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Free-ranging house cats in urban and rural areas in the north: Useful rodent killers or harmful bird predators?

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Abstract

The prey of 66 free-ranging urban and rural house cats Felis catus was studied in a mainland area in SW Finland. The data included 1624 home-brought prey animals, of which 92 % could be identified at least to the class level. The mean number of prey brought home was 4.1 per cat per month (excluding winter). Rodents were the most common prey (72 %), 18 % of prey being birds, 5.4 % insectivores, and the rest other mammals (hares, least weasels, pine martens, and a bat), reptiles or amphibians. Six “super predator” cats accounted for 40 % of all prey items captured. There were no differences between the sexes in the number or diversity of prey brought home. The prey of young cats was more diverse than that of older, more experienced cats. Especially old cats in rural areas benefit humans by killing many rodents. The proportion of birds captured was 24 % in urban areas where cats represent a possible threat to native birds: probably > 1 million prey animals are monthly killed by free-ranging cats in Finland, at least 144000 of these being birds. “Super predator” cats should thus be kept in the house, especially in urban areas, to prevent predation on birds.

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... To this end, we surveyed a large sample of cat owners living in France and estimated the personality traits of their cats using the Feline Five personality model of Litchfield et al. (2017) as well as the frequency of birds and mammals returned home by the cats as reported by their owners. We expected that cats with "low neuroticism (boldness, leading to travelling, exploring) or high extraversion (curiosity, leading to boredom), would potentially be more interested in hunting wild prey" , To control for potential confounding factors, we also included questions about variables previously shown to influence pet cat predation: type of environment around the home, time spent outdoors, individual characteristics, and breed (Castañeda et al., 2019(Castañeda et al., , 2020Cordonnier et al., 2022;Kauhala et al., 2015;Lepczyk et al., 2004;Robertson, 1998;Salonen et al., 2019). ...
... It was previously shown that domestic cats have highly variable predation rates: some cats frequently bring prey home, while a significant proportion rarely does so (Baker et al., 2008;Kauhala et al., 2015;Thomas et al., 2012;Tschanz et al., 2011). Given the high local ecological impact of pet cat predation, understanding the causes of this variation could potentially help identify ways of mitigating this impact. ...
... Because pet cats usually remain close to their home (~100 m radius in average; Kays et al., 2020) and are opportunistic hunters, their predation should reflect the fauna found in immediate proximity to their home (Barratt, 1997;Castañeda et al., 2019Castañeda et al., , 2020. Several studies on free-ranging pet cats found significant differences between rural and urban areas in terms of the amount and composition of prey brought home, probably reflecting differences in local prey availability induced by differences in land use (Kauhala et al., 2015;Krauze-Gryz et al., 2017;Piontek et al., 2021). In our study, predation analysis was conducted on cats with outdoor access ranging from <1 h per day to free-ranging cats. ...
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The domestic cat, Felis catus, is one of the most popular and widespread domestic animals. Because domestic cats can reach high population densities and retain at least some tendency to hunt, their overall impact on wildlife can be severe. Domestic cats have highly variable predation rates depending on the availability of prey in their environment, their owners' practices, and individual cat characteristics. Among these characteristics, cat personality has recently been hypothesized to be an important factor contributing to variations in the hunting activity of cats. In this study, we surveyed 2508 cat owners living in France about their cats' personalities, using the Feline Five personality framework, and the frequency with which cats bring home prey. Personality traits were analyzed using factor analysis and related to predation frequency using cumulative logit models. For both birds and small mammals, cats with high levels of extraversion or low levels of neuroticism had significantly higher frequencies of prey return. Owners whose cats had low levels of agreeableness or high levels of dominance reported a significantly lower frequency of bird return. Personality differences therefore seem to contribute to the high variability in predation rates among domestic cats. We also found that the owner‐reported prey return frequencies were significantly higher for cats spending more time outdoors, for non‐pedigree cats, and for owners living in rural or suburban areas as opposed to urban areas. By contrast, we did not detect an effect of cat sex or age on their reported prey return rates. Because domestic cats can reach high population densities and generally retain at least some tendency to hunt, their overall impact on wildlife can be severe, leading to increasing international interest and concern. Domestic cats have highly variable predation rates, depending in part on individual cat characteristics, but the reasons for this high level of variation are poorly understood. In our study, we used surveys of more than 2500 cat owners living in France to show that personality differences contribute strongly to the large variability in predation rates among domestic cats.
... Following Cecchetti et al. (2021a), we expected that cats with "low neuroticism (boldness, leading to travelling, exploring) or high extraversion (curiosity, leading to boredom), would potentially be more interested in hunting wild prey." To control for potential confounding factors, we also included questions about variables previously shown to influence pet cat predation: type of environment around the home, time spent outdoors, individual characteristics, and breed (Robertson, 1998;Lepczyk et al., 2004;Kauhala et al., 2015;Salonen et al., 2019;Castañeda et al., 2019Castañeda et al., , 2020Cordonnier et al., 2022). ...
... It was previously shown that domestic cats have highly variable predation rates: some cats frequently bring prey home, while a significant proportion rarely does so (Baker et al., 2008;Tschanz et al., 2011;Thomas et al., 2012;Kauhala et al., 2015). Given the high local ecological impact of pet cat predation, understanding the causes of this variation could potentially help identify ways of mitigating this impact. ...
... Because pet cats usually remain close to their home (~100 m radius in average; Kays et al., 2020) and are opportunistic hunters, their predation should reflect the fauna found in immediate proximity to their home (Barratt, 1997;Castañeda et al., 2019Castañeda et al., , 2020. Several studies on free-ranging pet cats found significant differences between rural and urban areas in terms of the amount and composition of prey brought home, probably reflecting differences in local prey availability induced by differences in land use (Kauhala et al., 2015;Krauze-Gryz et al., 2017;Piontek et al., 2021). In our study, predation analysis was conducted on cats with outdoor access ranging from less than 1 hour per day to free-ranging cats. ...
Preprint
The domestic cat, Felis catus, is one of the most popular and widespread domestic animals. Because domestic cats can reach high population densities and retain at least some tendency to hunt, their overall impact on wildlife can be severe. Domestic cats have highly variable predation rates depending on the availability of prey in their environment, their owners’ practices, and individual cat characteristics. Among these characteristics, cat personality has recently been hypothesized to be an important factor contributing to variations in the hunting activity of cats. In this study, we used surveys of 2,508 cat owners living in France to collect information about cat personalities using the Feline Five personality model and about the frequency with which the cats bring home prey. For both birds and rodents, cats with high levels of extraversion or low levels of neuroticism had significantly higher frequencies of prey return. Owners whose cats had low levels of agreeableness or high levels dominance reported a significantly lower frequency of bird return. Personality differences therefore seem to contribute to the high variability in predation rates between domestic cats. We also found that the owner-reported prey return frequencies were significantly higher for cats spending more time outdoors, for non-pedigree cats, and for owners living in rural or suburban areas as opposed to urban areas. By contrast, we did not detect an effect of cat sex or age on their reported prey return rates.
... While Robertson (1998) showed that the body condition of cats did not influence the frequency of captures, the number of birds and herpetofauna brought home per cat reported by Woods et al. (2003) was negatively related to the cat's age and condition. The prey of young cats was more diverse than that of older, more experienced cats, and old cats in rural areas killed more rodents according to Kauhala et al. (2015). Although less investigated, the color pattern of the cat could also be of 2013; Loss et al. 2013 for bird species) which may or may not be eaten. ...
... Although a large body of literature explores the number and diversity of individuals depredated by pet cats (Baker et al. 2005(Baker et al. , 2008van Heezik et al. 2010;Thomas et al. 2012;Loyd et al. 2013), fewer studies investigate the drivers of predatory behavior (but see Woods et al. 2003;Kauhala et al. 2015). As experimental manipulations of pet cats are difficult to implement, a frequent approach used to investigate predation by pet cats is to survey cat owners regarding the number of returned prey. ...
... These three components (environment, owner behavior, and intrinsic cat characteristics) potentially impact the predatory behavior of cats and should therefore not be considered separately. However, most previous studies on pet or feral cats have only focused on one (e.g., Yip et al. 2014) or more rarely two (e.g., Kauhala et al. 2015) of these components; very few studies consider all three simultaneously (but see Woods et al. 2003). ...
Article
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The domestic cat (Felis catus) is one of the most abundant predators and a serious threat to many wildlife species. While a large body of literature explores the number and diversity of individuals depredated by pet cats, the drivers of predation have been investigated much less. Although the environment of the cat, the owner behavior, and the intrinsic characteristics of the cat itself could impact the predatory behavior and should therefore not be considered separately, very few studies simultaneously take these three components into account. In this study, we explored 21 concomitant drivers of predation by pet cats linked to these three components at different scales, to explain the owners-reported frequencies of captured birds, mammals, and herpetofauna. Among the 1,400 sociological surveys received from cat owners, 740 reliable answers were analyzed. Results suggest that the owners-reported prey capture frequencies were strongly influenced by the environment, especially by factors relating to urbanization. Rural owners were around two times more likely to report more frequent predation events than owners living in urban areas, whatever the group of prey studied. As a result, the urban habitat variable had the highest impact on predation in this study. An experimental approach would be beneficial to identify the factors influencing the reported predation rates, which are causally related to the number of wild animals killed.
... Estimates of total numbers of wild animals predated by cats has numerous known issues, and while no numbers exist for dog predation, cat predation on birds has been estimated in several countries. Direct predation of birds by free-ranging and feral cats is estimated at 1.3-4 billion annually in the United States (Loss et al. 2013), 100-350 million annually in Canada (Blancher 2013), 5.4 million per month during the spring and summer in Great Britain (Woods et al. 2003), 0.1-0.3 million per month during spring in Switzerland (Tschanz et al. 2011), and 144 000 per month in Finland (Kauhala et al. 2015). This suggests that in some areas cats are the largest source of anthropogenic mortality for birds. ...
... This suggests that in some areas cats are the largest source of anthropogenic mortality for birds. Cat predation on mammals is estimated at 6.3-22.3 billion annually in the United States (Loss et al. 2013), whereas for all native animals in Australia the estimate is 2.8-4.9 million per year (Fougere 2000), and in Finland the estimate is 1 million per month (Kauhala et al. 2015). The taxa most impacted vary by location, season, and habitat; most studies report the largest effects on birds and mammals/marsupials (Risbey et al. 2000;Catling 1988;Dickman 2009;Coman and Brunner 1972;Tschanz et al. 2011;Brickner-Braun et al. 2007;Yip et al. 2014;Barratt 1997), but others report more consumption of reptiles (Loyd et al. 2013;Paltridge 2002) or invertebrates (Campos et al. 2007). ...
... Most studies report intraspecific variation in prey preference and predation rates, with some individuals not capturing any prey and a few individuals with high consumption rates of uncommon prey (Dickman 2009;Tschanz et al. 2011;Yip et al. 2014;Kauhala et al. 2015). This suggests that the behavioural composition of the local domestic animal assemblage will affect the abundance and diversity of prey taxa consumed and that this should be considered in management programs (Moseby et al. 2015;Dickman and Newsome 2015). ...
Article
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Humans have created a strong relationship with cats and dogs by domesticating them. Whether owned by a human or living feral, modern domestic cats and dogs interact extensively with people and the environment. The negative interactions between these domesticated animals and wildlife have been discussed in several reviews, but few reports have provided an overview of both the positive and negative impacts these domesticated animals have on wildlife conservation. Here, we describe the diverse issues associated with domestic cats and dogs and wildlife including predation, competition, pathogen transmission, hybridization, behavioural modification, harvest of wild animals for pet food, and creation of human-wildlife conflict. We then discuss their role in supporting conservation efforts (e.g., use in species identification and tracking, biological control), and shaping our social values towards animals and appreciation for nature. Finally, we suggest necessary steps to harmonize our relationship with cats and dogs and the conservation of wildlife. For owned animals, there is potential for pet owners to support conservation efforts through a pet tax' adopted by veterinary clinics and pet stores to be used for wildlife conservation. Moreover, information regarding the impacts of these animals on wildlife and potential solutions (e.g., voluntarily keeping cats and dogs inside or use of "pet curfews", use of bells to alert wildlife to cats) should be made available to owners who are most likely to have an influence on the behaviour of their companion animal.
... Most of the studies focused on the diet of free-ranging house cats have been conducted in the USA (Kays and DeWan 2004;Lepczyk et al. 2004), Australia and Oceania (Barrat 1997;Gillies and Clout 2003;Morgan et al. 2009;van Heezik et al. 2010). In Europe, where there is a relationship between high-density human populations and a high abundance of domestic cats, previous investigations were mainly located in the United Kingdom (i.e., Churcher and Lawton 1987;Woods et al. 2003;Baker et al. 2005;Thomas et al. 2012) but also in Sweden (Liberg 1984), Switzerland (Weber and Daily 1998;Tschanz et al. 2010), Poland (Krauze-Gryz et al. 2012a) and Finland (Kauhala et al. 2015). However, this topic has never been investigated in many central and eastern European countries. ...
