Traditional small waterbodies as key landscape elements for farmland bird conservation in Mediterranean semiarid agroecosystems

Farmland bird populations are declining worldwide as a consequence of agricultural intensification, and the loss of singular landscape elements has been suggested as one of the main drivers. This scenario of agroecosystem simplification is even more exacerbated in arid and semiarid regions, where traditional small waterbodies (SWB) are rapidly vanishing due to groundwater overexploitation and the declining extensive pastoralism. Here, we used data from breeding bird surveys at SWB and adjacent control sites to assess for the first time the landscape-scale contribution of three types of traditional SWB for supporting farmland bird communities in the most arid region of continental Europe. Four community metrics were calculated for each SWB: species richness, abundance, diversity and proportion of conservation-concern species. In general, a high proportion (71% on average) of the local breeding bird communities used SWB, irrespective of the SWB type. Cattle ponds supported a greater abundance and proportion of threatened species, whereas drinking troughs were used by more diversified bird communities. Traditional artificial pools showed intermediate values for all community metrics. Our results support that in semiarid regions any type of traditional man-made SWB, if properly designed and managed, can play a pivotal role in supporting farmland bird communities at landscape scale. Despite their ecological importance, traditional SWB are often overlooked from agri-environment schemes, and their role for supporting farmland biodiversity is rarely considered. Therefore, effective SWB management and conservation measures should be implemented in the framework of the new reform of the European Common Agricultural Policy and other similar eco-schemes in order to halt the decline of farmland biodiversity.