Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4668
Title: Modeling structured population dynamics using data from unmarked individuals
Author: Elise Zipkin, James T. Thorson, K. E. See, Heather Lynch, Evan Grant, Yoichiro Kanno, Richard Chandler, Benjamin H. Letcher, J. Andrew Royle
Publication Year: 2014
Journal: Ecology
Volume: 95
Issue: 1
Pages: 2229
Keywords: Detection probability, N-mixture model, Northern dusky salamander, State-space models, Stage-structured models,

 The study of population dynamics requires unbiased, precise estimates of abundance and vital rates that account for the demographic structure inherent in all wildlife and plant populations. Traditionally, these estimates have only been available through approaches that rely on intensive capture-recapture data. We extend recently developed N-mixture models to demonstrate how demographic parameters and abundance can be estimated for structured populations using only stage-structured count data. Our modeling framework can be used to make reliable inferences on abundance as well as recruitment, immigration, stage-specific survival, and detection rates during sampling. We present a range of simulations to illustrate the data requirements, including the number of years and locations necessary, for accurate and precise parameter estimates. We apply our modeling framework to a population of northern dusky salamanders (Desomgnathus fuscus) in the mid-Atlantic region and find that the population is unexpectedly declining. Our approach represents a valuable advance in the estimation of population dynamics using multi-state data from unmarked individuals and should additionally be useful in the development of integrated models that combine data from intensive (e.g., capture-recapture) and extensive (e.g., counts) data sources.


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