The Nine Lives of Trap-Neuter-Return in the Canary Islands

Introduction

In recent decades, Trap–Neuter–Return (TNR) has been widely adopted as a technical strategy for the management of cat populations living outdoors, positioning itself as a humane alternative to traditional lethal control (Robertson, 2008; Wolf & Schaffner, 2019). In a typical TNR program, free-roaming cats (Felis catus) are trapped in the street, surgically neutered, dewormed and vaccinated at a vet clinic, and then returned to their original location. This method aims to control cat populations by reducing their numbers over long periods, i.e., cats’ lifespan, while addressing ethical concerns regarding animal welfare. This technique is socially and ideologically contested, though. Conservationists often denounce free-roaming cats as an insidious, even staggering threat to native wildlife (Loss et al., 2022; Trouwborst et al., 2020). In contrast, animal welfare advocates defend the cats as community members that human beings need to take care of (Schaffner, 2016). The result is a polarized debate as outdoor cats navigate between the domestic sphere, as animals to be cared for, and the feral sphere, as animals to be removed from the environment (Crowley et al., 2020; Marvin & McHugh, 2014; Pons-Raga, 2024).

The controversy surrounding TNR highlights profound disagreements in values, knowledge, and even basic ontology (Palmer & Thomas, 2023; Wald & Peterson, 2020). TNR advocates, including veterinary scientists, law scholars and animal welfare groups, frame the management technique as a compassionate, science-informed solution that stabilizes cat colonies without resorting to killing. They point to studies suggesting that sterilized colonies can reduce population growth under proper long-term monitoring (Boone et al., 2019; Gunther et al., 2022; Levy et al., 2014; Luzardo, Vara-Rascón, et al., 2025). Amid a list of methods for controlling cat populations, spanning laissez-faire, ‘destroy on site’, trap-remove-euthanize, trap and relocate, non-surgical contraception, or controlling the source of cats (Robertson, 2008), TNR appears as the only humane, effective solution for reducing outdoor cat populations. Opponents, often ecology researchers and conservationists, counter that TNR keeps cats outdoors, where they continue to prey upon vulnerable fauna, including birds, reptiles, and small mammals. They see TNR as ineffective, fueling rather than addressing the issue. From this view, cats are devastating predators responsible for the 14% of extinctions worldwide and thus becoming a terrible menace for biodiversity (Loss et al., 2013), particularly in insular ecosystems where they may act as invasive species (Medina et al., 2011; Nogales et al., 2013).

Scientific communities are immersed in ‘cat wars’ (Marra & Santella, 2016; Wald & Peterson, 2020). In these polarized debates, TNR is contested through the touchstone notion of effectiveness. Discussing or questioning TNR is based on whether it does or does not achieve its stated aim: reducing outdoor cat populations (Coe et al., 2021; Swarbrick & Rand, 2018). Despite heated public and scientific debates, most research treats TNR as a standardized, portable technique: essentially the same device from Australia to Chile. By contrast, we ask how TNR is made to hold together locally as an assemblage (Nadaï et al., 2025; Ogden et al., 2013): an arrangement in which reproductive cycles, colony ecologies, and feline behaviors articulate with traps, anesthetic protocols, ear-tipping, microchipping, and GPS/GIS mapping, co-producing outcomes that make legal categories, municipal routines, and caregiver practices work. To do so, we draw on Actor–Network Theory (ANT) to trace the translations that align heterogeneous actors, while foregrounding the relational, ethical, and affective dimensions of human–cat interactions that sustain (or undo) that alignment.

TNR here is a hybrid system, in which biological parameters both afford and constrain sociotechnical orderings. Rather than treat ‘biology’ as background and ‘the social’ as foreground, we emphasize co-production: reproductive cycles, feline territoriality, disease ecology and seasonality intertwine with traps, surgical protocols, microchips, WhatsApp groups, municipal ledgers, and funding rules. Callon’s (1984) principle of translation proves useful to examine ethnographically how TNR is enacted across multiple sites. We treat the ‘cat problem’ as a problematization that positions colony-based TNR as the obligatory passage point through which caregivers, vets, councilors, and ecologists must now move if they wish to solve their divergent grievances. We thus read a legal statute, a trap, clinic form, or neighbor quarrel as a moment where the network is stabilized or frays, thereby letting the empirical material itself reveal how TNR is continually made and remade, assembled and disassembled through what Law (1994) has described as different ‘modes of ordering’, such as unpaid care practices or veterinary surgical interventions.

TNR: From a Management Technique to an Assemblage

STS and ANT-adjacent scholarship has analyzed a wide range of technoscientific controversies, from laboratories to infrastructures (Hess, 2016; Latour, 2018), while increasingly foregrounding animals and the enactment of human–animal relations in contested settings (Haraway, 2003; Whatmore, 2002). Recent work shows how classifications and governance of cats are made and disputed across conservation and public life (Palmer & Thomas, 2023), how veterinary and research experts perform ethical boundary-work around nonhumans (Anderson & Hobson-West, 2023), and how community engagement and caregiving infrastructures shape urban cat management (Ramírez Riveros & González-Lagos, 2024; Wu & Gu, 2024). Alongside animal domestication and enactment studies (Lien, 2015) and multispecies health governance (Hinchliffe, 2015), this literature treats human–animal conflicts as performed through relational practices, rather than as fixed problems.

In contrast, expertise around cats splinters along disciplinary lines, with their corresponding techniques of management. Beyond polarized confrontation between conservation biology and veterinary medicine, both agree that TNR can be applied worldwide, a ‘global assemblage’ in Collier’s (2006) terms. Thus, it is routinely treated as a standardized population-management technique (Boone, 2015; Coe et al., 2021). As a result, we know very little about how TNR is collectively negotiated and stabilized as a meaningful managerial practice (or indeed whether it is stable at all) in the middle of arduous scientific debates, legal statutes, and grounded, diverse realities.

Unlike lethal control (culling or ‘destroy on site’), relocation, or shelter-intake programs that remove animals from the environment, TNR is non-lethal and place-based: Sterilized cats are returned to their territories, contributing to population decline by attrition while maintaining territorial occupancy; consequently, effectiveness hinges on sustained caregiver networks, veterinary capacity, and municipal coordination over years, rather than one-off operations (Natoli et al., 2006; Robertson, 2008; Slater, 2002). Coupling biological intervention with civic infrastructures of care is what distinguishes TNR from most wildlife programs and underpins our framing of TNR as an assemblage. By comparison, many human–animal conflict programs pursue reintroduction or removal-focused strategies (e.g., carnivore translocations and culls, or island rodent eradications). Episodic non-lethal deterrents neither return animals to their original location nor rely on continuous lay caregiving (Eklund et al., 2017; Howald et al., 2007). Even where fertility control is used for wildlife (e.g., deer immunocontraception or pigeon nicarbazin bait), it is typically agency-run and time-limited, rather than community-embedded (Fagerstone et al., 2010; Massei & Cowan, 2014). The closest analogues are contraceptive attempts to reduce wild boar populations (Massei, 2023), a topic prominent in Europe after recent African Swine Fever outbreaks (Broz et al., 2021), and street-dog sterilize–vaccinate–return for rabies control, which similarly hinges on community participation but operates under a different moral economy and policy frame (public health rather than biodiversity and welfare) (Reece & Chawla, 2006).

