dierent #abitats and at "arious latitudinal and altitudinal sitesappear to #a"e some eatures in common) but ot#ers are #ig#l' distinct =oulsen)199F. $tudies o MCDs #a"e illustrated se"eral patterns. Dirst) t#e number o speciesin MCDs in 1 localit' relects t#e local bird ric#ness =utto) 199-> atta and &underle)199F> Co#6rquez) 200*> Crandt et al.) 2009> er6n and (roc#et) 2009. $econd) orestragmentation and #abitat dierences aect MCD acti"it' and species composition=(roxall) 19,-> Munn) 19?5> $touer and Cierregaard) 1995> Maldonado+(oel#o andMarini) 2000> Ee"ele' and $touer) 2001> ee et al.) 2005> $rid#ar and $an!ar)

200?. oulsen) 199F> Mac#ado) 1999>Darle' et al.) 200?) and c#anges in t#eir requenc' and composition t#roug#out t#e'ear =Ea"is) 19-F> Eean) 1990> Mac#ado) 1999> Ee"ele' and eres) 2000>Maldonado+(oel#o and Marini) 200*>


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dierent #abitats and t#roug# time> =- e"aluating i t#ere is e"idence o co#esion int#ese groups b' testing t#e #'pot#esis t#at species oin MCDs randoml'> and =5placing our data in t#e rame%or! o ot#er studies conducted around t#e %orld.

Materials and methods

Study area. &e conducted ield %or! at a atasola natural reser"e =-I-1J ,5I**J&)2 200K2 F00 m asl> t#e site is considered an /mportant Cird Area =Cird ie/nternational 2010.


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+ata collection. Eata collection %as carried out b' conducting - ield trips bet%een$eptember o 200F and Debruar' o 200,. ac# ield trip lasted * to - da's) includingobser"ations or a total o 10? #ours =*F #ours in eac# section. &e deined a MCD as1 group o 2 or more indi"iduals o dierent species mo"ing around acti"el') s#o%inge"idence o co#esion =e.g.) constant "ocalizations and indi"iduals mo"ing in t#e samedirection %it#out t#e presence o an external concentration o ood resources. A

similar deinition or MCD %as used in ot#er studies =e.g.) Morse) 19,,> Ee"ele' and$touer) 1999> Maldonado+(oel#o and Marini) 2000> /ppi and erzog et al.) 2002. A similar result %as reported or MCDs in Asia =Hotagamaand oodale) 200-. /t is suggesti"e t#at t#e same MCD is not maintained or a longtime. o%e"er) to a"oid ta!ing data rom t#e same MCD repeatedl' %e used * dierentstrategies. Dirst) %e c#ec!ed t#e direction o mo"ement o eac# MCD and comparedt#at %it# t#e next MCD detected) assuring t#at it %as coming rom a dierent direction.$econd) %e conducted obser"ations in eac# section or onl' * #ours dail') a"oidingprolonged continuous obser"ations in t#e same place. Dor t#is reason %e di"ided eac#da' into sampling periods as ollo%s: =1 0F:00K09:00 #ours> =2 09:00K12:00 #ours>and * 1-:*0K1,:*0 #ours. t#ese cases %ereexcluded rom t#e anal'ses dealing %it# t#e number o species. Dor t#e speciesobser"ed) %e ollo%ed t#e taxonomic treatment o Remsen et al. =2010) and classiiedt#em according to t#eir occurrence in MCDs as: regular =present in 25 L or more ot#e MCDs) common =10K2-.9L) uncommon =*K9.9L) and rare = 2.9 L ollo%ingMac#ado =1999.

+ata analyses.


