THE BEHAVIOR OF SPOTTED ANTBIRDS BY EDWIN O. WILLIS ORNITHOLOGICAL MONOGRAPHS NO. 10 PUBLISHED BY THE AMERICAN ORNITHOLOGISTS' UNION 1972 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 OF SPOTTED ANTBIRDS BY EDWIN O. WILLIS ORNITHOLOGICAL MONOGRAPHS NO. 10 PUBLISHED BY THE AMERICAN ORNITHOLOGISTS' UNION 1972 ORNITHOLOGICAL MONOGRAPHS This series,published by the American Ornithologists'Union, has been establishedfor major paperstoo long for inclusionin the Union's journal, The Auk. Publicationhas been made possiblethrough the generosityof Mrs. Carll Tucker and the Marcia Brady Tucker Foundation,Inc. Correspondenceconcerning manuscripts for publicationin the series shouldbe addressedto the Editor, Dr. Robert M. Mengel, Museum of Natural History, University of Kansas,Lawrence, Kansas 66044. Copiesof OrnithologicalMonographs may be orderedfrom the Treasurer of the AOU, Butt L. Monroe,Jr., Box 23447, Anchorage,Kentucky 40223. (See price list on insideback cover.) OrnithologicalMonographs, 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 CongressCatalogue Card Number 72-87186 Printedby the Allen PressInc., Lawrence,Kansas 66044 TABLE OF CONTENTS INTRODUCTION ................................................................................................................... 1 Spotted Antbirds and Their Relatives ..................................................................... 1 Army Ants ................................................................................................................ 3 Study Areas ............................................................................................................... 3 Methods of Study ....................................................................................................... 4 ACKNOWLEDGMENTS .......................................................................................................... GENERAL BEHAVIOR ............................................................................................................ 6 Calls and Songs ..................................................................................................... 6 Normal Postures and Movements ............................................................................ 9 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 ..................................................................................................... 16 Discussion .................................................................................................................. 16 REACTIONS TO DANGER ...................................................................................................... 18 Freezing ................................................................................................................... 18 Chipping and Panicking.......................................................................................... 19 Chitring and Mobbing ..............................................................................................20 Fleeing and Tameness................................................................................................ 23 Investigating .............................................................................................................. 24 Reactionsof Captives............................................................................................... 24 Discussion .................................................................................................................. 24 AGONISTIC BEHAVIOR .......................................................................................................... 29 Submissiveand Escape Behavior ........................................................................... 29 AggressiveDisplays and Attack Behavior ............................................................... 30 Sequencesof Agonistic Behavior ............................................................................ 34 Discussion ................................................................................................................. 36 REPRODUCTIVE BEHAVIOR .................................................................................................. 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 Distraction Displays and Parental Alarm ................................................................ 63 Development of Young out of the Nest ................................................................ 65 Renesting and Nest Success.................................................................................... 67 Breeding Season.............................................................................................. 70 Discussion ............................................................................................................... 7 ! WANDERING YOUNG AND TERRITORIAL ADULTS: SPATIAL BEHAVIOR ........................ 83 Dominance and Territoriality ............................................................................... 87 Territory Size, Densities, and Biomasses.................................................................. 89 Habitat Selection ........................................................................................................ 89 Discussion .............................................................................................................. 90 FORAGING BEHAVIOR ................................................................................................... 96 Perch Selection ................................................................................................. 97 Foraging Away from Ants ....................................................................................... 99 Searchingfor Army Ants ......................................................................................... 100 Following the Army Ants ........................................................................................101 Prey and Prey Treatment .................................................................................... 103 Numbers at Swarms ................................................................................................... 106 Competition at Swarms ........................................................................................... 109 Discussion .................................................................................................................. 116 ASSOCIATION WITH INTERSPECIFIC FLOCKS ....................................................................... 123 Other Members of Flocks ........................................................................................ 126 CompetitionAmong Flocking Birds .......................................................................133 Discussion .................................................................................................................... 135 SUMMARY ...........................................................................................................................