Analyzing approaches to feral cat management

Stoskopf, M. K., & Nutter, F. B. (2004). Analyzing approaches to feral cat management-one size does not fit all. Journal of the American Veterinary Medical Association, 225(9), 1361-1964.
"... A varied array of tools needs to be available to facilitate humane solutions to a highly varied set of problems posed by the amazingly adaptable feral cat ..."

Citizen science as a tool for conservation

Cooper, C. B., Dickinson, J., Phillips, T., & Bonney, R. (2007). Citizen science as a tool for conservation in residential ecosystems. Ecology and Society,12(2), 11.

Human activities, such as mining, forestry, and agriculture, strongly influence processes in natural systems. Because conservation has focused on managing and protecting wildlands, research has focused on understanding the indirect influence of these human activities on wildlands. Although a conservation focus on wildlands is critically important, the concept of residential area as an ecosystem is relatively new, and little is known about the potential of such areas to contribute to the conservation of biodiversity. As urban sprawl increases, it becomes urgent to construct a method to research and improve the impacts of management strategies for residential landscapes. If the cumulative activities of individual property owners could help conserve biodiversity, then residential matrix management could become a critical piece of the conservation puzzle. “Citizen science” is a method of integrating public outreach and scientific data collection locally, regionally, and across large geographic scales. By involving citizen participants directly in monitoring and active management of residential lands, citizen science can generate powerful matrix management efforts, defying the “tyranny of small decisions” and leading to positive, cumulative, and measurable impacts on biodiversity.

Uses cats vs. wildlife as example

Identification of sites of high conservation priority impacted by feral cats in Australia

Dickman, C. R., Denny, E. A., & Buckmaster, T. (2010). Identification of sites of high conservation priority impacted by feral cats. Report to the Department of Environment, Water, Heritage and the Arts, Canberra.

Feral cats (Felis catus) have been recorded throughout the Australian mainland and on many offshore islands. Predation by feral cats has been implicated, together with other factors, in the population declines of many species of native vertebrates. Some of these declines have resulted in the shifting of species’ conservation status to a more endangered level, with several native species having become extinct. Predation by feral cats is classified as a key threatening process by the Australian Government under the Environment Protection and Biodiversity Conservation Act 1999. 

The cryptic nature of the cat, its exploitation of both modified and unmodified habitats, its status as both a pest and a pet species, and the abundance of introduced prey species and supplemental food sources throughout its range, all contribute to the many acknowledged problems associated with the control or eradication of feral cats in Australia. 

In the absence of a single, robust way to measure cat densities and the known difficulties associated with assessing cat impacts at the species level, indirect methods are required to prioritise sites for the implementation of cat control programs. 

This report uses an interactive decision-making tree based on characteristics of prey species to provide a relative measure of probable cat impacts between sites on the Australian mainland and offshore islands. The decision-making tree provides a single score for geographical (IBRA) regions, specific mainland sites and offshore islands that may be used comparatively for the allocation of resources for cat control programs. Although the scores in this report are based only on those species listed in the Australian Government’s Threat Abatement Plan for Predation by Feral Cats (2008), comparative scores can be calculated and allocated for sites that support any species at risk of predation by feral cats and classified as threatened, endangered, or vulnerable at the national, state or local level. Indeed, the decision-making tree also allows non-threatened species to be assessed for their risk of predation from cats, should the need arise to do so.

The interactive decision-making tree provided comparative scores for the potential impact of cats in each IBRA region of Australia. These scores varied from a high of 328 for the South Eastern Highlands IBRA region of eastern Australia, to a low of 24 for the Gawler IBRA region of South Australia and for three other IBRA regions located wholly or largely in Western Australia. However, there were also 9 IBRA regions with no extant TAP-listed species; these consequently received no scores. The decision-making tree also rovided comparative scores for the impact of feral cats in specific sites throughout the mainland and on offshore islands. These scores, based on data provided by land managers or available in the literature, varied from highs of 117 for the Diamantina National Park in Queensland and 108 for the East Gippsland area in Victoria, to a low of 10 for Dirk Hartog Island off the Western Australian coast. Further scores were calculated for sites at which cat control is uncertain (‘data deficient’) and from which cats have been eradicated or never recorded to identify sites that could be potentially impacted by feral cats in future. These scores varied from a high of 201 for sub-Antarctic Macquarie Island to a low of 9 for Boondelbah Island off the coast of New South Wales. 