Overarching reviews, field evaluations, and simulation models then compare cat population management programs like TNR with alternative management portfolios over multi-year horizons—showing that outcomes hinge on scope, intensity, duration, and local demography (Boone et al., 2019; Levy et al., 2003; Ramírez Riveros & González-Lagos, 2024; Spehar & Wolf, 2017). Yet when read through STS, this ostensibly bounded ‘technique’ in practice becomes infrastructure-in-use whose effects depend on continuous maintenance and care across many moments and many human/nonhuman actors—volunteer caretakers, veterinarians, municipal services, data and monitoring systems, and the cats themselves. This aligns with classic insights on infrastructure, repair, and care (technologies are kept going through iterative, distributed work) so the ‘managed’ object is perpetually deferred and re-assembled over time (Puig de la Bellacasa, 2017; Star, 1999).

Our contribution is to make this diachronic, multispecies labor visible, showing TNR as an assemblage made to cohere locally, sustained by ongoing care rather than a one-off intervention, and to explain why engagement and program design shape effectiveness across contexts. In other words, for holding itself as an object (Gan & Tsing, 2018), TNR depends on the sustained coordination of many actors (above all colony caregivers who commit daily over years) alongside pet owners, animal-welfare groups, and municipal services working to shared norms and procedures. Beyond academic tug-of-wars, TNR is made in grounded practice: largely female volunteer networks enact and translate the program through a chain of steps and obligatory passage points (trapping, surgery, ear-tipping, registration, feeding), each opening alternative pathways and possibilities of failure. Unlike most wildlife control schemes, TNR sprawls across lay labor and stray lives; it demands continuous affective care and logistical work, unfolding over long temporalities and predominantly urban spaces. Together, these practices allow us to recognize TNR not as a singular, stable object, but as an assemblage through diverse practices that appear differently depending on context. Each enactment coexists, demanding continuous negotiation among actors to maintain coherence. Each assemblage is shaped by human intention and policy, yet irreducible to mere human intervention due to its embeddedness in biological realities: cats’ behaviors, reproduction, and interactions. This framing guides the analysis that follows, in which we show, site by site, how the legal, clinical, epistemic and caregiving enactments of TNR are made partially compatible (or not) through specific translations and care-based orderings.

Methods and Structure

Fieldwork consisted of four months of ethnographic mapping conducted in Tenerife, Canary Islands (Spain) in 2023, and a subsequent round of follow-up ethnography, including targeted return visits, in-depth interviews, and ongoing WhatsApp/phone contact with key interlocutors until mid-2025. This methodological approach aligns with contemporary moves that empirically re-ground ANT through translations and controversies (Americo et al., 2025; Muecke, 2024) and with recent multispecies ethnographies that refine method and analytics beyond the human (Hohti & Tammi, 2024; Swanson et al., 2018; Van Dooren, 2019).

Fieldwork involved participant observation and qualitative interviews with actors engaged in TNR programs (animal welfare advocates, conservationists, city officials, veterinarians, community volunteers, affected residents, and cats themselves). In conjunction with fieldnotes and participant observation, quasi-casual and semi-structured interviews illustrate how each actor understands and/or navigates the meaning, purpose, or acceptability of TNR. Ethnographic methods allowed capturing how TNR plays out in various ways across socio-political and socio-technical conditions (e.g., legal statutes, animal welfare blueprints, expert conferences, veterinary clinics, municipal meetings, ecological study sites, a range of different cat colonies). The practice of generalized symmetry in analytical processes involved giving nonhuman and human actors the same importance when tracing actor-networks. Practically, this symmetry meant moving fluidly between human discourses (interviews, policy documents, scientific reports) and nonhuman materialities (veterinary instruments, cat bodies, multiple landscapes).

We observed human-cat interactions at colony sites, vet clinics, and urban and rural settings, including natural protected areas that have become flashpoints of intense controversy in the Canary Islands (Luzardo, Hansen, et al., 2025). Cats actively participate in making complex, fluid assemblages, and we noted how different feline behaviors, presences, and agencies acted on our human ones. Through walkabout methods (Strang, 2010), our ethnographic fieldwork not only documented human narratives, but captured feline movements and activities or resistances (e.g., avoidance of traps, colony dynamics, and territorial behaviors), actions that directly influence the outputs of TNR programs.

Our focus is primarily on a municipality in Tenerife. Home to approximately 24,000 human residents and comprising more than twenty villages, this municipality is cited by animal welfare advocates on the island as a paradigmatic case of TNR ‘by the book’. Several factors underscore the analytical relevance of this field site, including a well-organized animal welfare association, led by a highly committed president and supported by over 70 volunteers, mostly women, who act as cat colony caregivers as they are distributed across diverse settings, from the coast to mid-mountain areas, and from urban to rural zones. This enabled us to access to rich, situated data on the complexity, fluidity, and (in)stability of the implementation of TNR practices in action.

Assembling TNR as a Legal Object Under the New Animal Welfare Law

Across Europe few countries host as many free-roaming cats as Spain. Municipal surveys and NGO tallies converge on hundreds of thousands of free-roaming cats organized in several thousand colonies (European Commission, 2024; Fatjó, 2020). These figures rival Italy’s well-known Roman colonies and far exceed those reported for the UK or Germany, where colder weather, stricter abandonment laws and mandatory micro-chipping curb colony formation. Until the 2023 national Animal Welfare Law (AWL), Spain offered no uniform legal category for these animals: Some public institutions treated them as pests, others as de-facto community pets, but most had no ordinance at all. The resulting legal-administrative patchwork left vets unsure who could authorize surgery, volunteers vulnerable to neighbor complaints, and ecologists frustrated by the absence of enforceable population caps in biodiversity hotspots.

Conservation biologists argue that a permissive, nationwide right of cats to return to their original outdoor locations will normalize an invasive predator in island ecosystems already under siege; they lobby for location-based culling exemptions. Animal welfare coalitions reply that without the legal shield of compulsory TNR schemes for all cats (funded, monitored, and audited), Spain will simply continue to export unneutered cats to the outdoors via abandonment. In short, regulation is now on the books, yet its implementation has become the new terrain on which ecologists and animal welfare advocates, despite sharing, in theory, the common goal of a future with no cats in the outdoors, contest whose expertise should dictate how, where, and whether colonies may persist (Carrete et al., 2022; Luzardo, Hansen, et al., 2025).