... Previous studies have focused on the diets of free-ranging house cats to better understand their spatial and temporal variations (e.g., Barrat 1997;Baker et al. 2005;van Heezik et al. 2010;Kauhala et al. 2015), but several knowledge gaps still exist. The dietary composition of domestic house cats may differ from the empirical patterns observed in wild carnivores as most of house cats are supplementary fed by their owners, so they can continue to hunt a certain prey category even if the hunt is no longer profitable in terms of the costs-to-energy gain ratio. ...
... In this study, we investigated the seasonal variability and the effects of two environments on the prey composition of free-ranging house cats in Poland. In previous studies, the diet composition and predation pressure of cats in natural and rural habitats have been contrasted with records from more transformed and built-up areas (e.g., Gillies and Clout 2003;Lepczyk et al. 2004;Kauhala et al. 2015), but few, if any, studies have addressed the seasonal variation in prey composition in this context (but see Kauhala et al. 2015). We attempted to do so and analysed the year-round variability in the different prey items killed by domestic cats at 26 sites in rural and urban environments, which provided us with the opportunity to separate the effects of time and the environment and to test the following three predictions. ...
Article
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The threat that domestic cats pose to wildlife has gained increased recognition by researchers and conservationists, and in this study, we investigated the seasonal variability and the effects of environment type (rural vs. urban) on the prey composition of free-ranging house cats in Poland. We analysed the variability in 307 monthly prey samples of different prey items killed by cats and brought to their owners (i.e., prey brought home by cats living in one home in one month) between 2002 and 2007 at 26 rural and urban sites. The variability in prey composition over time was analysed using additive models and canonical correspondence analysis. In total, we recorded 1348 prey items. Rodents were the most common prey in both environments, but shrews and reptiles were killed by cats more often in the rural environment while birds (mainly sparrows and pigeons) were more common in the urban environment. Additionally, prey composition changed seasonally. The pooled number of vertebrates killed by cats was largest in September and lowest in January, and rodents were killed most often in September, shrews and birds in June, and reptiles in April. The seasonal variation in the prey composition of cats was relatively high in the rural environment and more stable in the urban environment. Prey composition seemed to follow temporal and spatial variations in prey availability, thus confirming a facultative feeding strategy in free-ranging house cats.
... Die Frage, wie viele Katzenhalter tatsächlich an der Studie teilnehmen, bleibt offen und die Anzahl der gehaltenen Hauskatzen basiert oft auf Schätzungen und ist schwer zu ermitteln. Zur Vorsicht bei der Interpretation und Verallgemeinerung dieser extrapolierten Daten ist zudem geraten, da die Zahlen von getöteten und vorgelegten Tieren durch Hauskatzen extrem schwanken je nach Untersuchungsgebiet und Jahreszeit (Woods et al., 2003;van Heezik et al., 2010;Tschanz et al., 2011;McDonald et al., 2015;Crowley et al., 2019 (Kauhala et al., 2015). ...
... Hauskatzen keine getöteten Tiere vorlegten. Entweder brachten also diese Hauskatzen überhaupt keine wilden Tiere zur Strecke (es dürfte individuell sehr große Unterschiede im Jagdverhalten geben (Kauhala et al., 2015)), oder aber sie legten sie gar nicht zu Hause vor. ...
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The impact of domestic cats on vertebrates is now known globally - they are a major risk for endangered and threatened species. Hybridization of domestic and wild cats must also not go unnoticed, so there are already studies across Europe with differentiated results on this. Especially in the last decades, however, the domestic cat has become an increasingly popular pet throughout the western world, and its numbers continue to increase, which can lead to unnaturally high densities in settlements, for example. To summarize the current state of knowledge on this topic we supplemented the previously published report of Hackländer et al. (2014) with current data and literature. In particular, the topics of hybridization, potential management measures, legal framework and food analyses, which specifically address the impact of domestic cats on biodiversity, were considered in an expanded manner. The research revealed the need for action on the topic, which should not be underestimated, and the necessity of both the acceptance of personal responsibility and the consistent implementation of given political frameworks. The paper appeared in the BOKU Berichte zur Wildtierforschung und Wildbewirtschaftung and is available online. Translated with www.DeepL.com/Translator (free version)
... For selection to be efficient, studying the environmental factors involved in the success of either prey escape or predator hunt is necessary [110]. For instance, young cats have been reported to hunt more diverse prey than older more experienced ones from whom humans especially benefit, as they are rodent controllers in rural livelihoods [111]. Literature has suggested keeping "super predator" cats in houses, especially in urban areas, prevents rodent predation on birds [111]. ...
... For instance, young cats have been reported to hunt more diverse prey than older more experienced ones from whom humans especially benefit, as they are rodent controllers in rural livelihoods [111]. Literature has suggested keeping "super predator" cats in houses, especially in urban areas, prevents rodent predation on birds [111]. Additionally, new biologically friendly strategies focus on the use of wild feline predators, such as leopard cats, as biological pest-controller of rats in oil palm plantation landscapes as effective replacers of traditionally used expensive and environmentally polluting chemical rat poisons [112,113]. ...
Article
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The individuals engaged in predation interactions modify their adaptation strategies to improve their efficiency to reach success in the fight for survival. This success is linked to either capturing prey (predator) or escaping (prey). Based on the graphic material available on digital platforms both of public and private access, this research aimed to evaluate the influence of those animal- and environment-dependent factors affecting the probability of successful escape of prey species in case of attack by big cats. Bayesian predictive analysis was performed to evaluate the outcomes derived from such factor combinations on the probability of successful escape. Predator species, age, status at the end of the hunting act, time lapse between first attention towards potential prey and first physical contact, prey species and the relief of the terrain, significantly conditioned (p < 0.05) escape success. Social cooperation in hunting may be more important in certain settings and for certain prey species than others. The most parsimonious model explained 36.5% of the variability in escaping success. These results can be useful to design translatable selective strategies not only seeking to boost predation abilities of domestic felids for pest control, but also, biological antipredator defence in potential domestic prey of big cats.
... Larger studies have surveyed cat owners to monitor prey deposition at owner's residences. In Canberra, Australia, a year-long study which recorded a total of 1,961 prey from 214 cats found only five bats (0.25%) (Barratt, 1997), which agrees with a study in the UK which showed that 30 out of 9,852 (0.3%) of mammals brought in by cats were bats (Woods, McDonald, & Harris, 2003), with lower bat predation rates of just 0.06% recorded in mainland southwest Finland (Kauhala, Talvitie, & Vuorisalo, 2015). In some reports, the reason for assigning bat deaths due to cat predation is not clearly defined. ...
... As it is not uncommon for bat carers to report the same cat presenting bats in successive years, there was the possibility that the same cat may be responsible for more than one bat interaction. Although no DNA profile matches were observed here, a study in mainland Southwest Finland, proposed the idea of "super predator cats", where just six cats (9%) accounted for 40% of all observed captures in or around the city of Turku, with no difference between male and female cats (Kauhala et al., 2015). This supports the principle of prey specialization in cats; ...
Article
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Cat predation upon bat species has been reported to have significant effects on bat populations in both rural and urban areas. The majority of research in this area has focussed on observational data from bat rehabilitators documenting injuries, and cat owners, when domestic cats present prey. However, this has the potential to under- estimate the number of bats killed or injured by cats. Here, we use forensic DNA analysis techniques to analyze swabs taken from injured bats in the United Kingdom, mainly including Pipistrellus pipistrellus (40 out of 72 specimens). Using quantitative PCR, cat DNA was found in two-thirds of samples submitted by bat rehabilitators. Of these samples, short tandem repeat analysis produced partial DNA profiles for approximately one-third of samples, which could be used to link predation events to individual cats. The use of genetic analysis can complement observational data and potentially provide additional information to give a more accurate estimation of cat predation.
... Feral cats can impact on the dynamics of their prey, but there is much stronger data indicating that cats influence native wildlife ( Kauhala et al., 2015;Kikillus et al., 2017) than city rats. For example, in Australia ( Davies et al., 2017) and the US ( Loss et al., 2013), cats represent the greatest source of anthropogenic mortality for native birds and mammals. ...
... In Finland, researchers found that 72% of all prey brought home by cats were rodents. However the authors did not distinguish between mice and rats, and indicated that almost half of all kills belonged to exceptionally large cats ( Kauhala et al., 2015). Experimental release of 20 native long-haired rats (Rattus villosissimus) in Australia led to rapid extirpation by cats ( Frank et al., 2014). ...
Article
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Feral cats (Felis catus) are predators that cause widespread loss of native wildlife in urban ecosystems. Despite these risks, cats are commonly released as control agents for city rats (Rattus spp.). Cats can influence their prey directly by killing or indirectly through changes to feeding or space-use. However, cats prefer defenseless prey, and there are no data suggesting that cats influence large (>300 g) urban rats. We used a pre-existing radiofrequency identification assay (microchipped rats and field cameras) and ethograms to assess the impact of cats, including temporal and space use patterns, on an active rat colony. From Dec 27, 2017 through May 28, 2018 we captured 306 videos of pre-identified cats and/or rats that shared the same space. There were three instances of predation and 20 stalking events. Logistic regression showed the likelihood of a rat being seen on a particular day is associated with the number of cats seen on the same day (OR = 0.1, p < 0.001) or previous day (OR = 0.15, p < 0.001). Space-use was also impacted. For every additional cat sighting, a rat is 1.19 times more likely to move in the direction of shelter. Our findings of low levels of predation support why ecologists believe the risks to native wildlife outweighs any benefits of releasing cats. Even though rats were less likely to be seen, they simply shifted their movements and remained present in the system. Our findings that cat presence led to fewer rat sightings may explain the common perception of their value as rat-predators despite the associated risks.
... It should not be overlooked that cats can play an important role in rodent control (Engelhaupt, 2017;Fitzgerald et al., 1991;Kauhala et al., 2015;MacDonald, 2006). Rats and other rodents can have more negative impacts than cats on biodiversity loss, even in some islands (Bellard et al., 2016;Bergstrom et al., 2009;Brown et al., 1998;Courchamp et al., 1999;Doherty et al., 2016;Le Corre, 2008;Ozella et al., 2016;Rayner et al., 2007). ...
Article
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Abstract Cats, Felis catus L. (Carnivora: Felidae), were domesticated because of their role in rodent control around human settlements. Free‐roaming cats (henceforth, referred to as “cats”) can predate on a wide variety of small‐ to medium‐sized animals and affect biodiversity. The impact of cats on biodiversity varies from country to country, region to region, and habitat to habitat. Depending on the location and context, the overall impact of cats on biodiversity can be negative, neutral, or positive. Management of cats should take into account the complex interactions that occur between cats, rodents, and the species they prey upon.
... Furthermore, cats can eat more than one mouse. Cats not fed by humans kill, and probably consume, in average about one mammal per day, consisting of mice, voles and others [33,34]. In addition, owners of cats included in the present study described somnolent and dead mice being detected outside of traps i.e., mice more easily caught and consumed by cats and other carnivores. ...
Article
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Background Alpha-chloralose (AC) is a compound known to be toxic to various animal species and humans. In 2018 and 2019 an increase in suspected cases of AC poisoning in cats related to the use of AC as a rodenticide was reported to national veterinary and chemical authorities in Finland, Norway and Sweden by veterinarians working in clinical practices in respective country. The aims of this study were to prospectively investigate AC poisoning in cats, including possible secondary poisoning by consuming poisoned mice, and to study metabolism and excretion of AC in cats through analysis of feline urine. Methods Data on signalment, history and clinical findings were prospectively collected in Finland, Norway and Sweden from July 2020 until March of 2021 using a questionnaire which the attending veterinarian completed and submitted together with a serum sample collected from suspected feline cases of AC-poisoning. The diagnosis was confirmed by quantification of AC in serum samples. Content of AC was studied in four feline urine samples, including screening for AC metabolites by UHPLC-HRMS/MS. Bait intake and amount of AC consumed by mice was observed in wild mice during an extermination of a rodent infestation. Results In total, 59 of 70 collected questionnaires and accompanying serum samples were included, with 127 to 70 100 ng/mL AC detected in the serum. Several tentative AC-metabolites were detected in the analysed feline urine samples, including dechlorinated and oxidated AC, several sulfate conjugates, and one glucuronic acid conjugate of AC. The calculated amount of AC ingested by each mouse was 33 to 106 mg with a mean of 61 mg. Conclusions Clinical recognition of symptoms of AC poisoning in otherwise healthy cats roaming free outdoors and known to be rodent hunters strongly correlated with confirmation of the diagnosis through toxicological analyses of serum samples. The collected feline exposure data regarding AC show together with the calculation of the intake of bait and subsequent AC concentrations in mice that secondary poisoning from ingestion of mice is possible. The results of the screening for AC metabolites in feline urine confirm that cats excrete AC both unchanged and metabolized through dechlorination, oxidation, glucuronidation and sulfatation pathways.
... Co-introduction of parasites and their hosts is a common phenomenon when hosts are invasive, introduced, or immigrating to new or empty niches (Williamson and Griffiths, 1996;Laurimaa et al., 2016;Lesniak et al., 2017). On the other hand, T. cati life cycle is well-established and maintained in Finland with contributions by domestic cats (Kauhala et al., 2015;Näreaho et al., 2012). While little is known on the level of local environmental contamination with T. cati eggs as well as on the prevalence of the infection in relevant paratenic hosts, the parasite is endemic and can infect the dispersing lynx. ...
