Modelling bird population changes at large spatial scales

Speaker: Stephen Baillie (BTO)

Abstract

Extensive volunteer-based programmes for monitoring avian abundance and demography allow us to investigate some of the factors that determine bird population changes at very large spatial scales. Intensive studies of small areas often provide good insights into factors determining local population size, but scaling up from these studies to regional and continental scales is not straightforward. The BTO/JNCC/RSPB Breeding Bird Survey (BBS) and Constant Effort ringing Schemes (CES) co-ordinated through the European Union for Bird Ringing (EURING) illustrate the value of well designed monitoring projects. The BBS has been central to measuring declines amongst farmland birds and is now being used to evaluate the effectiveness of agri-environment schemes. A recent study of the possible effects of predation on bird populations in England illustrates both the power of such large-scale analyses and the limitations of a purely correlative approach. European scale modelling of the demography of a suite of Palaearctic-African migrants is providing insights that could not be obtained using data from individual countries. There is an urgent policy need for better predictions of the impact of climate and environmental change on biodiversity which we are starting to address through spatial modelling of BBS data. In many of these areas close collaboration between ecologists and statisticians can help us to answer challenging ecological questions and to provide more effective advice to policy makers.