Scientific evidence on cat colonies and the TNR method
A selection of scientific papers, datasets and official texts on cat colony management and the TNR method (Trap-Neuter-Return): programme evaluations, population models, health and zoonoses in free-roaming cats, coexistence with wildlife, and the regulations and plans that govern them. It also includes work that is critical of TNR, so that everyone can consult the different positions in their original source.
Each record summarises in one or two sentences what the document is about and links to its original source (DOI or official page). Meow Metrics does not interpret the results or the scope of the regulations: to learn about them, always consult the source.
Cat colonies and TNR
Anthropogenic foods sustain free-roaming cats on a Mediterranean island, but neutering reduces wild bird consumption
Cecchetti, Martina; dell’Omo, Giacomo; Ozella, Laura
Seasonal diet of free-roaming cats on a Mediterranean island: anthropogenic foods and the effect of neutering on wildlife predation.
Coded analytical matrix of Environmental Impact Assessment reports for managed free-roaming cat colonies in protected natural areas of Gran Canaria, Spain (2025)
Manzanares-Fernández, Ruth; Travieso Aja, María del Mar; Martínez-Campos, José
Coding matrix of environmental impact assessment reports on managed cat colonies in municipalities of Gran Canaria.
Community-cat caregivers in Spain (ONECAT-SOC, 2026): de-identified analytic dataset and reproducibility code
Luzardo, Octavio P.; Travieso Aja, María del Mar; Parga-Dans, Eva
Reproducible package of the 2026 ONECAT-SOC survey of cat colony caregivers in Spain, without personal data.
Daily GPS movement and activity of free-roaming male cats before and after gonadectomy — a longitudinal within-individual study (Barlovento, La Palma)
Travieso Aja, María del Mar; Rodríguez-Concepción, Sonia; Luzardo, Octavio P.
Daily GPS and accelerometry data from cats in a TNR (Trap-Neuter-Return) colony in Barlovento (La Palma), before and after gonadectomy.
Home range and daily movement before and after gonadectomy in adult and juvenile free-roaming male cats: A longitudinal GPS tracking study within a managed colony
del Mar Travieso-Aja, María; Rodríguez-Concepción, Sonia; Luzardo, Octavio P.
Within-individual GPS tracking of the effect of gonadectomy on the home range of cats in a managed colony on La Palma (Canary Islands, Spain).
The Nine Lives of Trap-Neuter-Return in the Canary Islands
Pons-Raga, Ferran; Alonso González, Pablo
Ethnographic study of TNR (Trap-Neuter-Return) as a socio-technical assemblage on Tenerife (Canary Islands, Spain).
Colonias Felinas (Málaga) - ubicación de colonias registradas
Ayuntamiento de Málaga
Geographic layer with the location of registered cat colonies in Málaga (KML/GML/ZIP download).
Four Years of Promising Trap–Neuter–Return (TNR) in Córdoba, Spain: A Scalable Model for Urban Feline Management
Luzardo, Octavio P.; Vara-Rascón, Mercedes; Dufau, Agnès
City-scale TNR (Trap-Neuter-Return) program in Córdoba (Spain) as a model for urban feline management.
Integrating Conservation and Community Engagement in Free-Roaming Cat Management: A Case Study from a Natura 2000 Protected Area
Luzardo, Octavio P.; Hansen, Andrea; Martín-Cruz, Beatriz
The case of La Graciosa (Canary Islands, Spain; Natura 2000): a TNR (Trap-Neuter-Return) campaign and community engagement for conservation.
Planning and optimizing neutering programs for free-roaming cat populations: An interactive tool for cost-effective management in closed systems
Cecchetti, Martina; Nelli, Luca
Data from the interactive tool for planning neutering programs for free-roaming cats (cost-effectiveness).
Planning and optimizing neutering programs for free‐roaming cat populations: An interactive tool for cost‐effective management in closed systems
Cecchetti, Martina; Nelli, Luca
Interactive tool for planning and optimizing cost-effective neutering programs for free-roaming cats (with an associated Dryad dataset).
