Data from the General Directorate for Environmental Protection, made available until a widely accepted methodology for estimating large predator populations is adopted by the scientific community.
The estimates are not based on fieldwork conducted according to a uniform methodology, but are collected annually from the same sources, and some of them may rely on the results of inventories carried out in previous years. The accuracy of the data and their comparability over time may also be affected by the natural migration of individuals of the respective species. The exception is the European bison, the number of which is presented on the basis of data from the ""European Bison Pedigree Book"".
The data come from the regional directorates for environmental protection, which obtain them, among other sources, from the organizational units of the State Forests and national parks, as well as on the basis of natural inventories conducted in previous years and literature data.