Beyond the reserves: The role of non-protected rural areas for avifauna conservation in the area of Barcelona (NE of Spain)

This paper explores the association of a set of land variables with bird species richness in the area of Barcelona, subgrouped into nesting and wintering, and three classes of conservation concern: total species, species of European Concern (SPEC 2 and 3), and species included in the Birds Directive. It also analyzes the association of the species richness among these groups, and compares their values inside and outside of the protected areas. Bird data were obtained by field sampling within 1700 l km × l km UTM grid cells, which were sampled between 1990 and 1998 until the entire study area had been assessed. For each cell, derivatives of the following variables were calculated: climate, relief, landscape, geographic position, and human settlement. Relative forest and cropland covers and landscape diversity were the main positive correlates of total species richness, while the average elevation was the prime negative correlate for wintering species. SPEC and Birds Directive species richness were negatively related to forest and urban covers, and positively related to that of croplands and shrublands–grasslands. The species richness of birds of no conservation concern (non-listed) was generally positively related to those of SPEC and Birds Directive species, regardless of whether they were wintering or nesting. There was significantly more bird richness outside the reserves in all but one of the classes of conservation concern—nesting Birds Directive. The study confirms the importance of open habitats and heterogeneous rural landscapes for bird species richness in the study area, and provides conservation guidelines based on regional policy.