Article
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In Finland, free-ranging Eurasian lynx (Lynx lynx) population has grown from 30–40 individuals to 2800 individuals since the species became partly protected in 1962. Changes in host population size are known to have an impact on host-parasite dynamics, and the Eurasian lynx population in Finland provides a unique opportunity for studying the potential effects of dramatic population increase and expansion of a solitary apex predator on their parasite prevalence and abundance. Toxocara cati is a zoonotic gastrointestinal parasite infecting domestic cats and wild felids worldwide. We studied T. cati infection prevalence and worm burden in 2756 Eurasian lynx individuals from Finland, covering the years 1999–2015. Toxocara cati worms that had been collected from intestinal contents were identified based on morphology. We performed regression analyses to investigate possible associations of age, sex, and host population density with T. cati infection. We found T. cati from 2324 (84.3%, 95% confidence interval 82.9–86.0) of the examined lynx. Each year, the infection prevalence was higher than 75% and not density dependent. The parasites were strongly aggregated, with older individuals harboring fewer T. cati than younger ones did. Old females aged 9–15 years had higher T. cati abundance than males of the same age group. Our results indicate that T. cati was a common and abundant parasite of Eurasian lynx throughout the study period, regardless of the changing population size and density.
... Avian predator density in urban parks was not an important predictor of quail occupancy, whereas, in the wild, avian predation is assumed to be the main source of mortality for quail (Calkins et al., 2014). We expected mesopredators to be an important source of predation in urban areas, given higher densities of free-roaming cats (Lepczyk et al., 2004) and their increased likelihood of taking avian prey compared with their rural counterparts (Kauhala et al., 2015). The presence of coyotes may suppress free-ranging cat populations (Gehrt et al., 2013), and we found the presence of coyotes substantially increased the likelihood of a park being occupied by quail-an increase of 73.3%-potentially because of mesopredator release. ...
Article
Preserving and restoring wildlife in urban areas benefits both urban ecosystems and the well‐being of urban residents. While urban wildlife conservation is a rapidly developing field, the majority of conservation research has been performed in wildland areas. Understanding the applicability of wildland science to urban populations and the relative importance of factors limiting species persistence are of critical importance to identifying prescriptive management strategies for restoring wildlife to urban parks. We evaluated how habitat fragmentation, habitat quality and mortality threats influence species occupancy and persistence in urban parks. We chose California quail Callipepla californica as a representative species with potential to respond to urban conservation. We used publicly available eBird data to construct occupancy models of quail in urban parks across their native range, and present an application using focal parks interested in exploring quail reintroduction. Urban parks had a 0.23 ± 0.02 probability of quail occupancy, with greater occupancy in larger parks that were less isolated from potential source populations, had higher shrub cover and had lower impervious cover. Less isolated parks had higher colonization rates, while larger parks had lower extinction rates. These results align with findings across urban ecology showing greater biodiversity in larger and more highly connected habitat patches. A case study highlighted that interventions to increase effective park size and improve connectivity would be most influential for two highly urban focal parks, while changes to internal land cover would have a relatively small impact. Low joint extinction probability in the parks (0.010 ± 0.013) indicated reintroduced populations could persist for some time. Synthesis and applications. We show how eBird data can be harnessed to evaluate the responsiveness of wildlife to urban parks of variable size, connectivity and habitat quality, highlighting what management actions are most needed. Using California quail as an example, we found park size, park isolation and presence of coyotes are all important drivers of whether quail can colonize and persist in parks. Our results suggest reintroducing quail to parks could be successful provided parks are large enough to support quail, and management actions are taken to enhance regional connectivity or periodic assisted colonization is used to supplement local populations. We show how eBird data can be harnessed to evaluate the responsiveness of wildlife to urban parks of variable size, connectivity and habitat quality, highlighting what management actions are most needed. Using California quail as an example, we found park size, park isolation and presence of coyotes are all important drivers of whether quail can colonize and persist in parks. Our results suggest reintroducing quail to parks could be successful provided parks are large enough to support quail, and management actions are taken to enhance regional connectivity or periodic assisted colonization is used to supplement local populations.
... These effects of cats on individual birds have led to the inference that reducing the density of free roaming cats in urban areas would increase the abundance and diversity of urban bird communities [13][14][15], although this view is not universal [16,17]. Nevertheless, this inference has, at least in part, led many urban municipalities to contemplate or introduce legislation to keep owned cats indoors [18][19][20]. ...
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Domestic cats (Felis catus) are ubiquitous predators of birds in urban areas. In addition to the lethal effect of predation, there can also be sublethal, negative effects of domestic cats on individual birds. These effects have led to the inference that reducing outdoor cat densities would benefit urban bird communities. Here we estimate the likely result of policies/programs designed to reduce densities of owned outdoor cats in urban areas, estimating relationships between bird richness/abundance and cat densities across 58 landscapes in Ottawa, Ontario, Canada. We estimate that we would most likely observe one additional bird species, and 0.003 additional individuals per species, if policies/programs reduced owned outdoor cat densities to zero in an average landscape in Ottawa (with 130.2 cats/km2). However, these effects of cat density on birds were uncertain, with 95% confidence intervals crossing zero. Our findings—in combination with those of previous studies—suggest a need for research to resolve the apparent disconnect between the strong, negative effects of cats on individual urban birds and the weak, uncertain effects of cats on bird populations. Although measures that reduce owned outdoor cat densities are justified based on the precautionary principle, evidence to date does not support prioritizing these measures over those addressing threats that have consistently strong effects on bird populations.
... We used breeding success and density of occupied nest boxes as our indicators of habitat suitability and hoped to understand which of the three aforementioned habitats best suited the study species. We expected to find that rural areas would have the highest levels of nest loss owing to predation (e.g., domestic cats Felis catus, [23]), while the forest edge would have the lowest occupancy and nesting success (cf. [22,24]). ...
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As is well known, endemic island bird species are especially vulnerable to extinction from anthropogenic environmental change and reduced fitness compared with mainland taxa. The Cyprus Scops Owl Otus cyprius is a recently recognized island endemic species whose ecology and breeding biology have not been extensively studied. It nests mainly in holes in trees and buildings so the felling of old trees, modern architectural practices, and the renovation of old houses in villages may reduce nest site availability; its population trend is also unknown. Therefore, to better determine its ecological requirements and habitat preferences we placed nest boxes in villages adjacent to the forest, in the forest, and in the ecotone between them, and used breeding success as our indicator of habitat suitability. We found that breeding parameters like laying date, clutch size, length of the incubation period, hatching day, hatching success, and number of nestlings did not differ between the three habitats. Despite the low level of nest box occupancy rate (5 to 11 %) the endemic Cyprus Scops Owl readily breed in artificial nests. Therefore, although we are unaware of any current threats to the Cyprus Scops Owl, we recommend that its conservation be prioritized, including studies, monitoring, habitat conservation, and the provision of nest boxes.
... The majority of studies a priori perceive the very existence of feral colonies as a problem that needs to be solved by human intervention [4]. In recent decades there is increasing concern for the conservation of species that fall prey to roaming cats [8,36]. In addition to predation, problematic factors often named include disease transmission (to pets, livestock, wildlife, humans), noise during mating, and the presence of excrement in public spaces [23,37]. ...
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Urban environments are inhabited by several types of feline populations, which we can differentiate as feral cats, free-roaming pets, and confined pets. Due to a shift in the cultural representation of cats from pest controllers to companion animals, cats living semi-independently of humans are perceived increasingly negatively, while the pet population has become the object of intense care. A regulative approach converges with a concern for welfare in the operation and educational campaigns of municipal shelters, which through their implementation of neutering policies have proven to be key players in the contemporary relation of urban cats and humans. The generally widespread notion of cat welfare associated with a secure life comes into tension with the fact that the psychobiological needs of feral cats are significantly different than those of pets. It becomes apparent that individual interactions between humans and cats in urban environments in the Anthropocene are increasingly influenced by the intervention of institutions that can be characterized as seeking to administer the wild.
... Differences in the composition of prey brought home in rural and urban areas probably reflect local prey availability, driven by differences in land use. The diets of cats on farms exhibit temporal variation according to seasonal variability in small mammal populations, while bird captures are more frequent among urban cats, reflecting the relative abundance of resident garden birds (Kauhala et al. 2015, Krauze-Gryz et al. 2017). This might alternatively reflect variation in the tendency to keep owned cats in urban areas inside at night, when small mammals are more active (Woods et al. 2003) and wider ranging by rural cats (Hanmer et al. 2017). ...
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en • Domestic cats Felis catus are distinct from other domesticated animals because their phenotype and genotype are relatively unchanged. While they live with people as pets or pest controllers, they retain capacity for survival independent of human support and readily persist as feral animals. Most cats retain some propensity to express hunting behaviours, even if hunting is not required for nutrition. In some settings, depredation by cats is a threat to biodiversity conservation, leading to attempts to mitigate their impacts. • We characterise drivers and facilitators of the hunting behaviour of domestic cats: evolutionary origins, diet, life history, personality and environment. Hunting is driven particularly by evolutionary constraints and associated physiological and nutritional requirements. Proximate causes of variation in hunting behaviours relate to prey availability, husbandry and degree of domestication, while early life history and personality play further roles. • We review cat management approaches in terms of effectiveness, feasibility and welfare. Amongst lethal, large‐scale methods of population control, poisoning is most frequently used in cat eradications from islands. Because poisoning is challenged on welfare grounds, euthanasia is used at smaller scales and in inhabited, mainland settings. Non‐lethal approaches, primarily surgical sterilisation, are favoured by cat advocates but entail challenging logistics and scale. In attempts to inhibit predation of wild species by pet cats, owners restrict outdoor access and use collar‐mounted devices, including bells, sonic devices, collar covers and bibs. Other individual‐level interventions, such as dietary and behavioural enrichment, some of which may improve cat welfare, have potential, but effects on hunting remain untested. • Understanding and managing the hunting behaviour of cats are complex challenges. We highlight drivers and facilitators of this behaviour, representing starting points for formulating solutions that might be acceptable to cat owners and wider groups of people who value cat welfare, while also being effective for wildlife conservation. RIASSUNTO IN ITALIANO it • I gatti domestici Felis catus si distinguono dagli altri animali domestici poiché i loro fenotipo e genotipo sono rimasti relativamente invariati. Nonostante vivano con le persone come animali domestici o vengano impiegati per il controllo dei roditori infestanti, i gatti domestici hanno mantenuto la capacità di sopravvivere indipendentemente dal supporto umano, e possono facilmente persistere come animali ferali (rinselvatichiti). La maggior parte dei gatti ha mantenuto una certa propensione alla caccia, nonostante questa non sia necessaria a sopperire a esigenze nutrizionali. In determinati ecosistemi la massiccia predazione da parte dei gatti rappresenta una minaccia per la conservazione della biodiversità, determinando quindi la necessità di adottare soluzioni per mitigare i possibili effetti negativi. • In questo studio vengono caratterizzati i fattori chiave che inducono i gatti domestici a cacciare, nonché quelli che ne facilitano l’espressione: le origini evolutive, il regime alimentare, le esperienze fatte nel corso della vita, la personalità e l’ambiente. Il comportamento di caccia è primariamente determinato da vincoli evolutivi e da fabbisogni fisiologici e nutrizionali ad esso associati. Le cause prossime coinvolte nelle variazioni di tale comportamento sono legate alla disponibilità di prede, dal metodo di allevamento del gatto e dal suo grado di addomesticamento; le esperienze fatte nei primi mesi di vita e la personalità del gatto ricoprono anch’essi un ruolo importante. • Abbiamo revisionato i diversi approcci impiegati nella gestione dei gatti in termini di efficacia, fattibilità e benessere. Tra i metodi letali impiegati su larga scala nel controllo di popolazione, l’avvelenamento è risultato essere quello più frequentemente utilizzato per l’eradicazione dei gatti dalle isole. Poiché l’avvelenamento è contestato per motivi legati al benessere, su scala più piccola e in posti abitati sulla terraferma viene preferita l’eutanasia. Gli approcci non letali, in particolare la sterilizzazione chirurgica, sono favoriti dai sostenitori dei diritti dei gatti, ma implicano complicazioni sul piano logistico e risultano comunque essere di portata più limitata. Nel tentativo di inibire la predazione dei gatti domestici sulle specie selvatiche, i proprietari ne limitano l’accesso all’esterno e utilizzano dispositivi che si attaccano ai collari, come campanelle, dispositivi sonori, copri collari colorati e bavagli ingombranti. Altri interventi a livello individuale come, ad esempio, l’arricchimento alimentare e quello comportamentale hanno un potenziale (alcuni potrebbero incrementare il benessere del gatto stesso), ma gli effetti sul comportamento di caccia non sono stati ancora testati. • La comprensione e la gestione del comportamento di caccia dei gatti rappresentano delle sfide complesse. Il presente lavoro evidenzia i fattori che guidano e quelli che facilitano tale comportamento, che rappresentano i punti di partenza per formulare soluzioni che potrebbero essere accettate dai proprietari dei gatti e da tutte le persone che ne valorizzano il benessere, e che al contempo siano efficaci nel salvaguardare gli animali selvatici.
