Assessing the long-term effect of Natura 2000 network on common breeding bird communities

Abstract

The Natura 2000 network (N2000) is currently the largest coordinated network of protected areas in the world, and focuses on the conservation of most valuable and threatened species and habitats in Europe. Although there has been several assessments of N2000, few studies have looked at the long-term effect of this protection network on biodiversity, and even fewer on common species. A recent study by Pellissier et al. 2013, highlighted that common bird species have actually benefited from the designation of N2000 directed toward other target species, but has not been able to provide strong evidence regarding the temporal efficiency of the network. As such, questions remain as to whether this reflects a lack of efficiency of N2000 or that temporal responses could not be not detected because of potential time lags. Here, using data from the French Breeding Bird Survey, we investigated the effect of the protection network on the temporal trends of non-threatened avian biodiversity in France, over the period 2002-2016. For this purpose, we tested for differences in temporal changes in abundance and in community structure between sites inside or outside the N2000. We considered abundance of i) the overall bird populations, ii) of habitat specialists (farmland, woodland, and generalist) and iii) of species of concern (listed in the Annex I of the Bird Directive). Changes in community structure were measured through two functional indices: the Community Specialisation Index and the Community Trophic Index. We found consistent results with previous findings pointing out at a significant decline of common bird populations over time. However, our results show that this decline is weaker within N2000 areas than outside N2000, especially for farmland specialists. This emphasises that common bird species - not directly targeted by the European Birds and Habitats Directives - may have benefited from the protection or management measures of the N2000. From our knowledge, this is the first study highlighting significant long-term effects of Natura 2000 on common bird populations. Despite these encouraging outputs, we did not find any long-term benefit of the protection network for the bird species targeted for the designation of Natura 2000 areas. We note, however, that our results did not show any significant trend in abundance for these specific populations, meaning that these may have remain stable over the past decade or so. Also, we did not find any significant long-term protection or management effect of N2000 on bird communities. These lack of findings may reflect either a limited capacity of N2000 to deliver large benefits or the need for longer time series to detect protection or management effects at a community level. Overall our study support the fact that Breeding Bird Survey is a useful tool to assess a protection network, and we encourage further studies to re-evaluate the impacts of the network in the coming future.