Territorial Constraints on Trap–Neuter–Return in Insular Landscapes: Demographic and Ecological Implications of a Conservation-Oriented Policy
Manzanares-Fernández, Ruth; Martínez-Campo, José; Travieso-Aja, María del Mar
Governance and demographic simulations of neutering regimes on islands with TNR (Trap-Neuter-Return) restrictions in protected areas (Canary Islands, Spain).
Territorially Stratified Modeling for Sustainable Management of Free-Roaming Cat Populations in Spain: A National Approach to Urban and Rural Environmental Planning
Luzardo, Octavio P.; Manzanares-Fernández, Ruth; Becerra-Carollo, José Ramón
Territorially stratified modeling for the management of free-roaming cat populations in Spain.
Community Engagement and the Effectiveness of Free-Roaming Cat Control Techniques: A Systematic Review
Ramírez Riveros, Daniela; González-Lagos, César
Systematic review (PRISMA 2020): influence of community engagement on the effectiveness of non-lethal cat control.
Evaluation of Population Management Based on Trap–Neuter–Return and Trap–Neuter–Adoption Practices in a Free-Roaming Cat Colony in the Federal District, Brazil
Junqueira, Ana Nira Nunes; Galera, Paula Diniz
Evaluation of population management based on TNR (Trap-Neuter-Return) and TNA (trap, neuter, adopt) in a cat colony in Brazil.
The Role of Veterinarians in Managing Community Cats: A Contextualized, Comprehensive Approach for Biodiversity, Public Health, and Animal Welfare
Luzardo, Octavio P.; Zaldívar-Laguía, José Enrique; Zumbado, Manuel
Framework for veterinarians to take part in managing community cats in Europe, in coordination with local governments, animal shelters and volunteers.
Por qué la ley que protegerá los gatos callejeros también ayudará a proteger la biodiversidad
Luzardo, Octavio
Popular-science article: why the Spanish law that will protect stray cats will also help protect biodiversity.
Reduction of free-roaming cat population requires high-intensity neutering in spatial contiguity to mitigate compensatory effects
Gunther, Idit; Hawlena, Hadas; Azriel, Lior
Long-term controlled field experiment on the intensity and spatial contiguity of neutering in an urban free-roaming cat population.
Free Roaming Cats in Public Spaces
Elshater, Abeer; Abusaada, Hisham
Dataset by Elshater and Abusaada on free-roaming cats in public spaces.
A Case of Letting the Cat out of The Bag—Why Trap-Neuter-Return Is Not an Ethical Solution for Stray Cat (Felis catus) Management
Crawford, Heather M.; Calver, Michael C.; Fleming, Patricia A.
Article on the TNR (Trap-Neuter-Return) method and its ethical assessment in the management of stray cats.
A Long-Term Lens: Cumulative Impacts of Free-Roaming Cat Management Strategy and Intensity on Preventable Cat Mortalities
Boone, John D.; Miller, Philip S.; Briggs, Joyce R.
Long-term simulation of several management scenarios for free-roaming cats.
Back to School: An Updated Evaluation of the Effectiveness of a Long-Term Trap-Neuter-Return Program on a University’s Free-Roaming Cat Population
Spehar, Daniel D.; Wolf, Peter J.
Updated evaluation of a long-term TNR (Trap-Neuter-Return) program on a university campus.
Decrease in Population and Increase in Welfare of Community Cats in a Twenty-Three Year Trap-Neuter-Return Program in Key Largo, FL: The ORCAT Program
Kreisler, Rachael E.; Cornell, Heather N.; Levy, Julie K.
Population and welfare of community cats in a long-term TNR (Trap-Neuter-Return) program in Ocean Reef (Key Largo, Florida).
Reply to Crawford et al.: Why Trap-Neuter-Return (TNR) Is an Ethical Solution for Stray Cat Management
Wolf, Peter J.; Rand, Jacquie; Swarbrick, Helen
Reply to Crawford et al. on TNR (Trap-Neuter-Return) as an ethical solution for the management of stray cats.
