1. Simple, easy to understand indicators are essential to enable the assessment of public policies in meeting their stated objectives and communicating success (or otherwise) to a wide variety of audiences. For instance, there is a crucial need for robust and appropriate biodiversity indicators to measure progress towards goals for the conservation of biodiversity (such as reducing the current rate of loss, and then establishing progress in recovering lost biodiversity e.g. Mace et al. 2018) whether set at global, regional or national scales (see below for a review of relevant policy targets for Scotland). In addition, biodiversity indicators can be relevant for measuring the impact of a broad range of human activities upon the natural environment, and for assessing the success of measures intended to mitigate against such impacts.
2. This report describes the work conducted by the RSPB, Centre for Ecology & Hydrology, James Hutton Institute and University of Sheffield, under contract to the Scottish Government (reference SPB/001/18), in order to identify the most appropriate high-level indicator to measure and report trends in both terrestrial and marine biodiversity in Scotland. This indicator will enable trends in biodiversity to be considered as one of the 81 National Indicators in the National Performance Framework (one of eight used to measure progress towards the National Outcome for the Environment). The indicator on terrestrial birds, as used in the previous National Performance Framework, whilst based on robust and annually updated data and likely to be broadly representative of changes in Scottish terrestrial and freshwater biodiversity, had a number of shortcomings (most notably, but not restricted, to the absence of marine data) which a new indicator should seek to address.
3. This report describes the work conducted in order to identify the most suitable indicator, which was conducted as a number of components: i) a review of published literature relevant to the aims of this project; ii) a review of data on biodiversity in Scotland that might be used in a high-level indicator; iii) extensive consultation with a range of stakeholders to select the most suitable data and indicator format; iv) the collation of datasets required for indicator construction; and v) the creation of a draft indicator as presented in this report.