The animal welfare, environmental impact, pest control functions, and disease effects of free‐ranging cats can be generalized and all are grounds for humanely reducing their numbers

Although the domestic cat Felis catus is implicated in multiple faunal extinctions and threatens many extant species, there is widespread, well‐funded advocacy for desexing unowned cats near human habitation and returning them to site to be fed by volunteers, arguing that this prevents euthanasia, is unlikely to be hazardous to wildlife or a public health risk, and controls non‐native rodents. To the contrary, we present unequivocal evidence that this approach harms cat welfare, does threaten wildlife and public health, and exacerbates rather than controls rodent problems. We argue instead that unowned cats near human habitation can be controlled effectively by intensive adoption and responsible euthanasia when necessary, supported by licensing and containment of adopted/owned cats.

Readers of the Perspectives by Carrete et al. (2022), who oppose managing stray cats Felis catus by Trap-Neuter-Return (TNR) in Spain, and by Badenes-Pérez (2022), who supports Spanish legislation to protect stray cat clowders and require TNR, know that their respective views are held strongly and claimed to be evidence-based.Here, we contribute to the arguments centering on putative effects of free-ranging cats on biodiversity through predation (especially given cats' catholic diet) as well as highlighting disease spread, and management of pest rodents.Significant omissions we cover are cat welfare, public health and the importance of delineating the ownership categories of freeranging cats (Box 1).We conclude with generalizations regarding the environmental impacts of free-ranging cats and management suggestions.
Free-ranging, unowned cats around human habitation encounter similar risks as free-ranging pets, but with less human intervention if injured, or prophylaxis, such as vaccination or deworming.Many ailments, including comorbidities, are detected where unowned, free-ranging cats are trapped and health checked (Calver et al., 2022), yet health checks are declining among practitioners (Aeluro et al., 2021).Furthermore, necropsies on culled, unowned cats reveal high parasite infestation and ingestion of hazardous refuse (Crawford et al., 2020).
Research varies as to whether TNR programs improve cat health, because vaccination and food provisioning vary.Some reports claim TNR cats are healthy using visual assessments (Gilhofer et al., 2019;Zito et al., 2019), fight less relative to intact cats (Finkler & Terkel, 2010;Gilhofer et al., 2019), live longer (Kreisler et al., 2019), are less active (Cafazzo et al., 2019) or have less infectious disease (Kreisler et al., 2019).Notably, the ORCAT program (Kreisler et al., 2019) ran over two decades, was managed by paid staff, regularly re-trapped individuals and updated their prophylaxes, and was restricted to a gated community valuing and funding the program extensively.In contrast, reports of poor health outcomes for other TNR projects include skin infections, weight loss, fight scars and blindness, alopecia, dental problems, anemia, diabetes, and FIV (Castro-Prieto & Andrade-Núñez, 2018;Seo et al., 2022Seo et al., , 2023)).Furthermore, TNR feeding stations may encourage cat BOX 1 Definitions around the ownership categories of free-ranging cats.
Categorization of free-ranging cats needs clarification, because management interventions vary depending on ownership and human interactions.'Free-ranging cat' describes objectively a cat's ability to move unrestrained, but masks ownership sub-categories important for cats' welfare, potential environmental and health impacts, and utility as pest controllers.Some free-ranging cats are owned, others are supported by human caregivers who do not own them, some scavenge refuse, and some live remotely from humans (Lepczyk & Calver, 2022).The welfare issues for these sub-categories and their potential to interact with wildlife, spread zoonoses or control pests vary, yet our understanding of population dynamics and interactions among the subcategories and the difficulty assigning individual free-ranging cats to groups in situ (Cove et al., 2023) are reminders that management implications are context-specific.abandonment (Castillo & Clarke, 2003;Kilgour et al., 2017;Natoli et al., 2006), and attract native and invasive wildlife species, causing problems such as disease transmission (Herrera, Cove, McShea, Decker, et al., 2022;Tamayo-Uria et al., 2014;Theimer et al., 2015).
We therefore question TNR on welfare grounds, even with intention for vaccinations, veterinary checks, and caretaker support.Although some animal welfare groups support TNR, especially with veterinary components (e.g., HSUS, 2023), we find it illogical to advocate containing owned animals for compelling welfare reasons, while unowned animals remain at large (Read, 2019).Instead, we agree that owned cats should be contained and that TNR is generally unsuitable for welfare reasons (Kretzer, 2018;Mullins, 2022;PETA, undated).

