Home range of feral cats as introduced apex predators in insular ecosystems

Recio, M. R., & Seddon, P. J. (2013). Understanding determinants of home range behaviour of feral cats as introduced apex predators in insular ecosystems: a spatial approach. Behavioral Ecology and Sociobiology, 1-11.

The introduced feral cat (Felis catus) is a widespread generalist with flexible social behaviour and an apex predator without major interspecific competitors in insular ecosystems that evolved in the absence of predators. Mechanistic definitions consider an animal’s home range to be the spatial expression of a cognitive map that is kept up-to-date with the status of critical resources that contribute to animal fitness. We assumed there are two major determinants structuring the home range of cats as apex predators in insular ecosystems: the distribution of critical food resources and conspecific distribution. We hypothesized that cats structure their home ranges by optimizing the use of staple critical food resources and that as a consequence of the presence of rich resources cats tend to socialise, aggregate and share space. We carried out spatial analyses using location data for feral cats tracked using lightweight GPS collars in conjunction with the suitability value of rabbit patches and their associated ownership costs for cats within a New Zealand braided-river environment. Cat home ranges and spatial distribution, especially for females, were related to the inclusion of rabbit patches within home ranges with higher mean value than the average of neighbourhood patches in the landscape. Cats showed solitary behaviour but tolerance to conspecific presence by sharing high-use areas and high-value rabbit patches, mostly at different times, resulting in occasional encounters among males and females. Home range size and patterns of spatial overlap were dependant on sex and season. Solitary spacing patterns as consequence of innate preferences together with resource constraints may regulate feral cat population densities.

Roaming, stray, and feral domestic cats and dogs as wildlife problems

Van't Woudt, B. D. (1990). Roaming, stray, and feral domestic cats and dogs as wildlife problems. Proceedings of the Fourteenth Vertebrate Pest Conference 1990, Sacramento, California

From several centers of domestication, cats and dogs have become the near-ubiquitous companion of man. Their dependence on man is such that when abandoned in a rural environment most succumb to malnutrition in combination with predation, diseases, parasites, and exposure. Where not subject to predation and where native or introduced prey is adequate, some survive to form feral populations. This applies on oceanic islands, in Australia and New Zealand. Elsewhere, as far as is known today, requirements for survival are met with in parts of the U.S. and Europe only, in remote wilderness areas in the case of dogs, and more widespread, with a tendency to fall back on surplus and waste products of man during hard times in the wild, in the case of cats. Where vermin populations, such as those of rabbits, rats and mice are dense, cats provide inadequate control; they can be useful in keeping small vermin populations small. Away from oceanic islands and desert areas, where their impact on native animals can be disastrous, this makes them sufficiently useful for damage to wildlife (notably to lizards, small marsupials and some birds) to be outweighed, without providing a clear-cut case for a need for control of either roaming, stray or feral cats in rural areas. On the other hand, dogs are potentially destructive animals, whether roaming, stray, or feral; they demand strict control

TNR vs. TVHR to control feral cats

McCarthy, R. J., Levine, S. H., & Reed, J. M. (2013). Estimation of effectiveness of three methods of feral cat population control by use of a simulation model. Journal of the American Veterinary Medical Association,243(4), 502-511.

Objective—To predict effectiveness of 3 interventional methods of population control for feral cat colonies.

Design—Population model.

Sample—Estimates of vital data for feral cats.

Procedures—Data were gathered from the literature regarding the demography and mating behavior of feral cats. An individual-based stochastic simulation model was developed to evaluate the effectiveness of trap-neuter-release (TNR), lethal control, and trap-vasectomy-hysterectomy-release (TVHR) in decreasing the size of feral cat populations.

Results—TVHR outperformed both TNR and lethal control at all annual capture probabilities between 10% and 90%. Unless > 57% of cats were captured and neutered annually by TNR or removed by lethal control, there was minimal effect on population size. In contrast, with an annual capture rate of ≥ 35%, TVHR caused population size to decrease. An annual capture rate of 57% eliminated the modeled population in 4,000 days by use of TVHR, whereas > 82% was required for both TNR and lethal control. When the effect of fraction of adult cats neutered on kitten and young juvenile survival rate was included in the analysis, TNR performed progressively worse and could be counterproductive, such that population size increased, compared with no intervention at all.

Conclusions and Clinical Relevance—TVHR should be preferred over TNR for management of feral cats if decrease in population size is the goal. This model allowed for many factors related to the trapping program and cats to be varied and should be useful for determining the financial and person-effort commitments required to have a desired effect on a given feral cat population.



