Does Experimental Non-Reclaimed Sites Differ from Technically Reclaimed Areas in the Risk of Artificial Bird Nest Predation?

Areas left to natural development have been found to be sites with higher diversity and conservation value of local communities, including bird communities, compared to artificial reclamation of post-industrial areas. Most of the studies conducted so far have focused primarily on bird communities of post-mining areas, in terms of the diversity and richness of species. Our study dealt with bird nest predation on specific case of two experimental sites (20 and 32 ha) with more than a 20-year history of primary spontaneous succession established within the technical reclamation of the Radovesická spoil heap (approx. 1,200 ha, North Bohemia, Czech Republic). In the spring of 2018, we conducted a predation experiment using artificial nests (ground and elevated), installed within both succession areas and beyond, in the adjacent artificially reclaimed areas. We monitored the way of restoration and the distance of the nest placement from the succession-reclamation sites edge. The rate of predation was very high: 92.5 % in reclaimed area and 89.4 % in spontaneous successions. None of the observed factors analysed in the generalised linear model (GLM) have conclusively explained the risk of predation. The two experimental succession sites did not differ from the surrounding reclaimed sites in terms of the risk of predation, nor did they significantly influence predation risk on reclaimed sites. We believe that both relatively small and mutually isolated areas do not provide enough of an inner environment without or with at least a limited effect of predation pressure coming from adjacent reclaimed areas.