In the present study, we employed a citizen science approach to provide a baseline list of species affected by cat predation, their capture rate, and critical insights for policymakers in an urban area in the Neotropical region. While similar studies have been conducted in other cities surrounded by humid forests in the Neotropics (Assis et al. 2022; Mella-Méndez et al. 2022), this is the first report of the impact of cats on wildlife in dry ecosystems in this diverse region. We estimated that domestic cats have an average capture rate of two prey items per cat per year. Considering only the cats that hunt, the capture rate estimated is 5.5 prey items per cat per year, capturing a wide variety of prey (53 taxa) in the study area, with invertebrates (53.8%; n = 71) as the most common, followed by reptiles (27.3%; n = 36). Our results suggest that three factors favor the rate of prey capture by domestic cats: age, nocturnal confinement, and the presence of toys in their homes. Specifically, the latter stands out as an essential factor to be considered in developing public policy that regulates the responsible ownership of domestic cats, reducing the impacts on wildlife caused by these pets.
Capture rate, composition, and conservation status of prey
The capture rate in our study (5.5 prey items per hunting cat per year) is significantly lower than the global average (39 prey items per hunting cat per year; Legge et al. 2020). However, these rates differ because the global average was obtained from a meta-analysis of 47 studies, some of which employed more precise methodologies (e.g., crittercams and molecular analysis of stomach contents and scats). For instance, a study conducted in the temperate rainforests of Chile found that 168 vertebrates were captured per hunting cat per year using the scat analysis methodology (Silva-Rodríguez and Sieving, 2011). Another study conducted in two rural areas of Poland utilizing scat and stomach contents reported a capture rate of 443 vertebrates per hunting cat per year (Krauze-Gryz et al., 2019). Additionally, a study carried out in Georgia (USA) highlights the influence of the methodology used on the values of estimated capture rate by cats (Lloyd et al. 2013). These authors using animal-borne video cameras documented a capture rate of 125 prey items per hunting cat per year; in contrast, counting only the prey brought home by cats, they estimated a capture rate 4 times less (a rate of 28.7 prey items per hunting cat per year Lloyd et al., 2013). According to some studies, domestic cats typically bring home only 10 to 23% of the prey they capture (Loyd et al. 2013; Krauze-Gryz et al. 2019; Seymour et al. 2020). The remaining prey are either consumed or left on-site outside the home, aspects not accounted for in household owner counts; therefore, the capture rate obtained in our study is probably underestimated.
A recent study carried out in a neotropical city of Mexico (Xalapa), employing a similar owner survey methodology to ours, reports a capture rate of 4 prey items per cat per year (Mella-Méndez et al. 2022), which is high compared to that estimated in our study, namely two prey items per cat per year considering all cats in the study. The discrepancy observed can be primarily attributed to the type of ecosystem (mountain cloud forest) surrounding the urban areas. Rainforests are known for harboring higher biodiversity per square meter than other ecosystems (Abrams and Abrams 2020). Specifically, mountain cloud forest ecosystems contain unique flora and fauna characterized by high levels of richness and abundance (Almazán-Núñez et al. 2018). Since our study focuses on remnants of tropical dry forests and xerophytic shrublands, our ecosystems are less diverse than montane cloud forests, and a lower capture of prey and taxa is expected. Despite the lower capture rate in the study area, it is worth noting that the Ecuadorian coast holds the last threatened remnants of tropical dry forests and xerophytic shrublands characterized by their high degree of endemism (Cuesta et al. 2017). Estimating the wildlife captured by cats is crucial, as it provides insights into the potential impacts of cat predation on local ecosystems. Discrepancies in capture rates between regions underscore the importance of considering ecosystem types and biodiversity levels when evaluating these impacts, highlighting the need for targeted conservation efforts in areas like the Ecuadorian coast, to preserve unique and threatened ecosystems. No previous study has examined the impacts of cat depredation on wildlife in tropical dry ecosystems; hence, our study represents the first contribution to filling this information gap.
