Scientific Evaluation for the 5-Year Status Review of the Golden-Cheeked Warbler
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1 2 3 4 SCIENTIFIC EVALUATION FOR THE 5-YEAR STATUS REVIEW OF THE 5 GOLDEN-CHEEKED WARBLER 6 7 November 2010 8 9 10 Prepared for 11 U.S. Fish and Wildlife Service 12 13 14 Prepared by 15 Julie E. Groce, Heather A. Mathewson, Michael L. Morrison, and Neal Wilkins 16 17 Institute of Renewable Natural Resources 18 and the 19 Department of Wildlife & Fisheries Sciences 20 Texas A&M University, College Station,Texas 21 22 23 24 25 26 27 28 29 30 31 32 33 34 1 Table of Contents 35 EXECUTIVE SUMMARY ............................................................................................................ 9 36 CHAPTER 1. INTRODUCTION ................................................................................................. 12 37 1.1 Background ......................................................................................................................... 12 38 1.2 Objectives ........................................................................................................................... 12 39 1.3 Authors and Review Panel .................................................................................................. 13 40 1.3.1 Status Review Team .................................................................................................... 13 41 1.3.2 Review Panel ............................................................................................................... 13 42 1.3.3 Peer review................................................................................................................... 14 43 1.4 Scientific information and data quality ............................................................................... 14 44 1.5 Organization of the Scientific Evaluation ........................................................................... 14 45 1.6 Acknowledgements ............................................................................................................. 15 46 CHAPTER 2. GENERAL ECOLOGY......................................................................................... 16 47 2.1 Physical Appearance and Molts .......................................................................................... 16 48 2.2 Systematics ......................................................................................................................... 16 49 2.3 Geographic Distribution...................................................................................................... 17 50 2.3.1 Breeding Range ............................................................................................................ 17 51 2.3.2 Wintering Range .......................................................................................................... 18 52 2.3.3 Rare Occurrences ......................................................................................................... 21 53 2.4 Migration............................................................................................................................. 21 54 2.4.1 Route ............................................................................................................................ 21 55 2.4.2 Spring Migration .......................................................................................................... 21 56 2.4.3 Fall Migration .............................................................................................................. 22 57 2.5 Diet and Foraging Behavior ................................................................................................ 22 58 2.5.1. Breeding Grounds ....................................................................................................... 22 59 2.5.2 Wintering Grounds....................................................................................................... 24 60 2.6 Reproduction ...................................................................................................................... 25 61 2.6.1 Mating System and Extra-pair Relations ..................................................................... 25 62 2.6.2 Territories ..................................................................................................................... 26 63 2.6.3 Defense Behavior ......................................................................................................... 26 64 2.6.4 Nest Description........................................................................................................... 27 65 2.6.5 Nesting Phenology ....................................................................................................... 27 66 2.7 Vocalizations and Sounds ................................................................................................... 28 67 2.7.1 Types of Vocalizations ................................................................................................ 28 68 2.7.2 Daily and Seasonal Variation....................................................................................... 28 69 2.7.3 Social Context .............................................................................................................. 29 70 2.8 Responses to Conspecifics, Heterospecifics, and Predators ............................................... 29 71 2.9 Summary for General Ecology ........................................................................................... 31 72 Appendix 2.A. Golden-cheeked warbler molt schedule ........................................................... 32 73 Appendix 2.B. Non-breeding season records of golden-cheeked warblers in countries other 74 than the United States. .............................................................................................................. 33 75 Appendix 2.C. Locations and sample sizes for studies describing golden-cheeked warbler 76 foraging substrate and behavior on the breeding grounds of central Texas ............................. 36 77 2 Appendix 2.D. Locations and sample sizes for studies describing golden-cheeked warbler 78 foraging substrate and behavior on the wintering grounds. ...................................................... 36 79 Appendix 2.E. Bird species commonly found in mixed-species flocks with golden-cheeked 80 warblers on the golden-cheeked warbler’s wintering grounds ................................................. 37 81 CHAPTER 3. DEMOGRAPHY ................................................................................................... 38 82 3.1 Long-term Study Sites: Fort Hood, Balcones Canyonlands Preserve, and Camp Bullis ... 38 83 3.2 Trends in Relative Abundance and Density........................................................................ 39 84 3.2.1 Abundance on Fort Hood 1992–2008 .......................................................................... 39 85 3.2.2 Territory Density .......................................................................................................... 40 86 3.3 Population Structure............................................................................................................ 42 87 3.3.1 Age at First Breeding ................................................................................................... 42 88 3.3.2 Age Ratios .................................................................................................................... 42 89 3.3.3 Nestling and Hatch-year Sex Ratios ............................................................................ 43 90 3.3.4 Adult Sex Ratios .......................................................................................................... 43 91 3.4 Reproductive Success ......................................................................................................... 44 92 3.4.1 Pairing Success ............................................................................................................ 44 93 3.4.2 Recruitment index ........................................................................................................ 45 94 3.4.3 Territory and Pair Reproductive Success ..................................................................... 48 95 3.4.4 Nest Success................................................................................................................. 48 96 3.4.5 Productivity .................................................................................................................. 50 97 3.5 Dispersal and Site Fidelity .................................................................................................. 52 98 3.5.1 Juveniles ....................................................................................................................... 52 99 3.5.2 Adults ........................................................................................................................... 52 100 3.6 Annual Survival and Longevity .......................................................................................... 54 101 3.6.1 Juvenile Survival .......................................................................................................... 54 102 3.6.2 Adult Survival .............................................................................................................. 54 103 3.6.3 Longevity ..................................................................................................................... 56 104 3.7 Population Viability Analyses ...........................................................................................