Abstract from BTO Research Report No. 498:

D. Noble, M. Everard & A. Joys (2008)

Development of wild bird indicators for freshwater wetlands and waterways: provisional indicators ISBN 978-1-906204-35-8

Introduction

Much of the earlier history of bioindicator development in the UK was to reflect single pressures, such as organic pollution or acidification of wetland habitats. However, more recent legislation (particularly the EU Water Framework Directive (WFD)), broader-scale commitments (such as the Environment Agency’s Vision theme of An Enhanced Environment for Wildlife), agreements for delivery of public benefit in the UK such as the Defra (Department of Environment, Food and Rural Affairs) PSA (Public Sector Agreement) of “…biodiversity safeguarded and enhanced”, and evolving awareness of the interactions of environmental impacts means that we require more sophisticated and comprehensive indicators that demonstrate the integrated impacts of multiple pressures.

There are many types of biological indicators underpinned by various ‘surrogate species’ – including for example keystone species, flagship species, ecosystem engineers, etc. – each of which may serve different purposes by indicating various attributes of the environment and/or the pressures upon it. The characteristics of different taxa suit them to indicating different attributes of the aquatic environment, for example diatoms being sessile and responsive to local pressures whilst higher trophic level organisms such as birds and mammals are generally mobile across the landscape and more likely to reflect the cumulative effects of various environmental pressures. Moreover, in the UK birds have a high public profile, are highly visible, substantial population census datasets exist and there has been considerable development of analytical methods. Birds are therefore highly appropriate for the assessment of attributes of environmental quality at landscape scale.

The purpose of developing this new set of wild bird indicators is to reflect the general health of freshwater waterways and wetland habitats at landscape scale in the UK, based on existing data. This mirrors the development of the farmland bird indicator in the UK, which provided a focus for the aggregated pressures upon the environment from which the need for further investigation and novel land use policy became starkly apparent. By formulating indicators for different freshwater waterways and wetland habitats, it is likely that we will pick up ‘signals’ that we might otherwise miss, and which may better direct future policy, practice and influence to improve the health of the aquatic environment, its associated biodiversity and ecosystem services.

Throughout the development process, the project team sought synergy, and ultimately convergence, with the development needs of related bird-based indicators across the UK. Particularly important partner indicators were the England Biodiversity Group’s Water and Wetland indicator and the suite of sustainable development indicators reported upon routinely by Defra.

This report outlines the methods developed for the Environment Agency’s bird population indicators, providing an overview but also addressing the ecological, technical and statistical principles that underpin the approach. The approach is based on methods developed by the RSPB and BTO which are already accepted, widely-used and well-tested in other contexts. Details of methods used are noted in Annex 1, and Freeman et al. (2001) demonstrate the applicability of various of these methods to measuring population changes in farmland birds in the UK. Where different methods are suggested, reasons and relevant citations are provided. Underlying much of the statistical approach are questions about the aim of the indicators, which are as much policy-related as technical. Nevertheless, the methods explored here can be adapted to different purposes once consensus about aims has been achieved.

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