Cats generally hunt animals smaller than themselves, as shown by the high number of small prey found in the literature (Lepczyk et al. 2004; Kutt 2012; Paul and Friend 2020). Most of the studies report that birds and small mammals predominate among the prey items and species captured by domestic cats (Morgan et al. 2009; van Heezik et al. 2010; Díaz et al. 2023; Lepczyk et al. 2023). Unexpectedly, most of the prey items and taxa captured by cats in our study consist of invertebrates. These variations could be related to differences in prey population dynamics, as the presence and abundance of different species can vary significantly depending on local environments and the availability of resources (Lepczyk et al. 2023). In other words, if there is a higher presence of accessible invertebrates in the environment, cats may adjust their hunting patterns towards this taxonomic group. This observation aligns with studies conducted in some tropical islands, where cats prominently capture invertebrates, attributed to seasonal variations in prey abundance (Ferreira et al. 2014; Ferreira and Genaro 2017; Bruce et al. 2019). In urban settings, a higher abundance of captured invertebrates by cats is expected not only due to their high global diversity (Stork et al. 2015) but also to the habitat heterogeneity present in cities, such as parks and gardens, which offer suitable foraging and nesting sites for these animals (Hennig and Ghazoul 2012; Jones and Leather 2012). Considering that the predatory behaviors of cats towards wildlife in urban environments are influenced by various factors, such as prey abundance and ease of capture, making their understanding and management complex, it is crucial to address the variables comprehensively.
Cat owners often allow their cats to roam freely, employing them for pest control, since they frequently capture non-native animal species (Crowley et al. 2020; Trouwborst et al. 2020). This perception is partially supported by our results, which show that cats capture a significant number of species considered invasive species or pests in the study area, including brown lizards, house geckos, crickets, cockroaches, mice, and rats to a greater extent. The prey most captured were two non-native reptiles, the brown lizards (A. sagrei) and the house geckos (Hemidactylus sp.), given their higher abundance resulting from adaptability to urban environments. These species are frequently found in residential areas and parks, making them more susceptible to predators such as cats, as they require thermoregulation to remain active (Borroto-Páez and Pérez 2020; Horváth et al. 2020; Reynolds et al. 2021). Also, two non-native mammals, rats (R. rattus) and mice (M. musculus), were some of the most captured prey because they are abundant in urban areas, where they find food sources and refuges (Gillies and Clout 2003; Maeda et al. 2019). Predation by cats has also been demonstrated to impact native fauna. Our results showed that 56.6% of all prey taxa targeted by cats are native, aligning with findings in other Neotropical regions. In a study in a southern Brazilian municipality, for example, 64.0% of species reported as preyed upon by domestic cats were native (de Freitas et al. 2023), while in a southeastern Mexican city, 93.5% of the registered prey taxa were also native (Mella-Méndez et al. 2022). These results underscore the importance of considering the dual role of cats, both as contributors to controlling non-native pests and potential threats to native wildlife.
Our study documents, for the first time, predation by cats on native amphibians in northwestern South America. The absence of previous records of cats preying on amphibians aligns with the general trend of declining diversity and abundance of native herpetofauna caused by the expansion of urbanized areas (Hamer and McDonnell 2010; Faeth et al. 2011; Ackley et al. 2015). The limited capture of amphibian species was anticipated, given their lower diversity in Guayas, the least diverse vertebrate class in the province, and the threats posed by urbanization, including habitat loss, fragmentation, and degradation (Ortega-Andrade et al. 2019; Hamer and McDonnell 2008). Nevertheless, captured amphibian species (S. quinquefasciatus and L. melanonotus) exhibit varied responses to urbanization, influencing their presence and abundance in the study area. For instance, the locally abundant treefrog S. quinquefasciatus, known for its wide distribution and tolerance to anthropogenic activities, is found in urban areas of the Ecuadorian coast (Ron et al. 2018), making it a potential prey for cats. Nevertheless, some of the amphibian species registered (i.e., Leptodactylus spp.) may be abundant but also exhibiting anti-predatory behavior such as changing their body shape or inflating themselves, mouth gaping, and jumping away from predators (see Ferreira et al. 2019), which can help them in avoiding and escaping cat attacks. These findings emphasize the interplay between cat predation and amphibian responses, requiring further research.
Non-threatened local species are generally more abundant and may be more accessible to opportunistic predators such as domestic cats (Loss and Marra 2017; Mori et al. 2019). The record of cats preying on various common native dragonflies (E. vesiculosa, E. umbrata, and P. flavescens) in large quantities could be linked to their frequent occurrence in anthropogenic water bodies within urban areas, such as pools and garden fountains, particularly during dry seasons when natural water sources are scarce (Perron and Pick 2020; Husband and McIntyre 2021). Another common species that cats capture is the Ecuadorian ground dove (C. buckleyi), which is locally adapted and abundant, given its adaptability to urban areas. This species can utilize urban plants to feed on grains and seeds, primarily foraging in lower strata (Allieri and Man-Ging 2015; Carrión-Zambrano et al. 2022), making them available and exposed to urban predators such as cats. However, the record of threatened poorly studied snakes like C. dromiciformis, which is globally “Vulnerable” and “Near Threatened” locally, along with M. pulchriceps, which can be found solely in forest remnants (Amador-Oyala, 2015), contrasts with the common idea that domestic cats focus only on abundant prey (Dickman and Newsome 2015; Yip et al. 2015). This finding suggests that predation of threatened species by cats, in synergy with other pressures (e.g., habitat loss, road deaths), may even contribute to the decline of their populations (Medrano‐Vizcaíno et al. 2023). The interactions between cats and local species, both common and threatened, highlight potential impacts on general local wildlife conservation.