We conclude that feral cat control on the Australian mainland is a long-term, multifaceted,labour- and resource-intensive venture requiring site-specific control methods that provide systematic and regular downward pressure on feral cat populations. An effective program of management should also include concurrent control of populations of both stray and owned domestic cats. We conclude further that greater 

success in cat control programs will be achieved by targeting specific sites using site-specific control methods. Human activities such as urban and rural development, agriculture and habitat modification favour the establishment and maintenance of feral cats. We recommend that a ‘nil tenure’ approach to cat control, with management activities encompassing public- and privately-owned reserved land as well as adjacent urban, rural and semi-rural developments, is necessary to reduce the feral cat population on the Australian mainland and offshore islands. In the absence of a sustained and integrated approach of this kind, declines and losses of native species are likely to continue.

More on Macquarie island cats

See more on Dirk Hartog Island feral cat eradication proposal

Dog predation on livestock in NSW

Fleming , P.J.S. & T.J. Korn. 1989. Predation of livestock by wild dogs in eastern New South Wales. The Australian Rangeland Journal 11(2) 61 - 66

A monthly survey involving officers from eastern New South Wales Pastures Protection Boards was conducted over four years from 1982 to 1985. Information was collected on the number and type of livestock attacked within each board district, sightings of wild dogs, the number of wild dogs killed, the method by which they were killed and the locations at which the observations occurred. A total of 25,644 livestock animals were reported killed or wounded from four regions; the North-East Coastal Region, the North-East Tablelands Region, the Central-East Region and South-East Region. Sheep were the most commonly attacked domestic animals followed by cattle and goats. Regional differences were apparent in the type of livestock killed and seasonal patterns of predation were evident. We recommend that annual control programmes be brought forward from June/July to late April in order to precede predation peaks.

Cats: perceptions and misconceptions

Perry, G. (1999). Cats–perceptions and misconceptions: two recent studies about cats and how people see them. In Proceedings of the 8th National Conference on Urban Animal Management in Australia, Gold Coast, Queensland.

 Current figures suggest that cat ownership in Australia is declining, yet cats, properly managed, make ideal pets for those living in high density housing and/or whose lifestyles require that their pets spend long periods alone. State governments and local authorities are increasingly requiring that owners control their cats and that animal management staff enforce these regulations.

These studies suggest that the majority of cat owners are responsible. Once they have adopted a cat, usually a ‘moggie’, they have their cat neutered, but sometimes not until it has had a litter. While many of their cats hunt, as many do not and few hunt often, so this problem is probably overemphasised by non-owners. Contrary to popular belief, they more often hunt lizards than birds.

With the emphasis on the identification of owned cats, it is important to note the reasons given for identifying or not. Any education program to raise awareness of the importance of identification of cats should emphasise the problems which could occur for an unidentified cat and the value of microchipping as an identification tool. All companion animals cause community problems — dogs bark, parrots screech — but both provide companionship whose value outweighs the problems they cause. Cats are particularly misunderstood and often cat owners feel guilt for the sins of their much loved couch potato’s feral counterpart. It is important that the benefits of responsible cat ownership be acknowledged and that strategies are put in place to educate owners on the value of early desexing, confinement and correct identification.

Home range of free-roaming domestic cats

Horn, JA, Mateus-Pinilla, N, Warner RE, Heske EJ (2011) Home range, habitat use, and activity patterns of free-roaming domestic cats. Journal of Wildlife Management, 75: 1177-1185.

We used radio-telemetry and collar-mounted activity sensors to compare home range size, habitat use, and activity patterns of owned and unowned free-roaming cats on the outskirts of Champaign-Urbana, Illinois, USA. Owned cats (3 M, 8 F) had smaller home ranges than unowned cats (6 M, 10 F), but we failed to detect consistent differences in home range size between the sexes or among seasons. Home ranges of unowned cats included more grassland and urban area than predicted based on availability in all seasons, and farmsteads were selected in fall and winter. Within home ranges, unowned cats shifted their use of habitats among seasons in ways that likely reflected prey availability, predation risk, and environmental stress, whereas habitat use within home ranges by owned cats did not differ from random. Unowned cats were more nocturnal and showed higher overall levels of activity than owned cats. Space use and behavioral differences between owned and unowned cats supported the hypothesis that the care a cat owner provides influences the impact a cat has on its environment, information that is important for making decisions on controlling cat populations.

