Effects of Natura 2000 on nontarget bird and butterfly species based on citizen science data

The European Union's Natura 2000 (N2000), is one of the largest international networks of protected areas. One of its aims is to secure the status of a pre‐determined set of (targeted) bird and butterfly species. However, also non‐target species may benefit from N2000. We evaluated how the terrestrial component of this network relates to the abundance of non‐targeted, more common bird and butterfly species using data from long‐term volunteer‐based monitoring programs in 9,602 sites for birds and 2,001 sites for butterflies. In almost half of the 155 bird species assessed, and particularly among woodland specialists, abundance increased with the proportion of N2000 sites in the landscape. The corresponding positive relationship was found for 27 of the 104 butterfly species, although most of these species were generalists. These positive relationships disappeared for most of the species when land‐cover covariates were taken into account, hinting that land‐cover is a primary factor defining the positive effects of the N2000 network. The increase in abundance with N2000 was correlated with the specialization index for bird species, but not for butterfly species. Although the N2000 network supports higher abundance of a large spectrum of species, the low number of specialist butterfly species showing a positive association stresses the need to implement management plan improving the quality of habitats of N2000 areas potentially harboring openland butterfly specialists. For a better understanding of the processes involved, we advocate for a standardized collection of data on N2000 sites.

Article impact statement: Across Europe the abundance of a majority of nontarget birds and a quarter of nontarget butterflies increased with Natura 2000 coverage.