Five out of the 11 native vertebrate species reported in our study, including the white-browed gnatcatcher (P. bilineata), the variable seedeater (S. corvina), and the house wren (T. aedon), have wide distributional ranges inhabiting a variety of habitats and climates throughout the Americas. However, there are unique species in South America, such as the fasciated wren (C. fasciatus) and the shield head gecko (G. caudiscutatus), which have geographical distributions restricted to the northwestern part of the continent, which are also affected by cat predation. These findings illustrate the potential interaction between cats and locally adapted species, which can carry consequences for the function of ecosystems (Kitts-Morgan 2015; Escribano-Avila et al. 2017). A recent meta-analysis reported 89 species as prey of cats for the South American continent (Lepczyk et al. 2023), while we recorded 30 native taxa (21 species) solely in the study area, which has an area of approximately 3,000 km2. These results suggest that many more studies in South America are needed to reveal the true extent of the impact of cats on all native and endemic predated wildlife.
Intrinsic and extrinsic factors
Of the intrinsic factors considered for the model, only age was a significant factor in hunting activities, consistent with previous studies (Barrat 1998; McDonald et al. 2015). The positive association between the youth of cats and prey capture is consistent with the existing literature, suggesting that younger cats often exhibit more active and exploratory hunting behaviors than older cats (Fitzgerald and Turner 2000; Philippe‐Lesaffre et al. 2024). Indeed, the majority (77.8%) of actively hunting cats in our study are kittens or young adult cats (< 6 years), according to the Quimby et al. (2021) life stage classification. The youngest cat, in particular, captured the largest quantity of prey items. While younger cats become successful predators as they capture more prey to develop their hunting and killing techniques, which their mothers teach them (Crowell-Davis et al. 2004), older cats’ hunting activity may be reduced because of changes in their sensory systems and cognitive and physiological functions (Bellows et al. 2016; Cecchetti et al. 2021b). On the other hand, our data does not support the idea that sterilization influences the number of prey items captured by a cat, which is consistent with certain studies (Guttilla and Stapp 2010; Hall et al. 2016). However, this contrasts with other research findings that suggest that non-sterilized cats may roam more extensively, providing them with increased opportunities for predatory activity (Kitts-Morgan et al. 2015; Ferreira et al. 2020). Further investigation into the correlation between home range and predation is necessary to comprehend this discordance better.
Contrary to what was documented by Mella-Méndez et al. (2022), the tabby color of cats did not prove to be a determining intrinsic factor in prey capture rates. This result could be attributed to the primary mechanisms of predator recognition observed in the most captured taxa reported in the present study (insects and reptiles), which are not primarily based on the visual sense. In the case of insects, predator-induced responses involve not only visual stimuli but also olfactory, auditory, and tactile senses (Cinel et al. 2020). Moreover, some lizard species rely on their olfactory sense to identify predators’ scents through chemical cues rather than visual recognition (Ortega et al. 2018; Fernández‐Rodríguez and Braña 2022). Consequently, factors associated with visual stimuli, such as cat color, appear less influential than, for instance, exposure to cat scent as a triggering element for antipredator behavior (Cliff et al. 2022). This distinction likely affects the hunting success of cats with these taxa.
Among the extrinsic factors, the presence of toys in cats’ homes had a significant weight in the model. Toys are an essential part of the environmental enrichment that every cat should have (Ellis 2009). The literature suggests that cats with access to an enriching environment with toys that simulate common prey, scratchers, or towers can channel their energy into play and simulated hunting activities, which may reduce the need to hunt wild animals (Cecchetti et al. 2021a). Surprisingly, our results suggest that providing toys to domestic cats could increase the number of captured prey, as these toys can serve as tools for training activities to make their hunting events more efficient. This result may be supported by the fact that for cats, playing with objects and predation can share a motivational basis (Biben 1979; Hall and Bradshaw 1998). In this context, it could be inferred that providing toys (principally those that simulate birds, mice, and small reptiles) that produce rapid movements could motivate cats to engage in hunting behaviors and actively predate more (Chávez-Contreras 2016). However, other factors to assess the quality of play, such as the quantity and type of toys in their homes, positive hunting reinforcement, and playtime, should also be considered for a more comprehensive explanation of this phenomenon (Strickler and Shull 2014; Delgado and Hecht 2019; Cecchetti et al. 2021a).