In this context, Spain’s 2023 AWL tries to format TNR into a governable object. Sub-statutes and ordinances operationalize biological assumptions as administrative processes and compliance metrics, while invasion-biology tries to push cats back into the ‘wildlife/pest’ frame. This new, and still contested, regulatory landscape lands unevenly across Spanish territories. And nowhere is the tension more acute than in the Canary Islands. In this archipelago, cats have circulated for decades in rival networks, either as beloved companions for animal-rights groups or as invasive predators for conservation biologists (Pons-Raga, 2024). The Canaries inherit the same national legal mandate to run colony-based TNR, yet it layers that requirement onto a far more fragile socio-ecological stage.

As an acknowledged biodiversity hotspot with dozens of island-endemic birds, reptiles, and invertebrates, the Canaries face the triple pressure of globally significant endemic fauna, heavy year-round tourism, and a fine-grained archipelago of dispersed cat colonies sustained by seasonal visitors and local feeders. Under these conditions even a small number of free-roaming cats can spell disproportionate risk to red-listed taxa such as Gallotia giant lizards or breeding shearwaters (Flores Ravelo & Rando Reyes, 2021; Medina et al., 2011). In some ways similar to Hawaii in the US (Leong et al., 2025), this volcanic, subtropical laboratory offers, therefore, an ideal setting for tracing how TNR is (dis)assembled through frictional encounters among conservation biologists, veterinary science and law scholars, animal welfare campaigners, municipal officers, and the cats themselves. This section reveals the complex, fragile assemblage of social networks that were pulled together for the law to advance, showing that TNR needs to be framed as technically driven to become a legal object.

Article 3 of the AWL reads like a taxonomy lesson: thirty-plus bullet points that perform creatures into existence. First, it poses a fundamental question: What is a ‘companion animal’? The answer provides the legal shelter for those nonhuman beings to whom the statute applies. Besides the preliminary definition, according to which a companion animal, to be so, must be kept (i.e., fed and cared) by humans, the article explicitly highlights: ‘In any case, dogs, cats and ferrets, regardless of their intended purpose or the place where they live or where they come from, will be considered companion animals’ (Spanish Government, 2023, p. 12). In short, all individuals belonging to these three species (Canis familiaris, Felis catus, and Mustela furo), no matter the circumstances, are ‘companion animals’.

The article adds that ‘companion domestic animals will not be considered wild animals, even if they become feral’ (Spanish Government, 2023, p. 12). This nullifies the conservationist frame that seeks to treat free-roaming cats as feral animals and, consequently, as invasive fauna. The AWL frames them as ‘community cats’: unowned animals belonging to the species Felis catus, whose subsistence depends on anthropogenic sources of food, behavioral differences notwithstanding. For Callon (1984), such statutory practice constitutes the program, a moment of problematization that delineates an obligatory passage point through which municipalities, vets, and caretakers must now navigate. Through moments of translation, the network of multiple actors attempts to hold TNR itself together, whose success precisely depends on the enduring capacity to make it take shape as a stable, immutable object. Predictably, an anti-program emerges. Conservation biologists throughout Spain mobilize invasion-biology data, mortality counts and IUCN (International Union for Conservation of Nature) criteria to restore the ‘feral predator’ label the law has erased. Their journal articles, media news, and policy briefs act as interessement devices that attempt to forge alliances between different groups, and more concretely, to pry decision-makers away from the cat’s companion-animal frame. The statute draws the line, the ecologists redraw it, and the ontological status of the outdoor cat once again slips into contention (Figure 1).

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Figure 1.

Banner of a talk given by an ecology scholar on the negative impacts that free-roaming cats have in Teno’s natural protected area (Tenerife), organized by an environmental NGO. Source: Ferran Pons-Raga.

Following the same article from the AWL, TNR receives a concise, technocratic gloss: a ‘management method that includes trapping, neutering, and returning of community cats through harmless means for the animals’ (Spanish Government, 2023, p. 13). The statute casts TNR as a managerial, technically-driven neutral tool rather than a contested practice of enactment. Given TNR and community cat definitions, the article proceeds with a clarification of what is meant by ‘feline colony management’, while only one sub-clause speaks of veterinary technique, including neutering, vaccinating, microchipping, and removing parasites; the rest choreograph census forms, funding streams, and public-education campaigns. AWL therefore does not codify a veterinary technique as much as a legal-administrative toolkit.

A year later, a 2024 Technical Guideline attempted a second round of translation, transitioning from feline management plans to lived practice (Spanish Ministry of Social Rights, 2024). Regional administrations, municipal entities, colleges of veterinarians, and animal welfare associations were the stakeholders involved in the writing process. The Guideline is described as a ‘living document’, signaling that even lawmakers anticipated future slippage in the network they had just stabilized. In this technical stabilization, TNR appears to be the methodological conduit through which the necessary adaptive, integral management of feline colonies must proceed.

The Guideline’s nine-point checklist (from colony geolocation to adoption schemes) reveals that the legal object struggles with the changing nature of the assemblages it must address and attempt to regulate. As such, the checklist shows how the ‘community cat’ is enacted as a GIS coordinate, vaccination schedule, budget item, or foster candidate. High-intensity neutering (⩾ 80%) and a territory-wide scope operate as interessement devices, crafted to hook municipal coffers, vet associations, and volunteer time from animal welfare campaigners into a single calculus of ‘effectiveness’. These clauses reveal that even in its legal form, TNR is represented discursively as a shifting assemblage, always susceptible to the counter-translations of ecologists, vets, politicians, cat owners, animal welfare associations, and the cats themselves.

TNR’s Keyword: ME-THOD

Weeks after the AWL passed, Tenerife hosted the ‘Caring for the Caregiver’ conference. The second Feline Sessions held on this island gathered a large number of speakers from animal welfare associations from the archipelago and some legal and veterinary science experts. Among them, a veterinary scholar who had actively participated in the writing of the legal chapter devoted to the management of cats, showed a slide introducing TNR with an intriguing question to be solved by the audience: ‘Among all the words [Trap-Neuter-Return method] on this slide’, he asked, ‘what do you think is the most important one?’. The riddle was certainly revealing. Shifting the audience’s attention away from the three pillars of the management program, namely Trap-Neuter-Return, he highlighted that the actual keyword to introduce and capture the scope of this technique for the management of cat populations was ‘ME-THOD’, spelling it through a syllabic pronunciation.

Though the statement may have surprised the audience, long-time cat welfare advocates recurrently stress that TNR is a comprehensive, systematic approach that goes far beyond its three-word acronym; an all-in-one tool capable of sorting out not only animal welfare issues, but any kind of problem engendered by the presence of cats in the outdoors. The secretary of an animal welfare association put it bluntly: ‘All these problems, say animal welfare, neighborhood, or environmental issues, have only one solution, which is the TNR method.’ The attempt to fix TNR as a one-size-fits-all method can be read as an obligatory passage point fraught with scientific authority: an attempt to translate the messy multiplicity of practices (ear-tipping protocols, microchip registries, legal clauses, feline bodies, neighborhood politics) into a single technical object. This involves the demand for coherence in the face of inevitable slippage. Preliminary field notes insisted on this point: ‘It is not about neutering, or trapping. Neither of returning’, the vet scholar underscored. ‘It is a method because it is meant to be so, and this is what I like about it, because it is more than this [acronym], much more than this’, he emphasized.