... We also separately estimated cat predation for urban and rural areas (by separating prey data based on respondent answers to the question "Do you live in an urban or rural area?") because cats can have different predation rates in these different landscape types (Kauhala et al., 2015). For below-described analyses, we used estimates of numbers of total families and people in 2017 in China's urban areas (268,471,947 families, 813,470,000 people) and rural areas (190,300,330 families, 576,610,000 people) (China Statistics Press, 2018). ...
Article
Throughout much of the world, growing populations of free-ranging domestic cats pose an increasingly serious threat to biodiversity. However, no study has estimated the magnitude of wildlife mortality caused by cats in China, one of the largest and most biodiverse nations on earth. We used a novel, survey questionnaire-based approach to estimate annual predation on wildlife by cats in China; we separately considered predation rates in urban and rural areas and by both owned free-ranging cats and unowned cats (e.g., feral and semi-feral cats including those associated with feeding and trap-neuter-return (TNR) activities). Using statistical simulations based on 2187 questionnaire responses that included direct observations of prey returns to owners and predation events by unowned cats, we estimate that the minimum annual amount of predation by all free-ranging cats in China is: 1.61-4.95 billion invertebrates, 1.61 -3.58 billion fishes, 1.13-3.82 billion amphibians, 1.48-4.31 billion reptiles, 2.69-5.52 billion birds, and 3.61-9.80 billion mammals. Thus, we show that free-ranging cats cause a tremendous death that may be profoundly impacting China's wildlife populations and biodiversity. Our results indicate that there is an urgent need for increased research into the impacts of cats on wildlife in China, and for management and policy that reduces numbers of free-ranging cats and thus mitigates their harmful effects on China's wildlife.
... A potential key difference in the behavior of pet and feral cats is with regard to how far they move (Kays & DeWan, 2004;Bengsen et al., 2014;Hanmer et al., 2017). Although numerous studies have extrapolated the number of prey that cats kill, the spatial extent of cat predation has not been included in these analyses (Loss et al., 2013;Kauhala et al., 2015;Woinarski et al., 2017). Wider ranging by cats could be worse for conservation as cats that move more may be more likely to traverse into natural habitats. ...
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Domestic cats (Felis catus) are a conservation concern because they kill billions of native prey each year, but without spatial context the ecological importance of pets as predators remains uncertain. We worked with citizen scientists to track 925 pet cats from six countries, finding remarkably small home ranges (3.6 ± 5.6 ha). Only three cats ranged > 1 km2 and we found no relationship between home range size and the presence of larger native predators (i.e. coyotes, Canis latrans). Most (75%) cats used primarily (90%) disturbed habitats. Owners reported that their pets killed an average of 3.5 prey items/month, leading to an estimated ecological impact per cat of 14.2‐38.9 prey ha−1 yr−1. This is similar or higher than the per‐animal ecological impact of wild carnivores but the effect is amplified by the high density of cats in neighborhoods. As a result, pet cats around the world have an ecological impact greater than native predators but concentrated within ~100 m of their homes. Abbreviated summary for graphical TOC: Domestic cats (Felis catus) are a conservation concern because they kill billions of native prey each year, but without spatial context the ecological importance of pets as predators remains uncertain. We found that pet cats are a major concern for sensitive prey species that live near human housing as pet cats have an ecological impact 2–10 times that of typical of native predators.
... On the other hand, natural habitats might be more suitable and preferable to birds, but an extensive contiguous area of a natural type of vegetation (e.g., forest) can support only one functional guild of birds [65,66]. Finally, in urban areas, predation rates on birds are significantly lower than those in rural areas [67] due to the lower abundance of bird predators (with the exception of cats, which are generalist predators [68]), and evidence supports birds with lower parasite infestation than those in natural areas [69][70][71], thus resulting in higher species richness. This may be more evident in alien species for which their successful establishment might be explained by the absence of enemies (e.g., predators, parasites, pathogens) in the new range, i.e., the enemy release hypothesis [72,73]. ...
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Human activities like urbanization and agriculture affect spatial biodiversity patterns. The presence and activities of humans richly benefit alien species, but native species usually decline in human-impacted areas. Considering that the richness of alien and native species are inter-related, we explored the effect of human population density, human-related land uses (agricultural and urban), and natural land area on avian (alien and native) species richness of Massachusetts for two time periods using Generalized Additive Models. Avian alien species richness increased with native species richness in both time periods. Despite the predominant role of native species richness as a major driver of alien species richness, human activities play an important additional role in shaping species richness patterns of established aliens. Human-related land uses (urban and agricultural) and human population favored alien species richness in both time periods. Counter to expectations, human activities were also positively associated to native avian species richness. Possible explanations of these patterns may include habitat heterogeneity, increased availability of resources, and reduced predation risk.
... 41 In Finland, where fewer people and cats live, a study estimated that over 1 million prey animals are taken by free-ranging domestic cats per month, at least 144,000 of which are birds. 42 Yet another study focused on farm cats in Poland and estimated that these kill 136 million birds and 583 million mammals around Polish farms per year. 43 Uncertainty remains concerning precise predation rates and numbers, and concerning the precise magnitude of these impacts on the populations of prey species, given inter alia the difficulty of determining when predation is compensatory-ie cats killing birds that would have died anyway-and when it is additive. ...
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Free-ranging domestic cats (Felis catus) impact biodiversity through predation, disturbance , competition, disease and hybridisation. Scientific knowledge regarding these impacts has recently increased. This article interprets the European Union (EU) Birds and Habitats Directives (Nature Directives) in light of this knowledge. The outcome indicates that various obligations in the Directives, particularly concerning Natura 2000 sites and the generic protection of birds and other species, have significant implications for the management of free-ranging domestic cats. Regarding (unowned) stray and feral cats, these must be removed or controlled when they pose a threat to protected species and/or sites. Regarding (owned) pet and farm cats, the Nature Directives require EU Member States to ensure that letting cats roam free outdoors is forbidden and effectively prevented. Current practice across the EU does not yet conform to these requirements. Whereas the article identifies and assesses various factors that may explain this compliance gap, legally valid justifications appear absent.
... However, while some authors argue that corvids are major nest predators in cities (Groom 1993, Major et al. 1996, Matthews et al. 1999, Jokim€ aki and Huhta 2000, others indicate that this is not necessarily the case (Marzluff et al. 2001b, Borgmann and Rodewald 2004, Stracey 2011. Cats and squirrels are also highly abundant in many cities (Sorace 2002), and two recent reviews indicated that domestic cats are responsible for the majority of the predation pressure in urban environments (Kauhala et al. 2015(Kauhala et al. , E€ otv€ os et al. 2018). However, our results, despite supporting the importance of both corvids and cats in nest survival, do not show differences in corvid or cat abundance between the land-sharing and land-sparing urban areas and therefore do not indicate a direct link between these nest predators and the differential nest predation rate. ...
Article
Urban areas are expanding globally as a consequence of human population increases, with overall negative effects on biodiversity. To prevent the further loss of biodiversity, it is urgent to understand the mechanisms behind this loss to develop evidence-based sustainable solutions to preserve biodiversity in urban landscapes. The two extreme urban development types along a continuum, land-sparing (large, continuous green areas and high-density housing) and land-sharing (small, fragmented green areas and low-density housing) have been the recent focus of debates regarding the pattern of urban development. However, in this context, there is no information on the mechanisms behind the observed biodiversity changes. One of the main mechanisms proposed to explain urban biodiversity loss is the alteration of predator-prey interactions. Using ground nesting birds as a model system and data from nine European cities, we experimentally tested the effects of these two extreme urban development types on artificial ground nest survival and whether nest survival correlates with the local abundance of ground-nesting birds and their nest predators. Nest survival (n = 554) was lower in land-sharing than in land-sparing urban areas. Nest survival decreased with increasing numbers of local predators (cats and corvids) and with nest visibility. Correspondingly, relative abundance of ground nesting birds was greater in land-sparing than in land-sharing urban areas, though overall bird diversity was unaffected by the pattern of urban development. We provide the first evidence that predator-prey interactions differ between the two extreme urban development types. Changing interactions may explain the higher proportion of ground-nesting birds in land-sparing areas, and suggest a limitation of the land-sharing model. Nest predator control and the provision of more green-covered urban habitats may also improve conservation of sensitive birds in cities. Our findings provide information on how to further expand our cities without severe loss of urban-sensitive species and give support for land-sparing over land-sharing urban development.
... In contrast to rodents, likely due to their aesthetical qualities, birds are perceived largely positively by the public and enjoy a high level of protection in European countries (with the exception of pigeons, Columba livia domestica; see Bjerke and Østdahl 2004 for a survey of animal-related attitudes in Norway). 3 As a part of this broader cultural trend, cat predation on birds is perceived as a significant problem not only by their keepers, but also by some scientists (cf. Sims et al. 2008;Kauhala et al. 2015). Care for populations of urban birds (often without critical efforts to consider abundances of different species) contributes to a largely negative assessment of feral cats (cf. ...
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Interaction between humans and cats in urban environments is subject to dynamic change. Based on the frequency and quality of relations with humans, we can distinguish several populations of domestic cats (Felis catus): pedigree, pet, semi-feral, feral, and pseudo-wild. Bringing together theoretical perspectives of the Tartu school of biosemiotics and ethological studies of animal societies, we distinguish two basic types of cat cultures: the culture of street cats and the humano-cat culture of pets. The difference between these cultures is documented on the level of zoosemiotic interactions, ecological relations, and human representations. We introduce a threefold model of human-animal interactions in urban environments which steer a careful course between the Scylla of realistic ontology and the Charybdis of social constructivism. A case study on Estonian cat shelters illustrates the significance of cultural representations and institutionalized actions in human-cat cohabitation.
... Although predation pressure by natural predators in urban areas may be lower than in rural areas (Gering and Blair 1999;Jokimäki and Huhta 2000;Lopez-Flores et al. 2009;Evans et al. 2015), there is an increased possibility to encounter non-familiar species that might potentially be dangerous (especially domestic cats- Kauhala et al. 2015). ...
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Heterospecific alarm calls are typically found in situations where multiple species have a common predator. In birds, they are particularly common in mixed mixed‐species flocks. In species with highly developed social and cognitive abilities like corvids, there is the potential for differential responses to heterospecific vs. conspecific calls according to the riskiness of the habitat. We tested the responses of free‐ranging ravens (Corvus corax) to conspecific alarm calls and compared them to heterospecific alarm calls of jackdaws (Corvus monedula). We observed the proportion of ravens leaving the feeding site after the con‐ or hetero‐specific playback was presented in a situation of low threat (wild boar—Sus scrofa enclosure) and high threat of predation (wolf—Canis lupus enclosure). We show that ravens responded to conspecific calls more intensively at the wolves than at the wild boar, but the response to conspecific calls was in both enclosures stronger than to the control (great tit—Parus major song). The response to the heterospecific alarm was also stronger in the wolves’ enclosure, but it did not differ from control in the wild boar enclosure. These findings suggest that ravens are aware of the meaning of the jackdaw alarm calls, but they respond to it only in a situation of high predatory threat (wolves are present). In the wild boar enclosure, the ravens probably consider jackdaws warning against some other predator, very probably harmless to ravens. This interpretation requires further testing, as both enclosures differ also in respect to other parameters like food quality and shelter availability.
... In Gainesville, Florida, cats were responsible for over 70% of documented depredations on northern mockingbird (Mimus polyglottos) nests in residential neighborhoods, but were never documented depredating mockingbird nests in parking lots, pastures, or wildlife preserves (Stracey 2011). High variation in hunting activity among individual cats, including the occurrence of Bsuper predator^cats in certain studies (i.e. a few individuals who are responsible for the majority of prey returns), makes it difficult to predict where cats are likely to have the greatest impacts (Churcher and Lawton 1987;Barratt 1998;Baker et al. 2005;Tschanz et al. 2010;Thomas et al. 2012;Loyd et al. 2013;Kauhala et al. 2015). In addition, decisions of homeowners and catowners may play a role: where there is little encouragement to keep cats indoors, there may not be a close association between cats and impacts on avian communities due to uniformly high densities of outdoor cats (Sims et al. 2007). ...
