Ornithological Monographs 10

THE BEHAVIOR SPOTTED OF ANTBIRDS BY EDWIN ORNITHOLOGICAL O WILLIS MONOGRAPHS PUBLISHED THE AMERICAN BY ORNITHOLOGISTS' 1972 NO UNION 10 Above: Male Spotted Antbird BX, who occupied a territory near the center of Barro Colorado Island for at least the years 1960-1971 Below: Mist-netting a male Spotted Antbird Bands, read up the left leg and down the right, identify this individual as male CWRS (orange-red, white, red, black-yellow) THE BEHAVIOR SPOTTED OF ANTBIRDS BY EDWIN ORNITHOLOGICAL O WILLIS MONOGRAPHS PUBLISHED THE AMERICAN BY ORNITHOLOGISTS' 1972 NO UNION 10 ORNITHOLOGICAL MONOGRAPHS This series,publishedby the American Ornithologists' Union, has been established for major paperstoo long for inclusionin the Union'sjournal, The Auk Publicationhas beenmade possiblethroughthe generosity of Mrs Carll Tucker and the Marcia Brady Tucker Foundation,Inc Correspondence concerningmanuscriptsfor publicationin the series shouldbe addressedto the Editor, Dr Robert M Mengel, Museum of Natural History, University of Kansas,Lawrence,Kansas66044 Copiesof OrnithologicalMonographsmay be orderedfrom the Treasurer of the AOU, Butt L Monroe,Jr., Box 23447, Anchorage,Kentucky40223 (See price list on insideback cover.) Ornithological Monographs, No 10, vi + 162 pp Editor, Robert M Mengel Editorial Assistant,James W Parker Issued August 29, 1972 Price $6.00 prepaid ($4.75 to AOU Members) Library of CongressCatalogueCard Number 72-87186 Printedby the Allen PressInc., Lawrence,Kansas66044 TABLE INTRODUCTION OF CONTENTS Spotted Antbirds and Their Relatives Army Ants Study Areas Methods of Study ACKNOWLEDGMENTS GENERAL BEHAVIOR Calls and Songs Normal Postures and Movements Resting 13 Preening and Head-Scratching 13 Stretching 14 Egestionand Drinking 14 Sunning .15 Bathing 15 Anting 15 Attacks by Arthropods 16 Reactions to Rain Discussion REACTIONS TO DANGER Freezing 16 16 18 18 Chipping and Panicking 19 Chitring and Mobbing 20 Fleeing and Tameness 23 Investigating 24 Reactionsof Captives 24 Discussion AGONISTIC BEHAVIOR 24 29 Submissiveand Escape Behavior 29 AggressiveDisplays and Attack Behavior 30 Sequencesof Agonistic Behavior 34 Discussion REPRODUCTIVE BEHAVIOR 36 39 Singing and Wandering 39 Chirping and Flirting 39 CourtshipFeeding 40 Grooming 42 Pair Formation 44 Copulation 46 The Nest Site and Nest 48 Building the Nest 49 The Eggs and Incubation 51 Growth of the Young 57 Fledglings 59 DistractionDisplaysand Parental Alarm 63 Development of Young out of the Nest 65 Renesting and Nest Success 67 Breeding Season 70 Discussion WANDERING YOUNG AND TERRITORIAL ADULTS: SPATIAL BEHAVIOR 7! 83 Dominance and Territoriality Territory Size, Densities, and Biomasses 87 89 Habitat Selection Discussion 89 90 FORAGING BEHAVIOR Perch Selection 96 97 Foraging Away from Ants 99 Searchingfor Army Ants 100 Following the Army Ants 101 Prey and Prey Treatment 103 Numbers 106 at Swarms Competition at Swarms 109 Discussion 116 ASSOCIATION WITH INTERSPECIFIC FLOCKS Other Members of Flocks 123 126 CompetitionAmong Flocking Birds .133 Discussion SUMMARY 135 148 GAZETTEER OF LOCALITIES 151 LITERATURE CITED 152 APPENDIX 156 APPENDIX 158 vi INTRODUCTION SpottedAntbirds (Hylophylaxnaevioides,Formicariidae)are commonbirds of the undergrowthof lowlandtrc•picalforestsfrom Hondurasto Ecuador Skutch (1946, 1969), Johnson (1954), and Slud (1960) studied them briefly, but did not investigatethem in detail Since1960, as part of a study of ant-followingbirds on Barro ColoradoIsland in the PanamfiCanal Zone (Willis, 1967), I havestudiedthe behaviorof SpottedAntbirds This report detailsthe resultsof that study Spotted Antbirds(frontispiece) areir}teresting because theyareregularmembersof the two major typesof mixedbird flocksthat have attractedthe attentionof naturalists in tropicalforestssincethe time of Bates(1863) These two typesof flocksare thosethat followarmyants(Chapin,1932; Johnson, 1954) andwanderingflocks(Swynnerton,1915; Winterbottom,1943, 1949; Davis, 1946; Stanford,1947; Rand, 1954; Short, 1961; Moynihan,1962a; McClure,1967) The flocksaroundarmyantsgatherprimarilyto capture insects flushedby the ants,andthusareno•tverydifferentfromaggregations of birdsat fruitingtrees,garbagedumps,and otherconcentrated sourcesof food Wanderingmixedflocksseldomconcentrate at local food sources,so that the advantages of flockingare currentlyunknown Morse (1967) and othersfavorvarioustheoriesthat the birdsgainfoodadvantages by flocking, butMoynihan(1962a) andothersthinkthatflockingsomehow reduces predation Most authors have had little time for careful studies of individual species,and havebasedtheir theorieson tabulationsof all the individualsand species in observedflocks The studyof SpottedAntbirdsgivesinformation froma newdirection, andsuggests newapproaches for thestudyof wandering flocks After thepresentintroduction, therearesevensections in thisreport: these treatgeneralbehavior,antipredator behavior,agonistic behavior,reproductive behavior,spatialbehavior,foragingbehavior,and flockingbehavior.There is a discussion at the end of each of these seven sections SPOTTED ANTBIRDS AND THEIR RELATIVES Male SpottedAntbirds (frontispiece)are brightlypatternedwith white, chestnut, darkgray,andblack The namecomesfrom a necklaceof prominent blackspotsacross