Dung beetle richness is positively affected by the density of wild ungulate populations in forests

Dung beetles are a functionally important group of species, and the effects of large wild herbivores on these species are not well understood. Management of wild herbivores could, therefore, have considerable consequences for dung beetle assemblages and the ecosystem services they provide. Here, we analysed how species richness, biomass, abundance, and composition of dung beetle assemblages were affected by different dung availability as a consequence of different red deer (Cervus elaphus) densities under field conditions. This was done in spring and autumn over four independent study regions in Central Europe where red deer are the most important providers of dung in forests. Our results show that forest sites with high dung availability support higher species richness of dung beetles than sites with low availability. This effect is independent of season and could be explained by the different colonisation patterns of beetle species which vary in their competitiveness. As aggregated dung resources increase opportunities for low-competitive species, those species establish small populations and do not necessarily increase the abundance of the whole assemblage. Our results show that the current policies to limit deer populations also limit higher levels of species diversity of this functionally important arthropod taxon. We highlight the importance of hunting-free areas for the conservation of insect diversity associated with large herbivores. In strictly protected areas with low herbivore densities we suggest to reduce control of ungulate numbers to provide sufficient resources for maintaining dung beetle diversity.