Southwestern Willow Flycatcher Breeding Site and Territory ... Southwestern Willow Flycatcher...

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  • In cooperation with Arizona Game and Fish Department, New Mexico Game and Fish Department, and Bureau of Reclamation

    Southwestern Willow Flycatcher Breeding Site and Territory Summary—2007

    By Scott L. Durst, Mark K. Sogge, Shay D. Stump, Hira A. Walker, Barbara E. Kus, and Susan J. Sferra

    Open–File Report 2008–1303

    U.S. Department of the Interior U.S. Geological Survey

  • U.S. Department of the Interior DIRK KEMPTHORNE, Secretary

    U.S. Geological Survey Mark D. Myers, Director

    U.S. Geological Survey, Reston, Virginia 2008

    For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1-888-ASK-USGS

    For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1-888-ASK-USGS

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    Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report.

    Suggested citation: Durst, S.L., Sogge, M.K., Stump, S.D., Walker, H.A., Kus, B.E., and Sferra, S.J., 2008, Southwestern willow flycatcher breeding sites and territory summary—2007: U.S. Geological Survey Open–File Report 2008–1303, 31 p.

    Cover: Southwestern willow flycatcher (Empidonax traillii extimus), U.S. Geological Survey photograph.

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  • Contents Introduction .........................................................................................................................................................................1

    Additional Considerations in Using and Interpreting the Data in This Report.....................................................2 Subspecies Status of Each Site ...................................................................................................................................3 Population Estimates......................................................................................................................................................3

    Data Summaries .................................................................................................................................................................4 Changes in the Number of Known Territories over Time........................................................................................4 Numbers of Sites over Time: Surveyed vs. Estimated .............................................................................................5 Numbers of Territories over Time: Surveyed vs. Estimated ...................................................................................6 Recency of Survey Data ................................................................................................................................................7 Distribution of Breeding Sites by Number of Territories .........................................................................................8 Distribution of Territories by State ............................................................................................................................10 Distribution of Territories by Drainage .....................................................................................................................11 Distribution of Territories by Recovery Unit and Management Unit ...................................................................12 Elevation Range of Breeding Territories ..................................................................................................................14 Use of Native and Exotic Habitats .............................................................................................................................15 Dominant Tree Species at Breeding Sites...............................................................................................................16 Administration/Management of Sites and Territories ...........................................................................................17

    2007 Summary ...................................................................................................................................................................17 Acknowledgments............................................................................................................................................................18 References.........................................................................................................................................................................19 Appendix 1. Distribution of Flycatcher Sites and Territories by Year .....................................................................21 Appendix 2. List of Extirpated Sites...............................................................................................................................25

    References.....................................................................................................................................................................29

    Figures 1. Estimated number of known Southwestern willow flycatcher breeding sites and territories, from 1993 to 2007 .......................................................................................................................................................................................4 2. Number of estimated and surveyed Southwestern willow flycatcher breeding sites from 1993 to 2007 ......5 3. Number of estimated and surveyed Southwestern willow flycatcher territories, from 1993 to 2007 .............6 4. Number of territories at willow flycatcher breeding sites as of 2007...................................................................8 5. Graphs showing the distribution of Southwestern willow flycatcher by elevation.........................................14 6. Percentage of flycatcher territories occurring within breeding sites of differing compositions of native and exotic vegetation, as of the 2007 breeding season ............................................................................................15 7. Percentage of flycatcher territories occurring within breeding sites dominated by particular tree species during the 2007 breeding season...................................................................................................................................16 8. Percentage of flycatcher breeding sites and territories found under different land ownership, as of the 2007 breeding season ......................................................................................................................................................17

    Tables 1. Most recent year of survey data for sites and territories included in this report, as of 2007 ..........................7 2. Number of Southwestern willow flycatcher breeding sites and territories by state, as of 2007 ..................10

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    3. Number of Southwestern willow flycatcher breeding sites and territories by major river drainage, as of the 2007 breeding season ...............................................................................................................................................11 4. Currently known number of flycatcher breeding sites, territories, and number of territories necessary for recovery criteria, by recovery unit and management unit........................................................................................12 1-1. Distribution of flycatcher sites and territories by year and state based on both estimated and surveyed values..................................................................................................................................................................................21 2-1. List of the 142 sites that at one time had Southwestern willow flycatcher territories, but were unoccupied as of the most recent survey....................................................................................................................25

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    Southwestern Willow Flycatcher Breeding Site and Territory Summary—2007

    By Scott L. Durst1, Mark K. Sogge1, Shay D. Stump2, Hira A. Walker3, Barbara E. Kus4, and Susan J. Sferra5

    Introduction The Southwestern willow flycatcher (Empidonax traillii extimus; hereafter references to

    willow flycatcher and flycatcher refer to E.t. extimus, except where specifically noted) is an endangered bird that breeds only in dense riparian habitats in parts of six Southwestern states (Arizona, New Mexico, southern California, extreme southern Nevada, southern Utah, and southwestern Colorado). Since 1993, hundreds of Southwestern willow flycatcher surveys have been conducted each year, and many new flycatcher breeding sites located. This document synthesizes the most current information available on all known Southwestern willow flycatcher breeding sites.

    This rangewide data synthesis was designed to meet two objectives: (1) identify all known Southwestern willow flycatcher breeding sites and (2) assemble data to estimate population size, location, habitat, and other information for all breeding sites, for as many years as possible, from 1993 through 2007.

    This report provides data summaries in terms of the number of flycatcher sites and the number of territories. When interpreting and using this information, it must be kept in mind that a “site” is