Data on nesting densities of Bembix rostrata, a digger wasp inhabiting dynamic coastal dunes, were used to document the detrimental effects of trampling by cattle and vacationers. Both types of disturbance resulted in similar sand displacement and prey availability. Nesting densities of Europe's largest digger wasp declined dramatically with increasing trampling, probably below the critical population size. Hence, additional human disturbance, although resulting in similar environmental conditions compared to natural disturbance, significantly affected local population sizes. As a result, anthropogenic has to be avoided disturbance in order to restore or conserve natural dynamics and efforts to restore natural dynamics in a more natural way should be promoted. Although this is here only documented for one, large specialised invertebrate, the application of traditional management techniques, such as grazing by large herbivores, within newly evolved landscapes may introduce new pressures that affect pre-adapted species to natural disturbances negatively within short time spans.
A study was made of the influence of trampling by grazing animals on the nesting success of real nests (meadow pipit, Anthus pratensis; water pipit, Anthus spinoletta; and skylark, Alauda arvensis) and simulated nests (caps from jam-jars filled by green plasticine) on pasture in the Orlické Mountains and on unmanaged alpine meadows in the Jeseníky Mountains (Czech Republic, Central Europe). While the pasture was continuously grazed by livestock at high densities, unmanaged alpine meadow was grazed only by wild large herbivores at far lower densities. Trampling was the primary cause of nest failure in the Orlické Mountains, but was infrequent in the Jeseníky Mountains. The number of real nests lost by trampling corresponded to simulated nests within the localities. Spatial distribution of simulated nests had no effect on their survival on intensively grazed fields. The results indicate that grazing animals negatively influenced the nesting success of real and simulated nests of grassland passerines on continuously grazed mountain pasture. The use of simulated nests was an adequate method of predicting trampling losses by natural nests.