The biodiversity and environmental quality indicator uses existing population figures for selected bird varieties to measure the quality of nature and the environment in Germany.
In specific terms, the indicator measures changes to the population of selected bird varieties, which represents the five main types of landscape and habitat in Germany. In order to collect information on the condition of agricultural land, forests, settlements, inland waters, coastlines and seas, 51 bird varieties are observed and their populations measured using a target figure of 100 per cent for each type of habitat. When habitat quality improves, bird populations increase and the indicator rises.
Absolute biodiversity (number of varieties) is not the key factor, but the existence of "appropriate biodiversity" and how it is changing. The five sub-indicators are collated into an index, known as the bird index. Bird populations in each of the different types of landscape are weighted as follows in line with the size of the area as a proportion of Germany's total surface area: Agricultural land: 0.52, forest: 0.28, settlements: 0.11, inland water bodies: 0.06, coastline and seas: 0.03.
The data source is the German Federal Agency for Nature Conservation. The bird monitoring programme and other ongoing monitoring programmes will be supplemented and expanded to cover the whole of Germany.