<p>Many farmland wildlife species have shown a sharp population decline in European countries, mainly caused by changes in agricultural practices leading to habitat loss or degradation. This is especially interesting in Mediterranean environments, where biodiversity has decreased due to intensification. In this context, and aiming at assessing the benefit to biological diversity of certain agricultural management practices, we analysed the effects of herbaceous covers on biodiversity in olive orchards in central Spain. We compared species richness, overall abundance, and abundance of different functional groups of birds, and butterflies between olive orchards where herbaceous covers are intensively managed (ploughed) and extensively managed (covers are maintained). We found significantly higher bird species richness in olive orchards with herbaceous covers than without them. Birds were more abundant as the herb species richness of the orchards increased. Butterflies were significantly richer and more abundant as the amount of herbaceous cover increased, and all butterfly functional groups were more abundant in orchards with herbaceous covers. Our results show that the maintenance of naturally-growing herbaceous covers in olive orchards is crucial for the conservation of biodiversity in one of the primary agro-ecosystems of the Mediterranean landscapes.</p>