Fine‐tuning the assessment of large‐scale temporal trends in biodiversity using the example ofBritish breeding birds

Abstract

Bird populations are seen as useful indicators of the health of wildlife and the countryside because they occupy a range of habitats, they tend to be towards the top of the food chain, and data is provided by long‐term surveys. Hence, many countries apply wild bird indicators (WBIs), quantifying trends in biodiversity, to monitor environmental health. TheUK'sWBI, for example, has become one of the government's headline indicators of sustainable development. Understanding the population changes underlying the estimated trends is indispensable if we are to allocate limited resources more effectively. Employing a novel set of measures alongside the traditional geometric mean index, we analyse diversity trends amongBritish breeding birds. It reveals that species that are scarce, but not yet in the focus of conservation action, may be the ‘losers’ in biodiversity action plans. This suggests that additional resources should be devoted to species showing long‐term decline before they reach the low population levels that currently trigger large‐scale species‐specific rescue projects.