"Estimer la taille des populations et les paramètres démographiques cachés à l'aide de modèles d'espace d'état"

The American Naturalist
Submitted May 2, 2008; Accepted February 2, 2009; Electronically published April 8, 2009
DOI: 10.1086/598499

Estimating Population Size and Hidden Demographic Parameters with State‐Space Modeling

Giacomo Tavecchia,1,2,*

Panagiotis Besbeas,1

Tim Coulson,2

Byron J. T. Morgan,1 and

Tim H. Clutton‐Brock3

1. Institute of Mathematics, Statistics, and Actuarial Science, University of Kent, Canterbury, Kent CT2 7NF, United Kingdom;

2. Department of Biological Sciences and the Centre for Population Biology, Imperial College London, Silwood Park, Ascot, Berkshire SL5 7PY, United Kingdom;

3. Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom
Abstract:

Recent research has shown how process variability and measurement error in ecological time series can be separated using state‐space modeling techniques to combine individual‐based data with population counts. We extend the current maximum likelihood approaches to allow the incorporation of @#$%&‐ and age‐dependent counts and provide an application to data from a population of Soay sheep living on the St. Kilda archipelago. We then empirically evaluate the performance and potential of the method by sequentially omitting portions of the data available. We show that the use of multivariate time series extends the power of the state‐space modeling approach. The variance of measurement error was found to be smaller for males and the @#$%& ratio of lambs to be skewed toward females and constant over time. Our results indicated that demographic parameters estimated using state‐space modeling without relevant individual‐based data were in close agreement with those obtained from mark‐recapture‐recovery analyses alone. Similarly, estimates of population size obtained when the corresponding count observations were unavailable were close to those from the entire data set. We conclude that the approach illustrated here has great potential for estimating hidden demographic parameters, planning studies on population monitoring, and estimating both historical and future population size.

Y'a pas à dire, ils sont forts ces anglais.. smiling smiley

Généralités et Environnement

de l'estimation de la taille des populations