Four-year TNR study yields promising results

Study

“Four Years of Promising Trap-Neuter-Return (TNR) in Córdoba, Spain: A Scalable Model for Urban Feline Management,” published in the journal Animals, 2024. Complete article available online here.

Overview

A four-year study of a large-scale TNR program begun in 2020 in Córdoba, Spain, “demonstrates how citywide, well-coordinated interventions can ethically and effectively manage urban free-roaming cat populations” [1]. Authors of the study describe the program as “a scalable and pioneering model for large-scale urban feline management.”

Key Points

This program, a public-private partnership with the municipality funding services through veterinary clinics, sterilized roughly 5,000 cats in 225 colonies, with 95% of colonies achieving sterilization rates of 80% or greater.

Although the authors describe the program’s results during the first four years as “modest,” their analysis “projects a significant 55% population reduction by 2028, highlighting the importance of sustained efforts, community engagement, and targeted strategies.” [1].

"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."

This study’s 5.5% increase in census results during the two-year follow-up is not uncommon. Short-term studies of just one [2] or two years [3] have documented similar increases, as have longer studies—prior to subsequent, significant declines [4].

See related Issue Brief:

• What to do with feral cats: Examining TNR for population management

References

1. Luzardo, O.P.; Vara-Rascón, M.; Dufau, A.; Infante, E.; Travieso-Aja, M. del M. Four Years of Promising Trap–Neuter–Return (TNR) in Córdoba, Spain: A Scalable Model for Urban Feline Management. Animals 2025, 15, 482, doi:10.3390/ani15040482.

2. Bissonnette, V.; Lussier, B.; Doizé, B.; Arsenault, J. Impact of a Trap-Neuter-Return Event on the Size of Free-Roaming Cat Colonies around Barns and Stables in Quebec: A Randomized Controlled Trial. Canadian Journal of Veterinary Research 2018, 82, 192–197.

3. Castillo, D.; Clarke, A.L. Trap/Neuter/Release Methods Ineffective in Controlling Domestic Cat “Colonies” on Public Lands. Natural Areas Journal 2003, 23, 247–253.

4. Natoli, E.; Maragliano, L.; Cariola, G.; Faini, A.; Bonanni, R.; Cafazzo, S.; Fantini, C. Management of Feral Domestic Cats in the Urban Environment of Rome (Italy). Preventive Veterinary Medicine 2006, 77, 180–185.