Mankind has been involved in the eradication of many animal species throughout its existence. The European bison was found in danger of extinction at the beginning of 20th century as well, and its rescue came in the last moment. This diploma thesis investigates the process of bison reintroduction to the wild nature. I deal with the characteristics of natural conditions of the area of interest, biology and ethology of the European bison. In this work I further study the analysis of the history and present of the conservation management of the bison in the Poloniny National Park. I also deal with the issue of analysis of the density of the bison in the area of interest and in relation to ruminants. The aim of this work was to propose rationalization measures for the management of the bison population in the Poloniny National Park in the future. The aim of my work was to detect and prove that an increasing trend in the abundance of the bison population does not have a negative influence on the evolution of the abundance of other hunting species, particularly in relation to deers. On the basis of the analysis of the results presented, I consider this objective fulfilled. This work proves that it is never too late to save any endangered animal species and I see in this statement the benefit and importance of this final work.