Unowned Free-Roaming Domestic Cats: Reflection of Animal Welfare and Ethical Aspects in Animal Laws in Six European Countries
Natoli, Eugenia; Ziegler, Nadja; Dufau, Agnés
Reflection on welfare and ethical aspects in the laws affecting unowned free-roaming cats in Europe.
Effect of high-impact targeted trap-neuter-return and adoption of community cats on cat intake to a shelter
Levy, J.K.; Isaza, N.M.; Scott, K.C.
Targeted TNR (Trap-Neuter-Return) and adoption of community cats in a specific area, and their effect on cat intake at a shelter.
Simulating Free-Roaming Cat Population Management Options in Open Demographic Environments
Miller, Philip S.; Boone, John D.; Briggs, Joyce R.
Simulation of cat management options in demographically open settings (immigration and neutering).
Cats and wildlife
Cat colonies reshape the abundance and body size of lizards
Rodríguez, Airam; Rando, Juan Carlos; Rodríguez, Beneharo
Study of the abundance and body size of Tenerife lizards (Gallotia galloti) in relation to cat colonies.
DOI 10.1098/rsbl.2026.0195
Cat colonies reshape the abundance and body size of lizards
Rodríguez, Airam; Rando, Juan Carlos; Rodríguez, Beneharo
Biometric data, stable isotopes and locations of Gallotia galloti lizards close to and far from cat colonies in Tenerife.
DOI 10.20350/digitalcsic/18364
Lo que los gatos paracaidistas de Borneo nos enseñan sobre la gestión de especies
Luzardo, Octavio
Popular-science article drawing species-management lessons from the "parachuting" cats of Borneo.
Emerging laws must not protect stray cats and their impacts
Carrete, Martina; Clavero, Miguel; Arrondo, Eneko
Article on emerging animal protection laws and their relation to stray cats and their impacts.
DOI 10.1111/csp2.12706
Feral Cats and Biodiversity Conservation: The Urgent Prioritization of Island Management
Nogales, Manuel; Vidal, Eric; Medina, Félix M.
Article on prioritizing the management of feral cats on islands for biodiversity conservation.
DOI 10.1525/bio.2013.63.10.7
Health, zoonoses and One Health
Low Zoonotic Pathogen Burden in Free-Roaming Cats Revealed by 18S rRNA Metabarcoding: A Baseline Study from an Insular Natura 2000 Site in Spain
Travieso-Aja, María del Mar; Henríquez-Hernández, Luis Alberto; Hernández-Álvarez, Elisa
18S rRNA metabarcoding baseline of zoonotic pathogens in feces from community cats on La Graciosa.
Outdoor roaming of owned cats elevates risk of zoonotic pathogen exposure: A global synthesis
Wilson, Amy G.; Wilson, Scott; Marra, Peter P.
Global synthesis on outdoor access for owned cats and exposure to zoonotic pathogens.
Seroprevalence of zoonotic pathogens in stray cats in an urban area of northeast Spain
Peris, María Paz; Planas, Sandra; Langa, Jon
Seroprevalence of zoonotic pathogens in stray cats in Zaragoza, Spain.
Zoonotic parasites associated with predation by dogs and cats
Mendoza Roldan, Jairo Alfonso; Otranto, Domenico
Review of zoonotic parasites associated with predation by dogs and cats.
Urban landscape and infection risk in free‐roaming cats
Candela, Mónica G.; Fanelli, Angela; Carvalho, João
Seroprevalence of Chlamydia felis, Coxiella burnetii and Toxoplasma in free-roaming cats in Murcia (Spain) in relation to the urban landscape.
A cross-sectional study of Leishmania infantum infection in stray cats in the city of Zaragoza (Spain) using serology and PCR
Alcover, Maria Magdalena; Basurco, Asier; Fernandez, Antonio
Cross-sectional study of Leishmania infantum infection in stray cats in Zaragoza, Spain.
Implications of zoonotic and vector-borne parasites to free-roaming cats in central Spain
Montoya, A.; García, M.; Gálvez, R.
Zoonotic and vector-borne parasites in free-roaming cats in central Spain.