Nocturnal confinement has been shown to decrease the amount of prey hunted by cats, consistent with findings in other studies (Robertson 1998; Mella-Méndez et al. 2022). Considering that in highly urbanized areas, cats are more active at night (Bennett et al. 2021), it is during nocturnal hours when cats would have a greater opportunity to catch prey (e.g., Denny and Dickman 2010). Hence, nocturnal confinement is crucial to prevent cats from roaming and encountering nocturnal native wildlife (e.g., snakes), which are not typically found inside homes (Lilith et al. 2006). Even diurnal or crepuscular animals that change their behaviors because of light sources present in cities (Russart and Nelson 2018) or natural moonlight (Brisbane and Van Den Burg 2020) can be vulnerable to nocturnal predators. For instance, brown anoles (A. sagrei) are diurnal lizards that engage in foraging and reproductive activities at night influenced by urban lights (Rojas-González 2021), exposing them to cats.
Surprisingly, we found no effect of cat’s collar with bell, despite some studies suggesting that bells may decrease predation on wildlife (Calver et al. 2007; Gordon et al. 2010). Furthermore, time spent with the owner was hypothesized to decrease the capture rate, as owners actively engaged with their cats could potentially prevent hunting events. However, our analysis did not detect any significant effect. Additionally, the origin of cat food, associated with nutritional contributions, did not significantly affect cats’ hunting tendencies (Cecchetti et al. 2021a). Contrary to previous findings (Dickman 1996; Barrat 1998), our analysis of green areas did not reveal a correlation between the presence or larger size of green areas and an increase in captured prey. Other types of artificial green spaces present in urban environments, such as gardens and parks, have been documented to offer suitable habitats for domestic cats and should be considered in further studies. These specific green areas may provide opportunities to find potential prey (Pavisse et al. 2019), but they were not considered in the analysis.
Implications for the management
The management and control of cats undoubtedly represent a significant challenge in any neotropical city. The management of feral or ownerless cats falls under the responsibility of local authorities, while the care of owned cats is not directly included in their duties. However, efforts to prevent or mitigate any impact of cats on wildlife require knowledge of the situation and awareness strategies regarding the management and control of such impact (Crowley et al. 2019). Some studies express skepticism about the negative impact of domestic cats on biodiversity (Lynn et al. 2019; Turner 2022). However, searching for comprehensive strategies that reduce the impact of cats on wildlife and disseminating efficient mechanisms for controlling these animals in areas of high biodiversity is necessary (Trouwborst 2020).
Among the three variables that significantly affect the hunting behavior of the sampled cats, nocturnal confinement is the one that can be most effectively controlled through public policies. The measures that should be implemented involve nocturnal confinement for cats, which should remain indoors during a set schedule (e.g., from 6 p.m. to 6 a.m.). Several studies suggest nocturnal confinement as a practical measure (Lilith et al. 2006; Linklater et al. 2019; Cecchetti et al. 2021b; Mella-Méndez et al. 2022). Concurrently, this could be combined with other measures used for cat identification (microchips) and population control through sterilization (Grayson and Calver 2004), along with the implementation of cat-exclusion zones (Metser et al. 2010; Herrera et al. 2022). Promoting these measures is essential for owners of younger cats. Environmental enrichment is crucial for cats’ well-being (Grigg and Kogan 2019). Hence, before any restrictions are implemented, there should be further investigation into whether cats that play with toys that simulate their prey (birds, mice, and little reptiles) increase their prey capture.
More research about public perceptions and social attitudes toward responsible cat ownership and anti-predation strategies is needed, mainly focusing on nocturnal confinement. Additionally, outreach and environmental education projects regarding the impact of domestic cats on wildlife are necessary to foster greater acceptance by people of movement restriction policies for cats in urban areas. In this context, environmental awareness is necessary to convey the information obtained (Thomas et al. 2012; Woolley and Hartley 2019) and to counter misinformation (Loss et al. 2018; Gow et al. 2022).