Breeding birds in the largest historical urban park of Rome (Villa Doria Pamphilj): community structure and spatial patterns of species richness and occurrence

This study presents preliminary data obtained through intensive sampling using a spatial survey approach (breeding bird atlas) carried out in Rome’s largest historic urban park: Villa Doria Pamphilj (184 hectares). A total of 44 breeding bird species were recorded across 88 survey units, each measuring 160×160 meters (Chao2 species richness estimator: 45.19±1.82 species). Psittacula krameri, Corvus cornix, Cyanistes caeruleus, Sylvia atricapilla, Turdus merula, and Apus apus were the most widely distributed species, occurring in more than 50% of the sampling units. The forest and synanthropic species guilds were both the most species-rich and the most spatially widespread. Differences in frequencies of occurrences among ecological guilds were clearly illustrated in the Whittaker plots. High habitat heterogeneity at the landscape scale appears to provide a wide range of ecological niches and resources, promoting overall species diversity. Species richness was positively associated with the extent of forest cover and proximity to watersheds, with localized hotspots observed near small lakes surrounded by mature trees and riparian vegetation. Despite the abundance of open areas (e.g., meadows), species typically associated with these habitats were absent, likely due to intense anthropogenic disturbance (e.g., high human and dog presence, frequent mowing). At the finer scale of the survey units, habitat heterogeneity did not explain variation in species richness: no significant correlation was found between fine-scale habitat diversity and species richness. This suggests that the resolution of the atlas grid may not align with the ecological grain perceived by bird species. Local atlases conducted in large urban parks can serve as valuable tools for the long-term monitoring of spatial patterns in bird species and guilds, supporting both geographical and temporal comparisons.