Authors: Kačergytė, Ineta; Pärt, Tomas;Berg, Åke;Arlt, Debora;Żmihorski, Michał;Knape, Jonas;

Restoring wetlands to improve habitats for birds has become an important conservation tool as many species are in decline due to vast habitat loss and deterioration. To what extent such restorations are effective is not well known because surveys usually either lack data before the restoration or means of correcting for background trends. We gathered all available Before-After survey data on birds from Swedish wetland restorations in agricultural landscapes. We then quantified the effectiveness of 30 wetland restorations for 75 bird species from the resulting heterogeneous survey data, and used national survey data to correct for background population trends. While restoration measures seemed to benefit about half of the breeding wetland bird community, many species did not show a clear positive response to wetland restorations and some declined. Estimated species responses to restorations were highly site-dependent and variable, which we attribute partly to variability in methodology and lack of robust survey designs. We argue that if policymakers and environmental protection agencies set clear instructions and provide support for proper survey designs to assess effects of restorations, our ability to learn about the effectiveness of restoration actions could be greatly improved.