The subject of this bachelor thesis was the research of the Western Capercaillie population in the selected area of the Stolické vrchy Mountains and the impact of the change of the structure of the vegetation on its occurrence. The work includes the systematic inclusion of the Capercaillie, it's distribution, species abundance and its trends. The biology of the species, nesting and foraging ecology of the Capercaillie with a description of the habitat typical of the occurrence of the Capercaillie is also described in the thesis. The thesis summarises various threats for this species, the system of protection and management measures. The research dealt with the description of the SPA in which the research was conducted, the research methodology and the results processed with the characteristics of the investigated sites in which the Capercaillie population was studied. The discussion deals with the comparison of the results obtained from the research conducted in the same territory in the years 2011 - 2015. The process also includes the change of vegetation structures over the period and the impact of this on the population. From the changes identified, results and analysis of the causes of change and impact on the population are developed. At the same time, the thesis also contains proposals for the management and protection of Capercaillie. This consists of adapting the management of forests to a system of creating suitable habitats for the Capercaillie, minimising disturbing effects during the breeding period and maintaining the cooperation of foresters, hunters, nature lovers, tourists and workers of the State Nature Conservation of the Slovak Republic. It is important to use complex solutions to protect this species, by supporting the hunting associations in regulating predator status, appealing to foresters to practice environmentally friendly forestry techniques, and cooperating with the State Nature Conservation of the Slovak Republic in closely monitoring the population and determining its abundance and the status of its habitats with regard to negative impacts, which can threaten the delicate population.