Résumé
We studied the role played by the French protected area network on 100 common bird species at the population and community level. The long-term trend of each species was calculated over 15 years (1989–2003). We then used 418 plots monitored by the French Breeding Bird Survey over 2001–2005 either inside or outside the national protected area network (including Nature Reserves, National Parks and Special Protected Areas) to compare each species' average density inside and outside the protected areas. We then tested if the relative species densities in protected areas were related to the species long-term trends. At the community level, we assessed the average proportions of the most severe long-term declining species inside and outside protected areas as well as their temporal stability. We found that several species, which are mostly dependent on human activities, had both higher densities in unprotected areas and exhibited a negative long-term trend. However, for most species, we found that the more a species has declined over the 15 years, the higher its density in protected areas. At the community level, declining common species were found in higher proportion and exhibited greater temporal stability in protected areas. Our results emphasize that many common but declining species could benefit from protected areas and that large-scale monitoring programs provide highly valuable quantitative tools for extensive protected area assessments.