No abstract

A founder population of Przewalski's horses (Equus ferus przewalskii) was set free in a semi-reserve called Pentezug in the Hortobagy National Park (Hungary) in 1997. Beside the Przewalski's horses reconstructed aurochs (Bos taurus taurus) were bred as well in the 24.5-km 2 large area. Both species reproduced successfully in this steppe reserve, which was once the homeland of their distant ancestors. The number of large grazers has grown so quickly that different strategies of population control had to be implemented for reconstructed aurochs and horses in 2007 and 2013, respectively. The activity, habitat use, and body condition of Przewalski's horses were monitored regularly throughout the 22 years. We detected seasonal changes in the activity of the horses but the proportions of the main activity types were similar in two distant time periods. In contrast, habitat use and body condition scores for the horses showed remarkable differences between early vs. late years of the project, implying that horses were forced to use non-preferable areas and their condition was worsened in parallel with the increased population density of the large grazers. During the cold spring in 2018, there was a massive loss of both horses and cattle. These observations suggest that limited food sources could lead to changes in habitat use and/or worse body condition and a greater death rate in extreme weather conditions. In summary, strict birth control measures must be implemented in dense Przewalski's horse populations, and the habitat use and body conditions must be monitored to balance the population size and carrying capacity of the areas.

The acceleration of grassland loss on the global scale has been reported in many studies, which is often attributed to the combination of land use change and increased variability of climatic processes. Extensive steppe national par�s serve as an ideal study site for grassland conservation, especially wilderness areas where the natural effects of grazing on wildlife can still be trac�ed. In our study we aim to investigate the effects of habitat structure, grazing type and intensity as well as climatic vari� ables on species abundance, species richness and abundance of functional groups of ground�breeding bird species in the largest compact al�ali grassland area of central Europe. We applied the information theoretic approach estimating the importance of ecological predictors according models of substantial support. The main result of our study shows that ground�breeding bird communities in steppe areas exhibit highly species-specific responses to the species of grazers, grazing intensity, habitat com� position and climatic predictors. Across the most supported models, species-specific habitat composition values were the most supported predictors. Our findings show that although the response of ground-breeding birds to vegetation, grazing and climatic predictors is highly species-specific, consistent patterns of responsiveness to grazing and climatic patterns emerge, which calls for long�term studies on the combined effects of climatic variability and management of grazing systems.