Continent-wide test of the efficiency of the European union's conservation legislation in delivering population benefits for bird species

Birds are among the most important organisms for indicating the state of environmental health and their population changes may be thus informative for assessments of country-level conservation tools. One such tool applied in the European Union (EU) is the Birds Directive which (together with general protection of all bird species) lists a number of species under its Annex I and these species enjoy specific protection conditions. Although some previous studies found indications of the efficiency of the Annex I in delivering benefits for the listed species, the assessments where either confined to the so called old member states (i.e. countries entered EU before 2004) or did not include countries outside EU as a suitable control group. Therefore, it remains unclear whether this tool is efficient also in the new EU-member states (i.e. countries entered EU from 2004 onwards). For this purpose, we used publicly available information source and assembled a dataset providing country-level population trends of 252 European breeding bird species estimated for the time period 2001-2012 in 33 European countries containing old member states, new member states and non-member states. We predicted that if efficient, then listing the species under Annex I would result in significantly positive population trends of the listed species in EU countries irrespective to the time of their enterance, while no such pattern should be observed in non-EU countries. We tested this prediction using linear mixed effect models controlling for the effects of 11 species' traits reflecting the influence of other factors (e.g. climate change, land cover change, proximity to range edges) on trends and including the species and country indentifiers as random effects. We found that the listing under the Annex I had significantly positive effect on bird trends in both old and new member states, whereas no such effect was observed in the non-member states. Although the positive influence of listing was larger in the old and than in the new member states, the difference was not statistically significant. Our results imply that the Annex I of the Birds Directive is an important tool for bird conservation in Europe and that its positive influence on bird populations is detectable even in the new EU members entering EU relatively recently. As birds are often used as indicators also for other groups of organisms, these results suggest that not only birds may benefit from EU's conservation legislation but comprehensive assessments are needed.