The influence of landfill foraging: enteric helminths and bacteria in a population of White Stork (Ciconia ciconia) from central Spain

Anthropogenic food subsidies, such as municipal solid waste landfills, profoundly alter wildlife ecology and host–pathogen dynamics. Under a One Health framework, highly mobile synanthropic species exploiting these polluted sites act as biological vectors, effectively bridging human waste reservoirs with urban environments. In this study, we investigated how reliance on refuse shapes the gastrointestinal parasitome and enteropathogenic bacteria of an urban-breeding White Stork ( Ciconia ciconia ) population in central Spain (Alcalá de Henares) that recently adapted to local landfill closures by commuting to distant active sites. Gastrointestinal samples from 44 individuals were collected between 2022 and 2023. We specifically hypothesised that: (1) overall gastrointestinal parasite prevalence would be low due to reduced natural foraging; (2) the parasite community would be dominated by species with direct biological cycles, as bypassing natural prey interrupts indirect cycles; and (3) storks feeding on anthropogenic waste act as important biological vectors for zoonotic bacterial and parasitic pathogens. Our findings demonstrate how anthropogenic refuse drives epidemiological shifts in synanthropic birds and assess the associated public health risks for surrounding urban communities. Ultimately, this work underscores the far-reaching health implications of waste management policies, offering a valuable case study at the interface of urban wildlife ecology and public health.