Quantifying Conservation Concern - Bayesian Statistics and the Red Data Lists

Steve Brooks, Steve Freeman, Jeremy Greenwood, Ruth King and Chiara Mazzetta

Universities of Cambridge, St. Andrews and Kent and the British Trust for Ornithology


It is important to have accurate and precise measures of rates of population decline when prioritizing species for conservation action. For species that are still widespread, this inevitably means gathering representative sample data rather than undertaking a comprehensive census. We have found that considerable improvements can be made in interpreting declines by explaining annual fluctuations in terms of explicit and realistic population models (rather than merely fitting trends of an arbitrary mathematical form to the census data), through the simultaneous modelling of data from the census with those providing information on the demographic rates employed in the population models, and through adopting a Bayesian rather than a frequentist statistical approach. In this paper we provide details of the Bayesian approach and discuss the results and their implications for wildlife population monitoring.