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Growing human populations make it imperative for ecologists to identify strategies to conserve biodiversity in human-dominated landscapes, such as cities. Effects of urbanization on birds are particularly well-studied, but questions remain regarding the best conservation approaches. Debate about the relative utility of focusing conservation efforts on nature reserves versus developed lands has focused largely on comparing species abundance or presence, with few studies addressing underlying behavioral or demographic mechanisms. Here we evaluated differences in avian reproductive success in nature reserves and matrix habitats to test the assumption that nest predation is lower within areas protected from development. Specifically, we investigated 1) whether nest survival differed in replicated pairs of forest parks and residential neighborhoods and 2) whether differences in nest survival were associated with changes in which species most frequently depredated nests. From April–August 2007–2014, we monitored nests of two native birds, American robin (Turdus migratorius) and northern cardinal (Cardinalis cardinalis), and video-documented nest predators in paired forest-matrix habitats in the Columbus, Ohio metropolitan area. We found similar rates of nest survival in the two habitats for both robins (Χ21 = 0.715, p = 0.398, n = 741 nests) and cardinals (Χ21 = 0.926, p = 0.336, n = 1156 nests), but interactions between predators and prey differed. In particular, domestic cats (Felis catus) were over five times as likely to depredate cardinal nests in matrix habitats versus forest parks (Χ21 = 7.24, simulated p = 0.010; nforest = 3, nmatrix = 7). Our results suggest that at least in some circumstances, nest success of native birds may be equivalent between nature reserves and adjacent residential matrix habitats, and thus residential neighborhoods may contribute positively to bird conservation in urban landscapes.
... Indeed, it is important to realise that every area will be different, depending on the other predators and prey present. Thus, in America, native predators are able to control rodent pests (Forbush 1916) and, as in Britain (Baker et al. 2008) and Europe (Tschanz et al. 2011;Krauze-Gryz et al. 2012;Kauhala et al. 2015;), there is no problem of tree-climbing ship rats (Rattus rattus, Linnaeus, 1758). The devastating effect the cats (and other predators) have had on islands is beyond dispute (Medina et al. 2011;Doherty et al. 2016). ...
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To study the effects domestic cats may have on surrounding wildlife, a complete list was made of 558 items caught in the garden or brought into the house by one cat over 17 years, from 1988 to 2005. The effect on prey populations was assessed by comparing their abundance with the previous 15 years’ population without a cat. On balance, this cat (Cat 1) was clearly beneficial to the native bird species by killing rodents and deterring mustelids. The diet of a second cat (Cat 2) was recorded in the same way from 2006 to 2016. This cat caught half the number of items 148:287, but in the same proportions: house mice (37.8:42.6); ship rats (12.8:12.1); European rabbits (all young) (8.1:6.7); weasels (0.7:0.4); dunnock (12.8:9.2); house sparrow (2.0:3.1); blackbird (2.7:2.5); song thrush (1.4:1.3); European greenfinch (0.7:5.8); chaffinch (0.7:3.3); silvereye (10.1:8.3); New Zealand fantail (2.0:1.0); lizards (8.1:1.7). Despite this, there were significant differences: Cat 2 avoided finches (2:28, P = 0.004), and took a few more lizards (12:5). For both cats, birds apparently formed about a third of their diet: 33.4% and 34.5%, but comparison of the proportion of birds and rodents brought into the house (12:92) and found dead away from the house (49:45) implies that 320 rodent kills may have been missed, being far more difficult to find. As top predators, these cats were clearly beneficial to native birds, and proposed control or elimination may precipitate mesopredator release and a rabbit problem.
... In Gainesville, Florida, cats were responsible for over 70% of documented depredations on northern mockingbird (Mimus polyglottos) nests in residential neighborhoods, but were never documented depredating mockingbird nests in parking lots, pastures, or wildlife preserves (Stracey 2011). High variation in hunting activity among individual cats, including the occurrence of Bsuper predator^cats in certain studies (i.e. a few individuals who are responsible for the majority of prey returns), makes it difficult to predict where cats are likely to have the greatest impacts (Churcher and Lawton 1987;Barratt 1998;Baker et al. 2005;Tschanz et al. 2010;Thomas et al. 2012;Loyd et al. 2013;Kauhala et al. 2015). In addition, decisions of homeowners and catowners may play a role: where there is little encouragement to keep cats indoors, there may not be a close association between cats and impacts on avian communities due to uniformly high densities of outdoor cats (Sims et al. 2007). ...
Article
The abundance of anthropogenic foods in urban areas offers an excellent opportunity to examine the effects of supplementary food on animal communities, but few studies have examined the consequences of these supplements on relationships between predators and prey. We used observational and experimental approaches to investigate how supplementary food (i.e. bird feeders) affected predator abundances and nest survival of American Robins (Turdus migratorius) and Northern Cardinals (Cardinalis cardinalis) in 7 neighborhoods of Columbus, Ohio, USA. From April to August of 2011-2014, we quantified supplementary foods, the relative abundance of 6 common nest predators, and the nest survival of 2 songbirds. In April-August of 2013 and 2014, we supplemented 3 neighborhoods with additional bird feeders, the supplementary food most frequently available to predators. The effects of bird feeders varied among predator and prey species. Bird feeders were positively associated with the relative abundance of American Crows (Corvus brachyrhynchos) and Brown-headed Cowbirds (Molothrus ater). Neighborhoods with at least 15 feeders had on average 2.7×more crows and 3.2×more cowbirds than neighborhoods with 3 or fewer feeders. Relationships among bird feeders, predators, and nest survival were complex. Nest survival of robins declined with increasing numbers of bird feeders only where crows were most frequently detected. In neighborhoods with the most bird feeders and crows, fewer than 1% of robin nests were expected to survive to fledging (i.e. to 28 days), while in neighborhoods with fewer feeders and/or crows, up to 34% of robin nests were expected to successfully fledge young. In contrast, nest survival rates of cardinals were not related to either feeders or predators. Differences between robins and cardinals in vulnerability to specific predators and diet may partially explain the different patterns that we observed. Thus, although bird feeders generally did not promote nest predation, there may be nuanced and species-specific responses that have the potential to affect common breeding birds.
... Although predation pressure by natural predators in urban areas may be lower than in rural areas (Gering and Blair 1999;Jokimäki and Huhta 2000;Lopez-Flores et al. 2009;Evans et al. 2015), there is an increased possibility to encounter non-familiar species that might potentially be dangerous (especially domestic cats- Kauhala et al. 2015). ...
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Urban animals and birds in particular are able to cope with diverse novel threats in a city environment such as avoiding novel, unfamiliar predators. Predator avoidance often includes alarm signals that can be used also by hetero-specifics, which is mainly the case in mixed-species flocks. It can also occur when species do not form flocks but co-occur together. In this study we tested whether urban crows use alarm calls of conspecifics and hetero-specifics (jackdaws, Corvus monedula) differently in a predator and a non-predator context with partly novel and unfamiliar zoo animal species. Birds were tested at the Tiergarten Schönbrunn in the city of Vienna by playing back con- and hetero-specific alarm calls and control stimuli (great tit song and no stimuli) at predator (wolf, polar bear) and non-predator (eland antelope and cranes, peccaries) enclosures. We recorded responses of crows as the percentage of birds flying away after hearing the playback (out of those present before the playback) and as the number of vocalizations given by the present birds. A significantly higher percentage of crows flew away after hearing either con- or hetero-specific alarm calls, but it did not significantly differ between the predator and the non-predator context. Crows treated jackdaw calls just as crow calls, indicating that they make proper use of hetero-specific alarm calls. Responding similarly in both contexts may suggest that the crows were uncertain about the threat a particular zoo animal represents and were generally cautious. In the predator context, however, a high percentage of crows also flew away upon hearing the great tit control song which suggests that they may still evaluate those species which occasionally killed crows as more dangerous and respond to any conspicuous sound.
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Flestir sem fylgjast með fuglalífi hafa eflaust einhvern tímann velt fyrir sér áhrifum katta á fiðraða vini okkar. Það getur verið sársaukafullt að horfa upp á kött nágrannans tæma þrastarhreiðrið í garðinum, sem veitti okkur ómælda ánægju að fylgjast með, eða sjá ketti hverfisins flykkast þangað sem fuglavinir hafa lagt út fuglafræ og annað góðmeti. Ekki er um það deilt að sumir heimiliskettir veiða fugla og önnur smádýr, en hvaða afleiðingar hafa þessar veiðar og er eitthvað hægt að gera til að draga úr þeim, ef menn vilja gera það? Sambúð manna og katta á sér fornar og flóknar rætur. Sennilega eru fá dýr jafn umdeild í nútímasamfélagi og heimiliskötturinn. Hann er elskaður og hataður; sumir vilja ekki heyra á það minnst að fækka köttum eða hindra á einhvern hátt ferðir þeirra, á meðan aðrir vilja eyða öllum villtum heimilisköttum og banna með öllu lausagöngu gælukatta. Hér verður sagt frá köttum og áhugaverðum tengslum þeirra við manninn. Fjallað verður um áhrif katta á lífríki eftir heimshlutum og loks verður framtíð kattahalds skoðað. Er mögulegt að sætta ólík sjónarmið með hliðsjón af bæði náttúruvernd og dýravelferðarsjónarmiðum?
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DNA metabarcoding of faecal samples is being successfully used to study the foraging niche of species. We assessed the ability of two benchtop high-throughput sequencing (HTS) platforms, to identify a large taxonomic array of food items from domestic cats Felis silvestris catus, including prey and human-related food taxa (pet food and leftovers leaving undetectable solid remains in faeces). Scats from a captive feeding trial (n = 41) and from free-ranging individuals (n = 326) were collected and analysed using a cytb mini-barcode in independent PCR replicates on the Ion PGM and the MiSeq platforms. Outputs from MiSeq were more sensitive and reproducible than those from Ion PGM due to a higher sequencing depth and sequence quality on MiSeq. DNA from intact prey taxa was detected more often (82% of the expected occurrences) than DNA from pet food (54%) and raw fish and meat (31%). We assumed that this variability was linked to different degree of DNA degradation: The Ion PGM detected significantly less human-linked food, birds, field voles, murids and shrews in the field-collected samples than the MiSeq platform. Pooling the replicates from both platforms and filtering the data allowed identification of at least one food item in 87.4% of the field-collected samples. Our DNA metabarcoding approach identified 29 prey taxa, of which 25 to species level (90% of items) including 9 rodents, 3 insectivores, 12 birds and 1 reptile and 33 human-related food taxa of which 23 were identified to genus level (75% of items). Our results demonstrate that using HTS platforms such as MiSeq, which provide reads of sufficiently high quantity and quality, with sufficient numbers of technical replicates, is a robust and non-invasive approach for further dietary studies on animals foraging on a wide range of food items in anthropogenic landscapes.
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Understanding the dynamics of a disease spread requires information on various aspects of the ecology of vector species. The habitat selection and habitat use of raccoon dogs (Nyctereutes procyonoides), badgers (Meles meles), red foxes (Vulpes vulpes) and domestic cats (Felis silvestris catus) were studied in southeastern Finland between 2000 and 2004. The aim was to find out the habitats where these species are most likely to come into contact and possibly transmit diseases, such as rabies, to each other. Raccoon dogs and badgers showed preference for fields and deciduous forests in all scales studied. Raccoon dogs favoured also watersides in summer and young mixed forests in autumn. Foxes and cats showed more individual variation in their habitat selection/use. Analysis of the overlapping areas of seasonal home ranges further demonstrated the significance of deciduous forests and fields. These, and also young mixed forests and open areas, could be called the risky habitats in terms of rabies spread.
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Studies of cat trophic behaviour can be based on collections of the prey brought home or the prey eaten by cats (i.e. analyses of scat/gut contents). Both methods involve biases with respect to palatability, prey size and assessment of hunting rates. Furthermore, these methods are often used on different groups of cats (i.e. house‐based vs. feral), thus results are difficult to compare. In the present study, cats from the same area (rural areas in central Poland) were studied by both methods: prey brought home and prey eaten (scat and gut analyses). Both methods identified mammals as the most frequent prey (followed by birds). However, differences occurred in the percentages of the four main vertebrate groups brought home versus eaten by cats: reptiles tended to be brought home, whereas amphibians tended to be eaten. No such difference was found for birds and mammals. Second, the relative proportions of presumably more palatable and presumably less palatable prey differed. The relative proportions of mice and voles (the latter eaten more frequently) and the relative proportions of soricomorphs and rodents (the latter eaten more frequently) were different. Finally, small prey items (i.e. invertebrates) were recorded incompletely for the brought‐home method. Overall, the prey‐brought‐home method underrepresented small prey and underestimated the predation rate for cats, whereas the prey‐eaten method was less likely to record unpalatable prey. We thus recommend to combine these two methods to obtain fuller and truer assessment of cat predation.
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The house cat Felis catus was introduced to Australia as a pet and means of rodent control over 200 years ago, but now has established feral populations and has become a serious threat to native wildlife. Using stomach content analysis of 73 feral cats from semi-arid grassland habitats in Queensland, Australia, we aimed to identify dominant prey groups in the cats' diet and to explore associations between the diversity of prey eaten and attributes of the cats including body size, condition, sex, age and coat colour. We also sought to determine any relationships between cat size and the size of the dominant prey in the diet, the long-haired rat Rattus villosissimus. Mammals and reptiles were the dominant prey, with R. villosissimus occurring in 60 % of samples and comprising more than half of all prey by volume. Birds and terrestrial invertebrates were the next most important contributors to the diet, but fish, frogs and freshwater crustaceans also were surprisingly well represented. The dietary diversity of cats was largely unrelated to any of the cat attributes that we measured, although a positive relationship emerged between cat head width and the range of prey types eaten. Our study was conducted during a population irruption of R. villosissimus and confirms that cats are able to exploit an abundant focal prey resource when the opportunity occurs. Further research now is needed to explore associations between diet and cat attributes during periods when rats are scarce.
