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 Pentezug Wildhorse Reserve, located in the Hortobágy National Park, Hungary, has one of the biggest ex situ populations of Przewalski's horses and aims to preserve its landscape and to study this subspecies. Between September and November 2018, 79 faecal samples were collected from Przewalski's horses. The McMaster, Willis flotation, natural sedimentation and coproculture methods were applied to all the samples. Results showed an average level of 1287 eggs per gram (EPG), which is a high faecal egg-shedding level. All the samples were positive for strongyle-type eggs (100%). There were no statistical differences regarding the EPG values between different harems of the population. The same happened when considering sexes, ages, lactating status or when bachelors are compared with harem members. Cyathostominae were dominant, when compared to Strongylinae and Tricostrongylidae, and 15 different morphological infective third-stage larvae types and/or species belonging to the order Strongylida were identified. The subfamily Cyathostominae was prevalent in 100% of the horses. Strongylus vulgaris was the most prevalent strongylin (40.5%). Additionally, 27.8% were positive for Parascaris sp. and 2.5% showed Oxyuris equi in their faeces. This study revealed that there is a higher prevalence of Triodontophorus serratus and Poteriostomum spp. in juveniles. Horses with S. vulgaris showed lower levels of EPG. This was the first study involving this population, showing 100% prevalence of intestinal parasites.