Comparing sampling effort and errors in abundance estimates between short and protracted nesting seasons for sea turtles

Andrea Whiting, Milani Chaloupka, Colin Limpus

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Sea turtles have iteroparous reproduction, migrating periodically from foraging habitat to nesting grounds where they generally lay several clutches at regular intervals throughout a nesting season. The total length of the nesting season depends ultimately on environmental conditions that are conducive to the production of viable hatchlings, and varies from 3 to 4. months to year-round nesting. As with many migratory marine species, the ease of monitoring marine turtles on their nesting beaches opposed to on their foraging grounds, has resulted in a focus of research on breeding females for population studies and provides a useful albeit limited population index. To explore the precision of monitoring regimes to sample nesting turtle populations, we developed theoretical models for 3 1/2-month and 9-month nesting populations. We used individual-based models for tagged animals and parametric and non-parametric models to estimate annual nest abundance for track count data. These simulation models show that seasonality substantially influenced both the length and temporal position of optimal sampling regimes, showing a five to sevenfold greater effort in monitoring required for longer nesting seasons in order to encounter between 83 and 90% of the annual population. The implications for trend detection and inter-annual and inter-species variations are discussed.
    Original languageEnglish
    Pages (from-to)165-170
    Number of pages6
    JournalJournal of Experimental Marine Biology and Ecology
    Volume449
    DOIs
    Publication statusPublished - Nov 2013

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    sea turtles
    turtle
    sampling
    turtles
    monitoring
    foraging
    individual-based model
    sea
    beaches
    seasonality
    simulation models
    nest
    beach
    environmental conditions
    breeding
    nests
    environmental factors
    animal
    habitat
    habitats

    Cite this

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    title = "Comparing sampling effort and errors in abundance estimates between short and protracted nesting seasons for sea turtles",
    abstract = "Sea turtles have iteroparous reproduction, migrating periodically from foraging habitat to nesting grounds where they generally lay several clutches at regular intervals throughout a nesting season. The total length of the nesting season depends ultimately on environmental conditions that are conducive to the production of viable hatchlings, and varies from 3 to 4. months to year-round nesting. As with many migratory marine species, the ease of monitoring marine turtles on their nesting beaches opposed to on their foraging grounds, has resulted in a focus of research on breeding females for population studies and provides a useful albeit limited population index. To explore the precision of monitoring regimes to sample nesting turtle populations, we developed theoretical models for 3 1/2-month and 9-month nesting populations. We used individual-based models for tagged animals and parametric and non-parametric models to estimate annual nest abundance for track count data. These simulation models show that seasonality substantially influenced both the length and temporal position of optimal sampling regimes, showing a five to sevenfold greater effort in monitoring required for longer nesting seasons in order to encounter between 83 and 90{\%} of the annual population. The implications for trend detection and inter-annual and inter-species variations are discussed.",
    keywords = "abundance estimation, breeding season, comparative study, data set, environmental conditions, error analysis, feeding ground, individual-based model, interspecific variation, migratory species, nest site, numerical model, sampling, trend analysis, turtle",
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    language = "English",
    volume = "449",
    pages = "165--170",
    journal = "Journal of Experimental Marine Biology and Ecology",
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    Comparing sampling effort and errors in abundance estimates between short and protracted nesting seasons for sea turtles. / Whiting, Andrea; Chaloupka, Milani; Limpus, Colin.

    In: Journal of Experimental Marine Biology and Ecology, Vol. 449, 11.2013, p. 165-170.

    Research output: Contribution to journalArticleResearchpeer-review

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    AU - Chaloupka, Milani

    AU - Limpus, Colin

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    N2 - Sea turtles have iteroparous reproduction, migrating periodically from foraging habitat to nesting grounds where they generally lay several clutches at regular intervals throughout a nesting season. The total length of the nesting season depends ultimately on environmental conditions that are conducive to the production of viable hatchlings, and varies from 3 to 4. months to year-round nesting. As with many migratory marine species, the ease of monitoring marine turtles on their nesting beaches opposed to on their foraging grounds, has resulted in a focus of research on breeding females for population studies and provides a useful albeit limited population index. To explore the precision of monitoring regimes to sample nesting turtle populations, we developed theoretical models for 3 1/2-month and 9-month nesting populations. We used individual-based models for tagged animals and parametric and non-parametric models to estimate annual nest abundance for track count data. These simulation models show that seasonality substantially influenced both the length and temporal position of optimal sampling regimes, showing a five to sevenfold greater effort in monitoring required for longer nesting seasons in order to encounter between 83 and 90% of the annual population. The implications for trend detection and inter-annual and inter-species variations are discussed.

    AB - Sea turtles have iteroparous reproduction, migrating periodically from foraging habitat to nesting grounds where they generally lay several clutches at regular intervals throughout a nesting season. The total length of the nesting season depends ultimately on environmental conditions that are conducive to the production of viable hatchlings, and varies from 3 to 4. months to year-round nesting. As with many migratory marine species, the ease of monitoring marine turtles on their nesting beaches opposed to on their foraging grounds, has resulted in a focus of research on breeding females for population studies and provides a useful albeit limited population index. To explore the precision of monitoring regimes to sample nesting turtle populations, we developed theoretical models for 3 1/2-month and 9-month nesting populations. We used individual-based models for tagged animals and parametric and non-parametric models to estimate annual nest abundance for track count data. These simulation models show that seasonality substantially influenced both the length and temporal position of optimal sampling regimes, showing a five to sevenfold greater effort in monitoring required for longer nesting seasons in order to encounter between 83 and 90% of the annual population. The implications for trend detection and inter-annual and inter-species variations are discussed.

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