Effectiveness of nature reserves in France in protecting common birds: Evidence from long-term monitoring

In mainland France, 335 Nature Reserves protect 2428 km 2 of natural areas. To measure the effectiveness of these protected areas in conserving populations of common birds, we assessed temporal changes in bird abundance by analysing data from the French Breeding Bird Survey collected during fifteen years (2004–2018) using generalized linear models. Population trends were compared between 86 nature reserves sites and unprotected sites for 156 common bird species. Within nature reserves (all species confounded), trends were significantly positive (+ 14.4% in 15 years) and negative in unprotected areas (− 6.9%), with forest specialists showing the strongest positive trend (+ 29.7%) in the former. Notably, the beneficial effects of reserves extended beyond their administrative boundaries, with positive effects detected within 3 km from the reserve borders (+ 5.23%). Beyond species-level trends, we demonstrate that reserves maintain higher community specialisation and trophic complexity, resisting biotic homogenisation and preserving ecosystem functionality. This study highlights the importance of protected areas for common bird conservation and suggests that nature reserves positive effect have not only continued but strengthened compared to previous studies (1989–2003), providing landscape-scale benefits beyond their designated boundaries and that strategic expansion of reserve networks could amplify these conservation benefits. While birds serve here as indicators of ecosystem health, the habitat protection and ecological integrity maintained by this protection status would presumably benefit broader taxonomic groups and mitigate the substantial losses documented across continents.