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Habitat structure mediates the non-lethal effects of mesopredation

Arthur, A. D., Pech, R. P., & Dickman, C. R. (2004). Habitat structure mediates the non‐lethal effects of predation on enclosed populations of house mice. Journal of Animal Ecology, 73(5), 867-877.

1 Prey behavioural changes in response to predation risk can result in significant effects on prey body growth rates and reduced reproductive output, with resultant impacts on prey population dynamics. This paper examines the influence of habitat structure on these non-lethal impacts of predation using a model, field-based experimental system, with house mice as prey.
2 Three treatments were employed in eight 50 × 50 m pens that contained mice, but allowed access to a suite of free-living vertebrate predators, which included feral foxes, feral cats and native raptors: a treatment where the natural grassland vegetation in the pens was maintained at a height < 10 cm; a treatment where small, felled cypress pine trees covered with wire netting were added to low grassland vegetation to create refuge areas covering 10–15% of the area in a pen; and a treatment where predators were excluded from a 25 × 25 m section of some pens with an underlying grassland structure. A 5 × 5 grid of felled trees was added to grassland and predator-exclusion pens to allow assessment of mouse behaviour.
3 Mice in grassland pens avoided open areas, had lower body growth rates, and began breeding later in spring than mice in both predator-exclusion areas, where they foraged more readily in the open, and in refuge pens, where mice avoided open areas but had safe access to supplementary food located within the refuge. These results occurred despite mouse population densities being much lower in grassland pens, and presumably competition for food being much less, compared with under the other treatments.
4 The results indicate predators can have significant non-lethal impacts on prey, and these effects can be mediated by habitat structure.

Ecology of feral cats in open forest in Australia

MOLSHER, R. L. (2006). The ecology of feral cats, Felis catus, in open forest in New South Wales: interactions with food resources and foxes. Australian Nature Conservation Agency

This report provides an overview of the impact of feral cats Felis catus on native fauna of the Pacific region, with particular reference to Australia and its island territories. In Australia, cats take a wide variety of native species of mammals, birds and reptiles, but show evident preference for young rabbits or small marsupials where these are available. Reptiles are taken primarily in and habitats, while birds often feature predominantly in the diet of cats on islands. Despite their catholic diet, population-level impacts of feral cats on native fauna have been poorly documented. There is considerable potential for competition to occur between cats and carnivorous species such as quolls and raptors, but no critical evidence has yet been adduced. There is also potential for amerisal impacts to occur, either via transmission of the pseudophyllidean tapeworm Spirometra erinacei or of the protozoan parasite Toxoplasma gondii, but evidence for deleterious effects in freeliving animals is not compelling. Direct predatory impacts have been inferred from anecdotal and historical evidence, more strongly from failed attempts to reintroduce native species to their former ranges, and most critically from the decimation of island faunas and responses of prey species following experimental removal of cats or reduction of cat numbers. Attributes of the biology of feral cats and their prey species derived from the literature review were used to develop a rank-scoring system to assess the susceptibility of native species to cat predation. Species listed federally as endangered or vulnerable were designated as being at zero, low or high risk of impact from cats according to their attribute scores, and their distributions mapped from primary sources and actual locality data. Based on the number of threatened species they contain, localities and regions within Australia were placed in order of priority for future research to clarify the precise impacts of feral cats. Although difficult and expensive to carry out, controlled and replicated field removal experiments are recommended to elucidate cat impacts in all mainland areas. Removal of cats should take place also on offshore islands and island territories, but only if pilot studies show that this will not release populations of alternative predator species such as introduced rats. If release appears likely, cats should be removed only as a component of an integrated control program that targets all relevant predators.

Impact of exotic generalist predators on the native fauna of Australia

Dickman, C. R. (1996). Impact of exotic generalist predators on the native fauna of Australia. Wildlife Biology, 2(3), 185-195.