| PREDATORY IMPACTS OF FREE-RANGING CATS
Work on free-ranging cats remote from humans provides a logical framework to approach predation by freeranging cats in cities and towns.This involves confirming that predation at scale occurs, followed by ecological and behavioral work establishing impacts on prey communities.
Overall, we consider that cats remote from human habitation pose a significant threat to biodiversity given the evidence implicating them in multiple fauna extinctions and their threats to many extant species (Doherty et al., 2016(Doherty et al., , 2017)).While cats' impacts may interact with environmental disturbances (Stokeld et al., 2018(Stokeld et al., , 2021)), cats represent a significant threat because of high population densities, diverse habitat use and intense activity within their home ranges (Hamer et al., 2021).Furthermore, any predation by an introduced species removes prey from their natural role in the ecosystem, which is worthy of conservation action (Longcore & Smith, 2013).
The evidence for cat predation causing wildlife population declines near human habitation is debated, with conclusive results strongly influenced by study scale (e.g., species present on islands vs. mainland), and the geographic delineation of 'populations' under study (e.g., range-wide or local distribution) being undefined.Nevertheless, high predation rates relative to local wildlife population numbers are documented (Thomas et al., 2012;van Heezik et al., 2010), as are cases where cat predation caused local extirpation of prey (Bamford & Calver, 2012) or significant disruption to breeding and recruitment (Greenwell et al., 2019) (see also Table 1 in Calver et al., 2020).In Europe, bird banding data in France and Belgium show bird mortality from cat predation increased 50% between 2000 and 2015, coinciding with growth in the pet population-as significant a mortality as striking windows (Pavisse et al., 2019).
Studies correlating cat density with prey density are often inconclusive because of confounding variables such as other threats or habitat variation, not to mention analytical challenges (Grayson et al., 2007;Sims et al., 2008) and the likely rapidity of cat impacts (Bamford & Calver, 2012;Greenwell et al., 2019).Opportunity for experimental manipulations (e.g., reintroducing fauna to areas where cats are removed versus those where they are present) is limited near human habitation, but colonization by endangered Lower Keys marsh rabbits Sylvilagus palustris hefneri was rapid following cat removal in a patchy habitat matrix (Cove et al., 2018).Opportunistic cases where cats are present versus those were they are absent also support deleterious effects.For example, on O'ahu, wedge-tailed shearwater Puffinus pacificus breeding was more successful on islets where cats were absent (Smith et al., 2002), while Hawkins et al. (1999Hawkins et al. ( , 2004) ) reported reductions in numbers of native birds and native rodents near Californian cat feeding stations, with controls unaffected (but see Lilith et al., 2010 for an exception).
We judge the weight of evidence for likely impacts of free-ranging cats near human habitation as compelling, without needing justification for each species or locale, a generalization shared by Legge, Woinarski, et al. (2020) and Kays et al. (2020).In that context, given that cities are important globally for biodiversity conservation (Gaston et al., 2005;Ives et al., 2016;Lepczyk et al., 2023), plausible risk (and uncertainty in specific cases) justify precaution (Calver et al., 2011).Requiring conclusive evidence before action in each locality risks local extinctions before intervention.

| CONTROL OF NON-NATIVE RODENTS
Cats undoubtedly eat rodents.In Australia, for example, rodents occur in 35% (frequency of occurrence) of cat diet samples and form the largest component of cat diets (Fleming et al., 2022), with similar results elsewhere (e.g., Kauhala et al., 2015).However, this predation does not eliminate problems caused by non-native rodents in cities and towns.We agree with Jackson (1972, p. 283): "Some surveys have reported the amazing effectiveness of cats in controlling rodents …, but the writer has often wondered whether … surveys were influenced by what the respondent thought the answer ought to be." In urban areas free-ranging cats often prefer refuse or human provisioning rather than commensal rats and mice (Childs, 1986;Crawford et al., 2020), eating fewer rodents than rural cats (Jackson, 1951).Mainly, juvenile rats are hunted (Glass et al., 2009), removing rats that would have died or emigrated (Jackson, 1972) at ca. 20% of the mortality needed to maintain population stability (Jackson, 1951).Importantly, proximity to cat feeding stations in Madrid predicted rat infestations (Ayyad et al., 2018;Tamayo-Uria et al., 2014), while Hawkins et al. (1999Hawkins et al. ( , 2004) ) found that house mouse numbers increased near cat feeding stations, despite the increased intensity in predation (Herrera, Cove, McShea, Flockhart, et al., 2022).
The perceived efficacy of cats in rodent control may be caused partly by changes in rat behavior near cats (Parsons et al., 2018).In rural areas, using observational and anecdotal evidence, Elton (1953) considered high densities of free-ranging cats potential rodent controllers, especially in excluding rats after other controls.Kauhala et al. (2015) noted that rodent deaths could be a benefit of free-ranging cats (but without evidence of reduced rodent numbers), while acknowledging that 'super predator' cats might threaten bird populations.Further, Mahlaba et al. (2017) observed synergies between cats and domestic dogs Canis familiaris that reduced pest rodent activity at rural African homesteads, while neither predator alone elicited rodent fear responses.

