Accommodating Unmodeled Heterogeneity in Double-Observer Distance Sampling Surveys

Authors

  • D. L. Borchers,

    Corresponding author
    1. Research Unit for Wildlife Population Assessment, The Observatory, Buchanan Gardens, University of St. Andrews, Fife, KY16 9LZ, Scotland
      email:dlb@mcs.st-and.ac.uk
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  • J. L. Laake,

    1. National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, 7600 Sand Point Way NE, Seattle, Washington 98115, U.S.A.
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  • C. Southwell,

    1. Australian Antarctic Division, Channel Highway, Kingston, Tasmania, 7050, Australia
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  • C. G. M. Paxton

    1. Research Unit for Wildlife Population Assessment, The Observatory, Buchanan Gardens, University of St. Andrews, Fife, KY16 9LZ, Scotland
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email:dlb@mcs.st-and.ac.uk

Abstract

Summary Mark-recapture models applied to double-observer distance sampling data neglect the information on relative detectability of objects contained in the distribution of observed distances. A difference between the observed distribution and that predicted by the mark-recapture model is symptomatic of a failure of the assumption of zero correlation between detection probabilities implicit in the mark-recapture model. We develop a mark-recapture-based model that uses the observed distribution to relax this assumption to zero correlation at only one distance. We demonstrate its usefulness in coping with unmodeled heterogeneity using data from an aerial survey of crabeater seals in the Antarctic.

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