A new method for estimating visitation rates of cryptic animals via repeated surveys of indirect signs

Bernd Gruber, Björn Reineking, Justin Calabrese, Andreas Kranz, Katerina Poledníková, Lukas Polednik, Reinhard Klenke, Anett Valentin, Klaus Henle

    Research output: Contribution to journalArticle

    15 Citations (Scopus)

    Abstract

    1. Visitation rate is a measure of the frequency with which animals visit specific locations of interest. This information is crucial for various problems in the conservation and management of animal species, e.g. to determine the risk wildlife poses to human managed resources or the predation risks of nests. An important assessment tool, especially for cryptic animals, is to count indirect signs of presence, such as tracks or faeces. 2. Here we propose a maximum likelihood-based method that uses information on the age of tracks or signs, and we show that existing visitation rate/probability estimators are special cases of this more general approach. 3. Using simulated data, we compared the performance of the new visitation rate estimator to three other estimators, including the most commonly used estimator. These estimators make use of either fresh, aged or total signs, whereas our approach uses information simultaneously on both fresh and aged signs. The new estimator is, on average, in excess of three times more accurate than the next best estimator. Moreover, the new approach is very flexible and can be applied for sampling regimens with irregular time intervals between sampling. 4. We demonstrate the application of the method to field data by estimating the visitation rate of Eurasian otters (Lutra lutra) to a commercial fish pond. To facilitate the use of this method, we provide an easy-to-use Excel workbook and give recommendations on the most efficient sampling regimens. 5. Synthesis and applications. Visitation rate is an important quantity that can be estimated by repetitive sampling of indirect signs. We demonstrate the advantage of incorporating information explicitly on the age of signs over existing approaches. The new estimator can be applied to any species for which it is possible to discriminate between aged and new signs or tracks, and should be widely applicable in ecology and conservation biology.
    Original languageEnglish
    Pages (from-to)728-735
    Number of pages8
    JournalJournal of Applied Ecology
    Volume45
    DOIs
    Publication statusPublished - 2008

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    animal
    sampling
    predation risk
    nest
    pond
    method
    rate
    ecology
    resource
    fish
    wildlife
    animal species
    recommendation

    Cite this

    Gruber, Bernd ; Reineking, Björn ; Calabrese, Justin ; Kranz, Andreas ; Poledníková, Katerina ; Polednik, Lukas ; Klenke, Reinhard ; Valentin, Anett ; Henle, Klaus. / A new method for estimating visitation rates of cryptic animals via repeated surveys of indirect signs. In: Journal of Applied Ecology. 2008 ; Vol. 45. pp. 728-735.
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    title = "A new method for estimating visitation rates of cryptic animals via repeated surveys of indirect signs",
    abstract = "1. Visitation rate is a measure of the frequency with which animals visit specific locations of interest. This information is crucial for various problems in the conservation and management of animal species, e.g. to determine the risk wildlife poses to human managed resources or the predation risks of nests. An important assessment tool, especially for cryptic animals, is to count indirect signs of presence, such as tracks or faeces. 2. Here we propose a maximum likelihood-based method that uses information on the age of tracks or signs, and we show that existing visitation rate/probability estimators are special cases of this more general approach. 3. Using simulated data, we compared the performance of the new visitation rate estimator to three other estimators, including the most commonly used estimator. These estimators make use of either fresh, aged or total signs, whereas our approach uses information simultaneously on both fresh and aged signs. The new estimator is, on average, in excess of three times more accurate than the next best estimator. Moreover, the new approach is very flexible and can be applied for sampling regimens with irregular time intervals between sampling. 4. We demonstrate the application of the method to field data by estimating the visitation rate of Eurasian otters (Lutra lutra) to a commercial fish pond. To facilitate the use of this method, we provide an easy-to-use Excel workbook and give recommendations on the most efficient sampling regimens. 5. Synthesis and applications. Visitation rate is an important quantity that can be estimated by repetitive sampling of indirect signs. We demonstrate the advantage of incorporating information explicitly on the age of signs over existing approaches. The new estimator can be applied to any species for which it is possible to discriminate between aged and new signs or tracks, and should be widely applicable in ecology and conservation biology.",
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    Gruber, B, Reineking, B, Calabrese, J, Kranz, A, Poledníková, K, Polednik, L, Klenke, R, Valentin, A & Henle, K 2008, 'A new method for estimating visitation rates of cryptic animals via repeated surveys of indirect signs', Journal of Applied Ecology, vol. 45, pp. 728-735. https://doi.org/10.1111/j.1365-2664.2007.01406.x

    A new method for estimating visitation rates of cryptic animals via repeated surveys of indirect signs. / Gruber, Bernd; Reineking, Björn; Calabrese, Justin; Kranz, Andreas; Poledníková, Katerina; Polednik, Lukas; Klenke, Reinhard; Valentin, Anett; Henle, Klaus.