Human attitudes towards stray cats management options

Ash, S. J., & Adams, C. E. (2003). Public preferences for free-ranging domestic cat (Felis catus) management options. Wildlife Society Bulletin, 31(2): 334-339.

Debate has occurred in recent years regarding the control of cat (Felis catus) populations. We investigated attitudes of Texas A&M University (TAMU) employees toward domestic cats living on university property and methods available for population control. We randomly selected 1,000 TAMU faculty and staff of the College Station campus from among 9,562 names in the university directory and mailed them a self-administered questionnaire. Questions addressed personal characteristics; attitudes about nuisance behaviors associated with cats, euthanasia, and cat overpopulation; preferred control method for cat populations in 6 locations; and expected outcomes of each control method. Preference of control method for cats on campus was influenced by respondents' sex, perception of nuisance, and expected outcome of each control method. While respondents in this study recognized the predatory impact of cats on wildlife species in natural areas and on campus, they did not believe the cat's exotic status or its predation on wildlife was a legitimate reason for controlling population numbers.

Dogs, one of the biggest threats to pudu

Silva-Rodríguez, E. A., Verdugo, C., Aleuy, O. A., Sanderson, J. G., Ortega-Solís, G. R., Osorio-Zúñiga, F., & González-Acuña, D. (2010). Evaluating mortality sources for the Vulnerable pudu Pudu puda in Chile: implications for the conservation of a threatened deer. Oryx, 44(01), 97-103.

We assessed the importance of potential sources of mortality for the Vulnerable southern pudu Pudu puda in southern Chile using the clinical records of wildlife rehabilitation centres, necropsies of animals found in the field and a review of the diet of potential predators. To assess whether the identified mortality sources operate in nominally protected areas, we conducted a camera-trap survey in two areas to determine the presence of pudus and their potential predators. Predation by domestic dogs Canis lupus familiaris and car collisions were the commonest causes of pudu admissions to rehabilitation centres (35 of 44) and of deaths of animals encountered opportunistically in the field (seven of 14). Field data suggest that poaching could also be an important threat to pudus. Pudus were detected in both areas surveyed, accounting for 15.6% of mammal detections. Dogs accounted for 47.8% of all detections of potential predator species, followed by pumas Puma concolor (17.4%), guignas Leopardus guigna (17.4%) and chilla foxes Lycalopex griseus (17.4%). The literature survey implicated only pumas as important pudu predators among native carnivores. Our data suggest that, aside from forest loss, dogs, road kills and probably poaching are important concerns for pudu conservation. Our frequent detections of free-ranging dogs associated with roads within nominally protected areas suggest that long-term efforts to conserve pudu will require not only the protection of remnant native forest but also substantive environmental education to modify dog management near protected areas.

Cat's diet and prey impact in Sweden

Liberg, O. 1984. Food habits and prey impact by feral and house-based domestic cats in a rural area in southern Sweden. Journal of Mammalogy, 65(3): 424-432

Natural prey of domestic cats in the Revinge area in southern Sweden during 1974-79 was related to prey abundance, annual production, and availability. Of 1437 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 (294g/day during years with high rabbit abundance) was 4 times that of an average house-based cat (66 g/day).

