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.
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.
For the threat analysis, available data reflecting the occurrence and population trends of native species are assessed against the following four 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.
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.
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.
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 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.
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 threat 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.
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.
Information as to whether Germany has a specific international responsibility to protect a species is of major importance in order to prioritize appropriate conservation measures. This applies, for instance, if Germany constitutes the global centre of occurrence of a species or if a species is endemic to the country.
To analyse responsibility, three guiding parameters have been used consistently:
The integration of these guiding parameters leads to criteria that define six categories of responsibility:
Specific projects targeting the conservation of priority species for which Germany has a particular international responsibility can be supported within the framework of the Federal Biodiversity Programme. The German Federal Agency for Nature Conservation provides further information and an overview of all projects that are currently being supported.
The quality of information contained in the Red Lists is significantly enhanced if the threat assessment is supplemented by species-specific information. Relevant details may include explanations on how to distinguish closely related species, problems in verifying the existence of populations or potential risks of misidentification in the case of morphologically very similar taxa. Information on the specific causes of threat or a dependence on certain environmental factors can also be included. Other highly relevant information is the geographic range of the species in Germany and more specifically, significant changes in the extent of occurrence or areas of occupancy. In addition, a comparison with the threat level determined under the previous assessment period can be instructive.