Intestinal parasites and vector-borne pathogens in stray and free-roaming cats living in continental and insular Greece
Diakou, Anastasia; Di Cesare, Angela; Accettura, Paolo Matteo
Intestinal parasites and vector-borne pathogens in stray and free-roaming cats of mainland and island Greece.
Zoonotic Diseases Associated with Free‐Roaming Cats
Gerhold, R. W.; Jessup, D. A.
Review of zoonotic diseases associated with free-roaming cats.
Pollutants and rodenticides
Community cats managed under Trap–Neuter–Return as sentinels of human diet-linked chemical exposure across contrasting feeding contexts
Travieso-Aja, María del Mar; Luzardo, Octavio P.; Ruiz-Suárez, Norberto
Community cats managed under TNR (Trap-Neuter-Return) as sentinels of chemical exposure linked to human diet (La Graciosa and Gran Canaria).
Companion animals: census, abandonment and adoption
Animals entry and exit number in Barcelona Pet Animals Welfare Center (CAACB)
Ajuntament de Barcelona (Medi Ambient)
Monthly series of dog and cat intakes and outcomes at the Barcelona municipal animal shelter.
Estudio "Él nunca lo haría" 2026 (datos de 2025): abandono, pérdida y adopción de perros y gatos en España
Fundación Affinity
Annual study on the abandonment, loss and adoption of companion animals in Spain (2026 edition, 2025 data).
Madrid Salud. Estadísticas Centro de Protección Animal
Madrid Salud / Ayuntamiento de Madrid
Half-yearly figures from the Madrid Animal Protection Center: intakes, adoptions, sterilizations and pick-ups.
Regulations, plans and institutional documents
Colonias felinas (Bienestar Animal - Ayuntamiento de Barcelona)
Ayuntamiento de Barcelona
Official page explaining the CERR method (capture, sterilization, registration and return), the role of accredited managing organizations and how to report incidents.
Plan de Acción 2026-2030 sobre gestión de poblaciones felinas y gatos comunitarios (Rev. 03, agosto 2026)
Dirección General de Derechos de los Animales (Ministerio de Derechos Sociales, Consumo y Agenda 2030)
Action Plan 2026-2030 on the management of feline populations and community cats: principles, situation in Spain and lines of action.
Programa de Gestión de Colonias Felinas 2026-2027 del Ayuntamiento de Madrid (aprobado por Acuerdo de la Junta de Gobierno de 29-12-2025)
Ayuntamiento de Madrid / Madrid Salud
Madrid City Council's 2026-2027 municipal cat colony management program (Spain), published in the BOAM.
Valencia abre el primer centro municipal de atención veterinaria de colonias felinas de España (noticia institucional, 05/05/2026)
Ayuntamiento de Valencia
Press release from Valencia City Council (Spain) on the municipal veterinary care center for cat colonies.
Zaragoza amplia el recinto para gatos del Centro de Protección Animal para acoger la colonia felina del Portillo (noticia institucional, 04/11/2025)
Ayuntamiento de Zaragoza
Press release from Zaragoza City Council (Spain) on the expansion of the cat enclosure at the Animal Protection Center.
Plan de Control y Gestión Ética de Colonias Felinas de La Adrada (Ávila; plan tipo de la Diputación de Ávila, firmado 10/07/2024)
Ayuntamiento de La Adrada / Diputación de Ávila
Example of a municipal plan for a small Spanish town, hosted by a provincial council that offers a common model to its municipalities.
Ley 7/2023, de 28 de marzo, de protección de los derechos y el bienestar de los animales
Jefatura del Estado
Official text of the Spanish national law on the protection of animal rights and welfare.
Pla estratègic de Gats de Barcelona 2020-30: Focus Colònies de gats ferals (gener 2022)
Ajuntament de Barcelona - Drets dels Animals
Municipal strategic plan with starting assumptions, short-term objectives and a 2030 vision for feral cat colonies and their coordination with organizations and districts.
These cards link to the original source; their record is in the Zoometrics catalog. The Zoometrics general catalog brings together these and other publications on urban wildlife, health and biodiversity: Zoometrics scientific catalog.
