Authors: Konvicka, Martin;Hajkova, Klara;Vodickova, Veronika;Vrba, Pavel;Sbaraglia, Claudio;Shovkun, Dmitry;Bartonova, Alena;Grill, Stanislav;Fric, Zdenek;

Restoring natural habitats by native megaherbivores refaunation is increasingly practiced across Europe, but very little is known regarding population dynamics of affected biota, including insects. To fill this gap in knowledge, we used mark-recapture to compare demography, dispersal and habitat utilization by five Melitaeini butterflies (Melitaea athalia, M. aurelia, M. britomartis, M. cinxia and M. didyma) co-occurring at grasslands of Podyjí National Park, Czech Republic, refaunated by Exmoor ponies. Both pre-(2017) and post-(2021) intervention surveys encompassed whole-season field work, amassing huge amount of material (e.g., total of 17,100 capture events). Still, the post-intervention findings differed in many ways from our pre-intervention predictions (J. Nature Conserv. 52, 125755), pointing to substantial variation among years due to such factors as weather. Findings attributable to the megaherbivores presence included longer butterfly movements and more uniform within-habitat distribution, probably because the horses uniformized the distribution of their resources. Encouragingly, the critically endangered M. britomartis, rarest of the five butterflies, benefited from the refaunation. Despite all the effort, two seasons can hardly grasp entire dynamics of a system, in which large mammals, vegetation, insects, and inter-annual weather variation interact.