thechest,betweentheconspicuously whiteupperbreastand the whiteto grayish-white belly The headis darkgray,contrasting slightly with the blackthroatand bill and with the dark rufouseyes The back is chestnut, asaretwobroadandconspicuous barsontheblackwings.The lesser coverts aretippedwithwhitespeckles, whilethedarkremiges aretippedor crossedby a third wingbar of buff to chestnuthue White basesto the central backfeathers forma largedorsalpatchthatis usually concealed, exceptwhen ORNITHOLOGICAL MONOGRAPHS NO 10 birds dispute Each brown tail feather has a black subterminalband and a buffy-whitishtip The femmeSpottedAntbird has bright buff to chestnutbandsand feather tippingson the blackishwings,but is otherwisemore soberlycoloredthan is the male She is brownish-chestnutabove, with a concealedwhitish dorsal patchthat canbedisplayedin disputes.The tail hasa buffytip and a brownishblack subterminalband The head is brown, fading to buffy-whitishon the indistinctsuperciliaryline and lower face and to white on the throat The whitishunderpartsare tinged with pale buff, especiallyon the sides,and thereis a more or lessobscurenecklaceor high breastband of brownishspots The bill and legsare dark gray and the eyesdark whitishgray ! have seenonly one partial albino, a male with much white on the wrist area on Barro ColoradoIsland on 22 July 1967 Spotted Antbirds range in Caribbean lowland forests from southeastern Hondurasto the lower MagdalenaValley of northernColombia Over the Cordillerade Guanacasteof northernCostaRica (Slud, 1964) and in central Panama(El Valle) they rangeonto the Pacific slope From centralPanama to central Ecuador they occur in most of the forestedPacific lowlands I havefound them as high as 900 m elevationon Cerro Campanain central PanamA,and there are specimensin the United StatesNational Museum from as high as 1,300 m on Cerro Tacarcuna,easternPanamA East of the Andeslive two very similar species,the Spot-backedAntbird and the Dot-backed Antbird (Common namesused in this paper are from Meyer de Schauensee,1966'; the correspondingscientificnames,exceptfor speciesmentionedin papers cited, are given in the index.) The latter is a flycatching,timid little bird of the vdrgea,or periodicallyfloodedwoodlands alongrivers It behavesand callsvery differentlyfrom the SpottedAntbird, despiteits similar appearance The Spot-backedAntbird behavesmore like the Spotted Antbird, but flycatchesin and near foliage more often and followsarmy antslessoften (Skutch [1946: 18] reportedthat an Ecuadorian speciesof Hylophylax, probably the Spot-backedAntbird on geographical and behavioral grounds,is much like the Spotted Antbird.) Since Spotbacked and Dot-backed Antbirds are similar morphologicallybut occur togetherwithoutinterbreeding,the similarSpottedAntbirdsmight also fail to interbreedwith Spot-backedAntbirdswere they to comein contact Among related antbirds,sympatricspeciesof a genusor subgenuscommonlydiffer as litfie as thesetwo in behavioror morphologyor both For thesereasons, * While many of these names may not now be truly "common," in the senseof having wide currency, it seemsto me that this is to be hoped for and will be promoted by using them PLATE1 Army ants (Eciton burchelli) Upper left, a major ("soldier") and a worker Upper right a dense swarm of army ants starting to raid Lower left, army ants carrying prey from the swarm to the bivouac Lower right, corner of a nomadic bivouac made of bodies of ants and enclosing the queen and larvae 1972 WILLIS: BEHAVIOR OF SPOTTED ANTBIRDS I shallfollow traditionaltaxonomicpracticeand regardSpottedand Spotbackedantbirdsas separate species, eventhoughthey are closelyrelated ARMY ANTS Rettenmeyer (1963), Schneirla (1957), and Willis (1967) summarize information on the army ants followed by birds The two important ant speciesare Eciton burchelli and Labidus praedator These ants form wide raidingswarms,flowingby the thousandsover the leaf litter and into tangles near or abovethe ground,in tropical to subtropicalforestsfrom M•xico to Argentina There are manyspeciesof birdsthat follow the antsand snapup arthropodsfleeingfrom the advancingarmies No bird, so far as is known, regularlyeatsthe antsthemselves Eciton burchelli (Plate 1), brown-and-yellowants that averagealmosta centimeterin length, swarm predictablyand in the daytime all year long These large ants flush many large arthropods,such as spiders,roaches, crickets,and katydids Labidus praedator, black ants averagingabout five mm long, flush more small prey, such as sowbugsand amphipods They swarmabovegroundmainlyin rainy weather,and swarmat any hour of day or night A raid of L praedatoris likely to disappearundergroundafter a few hours and leave ant-followingbirds stranded Those ant-following birdsthat follow army antsmore than 50 percentof the time usuallyfollow E burchellirather than the unpredictableL praedator Birds that follow army antslesspersistently including many migrantsas well as the Spotted Anthird•follow bothant species(Willis, 1966a: 211) There are a few otherarmy antsthat birds sometimes follow Nomamyrmex esenbecki,brown-and-yellowantsthat resembleEciton burchelli,occasionally form stragglingswarmson the leaf litter in Neotropical forests Five times on Barro Colorado I recordedSpottedAntbirds attendingraids of N esenbecki Once on Barro ColoradoI