This paper reviews the impacts of three species of introduced mammalian predators on native fauna in Australia. The feral cat Felis catus, introduced over 200 years ago, is linked with early continental extinctions of up to seven species of mammals, regional and insular extinctions of many more species of mammals and birds, and the failure of management programs attempting to reintroduce threatened native species to parts of their former ranges. Evidence for cat-impact is largely historical and circumstantial, but supported by observations that afflicted native species are, or were, small (<200 g) occupants of open habitat and hence likely to be especially vulnerable to cat predation. The red fox Vulpes vulpes was released successfully in 1871. Its subsequent spread into all except parts of arid and tropical Australia coincided with local and regional declines of medium-sized (450-5,000 g) mammals, birds and chelid tortoises. The fox has also created recent failures of many management attempts to recover threatened native species. Unequivocal demonstration of fox-impact has been obtained in removal experiments, especially on rock-wallabies Petrogale lateralis. The dingo Canis lupus dingo, introduced 3,500-4,000 years ago, probably caused the extinction of the thylacine Thylacinus cynocephalus and Tasmanian devil Sarcophilus harrisii on mainland Australia. It effectively suppresses extant populations of large mammals, such as kangaroos, and emus, over large areas. Impacts of all three predators are wrought primarily by direct predation. Negative impacts appear to be increased in spatially fragmented forests where native species are restricted to remnant vegetation, and in arid landscapes when native species become restricted temporarily to scattered oases during drought. Alternative prey, especially rabbits Oryctolagus cuniculus, enhance negative impacts on native species by supporting large populations of the predators. It is concluded that feral cats and especially foxes have major negative impacts on certain small and medium-sized native vertebrates in Australia, whereas dingoes have major negative impacts on large species. Dingoes could have positive effects on smaller native species if they significantly suppress populations of foxes and cats. Further quantification of both the direct and indirect impacts of the three predators on native fauna is needed, and should be obtained from experimental field studies.

Exotic mammals structure Australian biota

Davey, C., A. R. E. Sinclair, R. P. Pech, A. D. Arthur, C. J. Krebs, A. E. Newsome, D. Hik, R. Molsher, & K. Allcock (2006). Do exotic vertebrates structure the biota of Australia? An experimental test in New South Wales. Ecosystems,9(6), 992-1008

From 1993 to 2001, we conducted a series of experiments in a mixed grassland–woodland system in central New South Wales (NSW) to quantify the interactions between red foxes and their prey and competitors. Foxes were removed from two areas around the perimeter of Lake Burrendong, and data were collected from these areas and a nearby untreated area before, during, and after the period of fox control. The arrival of rabbit hemorrhagic disease (RHD) in 1996 provided an opportunity to examine the interactive effects of controlling foxes and rabbits. In this landscape, typical of central NSW, (a) the fox population was not affected by a large reduction in the abundance of rabbits, or vice versa; (b) the cat population declined in areas where foxes were removed after the large RHD-induced reduction in rabbit numbers, but there was no consistent response to the removal of foxes; (c) the abundance of some macropod species increased in response only to the combined removal of rabbits and foxes; (d) there were no consistent changes in the abundances of bird species in response to the removal of either foxes or rabbits, but there were clear habitat differences in bird species richness; and (e) there was likely to be an increase in woody plant species after the large reduction in rabbit populations by RHD. We conclude that (a) long-term field experiments (more than 3 years) are required to quantify the indirect consequences of controlling foxes and rabbits, and (b) single manipulations, such as fox control or rabbit control, are not necessarily sufficient for the conservation of remnant woodland communities in southeastern Australia.

Antipredator strategies of house finches in towns

Valcarcel, A., & Fernández-Juricic, E. (2009). Antipredator strategies of house finches: are urban habitats safe spots from predators even when humans are around?. Behavioral Ecology and Sociobiology, 63(5), 673-685.

Urbanization decreases species diversity, but it increases the abundance of certain species with high tolerance to human activities. The safe-habitat hypothesis explains this pattern through a decrease in the abundance of native predators, which reduces predation risk in urban habitats. However, this hypothesis does not consider the potential negative effects of human-associated disturbance (e.g., pedestrians, dogs, cats). Our goal was to assess the degree of perceived predation risk in house finches (Carpodacus mexicanus) through field studies and semi-natural experiments in areas with different levels of urbanization using multiple indicators of risk (flock size, flight initiation distance, vigilance, and foraging behavior). Field studies showed that house finches in more urbanized habitats had a greater tendency to flock with an increase in population density and flushed at larger distances than in less urbanized habitats. In the semi-natural experiment, we found that individuals spent a greater proportion of time in the refuge patch and increased the instantaneous pecking rate in the more urbanized habitat with pedestrians probably to compensate for the lower amount of foraging time. Vigilance parameters were influenced in different ways depending on habitat type and distance to flock mates. Our results suggest that house finches may perceive highly urbanized habitats as more dangerous, despite the lower number of native predators. This could be due to the presence of human activities, which could increase risk or modify the ability to detect predators. House finches seem to adapt to the urban environment through different behavioral strategies that minimize risk.

