OrnithologicalMonographs No.49 AvianReproductive Tactics: Femaleand Male Perspectives editors PatriciaG. Parker and Nancy Tyler Burley AVIAN REPRODUCTIVE TACTICS: FEMALE AND MALE PERSPECTIVES ORNITHOLOGICAL MONOGRAPHS Edited by JOHN M. HAGAN Manomet Center for Conservation Sciences P.O. Box 1770 Manomet, Massachusetts 02345 USA Ornithological Monographs,published by the American Ornithologists'Union, has been establishedfor major paperstoo long for inclusion in the Union's journal, The Auk. Publication has been made possiblethrough the generosityof the late Mrs. Carll Tucker and the Marcia Brady Tucker Foundation, Inc. Copies of Ornithological Monographs may be ordered from Max C. Thompson, Assistant to the Treasurer, Department of Biology, Southwestern College, 100 College St., Winfield, KS 67156. Communications may also be routed through the AOU's permanent address: Division of Ornithology, National Museum of Natural History, Washington, D.C. 20560. Editors of this issue, Patricia G. Parker and Nancy Tyler Burley. Price of OrnithologicalMonographs 49:$20.00 prepaid. Add 5 percenthan- dling and shipping charge in U.S., and 20 percent for all other countries.Make checks payable to American Ornithologists' Union. Library of CongressCatalogue Card Number 97-78467 Printed by the Allen Press, Inc., Lawrence, Kansas 66044 Issued January 29, 1998 Ornithological Monographs, No. 49 v + 195 pp. Printed by Allen Press, Inc., Lawrence, Kansas 66044 Copyright ¸ by the American Ornithologists'Union, 1997 ISBN: 0-935868-95-X AVIAN REPRODUCTIVE TACTICS: FEMALE AND MALE PERSPECTIVES EDITORS PATRICIA G. PARKER 1 and NANCY TYLER BURLEY 2 •Departmentof Zoology, 1735 Neil Avenue, The Ohio State University, Columbus, Ohio 43210-1293, USA 2 Departmentof Ecology and EvolutionaryBiology, University of California, Irvine, California 92697-2525, USA ORNITHOLOGICAL MONOGRAPHS NO. 49 PUBLISHED BY THE AMERICAN ORNITHOLOGISTS' UNION WASHINGTON, D.C. 1998 AVIAN REPRODUCTIVE TACTICS: FEMALE AND MALE PERSPECTIVES PATRICIA G. PARKER AND NANCY TYLER BURLEY TABLE OF CONTENTS CHAPTER 1 BURLEY,NANCY TYLER, AND PATRICIAG. PARKER.Emerging themes and questionsin the study of avian reproductivetactics .................................. 1 CHAPTER 2 JOHNSON,KRISTINE, AND NANCY TYLER BURLEY. Mating tactics and mating systemsof birds ..................................................................................... 21 CHAPTER 3 GRAY, ELIZABETHM. Intraspecific variation in extra-pair behavior of Red- winged Blackbirds (Agelaiusphoeniceus) ................................................ 61 CHAPTER 4 KETrERSON,ELLEN D., PATRICIA G. PARKER, SAMRRAHA. RAOUF, VAL NO- LAN, JR., CHARLESZIEGENFUS, AND C. RAY CHANDLER.The relative impact of extra-pair fertilizations on variation in male and female reproductivesuc- cess in Dark-eyed Juncos(Junco hyemalis) .............................................. 81 CHAPTER 5 STUTCHBURY,BRIDGET J. M., AND DIANE L. NEUDORF. Female control, breed- ing synchrony,and the evolution of extra-pair mating systems.................. 103 CHAPTER 6 WAGNER,RICHARD H. Hidden leks: sexual selection and the clustering of avian territories ...................................................................................... 123 CHAPTER 7 DU•N, PETERO., ANDANDREW COCK•URN. Costs and benefits of extra-group paternity in Superb Fairy-wrens .............................................................. 147 CHAPTER 8 MCKINNEY, FRANK, AND SUSAN EvARTS. Sexual coercion in waterfowl and other birds .............................................................................................. 163 Ornithological Monographs Volume (1997), pp. 1-20 CHAPTER 1 EMERGING THEMES AND QUESTIONS IN THE STUDY OF AVIAN REPRODUCTIVE TACTICS NANCY TYLER BURLEY • AND PATRICIA G. PARKER 2 •Departrnent of Ecology and Evolutionary Biology, University of California, Irvine, California 92697-2525, USA 2Departmentof Zoology, 1735 Neil Avenue, The Ohio State University, Columbus, Ohio 43210, USA ABSTRACT.--Manyresearchers have explored the ramifications of the idea that extra-paircopulation (EPC) is a male reproductivetactic to obtainparentage while avoiding parentalinvestment since this conceptwas advancedby Trivers in 1972. Consortship between males and their fertile mates has been interpreted almost exclusively in terms of mate guarding by males. Females have been thought to benefit little, if at all, from extra-pair activities. This mindset has persistedand influencesour interpretationof patternsof reproductivesuccess revealed by mo- lecular markers. Here we briefly trace the historical developmentof this line of reasoningand the newer, contrastingview--well representedin this volume that females as well as males have EPC tactics. We identify specific contributions made