The Hungarian meadow viper ( Vipera ursinii rakosiensis ) is one of the most threatened
vertebrates in Hungary, whose populations are not growing significantly despite enormous
conservation efforts. Previous studies suggested an influence of vertical vegetation
structure on habitat use, while the role of horizontal vegetation structure is still
poorly understood. In the present study, we used vegetation survey data to investigate
the effects of variables related to the horizontal structure and functional composition
of vegetation on the occupancy and density of the Hungarian meadow viper. During a
spring survey period, we collected viper occurrence data in 59 sampling quadrats alongside
plant community samples, then used single‐season occupancy models and N‐mixture models
for analysis. After model selection, the best models included the moisture‐related
vegetation gradient, species richness, graminoid‐forb ratio, and height of plants
as explanatory variables for both occupancy and density. Wetter meadows with fewer
plant species, a higher graminoid/forb ratio, and habitats with characteristically
lower‐growing plant species were more probable to be used by the vipers. Our results
suggest that the horizontal structure of the vegetation influences the habitat use
of vipers and also draw attention to the threats posed by more frequent droughts and
heatwaves.