The scholar was not alone on this perspective. A president of an animal welfare association based in southern Tenerife also described TNR along similar lines: ‘The TNR method. Trap-Neuter-Return is what we all know, the acronym. Easy, isn’t it? But the TNR project is much more than this.’ Soon after, she reminded the audience that: ‘Those of us who work with feline colonies must know … who we’re dealing with. We must analyze the [cat] caregiver to develop a good rapport with them; because without them, there’s no TNR project.’ Her insistence is not merely anecdotal: Without enrolling and mobilizing this distributed feminized volunteer infrastructure, TNR quickly unravels, showing that it is highly embedded in complex, even fluid, social networks filled with deep human-animal emotional attachments. It only holds together through the co-production of ‘method’. By foregrounding method, it shifts attention from moral yes/no questions (‘kill or care?’) to managerial ones (‘Who will pay?’ ‘Which protocol will be followed?’ ‘Which partners will be involved?’). This shift enlists particular allies, including municipal officers, veterinary suppliers, or grant-writing NGOs. It marginalizes others, notably the conservationist sector (ecology scholars and environmental NGOs) and some residents. These are mostly farmers and hunters, who contest the very premise of outdoor-cat category as companion animals and the ensuing caring obligations, and the premises of participatory processes in rural areas.

Despite this complex network of social entanglements and the highly emotional bearings in human-cat interactions, TNR is usually framed within the semantic field of ‘methodical management’, underpinned by scientific authority and thus ‘rendering technical’ previously complex, value-laden problems (Li, 2007). This terminological closure already signals the work required to hold TNR together. ‘Science are facts and objectivity’, asserted the veterinarian scholar at the Feline Sessions, ‘and there is a true fact: If you control the arrival of cats and neuter those in a colony, population numbers dwindle.’ However, he also warned the audience on how controlling outdoor cat populations may be an endless endeavor, highly conditioned by high rates of reproduction and abandonment. In sum, TNR method’s success was framed under the following moments of translation that must be enacted and re‑enacted if TNR is to endure: (a) fostering coordination and collaboration, (b) developing canons and budgets, (c) establishing methods and protocols, (d) keeping high neutering rates, and (e) constant monitoring. Each element marks a hinge point where the assemblage may tighten or loosen. High abandonment and reproductive rates (Natoli et al., 2006; Nutter et al., 2004), for instance, threaten to unravel the network faster than traps and scalpels can re‑knot it.

TNR never sits neatly inside the tidy triangle of method/management/science. Its day-to-day infrastructure is braided with emotion, care, and the situated know-how of civil society: animal-welfare groups and mostly female volunteers who keep colonies fed and records updated. Method is not what precedes practice; it is what the assemblage intermittently achieves. Rather than treat ‘method’ and ‘care’ as opposing logics, we show how the former functions as a contemporary politics of the latter: a way of standardizing, auditing, and funding care by translating affective obligations into protocols, metrics, and accountable roles (Puig de la Bellacasa, 2015). In this sense, management is not external to care; it is one of the infrastructures through which care is authorized, redistributed, and sometimes constrained, while care is an essential part of managing cats (Martin et al., 2015). Framing TNR as a universally applicable ‘method’ therefore may be counterintuitive: It requires transforming dispersed, affect-driven initiatives into a single, top-down campaign, a translation that inevitably glosses over the field’s messy, bottom-up realities.

Following this cue, TNR appears less as a method in progress toward stability than as a method that needs to take the improvisations of care as an intrinsic part of it. That is, a fluid assemblage, always becoming, always translating between municipal ordinances, colony head-counts, surgical routines, empathic human–cat bonds, and the cats’ own acts of refusal. Its vitality lies precisely in that restless traffic, not in any final state of order.

Heart-led, Mind-driven: Translating Caregivers into ‘Feline-colony Managers’

The second day of the Feline Sessions hosted Sara (a pseudonym), the president of a local animal welfare association based in northern Tenerife. Her talk closed with a slide that read ‘Heart-led, mind-driven’. The slogan distilled the core tension this paper tracks: TNR must feel humane and look managerial; the method must be both effective and affective, rationally planned and emotionally sensitive. In practice, care and management are co-constitutive: care is repeatedly reformatted into managerial forms to become legible and fundable, while managerial pipelines repeatedly integrate and revert to care when protocols fail and must be repaired in situ (Viseu, 2015). The talk’s title about the trajectory of her association was also telling: ‘From ZERO to TNR’. In Spanish, the original title played with the words ‘zero’ [cero] and the TNR acronym, which translates into CER, ‘Del CERO al CER’, as a way to convey the transition undergone in that municipality, from nulled collaboration, and even overt disputes with the public administration, to a close collaboration between the animal welfare association and the town council since 2022. What in her PowerPoint presentation looked like a linear ‘roll-out’ is, on the ground, a mode of ordering held together by incessant acts of translation, including: (a) a shifting census of 70-plus colonies, (b) the choreography of 60 caregivers who negotiate trap times, feeding slots, and kitten adoptions via WhatsApp, (c) budget lines that must jump from municipal spreadsheets into discounted surgery fees, (d) agreements with the municipal council and vet clinics, subjected to budget limitations and vet’s technical expertise, and (e) the cats themselves, whose refusals (slipping traps, birthing between spaying rounds) undo every tidy flow-chart.

Going walkabout with Sara, a veterinary assistant deeply committed to the implementation of TNR in her municipality, revealed to what extent TNR as a method must embrace the hassle. Every time she shifted from a council meeting to an emergency call (e.g., car accidents or abandonments), TNR’s status flickered: one moment enacted as a public-policy deliverable or fund-seeking, the next a human-cat care practice over a set of bodies. Each realignment re-does the object as an emergent assemblage: TNR endures because it can slide (heart one moment, mind the next) without ever fully settling.

In autumn 2021, Sara’s local animal welfare organization and the municipality reached an agreement to implement a ‘Neutering Plan of Feline Colonies’, funded with €35,000. Importantly, the president of the association added a critical amendment to the plan’s title: ‘through the TNR method’. That four-word add-on did heavy ontological work: it made a work of inscription, plugging the local plan into a transnational repertoire of ‘best practice’, borrowing authority from policy guides and academic papers.

