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An electronic system to collect distance-sampling data during helicopter surveys of northern bobwhite

Authors

  • Matthew J. Schnupp,

    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
    Current affiliation:
    1. King Ranch, Inc., Highway 141 W, Kingsville, TX 78363, USA.
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  • Fidel Hernández,

    Corresponding author
    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
    • Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
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  • Eric J. Redeker,

    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
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  • Fred C. Bryant,

    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
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  • Joshua P. Rusk,

    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
    Current affiliation:
    1. Iowa Department of Natural Resources, Grand River Wildlife Unit, 1796 250th Street, Mount Ayr, IA 50854, USA.
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  • Stephen J. Demaso,

    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
    Current affiliation:
    1. Gulf Coast Joint Venture, United States Fish and Wildlife Service, 700 Cajundome Boulevard, Lafayette, LA 70506, USA.
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  • Joseph P. Sands,

    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
    Current affiliation:
    1. U.S. Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232, USA.
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  • Trent W. Teinert,

    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
    Current affiliation:
    1. Texas Parks and Wildlife Department, Victoria, TX 79901, USA.
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  • Leonard A. Brennan,

    1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Blvd., Kingsville, TX 78363, USA
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  • Dale Rollins,

    1. Texas AgiLIFE Research, Texas A&M University, San Angelo, TX 79601, USA
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  • Robert M. Perez

    1. Texas Parks and Wildlife Department, La Vernia, TX 78121, USA
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  • Acting Editor: Rodgers

  • Associate Editor: Rodgers

Abstract

Distance sampling during aerial surveys has been used extensively to estimate the density of many wildlife species. However, practical issues arise when using distance sampling during aerial surveys, such as obtaining accurate perpendicular distances. We assembled a computerized, electronic system to collect distance-sampling data (e.g., transect length, detection location, and perpendicular distance) during aerial surveys. We tested the accuracy of the system in a controlled trial and a mock survey. We also evaluated the electronic system during field surveys of northern bobwhite (Colinus virginianus) conducted in the Rio Grande Plains and Rolling Plains ecoregions of Texas, USA, during December 2007–2008. For comparison, we evaluated the accuracy of visual estimation of distance during a mock survey. A strong linear relationship existed between estimated and actual distances for the controlled trial (r2 = 0.99) and mock survey (r2 = 0.98) using the electronic system. Perpendicular-distance error (i.e., absolute difference between estimated distance and actual distance) for the electronic system was low during the controlled trial (1.4 ± 0.4 m; equation image ± SE) and mock survey (3.0 ± 0.5 m) but not during the visual estimation of distance (10 ± 1.5 m). Estimates of bobwhite density obtained using the electronic system exhibited reasonable precision for each ecoregion during both years (CV < 20%). Perpendicular-distance error slightly increased with target distance (0.7-m increase in error for every 10-m increase in target distance). Overall, the electronic system appears to be a promising technique to estimate density of northern bobwhite and possibly other terrestrial species for which aerial-based distance sampling is appropriate. © The Wildlife Society, 2012

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