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House cats are increasingly suggested as having major ecological impacts in semiurban environments. Information on the activity of house cats is relatively scarce, especially in habitats such as wetlands. This study examines the movement and foraging behaviour of house cats living on the periphery of a wetland reserve in Christchurch city, New Zealand. Twenty-one domestic cats living in a suburban residential area were studied using radiotelemetry to determine home-range size, mean and maximum distances travelled into the adjacent wetland, and the proportion of time spent in the wetland over a 12-month period. Surveys of prey retrieval for 88 cats were also carried out by cat owners over the same 12-month period.. Cat age and the distance of the cat’s home from the periphery of the wetland were highly correlated with cat movement and hunting activity. These movements were not markedly influenced by season or time of day. Younger cats (<6 years of age) living on the periphery of the wetland had larger home-range sizes, moved significantly further into the wetland and spent a significantly greater proportion of time in the wetland. Cats living close to the wetland also brought a greater diversity and a greater total number of prey items to their home-site. Rates of predation were not significantly influenced by sex or whether the cat was wearing a bell. The most common prey items were introduced rodents and birds; however, 172 of 981 prey items were identified as a native common skink. Consequently, cats living in households on the wetland periphery currently pose a predation risk for the wetland species, and the impact of cats on the native skink population warrants further investigation. This study suggests that domestic cats will exploit wild habitats but that their potential impact will have both positive (predation of introduced pest species) and negative (occasional direct predation) effects on native wildlife.
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Since 1985 increasingly more foxes have been recorded from cities in Switzerland. The inquiry of town officials showed that foxes are observed in 28 out of the 30 largest Swiss cities today and breeding dens are known in 20 of these cities. Urban foxes are observed more often than one would expect in larger cities than in smaller towns. In Ziirich, the largest city in Switzerland, urban foxes were very scarce until the early 1980s. According to the hunting statistics, from 1985 onwards, there was a drastic increase in the urban fox population. In the adjacent rural areas, there was also a clear but less extreme increase in the fox population from 1984 onwards due to successful vaccination campaigns against rabies. As an explanation for the presence of foxes in human settlements we sug- gest two alternative hypotheses, which focus either on the population pressure in the rural areas or on the behavioural adaptations of urban foxes. The presence of foxes in urban areas influences behaviour and attitudes of people towards urban wildlife and it has a consequences for the manage- ment of foxes and the treatment of zoonoses such as rabies and the alveolar echinococcosis.
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Despite evidence that pet cats prey on urban wildlife and may transmit disease, there is uncertainty over whether they cause declines in wildlife populations. The uncertainty fosters disagreement about whether and how pet cats should be managed, and hampers the implementation of regulations. We suggest that the precautionary principle could be used in this context. The principle mandates action to protect the environment when there is a scientifically plausible but unproven risk, and provides a rationale for immediate intervention to protect wildlife from pet cats while we await definitive studies. In applying a 4-step guide for implementing the precautionary principle, we argue that: (i) current data documenting wildlife mortality caused by pet cats satisfy the precautionary trigger of scientifically plausible risk; (ii) the risk of significant declines or local extinctions of threatened wildlife, coupled with uncertainty in establishing population declines in response to pet cats, argue for strong levels of precaution; (iii) precautionary measures that should be considered include, but are not limited to, restrictions on the maximum number of cats allowed/household, mandatory sterilisation and registration of pet cats, curfews, requiring pet cats roaming outdoors to wear collar-mounted predation-deterrents or compulsory confinement of cats to their owners' premises; and (iv) the principle's requirement for extensive consultation in implementing precautionary measures should encourage collaborations involving conservation biologists, veterinarians, animal welfare activists, concerned citizens and municipal officers. Adherence to these steps should assist in choosing actions that have broad support and are applicable to unique local circumstances.
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1. A questionnaire survey of the numbers of animals brought home by domestic cats Felis catus was conducted between 1 April and 31 August 1997. A total of 14 370 prey items were brought home by 986 cats living in 618 households. Mammals made up 69% of the items, birds 24%, amphibians 4%, reptiles 1%, fish < 1%, invertebrates 1% and unidentified items 1%. A minimum of 44 species of wild bird, 20 species of wild mammal, four species of reptile and three species of amphibian were recorded. 2. Of a sample of 696 individual cats, 634 (91%) brought home at least one item and the back-transformed mean number of items brought home was 11.3 (95% CI 10.4–12.2). The back-transformed means and number of cats retrieving at least one item from each prey group were: 8.1 (7.4–8.9) mammals for 547 (79%) cats, 4.1 (3.8–4.5) birds for 506 (73%) cats, 2.6 (2.2–3.0) herpetofauna for 145 (21%) cats and 2.2 (1.8–2.7) other items for 98 (14%) cats. 3. The number of birds and herpetofauna brought home per cat was significantly lower in households that provided food for birds. The number of bird species brought home was greater in households providing bird food. The number of birds and herpetofauna brought home per cat was negatively related to the age and condition of the cat. The number of mammals brought home per cat was significantly lower when cats were equipped with bells and when they were kept indoors at night. The number of herpetofauna brought home was significantly greater when cats were kept in at night. 4. Based on the proportion of cats bringing home at least one prey item and the back-transformed means, a British population of approximately 9 million cats was estimated to have brought home in the order of 92 (85–100) million prey items in the period of this survey, including 57 (52–63) million mammals, 27 (25–29) million birds and 5 (4–6) million reptiles and amphibians. 5. An experimental approach should be taken to investigate the factors found by this descriptive survey to influence the numbers of prey brought home by cats. In particular, investigation of potential management practices that could reduce the numbers of wild animals killed and brought home by cats will be useful for wildlife conservation, particularly in suburban areas.
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Kauhala, K. & Holmala, K. 2006: Contact rate and risk of rabies spread between medium-sized carnivores in southeast Finland. — Ann. Zool. Fennici 43: 348–357. Spatial and temporal interaction between medium-sized carnivores (raccoon dog Nyctereutes procyonoides, red fox Vulpes vulpes, European badger Meles meles and domestic cat Felis silvestris catus) was studied in southeast Finland using radio-telemetry to estimate the risk of contact and contact rate (number of contacts) between individuals. There was a high level of overlap between home ranges both within and between species and individuals had frequent contact. The risk of contact was high for members of raccoon dog pairs, individual cats and badgers, but also for raccoon dogs and badgers and for raccoon dogs and cats. The lowest risk of contact was for neigh-bouring raccoon dogs and for male foxes. In this carnivore community the transmis-sion of disease, such as rabies, both within and between species is likely. The role of the badger as a vector of rabies is probably much greater than previously assumed.
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Domestic cats Felis catus, as companion animals provided with supplemental food, are not limited by the availability of wild prey and locally occur at extraordinary high densities. There is growing concern about the potential impact of large cat numbers on native prey populations. In the present study, we quantified the minimum number of animals killed in a rural village in Switzerland by asking owners (1) to estimate the predation rate in advance and (2) to record prey animals returned home by their pets. The frequency distribution of the numbers of prey items was markedly skewed: 16% of the cats accounted for 75% of prey, irrespective of sex, age or breed. A large fraction of owners considerably overestimated their cat’s predation, indicating that surveying predation rates by means of a questionnaire alone is not sufficient. The observed average rate of predation within 48days in spring was 2.29 prey items/cat/month (N = 32 cats); major prey types were rodents (76.1%) and birds (11.1%). The absolute number of prey items taken per area is striking and indicates that cat predation represents an important factor in ecosystems. Its role may be momentous in intensively fragmented urban habitats, where cat densities are especially high. We thus highlight the need to identify the factors determining predation rates of individual cats. Further extended studies, especially in urbanised areas, are needed to quantify the actual impact of cat predation upon the population dynamics of their prey. KeywordsPredation rate–Prey spectrum–Rural habitat–Birds–Small mammals–Conservation
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Cats are among the most successful and damaging invaders on islands and a significant driver of extinction and endangerment. Better understanding of their ecology can improve effective management actions such as eradication. We reviewed 72 studies of insular feral cat diet from 40 islands worldwide. Cats fed on a wide range of species from large birds and medium sized mammals to small insects with at least 248 species consumed (27 mammals, 113 birds, 34 reptiles, 3 amphibians, 2 fish and 69 invertebrates). Three mammals, 29 birds and 3 reptiles recorded in the diet of cats are listed as threatened by the IUCN. However, a few species of introduced mammals were the most frequent prey, and on almost all islands mammals and birds contributed most of the daily food intake. Latitude was positively correlated with the predation of rabbits and negatively with the predation of reptiles and invertebrates. Distance from landmass was positively correlated with predation on birds and negatively correlated with the predation of reptiles. The broad range of taxa consumed by feral cats on islands suggests that they have the potential to impact almost any native species, even the smallest ones under several grams, that lack behavioral, morphological or life history adaptations to mammalian predators. Insular feral cat’s reliance on introduced mammals, which evolved with cat predation, suggests that on many islands, populations of native species have already been reduced. KeywordsDomestic cat– Felis catus –Feeding behaviour–Food web–Island ecosystem–Conservation
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The domestic cat Felis catus has become a feral predator and conservation threat in many regions of the world. In the northern tropical savannas of Australia, there is limited data on feral cat diet, and there is evidence that some mammal populations in this region are starting to show signs of significant population decline. A total of 169 cat stomach samples were collected from north-eastern Australia from 1996 to 1998. Samples were collected from grassland and woodland habitats in winter and summer periods. A total of 106 unique prey types (grouped into 59 categories), representing 974 items, were recorded from all samples of which 8% were invertebrates, 9% amphibians, 41% reptiles, 20% birds, and 22% mammals. Relative significance of prey items was examined by calculating the Index of Relative Importance. Chi-square comparisons of frequency differences among habitat, season, and sex of cat were also undertaken. The most important prey items were grasshoppers (Orthoptera), centipedes (Chiloptera), dunnarts (Sminthopsis spp.), planigales (Planigale spp.), rabbits, quails (Turnix spp., Coturnix sp.), and geckos (Oedura spp., Gehyra spp.). Amphibians and invertebrates were more frequent in summer (wet season) samples, and mammals were more frequent in winter. Similarly, there were more amphibians in woodland samples and more invertebrates in grasslands. There was high dietary overlap and little difference in the diet of male versus female cats. Increasing cat predation in northern Australia may significantly affect the conservation of key groups already under decline (e.g., mammals) and careful innovative solutions to stem cat predation are needed. KeywordsFeral–Predators–Carnivores–Tropical savanna–Mammals–Birds–Conservation
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Assessing the impact (direct or indirect) of introduced predator species on native seabird populations is a clear management priority, particularly so in the simple sub-Antarctic ecosystems where these effects may be dramatic. We evaluated the diet of introduced feral cats (Felis catus L.) on the Grande Terre, Kerguelen archipelago, by analysing 149 scats from 5 sites. Overall, rabbits (Oryctolagus cuniculus) were the primary prey (72.6%), followed by house mice (Mus musculus) (11.6%) and birds (all species confounded, 14.9%). However, the proportions of the three prey species varied among sites, reflecting the spreading pattern of cats onto the Grande Terre. Birds were consumed much less frequently in this study (7.3%, all sites pooled but one) compared to a 1976 study in the same area (66.3%), suggesting that cats had a strong impact on the native avifauna.
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Home ranges and densities of medium-sized carnivores were studied in south-east Finland by radio tracking. The species studied included potential vectors of rabies: the raccoon dogNyctereutes procyonoides (Gray, 1834), red foxVulpes vulpes (Linnaeus, 1758), European badgerMeles meles (Linnaeus, 1758) and domestic catFelis silvestris catus (Schreber, 1777). Home ranges of badgers were largest (mean 14.7 km2) and those of cats smallest (1.5 km2). Home ranges overlapped largely, both within and between species. Most home ranges were larger and population densities lower in south-east Finland compared with those in Western Europe. The pooled density of medium-sized carnivores with overlapping home ranges was, however, high, which may indicate a high risk of a rabies epizootic in this multi-host community. Rabies might also spread rapidly to new areas, because of the large home ranges and, consequently, long dispersal distances. Key words Nyctereutes procyonoides - Vulpes vulpes - Meies meles - Felis silvestris catus -home range-density-rabies
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Analysis of contents of stomachs from feral cats killed during an eradication programme on sub-Antarctic Marion Island indicates that there has been a significant change in the diet. The presence of bird remains in cat stomachs reflects seasonal changes in the abundance of birds on the island, while mice Mus musculus are most frequently eaten when the majority of birds are absent from the island. The frequency of occurrence of mice in the diet increased significantly from 16.4% in 1975 to 60.3% in 1989, while burrowing petrels (Procellariidae) decreased significantly from 97.4% to 60.3%. Birds are still the preferred prey of cats, but because of the reduction in the number of birds as a result of cat predation mice are becoming an increasingly important component in the diet of the remaining cats. -Authors
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Food habits of feral cats (Felis catus) were studied on two small uninhabited islands in the central Pacific Ocean. Cat stomach contents, collected on Howland Island in May 1979 and on Jarvis Island during May 1979 and June-July 1982, revealed that sooty terns (Sterna fuscata) were the primary prey species. Other seabirds, lizards, insects and, on Jarvis Island, house mice were also eaten. Fetal cats may have virtually exterminated the wedge-tailed shearwater colony on Jarvis Island.