found a pair of SpottedAntbirds at a looseeveningswarmof Eciton mexicanurn,a mainly nocturnalspeciesthat lookslike a smallE burchelli.OnceI foundSpottedAntbirdsat a straggling swarmof an unknownspeciesof Eciton On Barro Colorado,and onceat a swarmof anotherunknownspecieson BuenavistaPoint near Barro Colorado Althoughcolumn-raiding army ants,especiallyEciton hamatum,are very commonon Barro Coloradoand in otherareaswhereI havestudiedSpotted Antbirds, I have never seen SpottedAntbirds show interestin them The columnraiders,the raiderswith stragglingswarms,and the semi-nocturnal raidersamongarmyantsareunlikelyto be importantfor diurnalant-following birds STUDY AREAS I studiedSpottedAntbirds at severallocalitiesin Panatariand Colombia (Appendix 1) All localitiesbut Yuto and Tanand6 (Choc6, Colombia) 1972 WILLIS: BEHAVIOR OF SPOTTED ANTBIRDS 149 the pair bond and precedesall copulafionsand nestings;mutual grooming occursamongmatedbirdsandbetweenparentsandyoung Agonisticbehavior is not prominentin courtship;perhapsit is useful mainly for speciesof ephemeraland otherwiseirregularhabitats,wherethere are shortpair bonds and many sibling species Young males setfieon territoriesin their first year Pairing occurswhen the male is on territory A femaleusuallyfirst nestsin the breedingseason after her hatching Females,perhapsbecausethey are subordinateto trespassingmales,usuallywander nomadicallyto new mates if the old ones disappear Widowed males,which are still wholly dominanton their own territories, generally stay on them The nestcup is usuallypendentfrom slendertwigson a smallsapling,0.3 to 1.4 m abovethe ground Building,by both maleand female,takesseveral mornings.Material is gatherednear the nest Two eggsare laid, two days apart Incubation,performedby both sexes,required15 daysin two cases and 16 daysin one;the two youngat one nesthatcheda few hoursapart, but the two youngat the lastnestnearlya day apart Male and femalefeed young, which stayin the nestalmost 12 days The completenestingcycletakes 35 to 40 days Young can barelyhop whenthey leavethe nest Parentslead the youngto low perchesin densevegetationand perform strikingdistractiondisplaysif one tries to capturethe young The male of a pair feedsone fledgling,the female feeds the other As the young acquire adult plumage, complete by aboutsix weeksafter leavingthe nest,the parentsstopfeedingthem and finallydrivethemoff Parentsrenestsoonafteror beforethe previousbrood becomesindependent.Predatorsrob over 90 percent of nests,but pairs renestup to 10 timesduringeachrainy season,April to November The helpby the maleat all stagesof nestingis probablyrelatedto habitat, becauseanimalsof regular habitatsare generallysexuallyegalitarianwhile animals of irregular habitats tend to have division of labor and sexual dimorphismand diethism Independentyoungshowlittle alarm behaviorand little agonisticbehavior when they wander nomadically,perhapsbecauseany noise would attract dominantadults The changefrom the "age rule" of dominanceto the "territorial rule," after the youngbird getsa territory,marksthe point wheresimple aggression stopsand aggression braked by limits begins;territorialityis not simpleaggression but a limit on aggression A SpottedAntbird follows swarmsof army ants about half the time It movesto the peripheryof swarmsor to a positionhigh abovethe ants when largerantbirdsattackit When excludedfrom the largeand regularnomadic raids of Eciton burchelli,it finds the irregularswarmsof Labiduspraedator, irregularstataryraids of Eciton burchelli,or foragesaway from ants al- 150 ORNITHOLOGICAL MONOGRAPHS NO 10 together.Althougha subordinate species,it has many foragingalternatives At one pair per 4.7 hectares(12 acres), this generalizedspeciesis much commonerthan the larger and dominantcompetitorsthat are more restricted to feeding with army ants A SpottedAntbird foragesmainly by waitingnear the groundand darting downto snapup smallprey, of one beak lengthor less It prefersperches of small diameter but often usesvertical perchesunlessit is preening At swarmsof ants it movesmore activelyand attemptsto captureprey about four timesasrapidlyas it doesawayfrom swarms.If competitorsare present, it indulgesin warblerlikeactivity,wanderingand snappingup prey Away from ants it sometimesjoins the wanderinginterspecificflocks of antwrens and other birds ("antwren alliances") of the forest interior It is somewhatmore timid with respectto humanswhen away from the alliances, and fleeseither to suchflocksor to densecoverwhen chased.Perhapssuch intently foraging speciesas the Spotted Antbird join interspecificflocks becausethey would otherwisehave to usemore foragingtime showingalarm or lookingfor predators.This hypothesisand observations suggestthat birds that tend to forage activelyin sucha way that they cannotbe alert are followers,unlessthey hide in densecoveror are very cryptic;that speciesthat forageby lookingaboutmoderatelyalertlyform intraspecific groupsand are leaders;and that birds (like flycatchers)that look aboutvery alertlyto forage tend to be solitaryand to desertflocksreadily For birdson Barro Colorado, thereis little evidencefor and severalpointsagainstthe alternativehypotheses that birdsof a wanderingallianceflush food for eachother, lead eachother to food, excludeeach other from their own