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dierences in t#e acti"it' o MCDs during t#e da' %e used a O2test to compare t#enumber o MCDs obser"ed in eac# #our o t#e da'. Dinall') %e used 2 dierentapproac#es to test i species oined MCDs on a random basis. n one #and) %e testedt#e eect o acilitation among species in t#e co#esion o MCDs) as a %#ole using(occur "ersion 1.0 =adau et al.) 200?. Digure 2. &e obser"ed t#at somespecies li!eAulacor:ync:us 'rasinus)Andigenanigrirostris) and @urdus?uscaterollo%ed some MCDs) but did not oin t#em in a consistent manner. * d..> p 0.51) n 10-. /n
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addition) around 1* L o t#e MCDs %ere obser"ed during rain' periods in %#ic#constituent indi"iduals did not decrease t#eir acti"it'. &e %itnessed 2 predator attac!supon MCDs and se"eral agonistic interactions among members o MCDs. Euring t#e 2predator attac!s) %e obser"ed t#at dierent indi"iduals in t#e MCD ga"e simultaneousalarm calls rom dierent places ollo%ed b' an e"asi"e be#a"ior. /n t#e irst case) araptor =possibl' Buteo magnirostris %as in"ol"ed. /n t#e second instance) a group o

5 !yanocora- yncasapproac#ed a MCD) %#ic# elicited an e"asi"e be#a"ior b' t#emembers o t#e MCD ater one o t#e a's "ocalized. &e detected 1F agonisticinteractions among indi"iduals in 10 MCDs) but %e onl' identiied t#e in"ol"ed specieson 9 occasions. Digure *. Digure 5) but 2acti"it' pea!s %ere obser"ed: 1 in t#e middle o t#e morning =9+10 # and anot#er att#e end o t#e aternoon =1F:*0K1,:*0 #. suggesting t#at t#e co+occurrence pattern bet%een MCDs species is aected b' interspeciic acilitationinteractions. &e obtained additional e"idence or non+random co+occurrences ospecies pairs in MCDs using a set o O2and Dis#erJs exact tests. t#e 12,5 speciespair comparisons perormed> 1, %ere signiicant =p 0.01 =


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1iscussion

ur data indicate t#at around -*L o t#e total species !no%n rom t#e studied regionparticipated in MCDs. $imilar proportions o species oining MCDs #a"e been reportedor ot#er $out# American a"ian communities in t#e Coli"ian Andes =Remsen) 19?5)t#e Atlantic orest =Aleixo) 199,) and t#e !errado=


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general pattern t#at t#e number o species oining MCDs in one zone is a relection ot#e local species pool =utto) 199-> atta and &underle) 199F> Co#6rquez) 200*>Crandt et al.) 2009> er6n and (roc#et) 2009. Additionall') t#e requenc' o MCDs andt#e mean number o species per MCD in our stud' zone are among t#e #ig#estdocumented or t#e Andes =Mo'ni#an) 19,9> erzog et al) 2002> Montero) 1999>Co#6rquez) 200*> oulsen) 199F) a region t#at apparentl' contains MCDs composed o

more species t#an ot#er regions in $out# America =e.g. !errado) asc#oal and aletti) 1995> Hotagama and oodale) 200-> Cuitr6n+Burado and $rid#ar and $an!ar) 200?. /n t#e eotropics some squirrelspecies suc# as Sciurus granatensis) S. ingrami) and)ycrosciurus ?laviventerex#ibit a

tendenc' to de"elop dierent interspeciic relations#ips =Mo'ni#an) 19,9> asc#oal andaletti) 1995> Cuitr6n+Burado and o%ell)19?5> erzog et al.) 2002> /ppi and


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Mac#ado) 1999> erzog et al.) 2002> Darle' et al.)200?. o%e"er) %e ound t#at t#e number o MCDs did not c#ange during t#e 5mont#s o our stud'. Alt#oug# a similar pattern #as been ound in ot#er eotropicalsites =Munn) 19?5> Co#6rquez) 200*) man' studies indicate "ariation in MCDs inrelation to reproducti"e season or luctuation in resources =Ea"is) 19-F> o%ell) 19,9>

Eean) 1990> Mac#ado) 1999> Ee"ele' and eres) 2000. erzog et al.) 2002.


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() bot# %it# orest #abitats) and not bet%een sections C and () %#ic# representdierent #abitats.

&e are a%are t#at some concerns could arise because t#e stud' area %as small =e.g.)results did not s#o% dierences among #abitats because MCDs can mo"e t#roug# t#eentire zone. o%e"er as %e #a"e said in t#e met#ods t#is stud' is not centered on

documenting dierences related to spatial separation. Cus!ir! etal) 19,2> Munn and oulsen) 199F) %#ic# could be used to indicatet#at in t#e stud' zone a single MCD does not mo"e t#roug# t#e entire area. Dinall') t#estud' area is not isolated> it is connected %it# ot#er larger continuous orests =e.g.)$antuario de Dauna ' Dlora tun+3uimba'a. As a result t#e MCDs could be mo"ing ina greater area %#ere t#e' could be Uc#oosingU t#e #abitats.

