Habitat Structure Outweighs Monastic Legacy in Shaping Bird Assemblages

Sacred natural sites are often considered potential refugia for biodiversity in human-dominated landscapes, but their effects can be confounded by present-day habitat structure. We tested whether extant Cistercian monasteries in western Poland influence breeding-bird assemblages at two spatial scales by conducting standardized 5 min point counts during two visits at 234 stations across 23 plots and comparing Cistercian plots with environmentally matched Control and Post-Cistercian plots. We recorded 133 breeding-bird species, numerically dominated by widespread farmland and synanthropic taxa. Neither plot category nor station placement within versus outside monastery grounds explained variation in Shannon diversity or rarefied species richness. In contrast, both diversity metrics increased with contemporary landscape complexity, especially along gradients from arable land toward grasslands and urban habitats and with increasing heterogeneous agriculture, while community composition was significantly associated with current landcover structure. These findings indicate that present-day habitat structure, rather than monastic legacy, is the main driver of breeding-bird diversity in this system. Conservation and land-use policy in agricultural regions should therefore prioritize the maintenance and restoration of heterogeneous landscapes, including mosaics of semi-natural habitat elements.