niches,locate mates, or practice populationcontrolby evaluatinginterspecificcompetition(Wynne-Edwards, 1962: 418) Speciesthat join suchflocks are onesthat rarely disputeor take the same foods or niches,for instance Many of the behavioraland morphologicalcharacteristics of SpottedAntbirdscanbe correlatedwith the low degreeof irregularityof their environment in regard to food and predation A moderatelyhigh degreeof aggressionat army ant swarmsis probably an adaptationto the variable niche of a subordinatespecies;the definitebut poorly enforcedterritorial systemis an aggression-limiting adaptationto a more predictableenvironmentaway from swarms.Aggressionis perhapsmostusefulwhenfood suppliesor covercan be defendedand are worth defending,which is most likely to be true in irregular environments.Sexual dimorphismand female flirting or submission are probably also adaptationsto moderatelyirregular lives when Spotted Antbirds are excluded by dominant large birds at ant swarms; otherwise SpottedAntbirds are sexuallyegalitarian,as is usually true of animals of regularhabitats Much evidencefor birdsindicatesthat moderatelyirregular environments are an influencein the other direction: that is, towardstrong 1972 WILLIS: BEHAVIOR OF SPOTTED ANTBIRDS 151 courtship displays, aggressiveness, strongmaledominance, shortpairbonds, polygamy or promiscuity, one sexonly caringfor offspring,and alert or crypticsolitary foraging.Intraspecific danformation alsooccurs in moderately irregularenvironments, however.Similartrendshavebeennotedin human societies of economically irregularenvironments the slumsocieties studied by OscarLewis(1968) andtheBedouins studiedby JohnGlubb (1963), for instance GAZETTEER OF LOCALITIES LocalitieswhereI have observedSpottedAntbirdsare listed here Coordinatesrefer to approximatesitesof observations, which may be severalkilometersfrom the town or geographical featureusedas a name Coordinates are to the nearestminute of north latitudeand westlongitude,respectively.Coordinatesare followedby elevations, in meters,estimatedfrom availablemapsor from altimeterreadings,and by the average yearlyrainfall,in millimeters, estimated from the vegetation and from averages at nearby stations PANAM•- Cerro Campana. 8ø 40', 80ø 04'; 900 m; 2,700 mm Mountaintop,partly forested and partly cleared,overlookingPunta Chamewestof the Canal Zone Antbirdsseen 29 August 1961 and 25 to 28 June 1968 Cerro Azul. ø 15', 79ø 20'; 700 m; 2,500 mm Ridge, partly forested,northeast of TocumenAirport and east of the Canal Zone; observations 23 June 1964, 31 May 1966 PANAMA CANAL ZONE Agua Salud. 9ø 12', 79ø 48'; 25-100 m; 3,000 mm Creek into Gatun Lake north of Frijoles, in wet forest about 40 to 60 years old Barro Colorado. 9ø 10', 79ø 51'; 25-165 m; 2,730 mm Forestedislandin Gatun Lake (see text) BohioPeninsula. ø 12', 79ø 51'; 25-100 m; 3,000mm Peninsulainto Gatun Lake north of Barro Colorado,with secondaryforest 40-60 years old Buenavista Point. 9ø 11', 79ø 50'; 25-50 m; 2,800 mm Peninsulainto Gatun Lake northeastof Barro Colorado; secondaryforest 20 to 40 years old EscobalRoad. 9ø 14•, 79ø 58'; 110 m; 3,500 mm Rolling hills, wet forest40-60 yearsold, on sideroad by Rio Medio north of Gatun Lake MaddenReserve. 9ø 06•, 79ø 37'; 50-200 m; 2,500 mm Secondary forest10 to 60 years old on rolling hills along continentaldivide COLOMBIA Apartad6. 7ø 56', 76ø 40'; 100 m; 3,000 mm Patchesof wet lowland forest on flats northeast of town; visited to March 1965 Chigorod6. 7ø 45', 76ø 40'; 130 m; 3,500 mm Patchesof wet foreston flatsnortheast of town and river; visited 10 March 1965 PuertoBelgica. 7ø 43', 75ø 17' 130 m; 2,500 mm Isolatedpatchesof tall forest in pasturesnorthwestof town on CaucaRiver; visited9-10 June 1962 Remedios. 7ø 02', 74ø 41'; 770 m; 2,500 mm Extensiveforestsnorth of town, on rolling hills; SpottedAntbird seen5 May 1962 Rio Verde. A branch of the Rio Sinfi, in partly cutover hill forests east of the Serranla de Abibe Rainfall from 2,500 mm at mouth of Verde (7 ø 505 76 ø 17') at 150 m elevationto over 4,000 mm on west slope of Filo de Abibe (7 ø 45•, 76 ø 31') at 152 ORNITHOLOGICAL MONOGRAPHS NO I0 635 m Except on the east slopeof the Filo on 26 March, SpottedAntbirds seen every day on hike up and back, 20 to 28 March 1965 San Pedro. ø 27', 76 ø 18'; 150 m; 2,500 mm Patchesof dry forestson rolling hills west of Rio San Juan and north for five kilometers, 12 and 15 March 1965 Tanand6. ø 37', 76ø 39'; 60 m; 9,000 mm Very wet, nearly flooded low forestsjust westof Rio Atrato a few miles upstreamfrom Quibd6; 23 February 1962 Tucurgt. 