Statistical inference on patch-specific survival and movement rates from marked animals

Michael J. Conroy, Jon E. Anderson, Stephen L. Rathbun, David G. Krementz

    Research output: Contribution to journalArticlepeer-review

    12 Scopus citations

    Abstract

    Empirical estimates of patch-specific survival and movement rates are needed to parametrize spatially explicit population models, and for inference on the effects of habitat quality and fragmentation on populations. Data from radio-marked animals, in which both the fates and habitat locations of animals are known over time, can be used in conjunction with continuous-time proportional hazards models to obtain inferences on survival rates. Discrete-time conditional logistic models may provide inference on both survival and movement rates. We use Monte Carlo simulation to investigate accuracy of estimates of survival from both approaches, and movement rates from conditional logistic regression, for two habitats. Bias was low (relative bias < 0.04) and interval coverage accurate (close to the nominal 0.95) for estimates of habitat effect on survival based on proportional hazards. Bias was high (x̄ relative bias 0.60) and interval coverage poor (x̄ = 0.26 vs. nominal 0.95) for estimates of habitat effect based on conditional logistic regression; bias was especially influenced by heterogeneity in survival and the shape of the hazard function, whereas both bias and coverage were affected by 'memory' effects in movement patterns. Bias estimates of movement rate was low (x̄ relative bias < 0.05), but interval coverage was poor (x̄ = 0.48-0.80), possibly as a result of poor performance of a Taylor series estimate of variance. An example is provided from a radio-telemetry study of 47 wintering American woodcock (Scolopax minor), illustrating practical difficulties in field studies to parametrize these models. We also discuss extensions of continuous-time models to explicitly include a movement process, and further examine tradeoffs between continuous and discrete models.

    Original languageEnglish (US)
    Pages (from-to)99-116
    Number of pages18
    JournalEnvironmental and Ecological Statistics
    Volume3
    Issue number2
    DOIs
    StatePublished - Jun 1996

    Keywords

    • Animal behaviour
    • Habitat use
    • Logistic regression
    • Mortality
    • Population model
    • Proportional hazards
    • Risk

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