Biology session

Understanding the determinants of population size and density is essential in the sciences of conservation biology, ecology, and biogeography. Species associated with grasslands, such as the Hungarian meadow viper (Vipera ursinii rakosiensis), are of particular importance in the way their habitat is managed. The aim of the research was to investigate the effect of the three most common grassland use mode: grazing, mowing and meadow-pasture switching use, on the density of reptile species occurring in the habitat. The study was carried out on the meadows of Peszéradacs in the Kiskunság National Park during an autumn and a spring aspect in 2019-2020. Sampling was implemented in 3-3 1-hectare quadrates per grassland usage mode, in which we recorded operational temperatures by 5 minute intervals that most affected reptile detection and reptile counts during repeated sampling (n = 15 × 9). N-mixture models and model selection were used to analyze the data. Data from the two aspects were analyzed separately for each species where min. 5 observations were recorded. All reptile species in the habitats were observed during the surveys, however only the European green lizard (Lacerta viridis, nautumn = 607, nspring = 241), the sand lizard (Lacerta agilis, nautumn = 137, nspring = 917) and the Hungarian meadow viper (nautumn = 10, nspring =0) records reached minimum required number of observations, therefore only the data of these species were analyzed. The zero-inflated Poisson and the negative binomial error distribution models fitted best to the data, and the results showed that the detectability of the studied species was significantly affected by the operating temperature in all cases, except for the autumn survey of the green lizard. The pasture use mode had a significant positive effect on the density of the Hungarian meadow viper and the sand lizard, while the mowing and meadow-pasture switching use had a negative non-significant effect. The density of the green lizard was not affected by the grassland usage mode. For the endangered Hungarian meadow viper and the sand lizard, pasture use is the best grassland use mode according to our results. In view of the above, in order to ensure the efficiency of habitat management for nature and species conservation purposes, grazing should be given priority over mowing and meadow-pasture switching grassland use, thus promoting the protection of species living on grasslands.