Initial steps in this new municipal-civil partnership were modest but enacted the paperwork materially. The municipality purchased trap cages, which were made available for association members at a local pet store, and acquired glass containers to be recycled by the animal welfare association into graffiti-art feline shelters, aiming to provide some colonies with institutional visibility. It also awarded a direct contract to a veterinary clinic to begin neutering outdoor cats. Lingering mistrust among caregivers (still wary of collaborating with public authorities after past negative experiences involving the ‘disappearance’ of 27 cats from a local colony) posed a challenge. This barrier was addressed through the creation of a new juridical subject: the ‘feline-colony manager’. Licenses for these managers were jointly stamped by both the animal welfare association and the town council. The plastic cards served as a kind of institutional shield, granting caregivers legal recognition when feeding cats and offering protection from possible confrontations with neighbors, environmental NGOs, or other governmental actors (Figure 2).

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Figure 2.

A recycled glass container for a feline colony in northern Tenerife. Source: Ferran Pons-Raga.

‘It’s one thing to be a manager, and another to be a caregiver. They are two different things’, Sara said. Caregivers have become managers: their affective, day-to-day labor is newly formalized as a node in an assemblage. Whereas caregivers ‘only’ feed and watch over cats, managers are charged with the full cycle of colony work: feeding, health monitoring, sterilization logistics, and the coordination of paperwork and data flows. Licensing makes this shift explicit: association members complete a TNR course that defines legitimate participation and issues a plastic credential. The card acts as an interessement device: it stabilizes who may trap, deliver cats to clinics, access discounts, and enter data, so routines proceed without constant renegotiation. Two inscription tools anchor this managerial process: a) TNR Record Cards; and b) TNR Colony Registers. The former joins veterinary and street data, and serves as comprehensive individual files for each cat, completed during veterinary visits for sterilization; the latter consists of a cumulative, evolving document that draws on the record cards to track changes within each colony. It forms the basis for the municipality’s outdoor cat census.

As Sara noted, keeping this mechanism of inscription updated is a constant source of tension:

When I have to make the census … I first ask them [the colony managers], because there may have been variations that I am not aware of … I need them to write everything down. That’s a constant argument I have with them. Now, for example, four cats have died in a colony in one week. I’m sure that, if I ask her today what day the cats died, she can’t tell me, because she hasn’t entered it in the registry.

The paperwork may appear mundane but is infrastructural: It enacts the colony as dynamic yet partially coherent. A handwritten notebook, folders stuffed with documents, and classified sheets at the president’s home constitute the administrative backbone of the TNR program. For the animal welfare association, these elements are the material semiotics that make it possible to answer fundamental questions: What are we doing, and when and how are we doing it? Crucially, these local inscriptions propagate along a chain of technical arrangements. Since 2025, each census card is paired on the spot (a vet operating table) with a microchip connected to Zoocan, the regional registry software run by the Canary Islands Veterinary College, which syncs with the municipal records. Recent STS work recasts ledgers, chipping and cloud dashboards as ‘animal infrastructures’ that materialize ethics in data flows (Greenhough & Roe, 2019). Our Zoocan microchip tightens the network that keeps TNR workable, turning care legible across animal welfare associations, clinics, councils, and cat colonies.

Caregivers enact TNR as relational labor by collecting and archiving these traces, which is not busywork; it is the condition of political survival. Only by feeding the municipality a credible, evolving dataset can the association keep public money flowing and fend off conservationist scrutiny. In that sense the paperwork stages a fragile alignment between welfare and ecology: fewer intact cats outdoors, fewer bureaucratic reasons to dismantle the program. Yet the alignment is always conditional: One lost register or one failed trap, a ‘maverick’ cat, or an unattended emergency. Rather than replacing care with management, TNR managerializes care: affective attachments are reformatted into appointment slots, registries, and accountabilities, while those very managerial devices require the integration of continuous care work to stay operational (Martin et al., 2015). Through day-to-day enrolment, traps, clinic timetables and WhatsApp rosters interlock those roles, allowing disparate tasks to cohere, if only provisionally.

Flexible Ordering: From Paperwork to Pavement

Technical guidelines prescribe high-intensity sterilization within a single colony before moving on to effectively reduce free-roaming cat populations. Yet, as Sara noted, this blueprint rarely holds up in practice:

I thought, following the TNR Project, I would start with one area and finish it. [But] it doesn’t work like this. It can’t be done this way. You can’t say, ‘Well, I’m gonna work hard for a month on this area.’

On the ground, the pipeline leaks. What looks bounded on paper is, in practice, a mesh of bodies, places, and timings that resists sequential ordering. As Sara put it:

Cats learn how the trap works. I’m telling you. A cat that sees the others getting caught will go in, eat the food, and come out … without touching the lever. [I swear] the trap is long, and to get the food, you have to step on it. … Well, they find a way. They lift their legs—one like this, another like that. They learn, they learn. By repetition. They watch it over and over again. … That’s why there are unneutered cats left behind.

Here the cat emerges not simply as part of a ‘messy reality’ that frustrates technical ordering, but as a recalcitrant actant that subverts the trap’s script, turning the program of capture into an anti-program and forcing the apparatus to be recalibrated in practice. This was evident in 11 of the more than 40 registered feline colonies in this municipality as of 2022. In these colonies, although over 90% of cats had gone through the TNR process, the cycle remained incomplete, i.e., one or more steps in the TNR loop process did not manage to close, due to failures in trappings, new arrivals, or unneutered individuals, so reproduction persisted. This insight has major implications for organizing trapping activities among more than 70 volunteers, while also coordinating weekly appointments at various veterinary clinics in the municipality. The logistical repercussions directly impact the WhatsApp scheduling economy described below.

In high-coverage colonies, remaining unneutered cats often avoid traps altogether. Waiting for them can become inefficient (not only in terms of time but also in the use of limited public funds) especially when many other cats elsewhere still require sterilization. Consequently, the blueprint gives way to flexible ordering: Resources are redeployed, zones reset, and calendars revised to keep momentum without stalling on a few holdouts. Sara’s reflections capture this evolving, and often fragile, configuration of TNR:

What did I do? Well, alternate. I scheduled two colonies a week. I had to organize it. One day one, one day the other. What happened next? Well, people [colony caregivers] didn’t have time, people couldn’t [do it]. Okay. Let’s then divide the appointments among the colonies we’ve already started. I’m getting more and more lax, right? Next: Okay, colonies we’ve already started have priority—or the ones with pregnant cats … And now, what do I do? Honestly. Who wants to make appointments, for God’s sake?! Doesn’t anyone have cats to neuter? The other day I got pissed off.

Her escalating improvisation (first alternating colonies, then prioritizing pregnant cats, finally begging for any cat at all) shows how coherence is maintained by continual reconfiguration across feline ethology, devices, and coordination: precisely the adaptive pattern highlighted in multispecies assemblage research (Gan & Tsing, 2018; Lacan et al., 2022). Every week, the association pre-books a limited number of vet appointments at various clinics in the municipality. These appointments function as a local obligatory passage point to be filled with cats transported in covered carriers. To coordinate this process, the president sends a WhatsApp message—typically on Saturdays—announcing the week’s available clinic slots. Crucially, the message also includes a list of individuals known as the ‘reserve team’ or ‘volunteer squad’ [retenes]: experienced volunteers who can reliably trap cats and take them to appointments on short notice. The volunteer squad functions as a redundancy layer, that is, an infrastructural fix that absorbs the program’s chronic indeterminacy.