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Natural prey of domestic cats (Felis catus) in the Revinge area in southern Sweden during 1974-79 was related to prey abundance, annual production, and availability. Of 1,437 scats collected, 996 contained remains of vertebrate prey. Most cats (80-85%) were house-based and obtained from 15 to 90% of their food from natural prey, depending on abundance and availability of the latter. Wild rabbits (Oryctolagus cuniculus) were the most important prey, and cats responded functionally to changes in abundance and availability of this prey. Prolonged snow cover made rabbits vulnerable to cats irrespective of abundance. Small rodents were the second most important cat prey, while brown hares (Lepus europeus) and birds were less important. In a period with high rabbit abundance, cat predation corresponded to 4% of annual production of rabbits and to about 20% of annual production of field voles (Microtus agrestis) and wood mice (Apodemus silvaticus). Prey choice of feral cats was similar to that of house-based cats, but as the former subsisted almost completely on natural prey, their absolute intake (294 g/day during years with high rabbit abundance) was four times that of an average house-based cat (66 g/day).
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(1) Detailed surveys in nine English towns--Bath, Bournemouth, Poole, Birmingham, Dudley, Sandwell, Solihull, Walsall and Wolverhampton--were undertaken to calculate the numbers of foxes present. Locally, densities were as high as five fox family groups km-2, but mean densities for each city were much lower, ranging from 0.188 (Wolverhampton) to 2.035 (Poole) fox family groups km-2. (2) The distribution and numbers of foxes in six of these urban areas, together with data already available for the city of Bristol, were correlated with habitat variables based on the type of land use and sociological features of the human population. (3) Foxes were found to occur most frequently in residential areas, and less often in city centres and around industry. They preferred areas of owner-occupied housing, particularly when the housing density and the number of people per household were also low. Foxes were less common in residential areas consisting of council-rented housing.
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The food habits of feral cats (Felis catus) were assessed by visual observations and scats collected in two seasons and at two sites in the Galápagos Islands. Cats were seen to both scavenge and attack live prey with a capture efficiency of 32%. In seasonal comparisons significantly more food items were included in the dry season (7.4) than the wet (5.7). Significantly more items were included in the diet at Tagus Cove (7.8) which was less productive than Cerro Colorado (6.7). The diet included both vertebrate and invertebrate prey but vertebrates constituted 71.9% of each scat by weight and 93.4% of the energy. The estimated daily intake of energy was 170 kcal which is at the caloric break even point for non-pregnant females, slightly below that for adult males and pregnant females and well below that for lactating females. The food habit and energetic data were combined to make some predictions about food preferences, foraging decisions and the role of available water on feral cats.
Article
Diets were determined for feral cats from the Victorian Mallee, Kinchega National Park in western New South Wales, and the Victorian eastern highlands. The percentages by weight of introduced mammals eaten (mainly European rabbit and house mouse) were 85, 64 and 45 for Mallee, Kinchega and eastern highland cats, respectively, of which rabbit contributed 74, 56 and 43% respectively to the total diets. The weights of native mammals eaten were 2% and 4% for Mallee and Kinchega cats; the species found were common brushtail possum, planigales and bats. For eastern highland cats the weight of native mammals eaten was 40% and at least 11 species were represented: the most important being southern bush rat (16%), common ringtail possum (8%), common brushtail and/or mountain brushtail possums (5%), brown antechinus (470) and sugar glider (4%). The weights of birds eaten were 9, 18 and 13% for Mallee, Kinchega and eastern highland cats. Less important foods were reptiles, amphibians, fish, arthropods and annelids; some food, both carrion and human food scraps, was scavenged. Seasonal changes in composition of the diet were evident in Mallee cats.
Article
Feral cats (Felis catus) occur throughout central Australia. In this study, we analysed the stomach contents of 390 feral cats collected between 1990 and 1994 from the southern half of the Northern Territory. Cats fed on a wide variety of invertebrates, reptiles, birds and mammals, including animals up to their own body mass in size. Mammals were the most important prey but reptiles were regularly eaten in summer and birds were important in winter. Invertebrates were present in the diet in all seasons. Carrion appeared in stomach samples during dry winters only and this has implications for future control of feral cats.
Article
Urbanization of the red fox (Vulpes vulpes) is usually considered a recent phenomenon, originated in southern England in the 1930s, and having only thereafter spread, or independently originated, elsewhere. In this paper we show that in Finland red foxes have probably been hunted in the vicinity or outskirts of towns at least since the 18th century, and that foxes have been well-known (although unwelcome) visitors in urban areas at least since the late 19th century. One hunter captured 56 red foxes in a small hilly area in the outskirts of the city of Turku, SW Finland, in 1743–1747. In the leading newspaper of Turku urban or periurban visits by red foxes were reported 15 times in 1890–1950, and in 1890–1920 local newspapers in Finland reported urban observations of red foxes in three of the nine cities with more than 10,000 inhabitants at the onset of the First World War. In several instances foxes were reported to have preyed upon domestic fowl. Several fox reports concerned apparently tame individuals. Red foxes were probably attracted to urban areas by the low hygiene levels and human-dependent fauna associated with urban agriculture. We found no direct evidence for reproduction of foxes within urban areas in the study period. Although urban areas were apparently included in the feeding territories of many foxes, active persecution probably prevented establishment of local urban populations.
Article
The domestic cat (FeZis catus) was introduced into the United States over 150 years ago. Imported in small numbers for the primary purpose of con- trolling rodents in our eastern seaboard cities, cats remained scarce for many years. Now an estimated 31 million cats exist across the country (American Humane Association, 1972), and rural cats probably rival in numbers all other large predators combined east of the Great Plains, west of the Sierra Nevada, and in various other localities. In terms of impact on the avifauna, cats may pose little direct threat, for they are reported to kill relatively few birds in most situations (Table 1). Yet as predators on rodents, cats inevi- tably compete for prey with many of our declining raptors, and therein may lie a serious problem. Cats are formidable competitors, able to kill rodents at a great and rapid rate. For example, the removal in eight months of over 4200 mice from a 35-acre study plot was ascribed principally to six cats by Pearson (1964). I am not suggesting a cause-and-effect relationship exists between the his- torical increase of cats and the historical decrease of raptors; however, cats, which are as efficient in their way as guns and DDT, accompany and add another dimension to man's encroachment into wildlife areas. The effects of cat abundance in and about wildlife areas should be monitored as a matter of prudence, especially in view of the decline (see Arbib, 1972) of such for- merly "common" raptors as the Red-shouldered Hawk (Buteo Zineatus), Red- tailed Hawk (B. jamaicensis) , Marsh Hawk (Circus cyaneus), and American Kestrel (P&o sparverius), each of which feeds on rodents to a marked de- gree (May, 1935; MacAtee, 1935). Most environments in rural America have suffered drastic and repeated alterations; many may be unable today to generate prey in sufficient den- sities to sustain both raptors and significant numbers of cats. I decided to probe this possibility when a female cat and two of her offspring killed an impressive number of mammals at my home in southern Illinois. I have studied continuously the predation by these cats over the past six years. During this time, shortages in the mammalian prey of hawks have appeared consistently in the cats' hunting grounds each winter. The present report describes and discusses the annual and seasonal predation by these cats from 1 January 1968 through 31 December 1971. Their predation on non-mam- malian vertebrates (various birds, reptiles, and frogs) is tabulated to round out the account.
Article
In this study we present a review on the diet of the fetal cat on the Canary archipelago, providing the first data from the relict laurel forest (Garajonay National Park). Among the 403 prey items identified in this habitat, rats were most numerous followed by reptiles. A total of 1,047 scat groups has been studied in the last eight years from the main habitats of the Canaries. Most of the 2,963 prey items identified represent introduced mammals (rabbit, Oryctolagus cuniculus; mouse, Mus cf. musculus and rat, Rattus sp.). These prey were commonly captured in most habitats with the exception of high mountain scrub. In this habitat, reptiles were taken instead introduced mammals. They were also more commonly included in the diet from open ground and open forest than from the denser forest. Birds were more frequently consumed in the forest than in open areas. Arthropods appeared in significant proportions in the scats from habitats where these items reached high numbers. The results indicate that the diet of feral cats clearly varies according to the different habitats.
Article
Reproduction was studied in feral cats collected over a 3-y period from south-eastern Australia. Litters were recorded in all months except April, but most births occurred between September and March; from October to January inclusive, all adult females collected were either pregnant or lactating. On average, females dropped two litters per year, the first in spring and the second in summer or early autumn; mean prenatal litter size was 4.4. For females, sexual maturity was reached at an estimated age of 10-12 months and a minimum weight of 2500 g. For males the onset of sexual maturity, as indicated by a more rapid increase in testes size, commenced at a mean weight of 3200 g and was completed at a mean weight of 3800 g and an estimated age of 12-14 months. The lightest males detected undergoing intial spermatogenesis weighed 2600 g. Adult males showed no significant monthly variations in either combined whole testes weight or percentage of seminiferous tubules containing spermatids or spermatozoa. However, significant monthly changes in combined epididymides weight indicated a low-intensity reproductive cycle.
Article
Volunteer cat owners from across the UK were recruited to take part in two trials designed to test the efficacy of collar-mounted warning devices in reducing cat predation rates of native wildlife. Cats equipped with a bell returned 34% fewer mammals and 41% fewer birds than those with a plain collar. Those equipped with an electronic sonic device returned 38% fewer mammals and 51% fewer birds compared with cats wearing a plain collar. There was no significant difference in prey return rates by cats wearing collars equipped with one bell, two bells or the sonic device. Warning devices mounted on quick-release collars are recommended as an effective way of reducing wildlife kill rates by domestic cats. Future research and development aimed at further improving the efficacy of sonic devices is recommended.
Article
The 558 prey items brought home by one domestic cat, recorded over its 17‐year lifetime, included 221 mice, 63 rats, 35 rabbits, 4 hares and 2 weasels. The cat hunted up to 600 m from the house, and prey was caught both inside and outside the 0.5 ha garden. Of the 223 birds brought in, 54 were native, including 43 silvereyes (Zosterops lateralis), but those killed were quickly replaced, so there was always a resident population of 1–2 pairs. The other known native birds comprised five fantails (Rhipidura fuliginosa), four warblers (Gerygone igata), a kingfisher (Halcyon sancta), and a shining cuckoo (Chrysococcyx lucidus). Only nine skinks (Cyclodina aenea) and one frog (Litoria raniformis) were brought in. The abundance of birds and reptiles in the garden showed no apparent change over the 17 years compared with the previous 15‐year‐period without a cat. By contrast, the cat exterminated the rabbit population in the garden, and “farmed” surrounding burrows during its whole life; all other prey killed declined in frequency after the cat was 8–9 years old.
Article
Studies of predation by house cats in Australia have not attempted to compare the composition of prey taken by cats with the relative availability of prey. Information on the composition of vertebrate prey caught by house cats in Canberra was collected by recording prey deposited at cat owners’ residences over 12 months. A total of 1961 prey representing 67 species were collected or reported. In all, 64% of prey were introduced mammals, especially mice and rats, with birds comprising 27% (14% native, 10% introduced, 3% unidentified), reptiles 7%, amphibians 1% and native mammals 1%. Predatory behaviour by house cats appeared largely opportunistic with respect to spatial (habitat) and temporal (daily and seasonal) prey availability and accessibility, although there is mounting evidence from this and other studies that small mammals are the preferred prey. While this means that introduced mice and rats are common prey of house cats in urban and suburban environments, it also suggests that in relatively undisturbed environments adjoining new residential developments, predation by house cats may have a substantial impact on locally abundant, patchily distributed populations of native fauna, particularly mammals. Imposing night-time curfews on cats is likely to lessen predation of mammals but will probably not greatly reduce predation of birds or reptiles.
Article
Prey available to feral cats has included a great variety of nesting seabirds, few of which are present now, landbirds and kiore Rattus exulans. Norway rats Rattus norvegicus reached the island in 1921, providing additional prey, and another potential predator of seabirds. Rats remain the main food, with land birds second in importance; seabirds are now a minor item. Over 90% of rats eaten by cats are kiore although more Norway rats than kiore are trapped. Eradicating cats from Raoul Island is feasible but because Norway rats too are important predators of birds on islands, it is likely that eradicating cats without also eradicating Norway rats will do little to restore the diversity of bird species on Raoul Island. -from Authors
Article
The diets of the fox, Vulpes vulpes, and feral cat, Felis catus, were studied at Yathong Nature Reserve in semi-arid western New South Wales. The overall occurrence of rabbit was 45.1% in stomachs of foxes and 540% in cats, representing 51.3 ahd 82.6% respectively of the weight of stomach contents. Both predators exhibited a functional response to rabbits, Oryctolagus cuniculus, (their staple prey) during the rabbit breeding season. Predation on rabbits was greatest on an increasing prey population during good pasture conditions and a decreasing population during drought. After the rabbit breeding season, diet changed to other prey and resulted in an annual prey cycle which was similar for foxes and cats. Both predators successfully co-exist in the semi-arid environment by primarily utilising different age groups of the same staple prey and to some extent different supplementary prey. Foxes mainly ate adult rabbits and cats young rabbits. During the drought foxes preyed heavily on adult rabbits; cats ate some rabbits but relied heavily on other food sources. The supplementary prey of foxes were invertebrates, birds, reptiles and carrion; small mammals and fruits opportunely eaten. Invertebrates, birds, reptiles and small mammals were supplementary prey for cats with carrion opportunely eaten.
