Red List Development and Methodology

Red List Development Process

Step 1: Taxonomic Checklist

At the beginning of the process, a checklist is compiled that includes all species and sub-species of a defined taxonomic group occurring in Germany. The checklist indicates taxa native to Germany and taxa that have been introduced by humans (alien or neobiotic species). Red List authors decide whether they should conduct also a threat assessment (step 3) for a given neobiotic species. Taxa of casual occurrence, i.e. species that have not (yet) become fully established, are pointed out as well.

Step 2: Data Collection

In addition to developing or revising the taxonomic checklist, Red List authors collate all relevant data available for a species. If this has already been done comprehensively for previous Red List assessments, data collection may focus on the time period following the most recent published Red List update. Relevant data may be available from provincial government agencies, organized expert groups, natural history museums, managers of regional mapping projects, landscape planning companies or individual researchers. Further data can be obtained from an evaluation of the literature, museum collections or through targeted mapping at known locations of a particular species. Citizen science projects may also provide data. Such data can be used if they have been reliably verified and confirmed by experts.

Step 3: Threat Analysis

For the threat analysis, available data reflecting the occurrence and population trends of native species are assessed against the following four criteria:

1. Current population status
2. Long-term population trend
3. Short-term population trend
4. Specific criteria (‘Risiko/stabile Teilbestände‘) – (formerly: risk factors and specific criteria)

Information or estimates of the first three of these criteria are assigned to distinct categories based on pre-defined scales. The fourth criterion integrates two aspects: It assesses the possible impact of risk factors and gives an outlook on the stability of remaining populations. Experienced experts carry out the threat analysis.

Current Population Status

This criterion aims to estimate the size and distribution of the populations of a particular taxon within Germany. Observations from the previous 10 to 25 years are included because it is not possible to obtain data for a specific point in time. Data for the same species in the same location but for different years are only counted once. For species that are difficult to detect, indirect assessment is an option. To estimate the current population status of a species, eight ‘classes‘ have been defined: very frequent; frequent; moderately frequent; rare; very rare; extremely rare; lost or extinct; unknown.

Long-term Population Trend

The long-term population trend describes changes in the frequency and distribution of a species over a prolonged period of time (50-150 years). This means that the status today is for example compared to the situation that existed in around 1920. Changes are categorised on a seven-class scale: very significant reduction; significant reduction; moderate reduction; reduction of unknown extent; constant; significant increase; data deficient.

Short-term Population Trend

The short-term population trend describes possible population developments during the previous 10 to 25 years. This period is short enough to allow assessment based on personal observations and experience on the part of the experts, in addition to analysing other sources of data. This approach has the distinct advantage that current trends in the population status are accurately reflected. Information on short-term population trends is summarised using the same categories as for the long-term assessment.

Specific Criteria

Specific criteria incorporate two projections: (1) a prediction whether the identified short-term population trend of a species is likely to deteriorate in the subsequent 10 years due to specific threats (e.g. from a present ‘constant‘ trend to a ‘moderate reduction‘); and (2) an estimation as to whether a species will become extinct within the foreseeable future if the current threats persist, or whether extinction is unlikely because of the presence of stable sub-populations.   

Red List Categories

The threat categorization of a species is based on the estimate of the four classes of criteria. A defined categorization system is used.

Red Lists do not only publish categories for individual species but also provide details as to how the threat criteria were applied. This allows for a more transparent documentation of the assessment process.

Species-relevant details

In addition, the Red Lists attempt to evaluate whether Germany has an international responsibility to protect a particular species. If so, this would indicate the prioritization of conservation measures for that species. Additional species-relevant details enhances the level of information contained in the Red Lists considerably.