7ø 56', 76 ø I0'; 150 m; 2,800 mm Wet forests on rolling hills east of Rio Sinfi, 16-17 June 1962; forestscut down by 1965 Yuto. ø 30', 76 ø 32'; I00 m; 9,000 mm Very wet hill forest by road south to Rio San Juan, a few kilometers from the Rio Atrato; 24 February 1962 LITERATURE CITED AKERMAN,B 1966a Behavioural effects of electrical stimulation in the forebrain of the pigeon I reproductive behaviour Behaviour, 26: 323-338 AKERMAN,B 1966b Behavioural effects of electrical stimulation in the forebrain of the pigeon II protectivebehaviour Behaviour,26: 339-350 ALLEE, W C 1926 Measurement of environmental factors in the rain-forest of Panama Ecology, 7: 273-302 ARMSTRONG, E A 1949 Diversionary display Pt II The nature and origin of distraction display Ibis, 91: 179-188 BASTOCK, M 1967 Courtship: an ethologicalstudy Aldine, Chicago, 220 pp BATES,H.W BELT,T.W 1863 The naturaliston the river Amazons Murray, London, 394 pp 1874 The naturalistin Nicaragua Longmans,London, 403 pp BERITOFF (BERITASHVILI), J S 1965 Neural mechanisms of higher vertebrate behavior Little, Brown, and Co., Boston,384 pp BLURTONJONES,N G 1968 Observations and experiments on causation of threat displaysof the Great Tit (Parus major) Animal Behav Monographs, I: 73-158 BOWMAN,R.I 1961 Morphological differentiation and adaptationin the Gal•tpagos finches Univ California Publs Zool., 58: 1-326 BROWN,J L., AND R W HUNSPERGER.1963 Neuroethology and the motivation of agonisticbehavior Animal Behav., 11: 439-448 C'I-IAmN,J.P 1932 The birds of the Belgian Congo, Part I Bull Amer Mus Nat Hist., 65: 1-729 CREBBS, T.C 1964 Longevity in the Plain-coloredTanager, Tangara inornata BirdBanding, 35: 264 CROOK,J.H 1964 The evolution of social organisation and visual communication in the weaver birds (Ploceinae) Behav Suppl., 10 CULLEN,J.M 1963 Allo-, auto-, and heteropreening Ibis, 105: 121 DAvis, D.E 1946 A seasonal analysis of mixed flocks of birds in Brazil Ecology, 27: 168-181 EISENMANN,E 1952 Annotated list of birds of Barro Colorado Island, PanamgtCanal Zone Smiths Misc Colls., 117(5): 1-62 GLUBB, J 1963 The empire of the Arabs Prentice-Hall, Inc., Englewood Cliffs, N.J., 384 pp GOss-CusTARD,J D 1970 Feeding dispersion in some overwintering wading birds Pp 3-35 in Social Behaviour in Birds and Mammals (J H Crook, editor) Academic Press, London, 492 pp HAMILTON,E J., III 1967 Social aspectsof bird orientationmechanisms.Pp 57-71 in Animal Orientation and Navigation (R M Storm, editor) Corvallis, Oregon State University Press, 134 pp 1972 WILLIS: BEHAVIOR OF SPOTTED ANTBIRDS 153 HARTLEY,H O., nNOE S PEARSON.1950 Tablesof the xMntegraland of the cumulative Poissondistribution Biometrika, 37: 313-325 HEmaER,H 1950 Wild animals in captivity Butterworth and Co., London, 207 pp HINGE, R.A 1961 Behavior Pp 373-411 in Biology and Comparative Physiology of Birds, II (A J Marshall, ed.) 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and temperate regions Living Bird, 8: 165-175 RI?LE¾,S D 1959 Competitionbetweensunbird and honeyeaterspeciesin the Moluccan Islands Amer Nat., 93: 127-132 ROWELL,C H.F 38-63 1961 Displacementgroomingin the chaffinch Anim Beh., 9: 1972 WILLIS: RUDEBECK, G BEHAVIOR OF SPOTTED ANTBIRDS 155 1950 The choiceof prey and modesof huntingof predatorybirds with specialreferenceto their selectiveeffect Oikos, 2: 65-88 SCHNEmLA, T C 1957 A comparison of species and generain the ant subfamily Dorylinaewith respectto functionalpattern InsectesSociaux,4: 259-298 ScoTt, T G (Editor) 1963 Grousemanagementsymposium.J Wildl Mgrnt., 27: 525-887 SELnNDER, R K 1964 Speciationin wrens of the genusCampylorhynchus.Univ California Publs Zool., 74: 1-305 SELAND•R, R.K 1966 Sexualdimorphismand differentialnicheutilizationin birds Condor, 68: 113-151 SHORT,L L., JR 1961 Interspeciesflocking of birds of montane forest in Oaxaca, M6xico Wilson Bull., 73: 341-347 SIBLắ,C.G 1957 The evolutionaryand taxonomicsignificance of sexualdimorphism and hybridizationin birds Condor, 59: 166-191 SKtrrcH,A.F 1946 Life historiesof two Panamanianantbirds Condor, 48: 16-28 SKUTCH, A.F 1949 Do tropicalbirds rear as many youngas they can nourish? Ibis, 91: 430-455 SKUTCH, A.F 1952 On the hourof layingandhatchingof birds'eggs.Ibis, 94: 49-61 SictrrcH,A.F 1962 The constancyof incubation.WilsonBull., 74: 115-152 SictrrcH,A F 1969 Life historiesof Central American birds, III Pacific Coast Avifauna, 35:580 pp SLUD,P 1960 The birds of Finca "La Selva,"Costa Rica: a tropicalwet forest locality Bull Amer Mus Nat Hist., 121: 49-148 SLim,P 1964 The birdsof CostaRica Bull Amer Mus Nat Hist., 128: 1-430 SMITH,N.G 1969 Provokedreleaseof mobbing a huntingtechniqueof Micrastur falcons Ibis, 111: 241-242 SMXTI-I, W.J 1966 Communications andrelationships in the genusTyrannus.Nuttall Orn Club Publ., 6: 1-250 SNow,D W., n•D B K S•ow 1963 Breeding andtheannualcyclein threeTrinidad thrushes Wilson Bull., 75: 27-41 STn•FORD, J.K 1947 Bird partiesin forestsin Burma Ibis, 89: 507-509 STOKES, A.W 1962 The comparative ethologyof great,blue, marsh,and coal tits at a winter feeding station Behaviour, 19: 208-218 SUTTON, G M 1968 Reviewof "The Shorebirds of North America,"G D Stout (ed.) Wilson Bull., 80: 500-503 SWX•N•RTO•,C F.M 1915 Mixed bird parties Ibis, 3: 346-354 TI•B•ROE•,L 1946 Die Sperwerals Roofvijandvan Zangvogels (with Englishsummary) Ardea, 34: 1-213 Ti•a•RO•, N 1940 Die 13bersprungbewegungen Zeits.f Tierpsych., 4: 1-40 TI•a•RO•, N 1959 Comparativestudiesof the behaviorof gulls (Laridae): a progressreport Behaviour, 15: 1-70 TINaERO•N,N 1963 The shellmenace.Nat Hist., 72(7): 28-35 TROY,RS, R.L 1971 The evolutionof reciprocalaltruism.Q Rev Biol.,46: 35-57 V•R•R, J., n•D M F WILLSO• 1966 The influenceof habitatson matingsystems of North Americanpasserinebirds Ecology,47: 143-147 WHITAKER, L.M 1957 A r6sum6of anting,with particularreferenceto a captive orchard oriole Wilson Bull., 69: 195-262 WILLIAMS, E.C 1941 An ecological studyof the floor faunaof the Panamarain- forest Bull Chicago Acad Sci., 6: 62-124 WILLIAMS,G.C 1964 Measurementof