Effects of dung-pad conditions and density on coprophagous beetle assemblages in a Mediterranean rangeland

Dung beetles highly depend on the ephemeral microhabitat dung which is food resource and larval habitat at the same time. Environmental conditions surrounding a dung pad, such as vegetation structure, have an impact on dung beetle assemblages. We investigated the influence of dung conditions and surrounding habitat characteristics on Mediterranean dung beetle assemblages in a permanently grazed landscape in northern Sardinia. We sampled the dung beetle assemblages of donkey and horse dung in three different vegetation types and assessed species richness and abundance of dung beetles. Species richness was determined by dung and surrounding habitat conditions, whereas abundance was solely affected by dung conditions. However, species richness and abundance decreased with increasing dung density. The effect of dung density on species richness varied depending on vegetation type, with dry grassland exhibiting the highest number of dung beetles species at high dung density. Species composition in dung pads was influenced by abiotic factors with dwellers being negatively affected by increasing dung-pad temperature. Our results underline the importance of diverse vegetation, particularly with respect to the complexity of vegetation which interrelates with the microclimate. Furthermore, our findings illustrate the negative effect of high dung densities on dung beetle assemblages, suggesting that the degree of the intensity of use by grazing animals is important when considering measures for the conservation of dung beetles.