Urban free-roaming cat populations (or community cats, according to the Spanish legislation) present complex challenges, including public health risks, coexistence conflicts with residents, animal welfare, and threats to biodiversity conservation. In 2020, Córdoba, Spain, initiated one of the most extensive citywide trap–neuter–return (TNR) programs, incorporating 225 groups of cats (usually
... [Show full abstract] named colonies) into a meticulously structured management framework. Over four years, the program stabilized cat populations, achieving 95% sterilization coverage and effectively limiting population growth despite external challenges, including abandonment, influxes from unmanaged areas, and compensatory effects. Although the overall population showed a modest decline of 2.68%, this outcome reflects not only the recent inclusion of numerous colonies still undergoing stabilization but also the prevention of an estimated 70% population growth without intervention, as projected by our population viability analysis (PVA). Key results highlight the program’s cost-effectiveness, with an average annual cost of EUR 0.62 per person. The long-term projections from a population viability analysis (PVA) using demographic modeling suggest a potential 55% population reduction by 2028, contingent on sustained efforts. The program’s integration of citizen science, systematic data collection, and adaptive management demonstrates its scalability and replicability as a model for urban and peri-urban feline management globally. Its significance lies not only in its scope and scale but also in demonstrating the ethical and practical feasibility of large-scale TNR initiatives in urban contexts. Córdoba’s program, which predates Spain’s Animal Welfare Law 7/2023 mandating structured feline colony management plans, demonstrates a pioneering framework for compliance and innovation in urban animal management. These findings underscore the critical role of sustained interventions, community collaboration, and legal frameworks in ensuring long-term success and addressing global challenges in urban animal welfare and biodiversity conservation.