Cats favoured by habitat fragmentation and isolation

Crooks, K.R. 2002. Relative sensitivities of mammalian carnivores to habitat fragmentation. Conservation Biology 16(2): 488-502.

I examined the effects of habitat fragmentation on the distribution and abundance of mammalian carnivores in coastal southern California and tested the prediction that responses to fragmentation varied with the body size of carnivore species. I conducted track surveys for nine native and two exotic carnivore species in 29 urban habitat fragments and 10 control sites. Fragment area and isolation were the two strongest landscape descriptors of predator distribution and abundance. Six species were sensitive to fragmentation, generally disappearing as habitat patches became smaller and more isolated; three species were enhanced by fragmentation, with increased abundance in highly fragmented sites; and two species were tolerant of fragmentation, with little to no effect of landscape variables on their distribution and abundance. Within urban habitat fragments, the carnivore visitation rate increased at sites with more exotic cover and closer to the urban edge, a pattern driven largely by the increased abundance of fragmentation-enhanced carnivores at edge sites. Finally, body size, in conjunction with other ecological characteristics, partially accounted for the heterogeneity in responses to fragmentation among carnivore species. These differential sensitivities are useful criteria for choosing appropriate focal species for ecological research and conservation planning, a choice that depends on the scale of fragmentation in a region and the commensurate responses of carnivore populations at that scale.

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Examiné los efectos de la fragmentación del hábitat sobre la distribución y abundancia de mamíferos carnívoros en la costa del sur de California y evalué la predicción de que las respuestas a la fragmentación variaban con el tamaño corporal de carnívoros. Se realizaron muestreos de huellas para nueve especies nativas y dos exóticas en 29 fragmentos de hábitat urbano y 10 sitios control. El área fragmentada y su aislamiento fueron los dos principales descriptores de la distribución y abundancia de depredadores. Seis especies fueron sensibles a la fragmentación, generalmente las especies desaparecían conforme los fragmentos eran más pequeños y aislados, tres especies fueron favorecidas por la fragmentación, con incremento en su abundancia en sitios altamente fragmentados, y dos especies fueron tolerantes a la fragmentación con poco o ningún efecto de las variables del paisaje sobre su distribución y abundancia. Dentro de los fragmentos de hábitat urbano, las tasas de presencia de carnívoros incrementaron en sitios con mayor cobertura exótica y cercanos al borde urbano, un patrón dirigido principalmente por el incremento en la abundancia de carnívoros favorecidos por la fragmentación en el borde de los sitios. Finalmente, el tamaño corporal, conjuntamente con otras características ecológicas, fueron parcialmente responsables de la heterogeneidad en respuestas a la fragmentación entre especies de carnívoros. Estas sensibilidades diferenciales son un criterio útil para seleccionar especies focales apropiadas para investigaciones ecológicas y la planeación de la conservación, una selección que depende de la escala de fragmentación en una región y de las respuestas apropiadas de las poblaciones de carnívoros a esa escala.

Rabies risk to Ethiopian wolf

Haydon, D. T., Laurenson, M. K., & Sillero‐Zubiri, C. (2002). Integrating epidemiology into population viability analysis: managing the risk posed by rabies and canine distemper to the Ethiopian wolf. Conservation Biology, 16(5), 1372-1385.

Infectious disease constitutes a substantial threat to the viability of endangered species. Population viability analysis (PVA) can be a useful tool for directing conservation management when decisions must be made and information is absent or incomplete. Incorporating epidemiological dynamics explicitly into a PVA framework is technically challenging, but here we make a first attempt to integrate formal stochastic models of the combined dynamics of rabies and canine distemper into a PVA of the Ethiopian wolf ( Canis simensis), a critically endangered canid. In the absence of disease, populations in habitat patches of every size were remarkably stable and persistent. When rabies virus was introduced, epidemics, assumed to arise from sporadic dog-to-wolf transmission, caused extinction probabilities over 50 years to rise linearly with the force of infection from the dog reservoir and particularly steeply in smaller populations. Sensitivity analysis revealed that although the overall pattern of results was not altered fundamentally by small to moderate changes in disease-transmission rates or the way in which interpack disease transmission was modeled, results were sensitive to the process of female recruitment to male-only packs. Completely protecting wolf populations from rabies through vaccination is likely to be impractical, but the model suggested that direct vaccination of as few as 20–40% of wolves against rabies might be sufficient to eliminate the largest epidemics and therefore protect populations from the very low densities that make recovery unlikely. Additional simulations suggested that the affect of periodic epidemics of canine distemper virus on wolf population persistence was likely to be slight, even when modeled together with rabies. From a management perspective, our results suggest that conservation action to protect even the smallest populations of Ethiopian wolves from rabies is both worthwhile and urgent.