    In: Journal of Applied Ecology, Vol. 45, 2008, p. 728-735.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - A new method for estimating visitation rates of cryptic animals via repeated surveys of indirect signs

    AU - Gruber, Bernd

    AU - Reineking, Björn

    AU - Calabrese, Justin

    AU - Kranz, Andreas

    AU - Poledníková, Katerina

    AU - Polednik, Lukas

    AU - Klenke, Reinhard

    AU - Valentin, Anett

    AU - Henle, Klaus

    PY - 2008

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    N2 - 1. Visitation rate is a measure of the frequency with which animals visit specific locations of interest. This information is crucial for various problems in the conservation and management of animal species, e.g. to determine the risk wildlife poses to human managed resources or the predation risks of nests. An important assessment tool, especially for cryptic animals, is to count indirect signs of presence, such as tracks or faeces. 2. Here we propose a maximum likelihood-based method that uses information on the age of tracks or signs, and we show that existing visitation rate/probability estimators are special cases of this more general approach. 3. Using simulated data, we compared the performance of the new visitation rate estimator to three other estimators, including the most commonly used estimator. These estimators make use of either fresh, aged or total signs, whereas our approach uses information simultaneously on both fresh and aged signs. The new estimator is, on average, in excess of three times more accurate than the next best estimator. Moreover, the new approach is very flexible and can be applied for sampling regimens with irregular time intervals between sampling. 4. We demonstrate the application of the method to field data by estimating the visitation rate of Eurasian otters (Lutra lutra) to a commercial fish pond. To facilitate the use of this method, we provide an easy-to-use Excel workbook and give recommendations on the most efficient sampling regimens. 5. Synthesis and applications. Visitation rate is an important quantity that can be estimated by repetitive sampling of indirect signs. We demonstrate the advantage of incorporating information explicitly on the age of signs over existing approaches. The new estimator can be applied to any species for which it is possible to discriminate between aged and new signs or tracks, and should be widely applicable in ecology and conservation biology.

    AB - 1. Visitation rate is a measure of the frequency with which animals visit specific locations of interest. This information is crucial for various problems in the conservation and management of animal species, e.g. to determine the risk wildlife poses to human managed resources or the predation risks of nests. An important assessment tool, especially for cryptic animals, is to count indirect signs of presence, such as tracks or faeces. 2. Here we propose a maximum likelihood-based method that uses information on the age of tracks or signs, and we show that existing visitation rate/probability estimators are special cases of this more general approach. 3. Using simulated data, we compared the performance of the new visitation rate estimator to three other estimators, including the most commonly used estimator. These estimators make use of either fresh, aged or total signs, whereas our approach uses information simultaneously on both fresh and aged signs. The new estimator is, on average, in excess of three times more accurate than the next best estimator. Moreover, the new approach is very flexible and can be applied for sampling regimens with irregular time intervals between sampling. 4. We demonstrate the application of the method to field data by estimating the visitation rate of Eurasian otters (Lutra lutra) to a commercial fish pond. To facilitate the use of this method, we provide an easy-to-use Excel workbook and give recommendations on the most efficient sampling regimens. 5. Synthesis and applications. Visitation rate is an important quantity that can be estimated by repetitive sampling of indirect signs. We demonstrate the advantage of incorporating information explicitly on the age of signs over existing approaches. The new estimator can be applied to any species for which it is possible to discriminate between aged and new signs or tracks, and should be widely applicable in ecology and conservation biology.

    KW - Eurasian otter

    KW - Lutra lutra

    KW - Mammalia: monitoring

    KW - maximum-likelihood estimate

    KW - track counts

    KW - visitation probability

    KW - visitation rate.

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    DO - 10.1111/j.1365-2664.2007.01406.x

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