Article
1. Urban areas contain high densities of non-native species, which in the UK include the domestic cat Felis catus (Linnaeus 1758) and the grey squirrel Sciurus carolinensis (Gmelin 1788). The direct predation effects of domestic cats on prey populations attract intense debate, and such influences of the nest-predatory grey squirrel are receiving increasing attention. In contrast, theory predicts that sublethal and indirect effects are more important, but empirical evidence is currently lacking. 2. We conducted controlled model presentation experiments at active urban blackbird Turdus merula (Linnaeus 1758) nests to provide the first empirical evidence that quantifies the potential sublethal and indirect effects of predators (domestic cat and grey squirrel) on avian reproductive success. 3. Domestic cat models reduced subsequent parental provisioning rates, a strong indicator of sublethal effects, by one-third relative to a nonpredatory rabbit Oryctolagus cuniculus (Linnaeus 1758) control. There was no compensatory increase in food load size. Previous experiments demonstrate that this magnitude of reduced food delivery will reduce nestling growth rates by c. 40%. The grey squirrel model induced similar but weaker effects. 4. Following the brief presence of the domestic cat model, subsequent daily nest predation rates, chiefly by corvids, increased by an order of magnitude relative to the squirrel and rabbit models. The intensity of parental nest defence elicited in response to model presentations predicts the probability of such third-party predator predation events, and the domestic cat model generated significant increases in nest defence behaviour. 5. Synthesis and applications. The brief presence of a domestic cat at avian nest sites reduces subsequent provisioning rates and induces lethal trait-mediated indirect effects. We provide the first robust evidence for these latter effects in any avian predator–prey system, although they are likely to be common in many avian assemblages with high predator densities. It is imperative that future assessments of the impact of predatory species on avian prey species take lethal trait-mediated indirect effects into account, as so doing will prevent biased estimates of predator effects and facilitate the design of more effective control strategies. Full mitigation of the sublethal and indirect effects of domestic cats would problematically require permanent indoor housing.
Article
While subsidised populations of feral cats are known to impact their prey populations, little is known about the ecological impact of inside/outside hunting cats (IOHC). We studied IOHC around a suburban nature preserve. Mail surveys indicated an average of 0.275 IOHC/house, leading to a regional density estimate of 0.32 IOHC/ha. A geographical model of cat density was created based on local house density and distance from forest/neighbourhood edge. IOHC hunted mostly small mammals, averaging 1.67 prey brought home/cat/month and a kill rate of 13%. Predation rates based on kills brought home was lower than the estimate from observing hunting cats (5.54 kills/cat/month). IOHC spent most outside time in their or their immediate neighbours' garden/yard, or in the nearby forest edge; 80% of observed hunts occurred in a garden/yard or in the first 10 m of forest. Radio-tracked IOHC averaged 0.24 ha in home-range size (95% minimum convex polygon (MCP)) and rarely entered forest. Confirming this, scent stations detected cats more often near the edge and more cats were detected in smaller forest fragments. There was no relationship between the number of cats detected in an area and the local small mammal abundance or rodent seed predation rates. Cold weather and healthy cat predator populations are speculated to minimise the ecological impact of IOHC on this area.
Article
House Cats Felis catus L., whether attached to human households or not, appear to be versatile opportunistic predators. Their principal prey in most areas are mammals (rodents and rabbits), with bird prey secondary. Trophic niche breadth, as measured by the standard deviation of the spectrum of logarithmically transformed prey sizes (‘SLH’), shows a latitudinal trend, being greater in low latitudes: it is also greater in periods of high prey availability. This appears to be influenced by inclusion of very small prey, especially insects, in areas and seasons when they are available. Both the niche breadth and the mean prey size (niche position) appear to be constant as population mean cat size increases. The most common prey size for cats is about 1% of their own body weights, which is much less than most previously reported values for carnivores.
Article
ABSTRACT As companion animals, domestic cats Felis catus can attain very high densities, and have the potential to exert detrimental effects on prey species. Yet, there is a paucity of information on the impact of cat predation in urban areas, where most cats are likely to be present. We quantified the minimum number of animals killed annually by cats in a 4.2-km2 area of Bristol, UK, by asking owners to record prey animals returned home by their pets. The potential impact of cat predation on prey species was estimated by comparing the number of animals killed with published estimates of prey density and annual productivity. Predator density was 229 cats/km2. Five mammal, 10 bird and one amphibian prey species were recorded. Mean predation rate was 21 prey/cat/annum. The most commonly recorded prey species was the wood mouse Apodemus sylvaticus. Predation on birds was greatest in spring and summer, and probably reflected the killing of juvenile individuals. For three prey species (house sparrow Passer domesticus, dunnock Prunella modularis, robin Erithacus rubecula), estimated predation rates were high relative to annual productivity, such that predation by cats may have created a dispersal sink for juveniles from more productive neighbouring areas. The impact of cats on these species therefore warrants further investigation.
Article
The movements of 10 house cats (4 desexed females, 5 desexed males and 1 intact male) living on the edge of a suburb adjoining grassland and forest/woodland habitat, and a neighbouring colony of seven farm cats, were examined using radio-telemetry over nine months Nocturnal home range areas of the suburban cats varied between 0 02 and 27 93 ha (mean 7 89 ha), and were larger than diurnal home range areas (range 0 02 to 17 19 ha – mean 2 73 ha) Nocturnal home range areas of cats from the farm cat colony varied between 1 38 and 4 46 ha (mean 2 54 ha), and were also larger than diurnal home range areas (range 0 77 to 3 70 ha – mean 1 70 ha) Home ranges of cats in the farm cat colony overlapped extensively, as did those of cats living at the same suburban residence There was no overlap of home ranges of female cats from different residences, and little overlap between males and females from different residences Four of the suburban house cats moved between 390 m and 900 m into habitat adjoining the suburb Polygons describing the home ranges of these animals were strongly spatially biased away from the suburban environment, though the cats spent the majority of their time within the bounds of the suburb Movements further than 100–200 m beyond the suburb edge were always made at night There is evidence that home range sizes and spatial movement patterns of house cats are largely determined by a) the density and spatial distribution of cats utilising separate food resources, b) the personality and social dominance of individual cats, c) the location of favoured hunting and resting/sunning sites, and, d) barriers such as busy roads
Article
We studied predation by approximately 70 domestic cats (Felis catus L.) in the Bedfordshire village of Felmersham over a one-year period. All the prey items brought home by virtually all the cats in the village were recorded and, where possible, identified. A total of 1090 prey items (535 mammals, 297 birds and 258 unidentified animals) were taken, an average of about 14 per cat per year. Twenty two species of birds and 15 species of mammals were identified. The most important items were woodmice (17%), house sparrows (16%) and bank voles (14%). Old cats of both sexes caught fewer prey over the year than young cats. Female cats on the edge of the village also caught more prey than female cats in intermediate or central areas of the village; male cats showed no such effect. The type of prey caught also varied with position in the village; ‘core’ cats caught proportionately more birds than ‘edge’ cats. There was some indication in the data that cats caught fewer prey in areas where cat density was highest, but this effect was impossible to disentangle from position in the village. Weather apparently influenced hunting success. Temperature had no direct influence, but fewer prey were caught in winter; cats also caught less on wet days and windy days. Estimates of the number of house sparrows in the village at the start of the breeding season, and the number of sparrows known to have been caught by the cats, suggest that at least 30% of the sparrow deaths in the village were due to cats. Domestic cats would appear to be major predators in this typical English village.
Article
The role of domestic cats Felis catus in the troubling, on-going decline of many urban bird populations in the UK is controversial. Debate, in the UK and elsewhere, has centred on the level of avian mortality directly imposed by cats, and on whether this is principally compensatory (the 'doomed surplus' hypothesis) or additive (the 'hapless survivor' hypothesis). However, it is well established that predators also have indirect, sub-lethal effects on their prey where life-history responses to predation risk affect birth and death rates. Here, using a simple model combining cat predation on birds with a sub-lethal (fear) effect of cat density on bird fecundity, we show that these sub-lethal effects may be substantial for urban songbirds. When cat densities are as high as has been recorded in the UK, and even when predation mortality is low (e.g. o1%), a small reduction in fecundity due to sub-lethal effects (e.g. o1 offspring year À1 cat À1) can result in marked decreases in bird abundances (up to 95%). Thus, low predation rates in urban areas do not necessarily equate with a correspondingly low impact of cats on birds. Sub-lethal effects may depress bird populations to such an extent that low predation rates simply reflect low prey numbers.
Article
While there is intense debate regarding the impact of domestic cat populations on wildlife, its resolution is hindered by the lack of quite basic information. Domestic cats are generalist and obligate predators that receive supplementary food, and their population density reflects that of humans more than the density of their prey. In such a predator–prey system there is the potential for cat populations to have negative impacts on avian assemblages, which may be indicated by negative correlations between cat density and avian species richness and density. Here we report on the nature of such correlations across urban areas in Britain both for groups of species classified regarding their vulnerability to cat predation and individual species. Taking the availability of green space into account, we find negative relationships between cat densities and the number of bird species breeding in urban 1 km × 1 km squares. These relationships are particularly strong among groups of species that are vulnerable to cat predation. We find positive correlations between cat and avian densities; these have low explanatory power and shallow slopes among the species groups that are particularly vulnerable to cat predation. Evidence that the densities of individual species that are vulnerable to cat predation are negatively correlated with cat densities is equivocal, with at least half the species showing no marked pattern, and the remainder exhibiting contrasting patterns. Our results appear not to be confounded by the density of nest-predating corvids (carrion crow, magpie, and jay), as the density of these species was not strongly negatively correlated with avian species richness or density. The general lack of marked negative correlations between cat and avian densities at our focal spatial scale may be a consequence of consistently high cat densities in our study areas (minimum density is 132 cats per square kilometre), and thus uniformly high impacts of cat populations on urban avian assemblages.
Article
Feral cat Felis catus predation on seabirds has been well documented; however, details regarding shifts in feral cat diet in relation to seabird availability, seabird predation rate and impact on seabird population dynamics are scarce. Here, we present data documenting a seasonal shift in feral cat diet at Juan de Nova Island, Mozambique Channel. We also quantify sooty tern Sterna fuscata predation by feral cats and examine the impact on sooty terns over both the short term (by removing individual cats from sub-colonies) and over the longer term by highlighting their influence on population growth rate (λ) using a deterministic matrix model. Cat diet shifted dramatically from insects, rats and mice outside the tern breeding season to primarily terns when terns were breeding. The predation rate of sooty terns at Juan de Nova was estimated at 5.94 terns cat−1 day−1, with a proportion of these (22%) being killed without being consumed (‘surplus kills’). When only one cat was removed from each sub-colony, tern predation declined tenfold in the short term. From our matrix model, the annual growth rate for sooty terns was 1.01 in the absence of cat predation. It remained above one until a predation impact equivalent to approximately three times the estimated cat density (12.04 per km2) was incorporated. Our results demonstrate that cats preferentially predate and have an impact on breeding sooty terns at Juan de Nova, and that an increase in cat density could lead to negative effects on population growth, despite the large breeding tern population.
Article
We evaluated whether a collar-worn pounce protector, the CatBib™, reduces the number of vertebrates caught by pet cats and whether its effectiveness was influenced by colour or adding a bell. Fifty-six cats identified as hunters were studied in Perth, Australia over six weeks in November/December 2005 (southern hemisphere spring/summer). Cats spent three weeks wearing a device and three weeks without it and we recorded the number of prey brought home during each period.Cats caught 65 birds (13 species), 67 herpetofauna (11 species) and 164 mammals (five species). Alone or together with bells CatBibs stopped 81% of cats from catching birds, 33% from catching herpetofauna and 45% from catching mammals. Cats wearing CatBibs or CatBibs and bells caught only 25% of all birds, 43% of all herpetofauna and 36% of all mammals captured. Both colours were equally effective. Adding bells conferred no additional protection. Only one cat did not adjust to the CatBib and there was no long-term evidence that CatBibs altered cats’ fighting or wandering behaviour.Owners volunteered because of one or more of: environmental concern (81%), curiosity (38%), personal (35%) or family (24%) distress caused by hunting. Most owners (70%) said they would continue to use CatBibs although only 17% were doing so eight months later because some cats had stopped hunting or lost their CatBibs. Although confinement of pet cats is the complete solution to preventing predation on wildlife, deterrents such as the CatBib are effective if used consistently.