Socio-Economic Status and Non-Native Species Drive Bird Ecosystem Service Provision in Urban Areas

Areas of higher socio-economic status within cities often support greater biodiversity than poorer areas, representing a form of environmental injustice. This inequality may result in lower income areas experiencing both lower cultural (e.g., bird aesthetics) and regulating (e.g., pest control) ecosystem service provision. Urban areas are also hotspots for non-native species, which can alter community functional structure and, consequently, ecosystem service provision. However, the influence of socio-economic status on services provided by both native and non-native urban biodiversity remains underexplored. We assessed how functional diversity related to avian cultural and regulating ecosystem services varied along the socio-economic gradient of functional urban areas (FUAs) in the Iberian Peninsula. Using breeding bird atlases from Spain and Portugal, we characterised bird communities in all FUAs, calculating species richness and functional dispersion based on traits linked to ecosystem services. We used generalised linear mixed models to examine relationships between diversity metrics and median household income. Additionally, we evaluated whether the presence of non-native species moderated community responses along the gradient. Both cultural and regulating ecosystem services were negatively associated with socio-economic status, while species richness increased with income. However, invaded communities supported higher species richness and cultural service provision than non-invaded ones. Our findings reveal a counterintuitive pattern in which ecosystem service provision is higher in lower-income areas, partly due to non-native species. These results underscore the need for urban management strategies that simultaneously address socio-economic and ecological inequalities, while considering the complex roles of non-native species in shaping urban biodiversity and its benefits.