by authorsin this volume, contrasttheir approaches,and discussthe impli- cations of their results for the understandingof avian mating systemsand the role of sexual selectionin avian social evolution. Finally, we illustratethe richnessof this collection of papersby expandingon key points. This volume had its origins in a symposium on "Avian Tactics for Extra-Pair Mating" organized by Patty Parker at the request of Thomas C. Grubb for the 1995 AOU meeting in Cincinnati, Ohio. Cognizant of the increasingnumber of substantialdata sets showing that rates of extra-pair fertilization (EPF) are com- monly much higher than was expectedeven a few years previously,Patty invited participantswith such data sets,fully expecting to find that patternsof EPF would be interpretedin a variety of ways. What emerged in the symposium,however, was a clear and compelling empirical consensus:acquisition of multiple genetic mates is a female reproductive tactic in avian specieshaving a diversity of social mating systems(monogamy, polygyny, promiscuity) and social organizations(co- operative breeders, territorial species,gregarious and colonial species).This con- sensusis reinforced by several recent papers (e.g., Gowaty and Bridges 1991; Kempenaerset al. 1992; Lifjeld and Robertson 1992; Wagner 1992; Burley et al. 1994, 1996; Lifjeld et al. 1994; Stutchbury et al. 1994). This idea provides a sharp contrastto the prevailing view, briefly discussedbelow as well as by several contributors to this volume (Johnson and Burley, Chapter 2; Ketterson et al., Chapter 4; Stutchbury and Neudorf, Chapter 5), that selection on males is the 2 ORNITHOLOGICAL MONOGRAPHS NO. 49 principal evolutionary force shaping extra-pair activities (Birkhead and M011er 1992). Invigorated by the successand timelinessof the symposium,Patty askedNancy Burley to join her as coeditor in developing this volume. A few of the original symposiumparticipants have not contributedto the volume, and two new papers were solicited. We invited Frank.McKinney and SusanEvarts' contributionon avian sexual coercion (Chapter 8) to provide some taxonomic balance and a com- plementaryconceptual perspective to other papersin the collection.Also, given the historical importance of the Red-winged Blackbird in avian behavioral ecol- ogy, this volume would not have been complete without Elizabeth Gray's contri- bution on intraspecificvariation in extra-pair mating tactics of Red-winged Black- birds (Chapter 3). Here we highlight someof the major findingsand ideasin the volume, principal of which is the developingview that extra-pair fertilization (EPF) is not a singular consequenceof selection on males (i.e., via sperm competition and male mate guarding).Rather, varying ratesof EPF within and acrossspecies reflect the prod- uct of a diversity of competing reproductive tactics of females and males. We frame our discussionby posing several questionswhose answersare intended to illuminate common themes and concernsof papers in this volume. Finally, we explore issues that our reading of the papers has led us to consider and that we believe are worthy of further thought and empirical inquiry. WHY IS THERE A SUDDEN FLOWERING OF UNDERSTANDING OF THE ROLE OF FEMALES IN EXTRA-PAIR ACTIVITIES? Darwin (1874) noted the possibility that extra-pair copulations(EPCs) might occurin populationsof "savages"and suggestedthat resultingEPFs would dilute the strength of sexual selection on males. Following Darwin, scatteredornitho- logical reports were made of observationsof "infidelity" and forced copulation (e.g., Huxley 1912; Christoleit 1929; Marler 1956; Weidmann 1956), but little was made of them. In the 1960s, ideas from economics,population biology, ge- netics, and ethology began to come togetherin ways that allowed scientiststo think clearly about individual tactics of behavior (for a brief history, see Gross 1994). These events set the stage for Bob Trivers' (1972) articulation of the idea that EPC is a mixed male reproductivetactic in pair-bondingspecies, including most birds. Trivers' (1972) suggestionproved to be very stimulating.His work and early papers by Geoff Parker (1970a, b) propelled researchon sperm competition(see referencesin Parker 1984; Smith 1984; Birkhead and M011er 1992). Sperm com- petition is usually defined as the competition between spermatozoaproduced by two or more males for the opportunityto fertilize ova producedby a single female (Parker 1970a), and that is the sensein which we use the term here. Recently, some authors have broadened this definition to include other aspectsof sexual selection, including aspectsof female mate choice (e.g., Birkhead 1995); in our view, such an approachis unfortunatein that it obfuscatesrather than illuminates the various processesand the complex