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Las enfermedades infecciosas constituyen una amenaza sustancial contra la viabilidad de las especies en peligro. El análisis de viabilidad poblacional ( PVA) puede ser una herramienta útil para dirigir la conservación para el manejo cuando las decisiones deben ser tomadas y la información es escasa o incompleta. La incorporación de dinámicas epidemiológicas explícitamente dentro de una marco PVA es técnicamente un reto; sin embargo, llevamos a cabo el primer intento para integrar modelos estocásticos formales de la dinámica de la rabia y del moquillo canino para un PVA del lobo etíope (Canis simensis), un cánido críticamente amenazado. En ausencia de la enfermedad, las poblaciones que habitan parches de hábitat de todos los tamaños fueron llamativamente estables y persistentes. Cuando se introduce el virus de la rabia, las epidemias, que supuestamente surgen de transmisiones esporádicas de perro a lobo, hicieron que las probabilidades de extinción sobre 50 años se incrementaran linealmente con la fuerza de la infección del perro reservorio y particularmente de manera abrupta en poblaciones pequeñas. El análisis de sensibilidad reveló que a pesar de que el patrón general de los resultados no haya sido alterado fundamentalmente por cambios pequeños o moderados en las tasas de transmisión de la enfermedad ni por la forma en que la transmisión de la enfermedad al interior del grupo fue modelada, los resultados fueron sensibles al proceso de reclutamiento de hembras en grupos de machos. La protección total de las poblaciones de lobos mediante vacunación contra la rabia probablemente no es práctica, pero el modelo sugiere que la vacunación directa de por lo menos un 20-40% de los lobos podría ser suficiente para eliminar las epidemias más grandes y por lo tanto proteger poblaciones con densidades muy bajas que harían poco probable una recuperación. Posteriores simulaciones sugirieron que las repercusiones sobre epidemias de moquillo canino en la persistencia de poblaciones de lobos serían probablemente ligeras, aún cuando se modelaran conjuntamente con la rabia. Desde la perspectiva del manejo, nuestros resultados sugieren que las acciones de conservación para proteger aún a las poblaciones más pequeñas de lobos etíopes de la rabia son importantes y urgentes.

Two studies on Dog Population in Makurdi, Nigeria

Omudu, E. A., Otache, E. O., & Adelusi, S. M. (2010). Studies on Dog Population in Makurdi, Nigeria (I): Demography and Survey of Pet Owners' Beliefs and Attitudes. Journal of Research in Forestry, Wildlife and Environment, 2(1), 85-93.

A survey of dog population in some residential areas of Makurdi, Nigeria, was investigated using household census and street observation methods, while residents' dog-related attitudes and beliefs were investigated using a structured questionnaire. The average number of dogs per household was 1.43. Dog-human ratio in the study location was 1 dog to every 4 persons, in Wurukum residential area this was however less with the ratio of 1 dog to every 3 persons. There was no significant (X² = 1.42, df = 1, P > 0.05) difference in the distribution of sexes of dogs. The difference between free roaming dogs and those restricted within residential compounds was also not statistically significant (X² = 1.08, P > 0.05). A total of 198 (98.0%) respondents who owned dogs kept them as house guards and/or security alert; only 18.8% of dog owners kept them as pets. The variation in reasons for keeping dogs was significant (X2 = 12.1, P < 0.05). The majority of respondents who do not own dog (91.7%) said it was to avoid dog bites. A significant proportion of respondents (48.0%) who kept dog could not mention any dog disease or disease transmitted by dogs. The implications of these findings are very critical in the control of rabies and other dog-borne disease and mobilization of residents for more responsible dog ownership in Nigeria.


Omudu, E. A., Okpe, G., & Adelusi, S. M. (2010). Studies on Dog Population in Makurdi, Nigeria (II): A Survey of Ectoparasite Infestation and its Public Health Implications. Journal of Research in Forestry, Wildlife and Environment, 2(1), 94-106.

