According to the Convention on the Conservation of Migratory Species of Wild Animals, the 'conservation status of a migratory species' (and by extension any species) means the sum of the influences acting on the species that may affect its long-term distribution and abundance. Conservation status will be taken as 'favourable' when: (1) population dynamics data indicate that the species is maintaining itself on a long-term basis as a viable component of its ecosystems; (2) the range of the species is neither currently being reduced, nor is likely to be reduced, on a long-term basis; (3) there is, and will be in the foreseeable future sufficient habitat to maintain the population of the species on a long-term basis; and (4) the distribution and abundance of the species approach historic coverage and levels to the extent that potentially suitable ecosystems exist and to the extent consistent with wise wildlife management. Conversely, conservation status will be taken as 'unfavourable' if any of the above conditions is not met.
In the case of an area, assessing conservation status means making an assessment of the status of ecological processes and of the viability of species populations in an ecoregion. The status categories generally used are "extinct", "critical", "endangered", "vulnerable", "relatively stable" and "relative intact". A final conservation status would take into account not only the current situation but also an analysis of threats to the ecoregion over the next 20 or so years.
Critical conservation status indicates there is a low probability of persistence of remaining intact habitat. Endangered conservation status means there is a medium to low probability of persistence of the remaining intact habitat.
The objective of the Coordination of Information on the Environment Programme (CORINE) was to assemble basic information on the state of the European Community environment and to improve its consistency, while assessing comparability and availability of data and methods of analysing data. The biotopes database includes detailed information on sites of Community importance on the basis of four criteria: (1) the presence of vulnerable species; (2) the presence of vulnerable habitats; (3) the richness of the site for a taxonomic group; and (4) the richness of the site as a vegetation unit. The aim was to include sites that contain one per cent or more of the Community population of a vulnerable species or which are among the 100 most important sites in the EU for such species. The database includes sites that are formally protected in the member states on biological, landscape, geological, geomorphological or archaeological grounds sites that are protected but through other mechanisms than legal instruments, such as private nature reserves, as well as non-protected sites which have been recognized of interest for nature conservation at European level.
By 1990 a database describing some 6000 sites of Community importance for nature conservation had been created. Each site is described on the basis of standard attributes: name, location, area, altitude, habitat type, habitat cover, designation, the reason for inclusion, the presence of human activities, the presence of important species, the species numbers and a site description. However, the information is not complete for all biotopes. Compilation of data on the areas has suffered from the fact, in the absence of a European overview, it was difficult for member states to interpret the notion of "the 100 most important sites in the EU". Furthermore, since all EU member states have been involved since 1992 in implementing the Habitats Directive, far more precise inventories of sites have been undertaken in this framework and incorporated into the Natura 2000 database. Updating the CORINE-Biotopes database in these countries is therefore no longer a priority. However, for the PHARE countries, CORINE-Biotopes provides sound information for inventories preliminary to the Emerald Network process.