| PUBLIC AND ENVIRONMENTAL HEALTH
Cats harbor zoonotic pathogens (Gerhold & Jessup, 2013;Legge, Taggart, et al., 2020), with 23 of concern to human health (Lepczyk et al., 2015).These diseases cause significant costs for human health and livestock production (Legge, Woinarski, et al., 2020).While the risk of freeranging cats transmitting diseases to or from people, domestic animals and wildlife varies according to subcategory of free-ranging cat (Mendoza Roldan & Otranto, 2023), Chalkowski et al. (2019) noted that all cats with outdoor access had increased risk of parasites.
Where cats are remote from humans, the concern is transmission of diseases to wildlife, with most attention focused on toxoplasmosis, caused by the felid specialist parasite Toxoplasma gondii.Cats may contaminate water bodies locally (e.g., drinking at water reservoirs), and oocysts in fecal matter may run off into rivers, streams, and finally the ocean, infecting marine wildlife distant from the cats themselves (Shapiro, Bahia-Oliveria, et al., 2019;Shapiro, VanWormer, et al., 2019).High prevalence of T. gondii infections in cats remote from human habitation is established internationally (e.g., Tasmania, Australia [Fancourt & Jackson, 2014]; Philip Island, Australia [Adriaanse et al., 2020]; Amami Oshima Island, Japan [Matsuu et al., 2017]) and wildlife infections are known (e.g., Pennsylvania, USA [Dubey et al., 2015], Hawaii, USA [Barbieri et al., 2016;Work et al., 2015], New Zealand [Roberts et al., 2021].Less is known of declines in wildlife populations following infection.Hillman et al. (2016) regarded it as a hypothesis for wildlife decline in Australia rather than an established cause.Nevertheless, Pacioni et al. (2015) identified toxoplasmosis as a priority disease for investigation associated with wildlife decline; it causes mortality in highly vulnerable birds and marine mammals in Hawai'i (Barbieri et al., 2016;Work et al., 2000Work et al., , 2015) ) and is a significant human health concern (Dubey et al., 2020).Presence of cats on inhabited islands is also a risk factor for zoonotic transmission (de Wit et al., 2019).
Clear evidence connects the prevalence of pathogen infection in free-ranging cats near human habitation with outdoor access (e.g., Chalkowski et al., 2019), so outdoor husbandry of pet cats and TNR programs may increase zoonotic disease infection (e.g., flea-borne rickettsiosis [Cummings et al., 2016]).As such, we are unconvinced by the argument that cat clowders provide rodent control and hence may reduce disease risk by controlling pathogen vectors because of the weak evidence that clowders provide control-supplemental food may contrarily increase rodent infestations (Ayyad et al., 2018;Tamayo-Uria et al., 2014) and facilitate parasite life cycles.Containment of cats is appropriate, given the risks (Ding et al., 2017;Gauss et al., 2005;Must et al., 2015).

| GENERALIZATIONS
From our survey of the issues, we generalize: 1. Around human habitation, free-ranging cats, regardless of ownership, have poorer welfare outcomes compared to contained cats.2. Allowing cats to range freely increases predation upon wildlife.Impacts may vary locally, but precautionary risk management discourages outdoor husbandry of cats-the risk is established to the point where action should be taken.3. The ability of free-ranging cats to control pest rodent populations is unsubstantiated, especially in cities. 4. Free-ranging cats transmit significant pathogens, including zoonoses.
Based on our collective experience, the welfare, environmental and public health issues associated with freeranging cats require intervention.For free-ranging, unowned urban cats, TNR is often presented as the only alternative to culling, but TNR cats have compromised welfare, may threaten wildlife, and harbor diseases.
Furthermore, provisioning them increases the likelihood of pest infestations (Ayyad et al., 2018;Tamayo-Uria et al., 2014;Theimer et al., 2015), while irresponsible owners may abandon animals near TNR clowders (Castillo & Clarke, 2003;Natoli et al., 2006;Kilgour et al., 2017).Long-term population reduction at scale using TNR is either unconvincing (excluding adoptions, census numbers at the end of TNR studies frequently reflect those at the start; Crawford et al., 2020), or expensive and requiring high effort (Gunther et al., 2022;Kreisler et al., 2019).Consequently, implementing TNR often means accepting cat clowders, with associated problems, indefinitely (see Natoli et al., 2019 where urban clowders persisted for 30+ years under TNR management).Such examples can be in public places or centered around residences of cat-feeding enthusiasts where neutered cats roam freely, affecting neighbors, harassing local wildlife and endangering public health.
Alternatively, intensive adoption programs can rehome unowned cats (Calver et al., 2022), especially if cat fostering increases sociability and adoptability of wary cats.Population reduction could be enhanced if used together with mandated desexing, registration, and containment of owned cats (e.g., ACT Government, 2021).Investing in responsible pet ownership should turn off the spigot allowing the continued flow of cats into unowned, free-ranging clowders.Responsible euthanasia is sometimes needed, particularly when animals are severely diseased or injured (as occurs in many TNR programs), or otherwise unadoptable.
Of course, reducing free-ranging cat populations is not a wildlife conservation panacea because of numerous other threats (Maxwell et al., 2016).These concerns do not, however, justify ignoring threats from free-ranging cats.Deflecting from cat management to other problems ultimately leads to no action at all, including inadequate responses to pressing questions of cat welfare.