This study investigated the current status of dog infestation by ectoparasites, compared infestation between stray and restricted dogs and investigated some beliefs and practices by dog owners in Makurdi. Ectoparasites were collected using the body brushing and hand-picking methods and identified by standard methods. Dog owners' attitude and perceptions were investigated using structured questionnaires. The prevalence of infestation with ectoparasites among male dogs was 31.5%, though this rate was higher when compared with female dogs that had infestation rate of 23.5%. The difference was not statistically significant (X²= 11.4, df = 1, P > 0.05). Male dogs accounted for 57.8% of the total ectoparasites collected during this study. Stray dogs accounted for 56% of total dogs examined during this study and 58.3% of the ectoparasites were recovered from them. The infestation rates between stray and restricted dogs was statistically significant (X²= 14, df =1, P<0.05). The relative abundance of Rhipicephalus species (53.5%) was statistically highest. Other species of ticks encountered were Boophilus (31.4%) and Amblyomma (8.4%). Lice and fleas recovered from the dogs during this study belong to Linognathus and Ctenocephalis species respectively. Of the dog-borne disease listed, rabies was the most frequently mentioned by 56% of respondents while only 5.2% mentioned tick infestation as potential health risk to dogs and humans. Bathing dogs with brush, soap and detergents (59.6%) was the most popular method of cleaning dogs in Makurdi. This study demonstrated that several dog owners in Makurdi do not have the adequate dog-care information that will protect the health of their pets and safe-guard human health. 

Planning cat eradication on Guadalupe Island

Luna-Mendoza,L., J. M. Barredo-Barberena, J. C. Hernández-Montoya, A. Aguirre-Muñoz, F. A. Méndez-Sánchez, A. Ortiz-Alcaraz, & M. Félix-Lizárraga. 2011. Planning for the eradication of feral cats on Guadalupe Island, México: home range, diet, and bait acceptance. Pages 192-197 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN, Gland, Switzerland.

Feral cats (Felis catus) introduced to new environments have caused the extinction of many vertebrate species, including six species of birds on Guadalupe Island, México. To save species from extinction and restore natural processes, cats have been eradicated from islands using a variety of techniques. Eradication campaigns have to be planned carefully; ideally supported by information about the population to be eradicated. Our study focuses on home range estimation (fixed kernel); bait consumption by feral cats and non-target species; and diet of feral cats on Guadalupe Island. Home range was 76 to 1098 ha (KE 95) and core areas 21 to 196 ha (KE 50). Feral cats and non-target species including Guadalupe junco (Junco hyemalis insularis), Guadalupe rock wren (Salpinctes obsoletus guadalupensis), western gull (Larus occidentalis), and house mouse (Mus musculus) consumed baits. Items most commonly found in diet samples were mice (66.5%) and birds (16.8%). Male cats were 2.9 ± 0.6 kg, and females 2.4 ± 0.9 kg. The results of this study will inform eradication decisions for Guadalupe Island, especially regarding the use of poison baits.

Cats milking seals!!!

Juan-Pablo Gallo-Reynoso, J.P. & C. L. Ortiz. 2010. Feral cats steal milk from northern Elephant Seals. THERYA, 1(3): 207-212

Feral cats abound at Isla de Guadalupe; they forage on birds, mice, and placental tissue as well as carcasses of northern elephant seals (Mirounga angustirostris), Guadalupe fur seal (Arctocephalus townsendi), California sea lions (Zalophus californianus) and stranded cetaceans such as Cuvier’s beaked whale (Ziphius cavirostris). We have found that feral cats are also drinking elephant seal’s milk, stealing it directly from the teats of nursing females. The amount of energy obtained this way might be significant for feral cats in the northern elephant seal rookeries on the island.

Bells and bibs reducing predation by cats in Australia

Calver, M., Thomas, S., Bradley, S., & McCutcheon, H. (2007). Reducing the rate of predation on wildlife by pet cats: The efficacy and practicability of collar-mounted pounce protectors. Biological Conservation, 137(3), 341-348.

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.

Read a short review about belling effectiveness

Bells and electronic sonic device reducing predation by cats in UK

Nelson, S. H., Evans, A. D., & Bradbury, R. B. (2005). The efficacy of collar-mounted devices in reducing the rate of predation of wildlife by domestic cats. Applied Animal Behaviour Science, 94(3), 273-285.

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.

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You can see early reports of CatAlert device here

Clark, N. A. & N.H.K. Burton (1998). A pilot field trial into the effectiveness of the CatAlert™ collar at reducing predation by domestic cats. British Trust for Ornithology.

Clark, N. A. (1999). Progress report on the effectiveness of the Mark II CatAlert™ collar at reducing predation by domestic cats. British Trust for Ornithology.

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Read a short review about belling effectiveness