consociation amongfishesand commentson the evolutionof schooling.MichiganStateUniv Mus Pub., Biol Ser., 2: 349-384 156 ORNITHOLOGICAL WILLIS, E MONOGRAPHS NO 10 1960a A study of the foraging behavior of two speciesof ant-tanagers Auk, 77: 150-170 WmLIS, E 1960b Red-crowned ant-tanagers, tawny-crowned greenlets, and forest flocks Wilson Bull., 72: 105-106 WILLIS, E 1961 A study of nesting ant-tanagers in British Honduras Condor, 63: 479-503 WILLIS E.O 65: WILLIS E.O 5: 1963 Is the zone-tailed hawk a mimic of the turkey vulture? Condor, 313-317 1966a The role of migrant birds at swarms of army ants Living Bird, 187-231 WILLIS E.O 1966b Interspecific competition and the foraging behavior of plainbrown woodcreepers Ecology, 47: 667-672 WILLIS E.O 79: WILLIS 1967 The behavior of bicolored antbirds Univ California PubIs Zool., 1-132 E O 1968 Studies of the behavior of Lunulated and Salvin's antbirds Condor, 70: 128-148 WmLIS E.O 1969a On the behavior of five speciesof Rhegmatorhina,ant-following antbirds of the Amazon basin Wilson Bull., 81: 363-395 WILLIS, E.O 1969b Review of A F Skutch's "Life Histories of Central American Highland Birds." Auk, 86: 363-365 WINTERBOI•FOM, J.M 1943 On woodland bird parties in northern Rhodesia Ibis, 85: 437-442 WINTERBOTTOM, J.M 1949 Mixed bird parties in the tropics,with specialreferenceto northern Rhodesia Auk, 66: 258-263 WOoD-GusH, D G M 1956 The agonistic and courtship behavior of the brown leghorn cock Br J Animal Behav., 4: 133-142 WOODreNO, W.P 1958 Geology of Barro Colorado Island, Canal Zone Smiths.Misc Colls., 135(3): 1-39 WYNNE-EDWARDS, V C 1962 Animal dispersionin relation to social behaviour Oliver and Boyd, Edinburgh, 693 pp APPENDIX CHARACTERISTICS OF MEMBERS OF FORESTFLOCKSON BARROCOLORADOISLAND Characteristic Species a b c d e f g h i Antwren, White-flanked 1 1 1 1 c c c a a 1 Greenlet, Gray-headed Tanager, Sulphur-rumped 1 1 1 1 1 1 c u c u c c g g g g 5 gl g8 Tanager,White-shouldered Antwren,Dot-winged Gnatcatcher,Tropical 1 u 1 1 1 1+ u 1+ 2 u u u g g g6 u u a a u r g g g4 Euphonia,Fulvous-vented Antvireo, Dot-crowned Antshrike, Slaty Gnatwren,Long-billed 1+ 1+ 22- c c g g g7 u c- a+ a 11 c c a* a r r a a 19 1 1+ 2 2 2 2 1+ 2 2- 2 22 2 u u c r j k m n o 1972 WILLIS: BEHAVIOR OF SPOTTED ANTBIRDS 157 A??V.NDIX (continued) Characteristic Species Antwren, Checker-throated Antbird, Spotted Antbird, Chestnut-backed Flycatcher, Dusky-capped Flycatcher, Yellow-margined Xenops, Plain Woodcreeper,Wedge-billed Woodcreeper,Buff-throated Woodcreeper, Black-striped Puffbird, White-whiskered Flycatcher, Ruddy-tailed Flycatcher, Bentbill Flycatcher, Ochre-bellied Spadebill,Golden-crowned Flatbill, Olivaceous Manakin, Red-capped Manakin, Golden-collared Woodcreeper,Plain-brown a b c d 2 2 2 2-2 2 e 2 f 2 2+ 1- 2 2* 2- g h i j k m n o 2 2 c u r c u u c c u a aa- a a a I 18 2 2 u c c c c c g g g g 4 g3 g2 2 2 2 2 2 2 2 2 2 2 1 u c c u c u r c r a a a a a a 2 10 2 2 2 2 u c c g g g5 333- 2+ 1- 3+ 3 3 3 3- 3-2 3- 2 u c u u c u c+ a a c a+ a u a a 4 12 13 33- 3+ 3+ 3 3 33- 2 2 u u u u r c a a 4 16 17 I u u u a a 2 c c c a a 2 r u r r r c a a a+ a 3 14 20 15 3 3 3 3 3 3 3 3 3-3-2 3-3-2 3 a a Redstart, American I- 1- 3 3 u u c+ g g m9 Warbler, Canada Warbler, Chestnut-sided Warbler, Bay-breasted Vireo, Red-eyed I- 1- 3 3 c c c a a ml 1- 1+ I 3 3 3 3 2 I c c c c c c a a a+ a 5 m3 m2 2- m8 Warbler, Kentucky Warbler, Black-and-white Flycatcher, Great Crested Flycatcher, Acadian 3 - u u r g g 1+ 3 2 u u c a a m7 2 2+ 1- 3 3 3 - 2 u u u u c c g- a g g m6 m5 2+ 3 2 u c c a m4 2- I- a a Foraging method: 1, moderatelyintent;2, very intent;3, lookswidely b Food source: 1, greenfoliage;2, deadmaterial; 3, both and air c•Family structure: I, clansformed; 2, pairs; 3, solitary d Chirping notes: 1, frequent;2, occasional;3, rare e Initial alarm: I, noisy;2, sometimesnoisy;3, quiet f -Subsequenttameness: 1, rapidly tame; 2, slowly tame; 3, tendsto flee g Leader?: 1, leadsor is followed;2, follows h Persistence: I, high per cent with flocks;2, moderateor low i Frequency in flocks: c, common;u, uncommon;r, rare j General abundanceon Barro Colorado: c, common; u, uncommon; r, rare k Forest type used: c, forest; u, vines and tangles;r, secondgrowth Foraging height: a, low; g, high m Flock type joined: a, antwren; g, greenlet n Taxon: I, antbirds; 2, furnariids; 3, manaklns; 4, flycatchers; 5, songbirds o Rank in Barro Colorado alliances: 1-20, antwren alliances;gl-g8, greenletalliances; ml to m9, migrants + or- meanstending higher or lower; in many casesI is higher than and is lower than 1, in a closed triangular series APPENDIX 2x •tccipiter spp. see Hawks Antbird, Bicolored ( Gyrnnopithysbicolor) 4ff Dot-backed ( Hylophylax punctulata) Chestnut-backed (Myrmecizaexsul) 20, 50, 51, 110, 111, 112, 116, 130, 133, 134, al Lunulated ( Gymnopithys lunulata) 28 Ocellated(Phaenostictus rncleannani) 18,20, 27, 28, 42, 76, 78, 106, 110, 111, 112, 115, 116, 119, 120, 122 Rufous-throated ( Gy•nnopithys ru/igula) 33 Scale-backed( Hylophylax poecilonota) 97, 98 Spot-backed (Hylophylax naevia) 2, 93, 95 White-bellied ( Myrmeciza longipes) 116 Antbirds (Formicariidae) 74, 132 Antpitta, Streak-chested( Grailaria perspicillata ) 116 Antshrike, Cinereous( Tharnnomanescaesius ) 143 Dusky-throated ( Thamnomanes ardesiacus ) 14 Slaw (Thamnophilus punctatusatrinuchus) 20, 48, 52, 54, 69, 76, 77, 78, 110, 112, 122, 127, 128, 129, 134, al Ant-Tanager, Red-crowned(Habia rubica) 76, 77, 78, 127, 128, 146 Red-throated (Habia/uscicauda) 64, 76, 77, 78, 100, 101, 127, 128, 143, 146 Antthrush, Black-faced (Formicarius analis) 116 Antvireo, Dot-crowned (Dysitharnnuspuncticeps)• 129, 132, a Antwren, Brown-bellied ( Myrrnotherula gutturalis) 129 Checker-throated(Myrmotherula/ulviventris) 110, 113, 128, 129, 134, 142, 143, al Dot-winged (Microrhopias quixensis) 6, 7, 127, 130, 132, 134, 136, al Fulvous-bellied (see Checker-throated) Gray (Myrrnotherula rnenetriesii) 146 Long-winged (Myrmotherula longipennis) 146 Rufous-tailed (Myrrnotherula erythrura) 129 Stipple-throated (Myrrnotherula haernatonota) 129 White-eyed ( Myrmotherula leucophthalrna) 129 White-flanked (Myrmotherula axillaris) 78, 110, 126, 127, 128, 129, 133, 136, 142, 145, 146, al Apodidae see Swifts Autornolus ochrolaernus see Foliage-gleaner, Buff-throated Baryphthengusru/icapillt•ts see Motmot, Great Rufous Becards (Pachyramphus spp., Platypsaris spp.) 132 Blackbirds (Icteridae) 135 Bluebird, Eastern ( Sialia sialis)•142 Bucconidae•see Puffbirds Bushtit (Psaltriparus minirnus) 138 Buteogallus anthracinus see Hawk, Common Black Capella gallinago•see Snipe, Common Chickadees (Parus spp.) 135 Contopus spp. see Pewees, Wood Cotingas (Cotingidae) 132, 140 Cuckoo, Squirrel (Piaya cayana) 110, 111, 113 Cyphorhinusphaeocephalus seeWren, Song • symbol: a • appendix number 158 1972 WILLIS: BEHAVIOR OF SPOTTED ANTBIRDS Dendrocincla /uliginosa see Woodcreeper, Plain-brown Dendrocolaptes certhia see Woodcreeper, Barred Dendrocolaptidae see Woodcreepers Dendroica spp. see Warblers Dysithamnus puncticeps see Antvireo, Dot-crowned Empidonax virescens seeFlycatcher, Acadian Eucometis penicillata see Tanager, Gray-headed Euphonia, Fulvous-vented(Euphonia /ulviventris) 130, al Flatbill, Olivaceous(Rhynchocyclusolivaceus) 132, al Flycatcher,Acadian (Empidonax virescens) i 10, 133, al Bentbill (Oncostomacinereigulare) 131, 135, 136, al Black-tailed (Myiobius atricaudus) 131, 138 Dusky-capped(Myiarchus tuberculi/er) 132, 133, 138, al Great Crested (Myiarchus crinitus) 133, al Ochre-bellied (Pipromorpha oleaginea) 131, al Olivaceous (see Dusky-capped) Ruddy-tailed(Terenotriccuserythrurus) 9, 110, 113, 131, al Sulphur-rumped( Myiobius sulphureipygeus ) 131, 138 Yellow-margined ( Tolmomyias assimilis) 132, a Flycatchers see Tyrant Flycatchers Foliage-gleaner,Buff-throated ( Automolus ochrolaemus) 130 Forest-falcon, Barred ( M icrastur ru[icollis) 140 Forest-falcons(Micrastur spp.) 28, 140 Formicariidae see Antbirds Formicarius analis Furnariidae see see Antthrush, Black-faced Ovenbirds Glaucidium spp. see Owls, Pygmy Glyphorynchusspirurus see Woodcreeper,Wedge-billed Gnatcatcher, Tropical (Polioptila plumbea) 130, al Gnatwren, Long-billed (Ramphocaenusmelanurus) 130, al Goldfinches (Spinus spp.) 79 Grailaria perspicillata see Antpitta, Streak-chested Greenlet, Gray-headed (Hylophilus decurtatus) 126, 127, al Greenlets (Hylophilus spp.) 126, 127 Gymnopithys spp. see Antbirds Habia spp. see Ant-Tanagers Harpagus bidentatu• see Kite, Double-toothed Hawk, Common Black (Buteogallusanthracinus) 20 Semiplumbeous( Leucopternissemiplumbea ) 5, 84 Tiny (•lccipiter superciliosus) 140 White ( Leucopternis albicollis) 84 Hawks (Accipitridae, Falconidae) 140 Helmitheros vermivorus see Warbler, Worm-eating Heterospingusrubri/rons see Tanager, Sulphur-rumped Hummingbird, Hermit (Phaethornisspp.)-•28, 78 Hummingbirds(Trochilidae) 74 Hylocichla spp. see Thrushes and Veery Hylophilus spp. see Greenlets Hylophylax spp. see Antbirds Icterids (Icteridae) 74, 135 159 160 ORNITHOLOGICAL MONOGRAPHS Kite, Double-toothed (Harpagus bidentatus) 20 Leafscraper,Scaly-throated(Sclerurusguatemalensis) 110, 113, 126, 138 Leafscrapers(Sclerurusspp.) 142 Leucopternis albicollis -see Hawk, White Malacoptila panamensis see Puffbird, White-whiskered Manacus vitellinus see Manakin, Golden-collared Manakin, Blue-crowned ( Pipra coronata) 131 Golden-collared ( Manacus vitellinus) 131, al Red-capped(Pipra mentalis) 110, 131, al Manakins (Pipridae) 74, 131, 132, 139 Micrastur spp. see Forest-falcons Microrhopias quixensis see Antwren, Dot-winged Mniotilta varia-•see Warbler, Black-and-white Motmot, Great Rufous (Baryphthengusru/icapillus) 20, I I0, 113 Motmots (Momotidae) 118 Myiarchus spp. see Flycatchers Myiobius spp. see Flycatchers Myrmeciza spp. see Antbirds Myrmotherula spp. see Antwrens Oncostoma cinereigulare see Flycatcher, Bentbill Oporornis formosus•see Warbler, Kentucky Ovenbirds (Furnariidae) 74, 130, 132 Owls, Pygmy (Glaucidium spp.) 140 Pachyramphus spp. see Becards Paridac see Titmice Parrots (Psittacidae) 74, 126, 132 Parulidae•see Warblers (Parulidae) Pewees, Wood (Contopus spp.) 133 Phaenostictus mcleannani see Antbird, Ocellated Phaethornis spp. see Hummingbirds, Hermit Piaya cayana see Cuckoo, Squirrel Picidae see Woodpeckers Pipra spp. see Manakins Pipridae see Manakins Pipromorpha oleaginea see Flycatcher, Ochre-bellied Platypsaris spp. see Becards Platyrinchus coronatus see Spadebill, Golden-crowned Polioptila plumbea see Gnatcatcher, Tropical Psaltriparus rainlinus see Bushtit Psittacidae see Parrots Puffbird, White-whiskered(Malacoptila panamensis) 