Once the message is sent out, caregivers ‘raise their hands’ in the chat to request specific appointment slots. Sara allocates based on availability and priority. But interessement never guarantees capture: traps fail, cats disappear, weather shifts. As she notes:

If the person who’s supposed to trap the cat can’t catch it, one from the volunteer squad says, ‘I’ve already got the cat in the carrier.’ And she takes it, so we don’t miss the vet appointment.

She then emphasized the unpredictability of the process: ‘There is no certainty. This is why we have the volunteer squad. Many colonies have been completed this way—without needing to secure a vet appointment in advance.’

In short, the weekly WhatsApp coordination of TNR through clinic appointments reveals a fluid system that resists rigid scheduling. Instead of adhering to a strict prioritization logic, the program functions as a dynamic mesh of human volunteers, digital communication tools, and feline behavior. Orderly planning gives way to situated improvisation and the distributed agency of phones, volunteers, and trap-savvy cats. TNR survives on the ground not by following guidelines or blueprints, but by folding, stretching and re-routing itself each week. This elasticity is continually triggered by the main reason for the ‘cat problem’, in the Canary Islands and elsewhere (Leong et al., 2025): abandonment. That is where that weekly improvisation begins.

Sara receives a phone call: six kittens have been abandoned in a pet carrier at a petanque pitch. What follows is a relay through obligatory passage points that will classify each kitten as household companion, long-term foster, or a new member on the association’s inventory of community cats. The young couple who found them express interest in adopting one, but before any decision is made, the kittens must be transported to a veterinary clinic for weighing, sexing, and de-worming. At the clinic, the president meets with the association’s secretary. Here the president’s pragmatism (‘let’s place them quickly’) meets the secretary’s protocol-adherence; an internal tension between flexibility and standardization that recurs across the assemblage. Either way, adoptions are rarely straightforward. Two years later, half of the six kittens were adopted by cat colony caregivers from the same municipality; the rest remained at the local animal welfare secretary’s flat, adding to the number in ‘provisional’ foster homes.

Each kitten must traverse at least two passage points (clinic, then foster) before adoption becomes an option. Foster homes are ordinary households where persons temporarily care for one or more cats awaiting adoption. These homes host three types of cats: unweaned kittens, the sick or injured, and healthy adults. Nominally transitional (and scarce), these homes often congeal into shadow shelters, in a classical ontological leakage (Mol & Law, 2004) from temporal care to informal refuge. Would-be adopters are required to meet several criteria. They begin by completing a questionnaire, followed by a phone interview with a representative from the association. If deemed suitable (cats are required to be kept indoors) a meeting is arranged to formalize the adoption. Each step is a filter that re-classifies the human as ‘suitable’ or ‘inadmissible’. Inadmissible adopters fill up a ‘black list’ shared by several cat welfare associations from the Canary Islands via another, much larger WhatsApp group.

The adoption contract obliges neutering, microchipping, vaccinating, and testing for parasites at four months of age. To support compliance, the association offers a 50% discount on veterinary services (resulting in a cost of €130 for females and €110 for males) through arrangements with select clinics. Paperwork here is more than bureaucracy; it is the flexible ordering that stitches private households into the public care assemblage. Parallel to these formal pathways, volunteers acknowledge the existence of a small but steady black market: informal Facebook and online site swaps, roadside sales, male/female exchanges among local peasants, and even tourist-to-tourist hand-offs, through which kittens circulate without paperwork, microchips, or welfare checks. The black market evades all safeguards animal groups try to build. Precisely to distance itself from that shadow trade, the association layers multiple gates of scrutiny.

The Surgical Object: In the Operating Room of a Vet Clinic

Vet clinics enact TNR as patient work and inscription. Surgical protocols, anesthesia, ear-tipping, microchips, and post-op care translate biological states (sex, age, pregnancy, disease) into durable records that circulate to associations and municipalities. In this veterinary room, individual bodies and devices co-produce ecological population trajectories: who returns, who is adoptable, who is removed.

It’s 10:30 a.m. A client arrives with a covered carrier. At the counter, Sara works as a veterinarian assistant in the clinic with two vets. Down the corridor, the operating light flicks on: a queen stretches on the table, paws Velcro-strapped, while she hands instruments to the surgeon. Here, methodical procedures are translated by scalpels, suture, and ear-tip: inscription devices that turn policy into flesh.

The vet starts the incision to remove the cat’s ovaries. The cut is minimal. The vet is well-known by cat welfare associations from the region for her expertise in making diligent and safe neutering surgeries to female cats, an operation that may entail post-surgical health issues. Caring influences the choice of expertise and the way the scalpel is used. If incisions go wrong and animals suffer, volunteers will balk, clinics lose trust, and TNR’s enrolments stall. As she proceeds with the removal of the gonads, she explains that cats have six ties, two for each ovary and two more that connect to the uterus. Once she has cut them all and before sewing up the scar, the vet checks with a cotton ball to make sure there’s no blood inside due to any of the ties coming loose.

The first surgery takes less than fifteen minutes. Next on the trolley is a colony cat, cage not carrier—material shorthand for a different regime. ‘Is it ours?’ the vet asks, adding: ‘Just to know if we need to cut the little ear.’ The possessive pronoun indexes a boundary shift from client medicine to colony management, distinguishing our cats, brought to the clinic by individual customers, from their cats, brought by colony managers belonging to an animal welfare association. A quick ear-tip will enroll only this body into the TNR census; an inscription that will travel to personal notebooks written by the president of the animal welfare association, colony caregivers’ and municipal spreadsheets, online apps, and grant reports. Owned and colony cats occupy the same table yet enact different ontologies. For the former, the clinic is a site of personalized care; for the latter, it is a waypoint in a population-level assemblage aimed at controlling the number of outdoor cats. On average, roughly half of weekly surgeries are colony cats, around seven spaying surgeries a week, illustrating how the clinic toggles between modes of veterinary practice.

As the assistant preps the abdomen she whispers, ‘Street and home cats, see the difference? Poor cat, look how she is.’ TNR, a method associated with control, order, management, and planning, clashes head on with her next statement: ‘She [the cat] comes from a colony out of control. The “Furry Colony” has just been started [by the animal welfare association], with kittens everywhere.’ This was just one of the 74 colonies in the municipality in 2023, including 675 cats, 250 of them unneutered. According to the colony’s caregiver, the same cat gave birth about three months ago, while the vet estimates that this cat ‘has given birth a ton of times’, observing teats and ovaries. Reproductive history is thus folded into the surgical present.