/n general) our results indicate t#at MCDs orage and tra"el t#roug# secondar' gro%t##abitats %it# bus#es and scattered trees in a similar manner as t#e' do in old gro%t#orests. /t seems to be e"idence or anot#er !ind o ad"antage gained b' indi"iduals

oining MCDs. %#ic# is t#e greater use o adacent "egetation patc#es =Munn) 19?5> Mac#ado) 1999. i!e%ise)Anisognat:ussom'tuosus) @angaranigroviridis# @. :eineii) @. art:us) and @. ru?icervi-meet some c#aracteristics o nuclearspecies =sensuMo'ni#an) 19,9 suc# as colorul plumage and t#e ormation o mono+speciic groups. $ome o t#ese species #a"e been reported also as nuclear in adierent region o t#e (olombian Andes =Mo'ni#an) 19,9> Co#6rquez) 200*. All t#isinormation indicates t#at tanagers #a"e an important role in t#e ormation and


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maintenance o MCDs in t#e Andes. Additionall') %e consider t#at ot#er species) suc#as!:loros'ingus o':t:almicus) !.canigularis) andAtla'etes albinuc:a) could #a"esimilar roles in MCDs. =2 MCDs are co#esi"egroups %#ere some species pairs co+occurrences are not dri"en b' c#ance> =*squirrels occasionall' ollo% MCDs> =- MCDs #a"e alert and reaction mec#anismstargeted against potential predators. o%e"er) our results also dier rom t#e generalpattern reported in pre"ious studies> or example) =1 dierent #abitats do not aectt#e number o species per MCD> =2 MCDs can use earl' secondar' gro%t# in a similarmanner as more mature orest #abitats> =* t#e number o MCDs did not s#o%signiicant dierences t#roug#out t#e da'. Additionall') a e% aspects pertinent to t#enumber and !ind o species t#at ma!e up MCDs in our stud' area diered romobser"ations o pre"ious studies. &e #ope t#at t#is stud' %ill enric# t#e understandingo t#is biological p#enomenon and contribute to t#e !no%ledge o t#e o"er%#elmingbiodi"ersit' o t#e (olombian Andes.

Ackno.ledgments


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Cird ie /nternational) 2010. Eata zone. nlineVR: #ttp:GG%%%.birdlie.orgGdatazoneGindex.#tml. ast access: 1-.0*.2010.

X in!sY

Co#6rquez) (. /. 200*. Mixed+species bird loc!s in a montane cloud orest o(olombia. rnitologia eotropical 1-:F,+,?. X in!sY

Corges) $. . and . (. $touer. 1999. Cird communities in t%o t'pes o ant#ropogenicsuccessional "egetation in central Amazonia. (ondor 101:529+5*F. X in!sY

Crandt) (. $.) . asenac!) R. R. aps and $. M. artz. 2009. (omposition o mixed+species bird loc!s in orest ragments o sout#ern Crazil. Zoologia 2F:-??+-9?.

X in!sY

Cuitr6n+Burado) . and M.


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Eolb') A. $. and


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Bones) $. . 19,,. (oexistence in mixed species ant%ren loc!s. i!os 29:*FF+*,5.X in!sY

Bullien) M. and B. (lobert. 2000.


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Munn) (. A. 19?5. ermanent canop' and understor' loc!s in Amazonia: speciescomposition and population densit'. eotropical rnit#olog'. rnitological Monograp#s*F:F?*+,11. X in!sY

Munn) (. A. and B. &.


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$touer) . (. and B. R. . Cierregaard.1995. Vse o Amazonian orest ragments b'understor' insecti"orous birds. colog' ,F:2-29+2--5. X in!sY

$tresemann) . 191,. Vber gemisc#te Qogel+sc#%arme. Qer#andlungen derrnit#ologisc#en esellsc#at in Ca'ern 1*:12,+151. X in!sY

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