20, I0, 111, 113, al Puffbirds (Bucconidae) -74, 118 Ramphastidae see Toucans Ramphastossulfuratus see Toucan, Keel-billed Ramphocaenusmelanurus see Gnatwren, Long-billed Redstart, American (Setophaga ruticilla) al Rhynchocyclus olivaceus see Flatbill, Olivaceous $clerurus guatemalensis see Leafscraper, Scaly-throated Seiurus spp. see Waterthrushes Setophagaruticilla see Redstart, American NO 10 1972 WILLIS: Sialia sialis BEHAVIOR OF SPOTTED ANTBIRDS 161 see Bluebird, Eastern Snipe, Common ( Capella gallinago) -26 Spadebill, Golden-crowned (Platyrinchus coronatus) 132, al Spinus spp. see Goldfinches Swifts (Apodidae) 126 Tachyphonusspp. see Tanagers Tanager, Gray-headed (Eucornetispenicillata) -9, 20, 110, 111, 112 Plain-colored (Tangara inornata) 140, 141 Sulphur-rumped(Heterospingusrubri/rons) 128, al Tawny-crowned (Tachyphonusdelattrei) 128 White-shouldered (Tachyphonus luctuosus) 127, al Tanagers (Thraupidae) 74, 126 Tangara inornata see Tanager, Plain-colored Terenotriccuserythrurus see Flycatcher, Ruddy-tailed Thamnomanes spp. see Antshrikes Thamnophiluspunctatusatrinuchus seeAntshrike,Slaty Thranpidaelsee Tanagers Thrush, Gray-cheeked (Hylocichla minima) 110, 111 Hermit ( Hy locichla guttata) 142 Swainson's( Hylocichla ustulata) 110, 111 Wood (Hylocichla mustelina) 133 Thrushes(Hylocichla spp.) 83, 110, 111, 113, 121, 122 Titmice (Paridae) 135 Tolmomyias assimilis see Flycatcher, Yellow-margined Toucan, Keel-billed ( Ramphastossul[uratus) 57 Toucans (Ramphastidae) 126, 132, 140, 145 Trochilidae•see Hummingbirds Troglodytidaelsee Wrens Trogon, Black-throated (Trogon ru/us) 20, 132, 145 Trogons (Trogonidae) 74, 132, 140 Tyrant Flycatcher (Tyrannidae) 74, 132, 133, 138 Veery (Hylocichla /uscescens) 110 Vireo, Red-eyed (Vireo olivaceus) al Warbler, Bay-breasted(Dendroica castanea) 133, al Black-and-white (Mniotilta varia) 133, a Canada (Wilsonia canadensis) 110, 111,113, 133, 134, 138, al Chestnut-sided(Dendroica pensylvanica) 133, al Kentucky (Oporornis/ormosus) 110, 133, 134, 135, al Worm-eating (Helmitheros vermivorus) 129 Warblers (Parulidae) 133, 135, 142 Waterthrushes (Seiurus spp.) 133, 142 Wilsonia canadensis see Warbler, Canada Woodcreeper, Barred (Dendrocolaptes certhia) 102, 110, 112 Black-striped (Xiphorhynchus lachrymosus) 50, 130, al Buff-throated (Xiphorhynchusguttatus) 110, 122, 130, al Plain-brown (Dendrocincla /uliginosa) 18, 20, 27, 50, 110, 111, 112, 121, 122, 131, al Wedge-billed (Glyphorynchusspirurus) 128, 129, al Woodcreepers (Dendrocolaptidae) I Woodpeckers(Picidae) 74, 132, 145 33 162 ORNITHOLOGICAL Wren, Song ( Cyphorhinusphaeocephalus ) 128 Wrens (Troglodytidae) 147 Xenops, Plain (Xenops minutus) 129, al Xiphorhynchusspp. see Woodcreepers MONOGRAPHS NO 10 ORNITHOLOGICAL No MONOGRAPHS A Distributional Studyof the Birds of British Honduras, by Stephen M Russell 195 pp., color plates 1964 Price $4.50 ($3.60 to AOU members) No A Comparative Study of Some Social Communication Patterns in the Pelecaniformes, by Gerard Frederick van Tets 88 pp., text figures 1965 Price $2.00 ($1.60 to AOU members) No The Birds of Kentucky, by Robert M Mengel Cloth bound,xiv + 581 pp., color plates plus text figures and vignettes 1965 Price $10.00 ($8.00 to AOU members) No Evolution of Some Arctic Gulls (Larus): an Experimental Study of Isolating Mechanisms,by Neal Griffith Smith 99 pp., 62 text figures 1966 Price $2.50 ($2.00 to AOU members) No A ComparativeLife-historyStudyof Four Speciesof Woodpeckers, by Louise de Kiriline Lawrence 156 pp., 33 text figures 1967 Price $3.75 ($3.00 to AOU members) No No Adaptationsfor Locomotionand Feeding in the Anhinga and the Double-crestedCormorant, by OscarT Owre 138 pp., 56 text figures 1967 Price $3.50 ($2.80 to AOU members) A Distributional Survey of the Birds of Honduras, by Burr L Mortroe, Jr 458 pp., 28 text figures, color plates 1968 Price $9.00 ($7.20 to AOU members) No An Approachto theStudyof Ecological Relationships amongGrdssland Birds, by John A Wiens 93 pp., 30 text figures 1969 Price $2.50 ($2.00 to AOU members) No Mating Systems, SexualDimorphism,and the Role of Male North AmericanPassefineBirds in the Nesting Cycle,by JaredVernerand Mary F Willson 76 pp 1969 Price $2.50 ($2.00 to AOU members) No I0 The Behaviorof SpottedAntbirds, by EdwinO Willis,vi + 162pp.,3 colorplates,27 textfigures 1972 Price $6.00 ($4.75 to AOU members) Like all other AOU publications, Ornithological Monographsare shipped prepaid Make checkspayableto "The AmericanOrnithologists' Union." For the convenience of thosewho wish to maintain completesetsof Ornithological Monographsand to receivenew numbersimmediatelyupon issue,standingorders will be accepted Orderfrom: Burt L Monroe, Jr., Treasurer,AmericanOrnithologists' Union, Box 23447,Anchorage, Kentucky40223 ... 15.6 13.6 61 18 10 67.0 19.8 11.0 60- 80 ø 80 -100 ø 53 106 15.8 31.6 163 628 8.3 31.9 1 1.1 1.1 100 -120 ø 120-140 ø 0.2 0.4 0.1 336 100 .0 1968 91 100 .0 Total Records Percent Preening 100 .0 Records... Army Ants 100 Following the Army Ants 101 Prey and Prey Treatment 103 Numbers 106 at Swarms Competition at Swarms 109 Discussion 116 ... THE BEHAVIOR SPOTTED OF ANTBIRDS BY EDWIN ORNITHOLOGICAL O WILLIS MONOGRAPHS PUBLISHED THE AMERICAN BY ORNITHOLOGISTS' 1972 NO UNION 10 ORNITHOLOGICAL MONOGRAPHS This series,publishedby the American