A cat may enter her first heat as early as four months and will cycle every two to three weeks for most of her 4- to 5-year outdoor life. Miss the six-week neuter window and each intact female can produce up to a dozen litters, with a handful of kittens each, before fertility tapers after about eight years. Quick, high-intensity and colony-wide sterilization is thus necessary. Strict timing compresses trapping, surgery slots, and volunteer labor into a brief burst, while monitoring by selfless volunteers must then stretch across multiple reproductive seasons.

The enduring presence of TNR as an object depends on this particular twofold relation to time. It must be implemented intensely and quickly within a compressed time, but it also requires, according to an internal document produced by Sara’s animal welfare association, the enduring caring of the colonies over time, the supervision of the appearance of new individuals (due to abandonments), and the monitoring of colony members’ welfare. TNR endures by coupling compressed intervention with extended maintenance. It requires the complex array of networks of relations to coalesce and hold together at a particular moment in time (synchronically), but also over a long period (diachronically) to remain stable. ‘For its effectiveness’, as asserted by a vet expert, ‘TNR needs to be done expansively and intensively.’ She added: ‘Not 80% of colony cats, but 100% of them must be spayed in a short period of time.’ And yet, cats act not only by learning traps but by re-timing the program: estrus, pregnancy, territorial movements, and visibility/invisibility force re-prioritization and re-scheduling, making the ‘pace of care’ a multispecies challenge (Puig de la Bellacasa, 2015).

Alien to these overall requirements, the vet proceeds with her surgical procedures. A distended bladder is drained; a cystic ovary is pulled; ear cartilage is clipped. Stray bodies slow the timetable: The tasks and time devoted to the cat from the colony are greater than those spent with a ‘domestic, queen cat’. This grey tabby is thin, toothless, maybe seven years old (‘kind of ugly’, the vet jokes). The operating room is therefore a key obligatory passage point where TNR’s epistemic ambitions meet the contingencies of scars, veterinary techniques, clinic economics, public administration requirements, and animal welfare associations’ budget.

Contingent Cats, Improvised Care: Doing TNR in a Fishing Village

Cats are not passive recipients of a technique. They are nonhuman actors whose refusals, pregnancies, and rooftops sidetrack every line in the municipal Neutering Plan. In 2023, a small fishing village hosted two colonies with 29 outdoor cats, yet a single untrapped queen and one silenced tomcat were enough to unravel the fiction of linear, colony-by-colony progress.

In early 2022, this village became the focus of neighbor complaints concerning the ongoing birth of kittens. Over three months, Sara personally led the trapping, neutering, and return of cats, aided by neighbors and feeders. The initial verdict was one of success. Three years on, that assessment has grown more cautious.

One initial episode reveals how contingency rather than plan often inaugurates TNR. A resident from the fishing village retrieved two kittens (male/female) from a rooftop near her home. She chose to bring only the female to the local veterinary clinic, explaining: ‘I don’t want to be overrun with cats’, a phrase she repeated several times, conveying a fairly widespread feeling among lay people: Spaying cats for individual, pragmatic interests rather than collective, animal welfare concerns. At the clinic, the vet assistant asked whether the cat was hers and lived indoors. ‘It’s mine, but it’s a street cat; I’m feeding her, but I don’t want to bring it into the house … and I don’t want to end up filled with them [cats].’ The assistant responded pragmatically: ‘If it’s a street cat, I can give you the number the town council provided—you can call the association and they’ll cover the cost [of neutering].’

A semi-owned female neutered for free thus became the point for TNR’s entry: no posters, no council briefing: TNR began as contingency, not coordination. Most residents remained unaware of TNR’s meaning or aims, they just saw cheaper neutering. Feeding centered near the pier, sustained by a handful of residents. One middle-aged female resident played a key role in mapping the local feline geography for the association. By July 2023, Sara reported that all cats, save one, had been neutered. ‘For sure’, she asserted, ‘I did it with my own hands … even owned cats with outdoor access.’ She recounted:

That was three months of hard work. … I’d go down three, four times a week to trap the cats. With my cages—I’d take them to my house, then to the vet the next morning, pick them up in the afternoon, and return them to the colony. I’d start again. And if I didn’t get the owned cats, I’d have to start all over.

In an inscription of labor as identity fusing persona and species, she was locally dubbed the ‘cat woman’. Her labor was intense and mostly admired, but far from frictionless. Beyond the sheer time spent, she faced a variety of challenges; some explicit, others silenced, some human, others feline. Most residents welcomed the intervention. Yet, this did not imply ideological alignment with TNR’s humane ethics or its goal of stabilizing and gradually reducing stray cat populations. In fact, many residents were unfamiliar with the acronym itself. A pair of ethnographic snippets illustrate this point. A neighbor from the same village thought that our research on TNR was about feline colognes, not colonies when he heard of our study—in Spanish, ‘colonia’ means both ‘colony’ and ‘cologne’. Similarly, graffiti painted on some walls in an adjacent village with the message ‘Feline TNR, NOW!’ needed the addition of the drawing of a cat some days after, once the author was told that the original message was received with bewilderment by the passing-by rural neighbors (Figure 3).

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Figure 3.

Graffiti demanding immediate implementation of feline TNR (‘CER FELINO YA!’), accompanied by a later-added silhouette of a cat, highlighting local advocacy and tensions around outdoor cat management in northern Tenerife. Source: Pablo Alonso González.

Lay people in Tenerife, from this village and adjacent rural or periurban areas, don’t usually adopt the population management mindset advocated by ecology scholars and pursued by TNR. Their attachment to cats may differ from individual to individual, regardless of whether they are owned, semi-owned or unowned cats. Their support was more pragmatic: fewer kittens on doorsteps at no personal cost. What the policy calls a technique appeared on the ground as an assemblage, a choreography of partial allies and tactical silences, feline evasions, nocturnal trapping, improvised subsidies. This case evidences the gap between the managerial fantasy of bounded colonies and the fluid, human-cat emergent practices that enact TNR on the ground.

Trap and Return as Contested Translations: Unwanted, Hidden, and ‘Smart’ Cats

Most cats in the fishing village are not indoor animals. They are familiar with human proximity but wary of touch. This behavior matters, because the ‘R’ in TNR hinges on returning each body to its exact micro-territory; a place ontology that Sara followed to the letter. Because cats tend to re-enact their feral behavior the moment the sedative fades, the process must be executed swiftly. But return is a contested translation: The place where a cat is fed is not always the place it is welcome.

One day, as she returned a cat to a rooftop, a neighbor shouted: ‘You lied to me! You said you were taking the cats, and here they are. Take them to your backyard!’

Her initial reply upheld TNR’s logic: ‘Yes, ma’am. I took them to be sterilized. But I have to return them. How could I possibly take them home?’ However, faced with the threat of poisoning Sara broke the very methodical protocol she defended: Four cats joined the thirteen already in her flat. Here affective responsibility overrode managerial purity (‘heart-led’ eclipsing ‘mind-driven’) and her home momentarily morphed into an informal shelter.

Thus, TNR depends not only on methodical trapping but also on local cooperation and feline compliance. These two conditions are not easily and not always guaranteed. A revealing case involves a female ‘smart’ cat who learned how to evade regular traps and the neighbor who had initially contacted the association to sterilize her female semi-owned cat, but never mentioned the male sibling, who remained unneutered. ‘I had no idea about this [tom] cat’, Sara later recognized. This oversight contradicted her earlier confidence: ‘There’s just one unneutered cat left, a tricolor female. The rest? Not should be—they are [all neutered]. I did it myself, even going door-to-door.’

Together, the unspoken male and the trap-savvy queen formed a counter-assemblage that unraveled the president’s confident claim: ‘All but one are fixed.’ The female, aware of the trapping process, repeatedly avoided capture:

She sees me. I set the trap; she watches. I go downstairs to wait, but when I come back, either some other spayed cat is inside, or the food’s gone. I tried putting extra food in to buy time. Nothing worked. She’s super smart.

Two years later, the tricolor cat gave birth twice, two litters of three kittens each. The first three still wandered around the village, unneutered; the little three still remained at a neighbor’s flat where they had been born, awaiting use as bait by the association’s president trapping the ‘savvy queen’.

These scenes show trap and return as a chain of obligatory passage points that can be unmade by neighbors, rooftops, and cats. Cats do not merely ‘resist’ technique; by re-timing capture and reproduction, they actively reorganize the pacing, triage, and accountability structures through which care is turned into method. The ‘R’ of Return is not a mechanical step but a negotiated translation across property lines, moral claims, and feline territorialities. Success cannot be measured in ‘effective’ sterilization rates alone. It must be assessed in light of the fragility of an assemblage that requires constant care, paperwork, and improvisation to hold together.

Conclusion

This article has argued that TNR is far more than a straightforward population-management method or technique; it is a dynamic assemblage continuously reassembled through everyday practices, relational negotiations, and constant improvisation. Far from a portable, invariant technical fix applied identically worldwide, TNR is reassembled through situated adaptations and local translations that make ‘the same’ method workable in different places. Rather than asking whether TNR ‘works’ or assessing its ‘effectiveness’, we have tracked how different actor-networks (veterinarians, ecologists, volunteers, laws, cats, and technologies) enact and re-enact its identity in shifting ways.

In Spain, where TNR is now legally mandated, its durability depends on the momentary cooperation of a wide array of human and nonhuman actors: ear-tipped cats, WhatsApp groups, rooftop feeders, vet clinics, and municipal spreadsheets. The fragility of this arrangement becomes evident when even one thread breaks—when cages stay empty, neighbors object, or unneutered cats reappear. TNR re-emerges as a shifting composite of veterinary instruments, municipal documents, volunteer labor, affective care commitments, feline resistance, and political frictions.

This fluidity calls for a shift in focus: from implementation to translation. On the ground, cats are alternately enacted as pests, predators, legal actors, companions, or patients, depending on the lens applied. These categories are made and unmade through situated, often competing practices of knowing and doing. Local feeders are recoded as colony managers; vet data becomes municipal infrastructure through software platforms like Zoocan. These translations stabilize the assemblage, turning cats and caregivers into spokespersons at policy meetings. Yet gaps persist. Trap-savvy cats, rooftop disputes, and public resistance reopen the assemblage, demanding ongoing adaptation. The strength of TNR lies less in resolving these tensions than in surviving through them.

Accordingly, the relevant question is not ‘Does TNR work?’ but ‘What work does TNR do?’ Based on ethnographic evidence, we have shifted the analytic frame from the heated welfare vs. biodiversity scientific controversies, and emphasized, instead, how TNR enacts multiple, often conflicting forms, depending on context: It is simultaneously ethical imperative, bureaucratic procedure, scientific intervention, and feline counter-strategy. TNR’s strength lies precisely in its flexible instability, which allows it to continuously adapt, yet also makes it inherently fragile. It survives not by imposing a rigid managerial order but by creatively negotiating the unpredictable entanglements of human and nonhuman actors. Out of this conundrum, one of TNR’s most tangible outputs may be informational. Through ear-tipping, vet records, and municipal forms, TNR has generated the first longitudinal dataset on urban-island cat ecologies in the Canaries. This infrastructure supports early-age neuter campaigns, offers legal cover for caregivers, gives policymakers baselines long missing, and equips biologists to model risk. Even when labeled ‘ineffective’, TNR builds capacity for multispecies governance.

The future of TNR hinges on reweaving its loosest threads into durable, mutually recognized obligations. Incentives for early-age neutering, integration of lay feeding into cat population control strategies, and legal frameworks for shifting protocols in biodiversity-sensitive zones are all essential. These measures must be translated into daily practices by caregivers, vets, councilors, and cats alike. Without this, legal instruments risk remaining only on paper.

This case sharpens a familiar STS point in a specific way: method and care are co-constitutive, not competing logics. The persistent contrast between care and method voiced by actors (‘heart-led, mind-driven’) should be read as an oscillation internal to TNR’s assemblage: Care becomes method when it is made portable and auditable as roles (manager), inscriptions (registries), and schedules (clinic slots), while method becomes care when standardized pipelines fail and must be repaired through situated attention to cats’ rhythms, volunteer capacities, and neighborhood relations (Martin et al., 2015; Puig de la Bellacasa, 2015). Put differently, management is one way care is organized at scale, and care is the condition of possibility for management’s claims to effectiveness. What appears as managerial rationalization from the municipality is often experienced as a demand to reformat care, and what appears as ‘mere care’ from outside is, in practice, a distributed system of accountability, pacing, and volunteer work. This co-constitution is why TNR’s stability is always provisional, and why it holds together only by making room for multiple goods (welfare, biodiversity, neighborly order, fiscal responsibility) that cannot be collapsed into a single metric of ‘effectiveness’. TNR depends on situated, plural ways of ‘being with’ cats that must be continually negotiated rather than finally resolved (Van Dooren, 2019).

Empirically, we show that the ‘mundane’ tasks such as paperwork, WhatsApp scheduling or trap-setting are the hinges where living processes are translated into the infrastructures that hold TNR together. For this reason, the ‘effectiveness’ favored in ecology and veterinary assessments (changes in outdoor cat numbers) cannot be attributed to a technique in isolation. It is an emergent property that involves caregiver recruitment and retention, clinic throughput and reliability, registry completeness and interoperability, time-to-surgery for queens in heat, trap availability and placement, neighborhood cooperation, and cats’ own responses. Our added point is that ‘method’ is itself an assemblage effect: it is intermittently achieved when care is rendered as accountable coordination, and undone when cats and contingencies force repair back into situated care.