Leash regulations lack of impact on small vertebrates

Forrest, A. & C.C. St. Clair. 2006. Effects of dog leash laws and habitat type on avian and small mammal communities in urban parks. Urban Ecosystems, 9:51–66

Remnant natural areas within urban settings can act as important refuges for wildlife, substantially increasing local biodiversity. However, habitat suitability for these species is potentially affected by human recreational activities including the presence of free-running dogs. To compare the diversity and abundance of songbird and small mammal communities between areas with bylaws that require, or do not require, dogs to be leashed, point counts and live-trapping surveys were conducted in three habitat types (deciduous, coniferous, and meadow) in the river valley parks of Edmonton, Alberta. Among birds, there was no difference between areas with different leashing bylaws in species diversity for any of the three habitat types. Similarly, there was no difference in bird diversity for a subset of species that were plausibly breeding at these sites. However, higher bird diversity was recorded in deciduous and coniferous sites than in meadow sites, regardless of leash designation, probably as a function of the horticultural practice of mowing meadows. Among both birds and small mammals, there was no difference in the abundance of individuals as a function of leashing bylaws. Our results suggest that off-leash dogs have no effect on the diversity or abundance of birds and small mammals in urban parks, but it is also possible that other factors, such as leash law compliance, reduced or obscured the effects of off-leash dogs in this study.

Rabbit control to control cats

Glen, A., J. Cruz & R. Pech. 2013. Can rabbit control reduce feral cat numbers at a regional scale? Kararehe Kino, Vertebrate pest research, 21: 20-21

One of the most important factors affecting the abundance of predators is the availability of their prey. In New Zealand, introduced rabbits support populations of introduced predators, including feral cats. The abundance of rabbits may therefore affect the level of predation by cats on native birds, lizards and invertebrates.

...

By adopting a multispecies approach, in which rabbit and cat populations are targeted simultaneously, that both species can be supressed over large areas for long periods. This should have considerable benefits for pasture and for native vegetation and fauna.

Pets or food?

Vigne J.-D. & Guilaine J. 2004. Les premiers animaux de compagnie, 8500 ans avant notre ère ? … ou comment j’ai mangé mon chat, mon chien et mon renard. Anthropozoologica 39 (1) : 249-273. 

The earliest pets, 8500 BC ? …or how I ate my cat, my dog and my fox.

Because they are of little interest economically, the carnivore mammals provide especially favourable characteristics for the archaeological study of the social and symbolic aspects of domestication in the early Neolithic periods. A short review of available data on the beginnings of the domestication of the dog, the cat and other carnivores, mainly in the Near East, allows us to ask questions about the conditions of their domestication.

Recent discoveries from the Preceramic Neolithic of Cyprus shed new light on these questions. They confirm that dog (Canis familiaris), fox (Vulpes vulpes) and cat (Felis s. lybica) were voluntarily brought to the island, and that this took place during the second half of the 9th millennium, the first half and the second half of the 8th millennium, respectively. This introduction suggests taming and appropriation of the animals by the human beings. A burial associating a human and a cat even suggests that these animals were kept as pets. But an important proportion of the bone remains of the three carnivores indicate that people did eat them. Moreover, several clues suggest that all or a part of these animals escaped human control and lived in feral groups. It seems that few dogs or none at all lived in the immediate vicinity of human dwellings. These observations, which conflict with our modern occidental conventions, suggest, for these early Neolithic phases, that the boundary between domestic and wild was fine and variable.


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Cat and dog's gene introgression

Daniels, M.J. & L. Corbett. 2003. Redefining introgressed protected mammals: when is a wildcat a wild cat and a dingo a wild dog? Wildlife Research 30(3) 213 - 218

Interbreeding between protected species and their domestic forms presents a conundrum for wildlife managers and legislators with respect to both defining the taxa concerned and enacting or enforcing conservation measures. Recent research on two species geographically distant but with highly analogous histories, the wildcat (Felis silvestris) in Scotland and the dingo (Canis lupus dingo) in Australia, illustrates the challenges faced. Introgression has left the contemporary wild form of both species difficult to distinguish from many of their domesticated forms. Furthermore, historical definitions, and the protective legislation based on them, have been rendered obsolete by subsequent anthropogenic environmental change. We argue that a new approach is necessary for defining mammalian species in the face of introgression with their domestic forms and environmental change, including persecution. Protecting animals for where and how they live, and for their cultural or ecosystem function value rather than focusing on their appearance, offers the best solution for maintaining their conservation status.

Intraguild interactions between dogs and wild carnivores

Vanak, A.T. 2008. Intraguild interactions between native and domestic carnivores in Central India. PhD. University of Missoury

I determined the various factors affecting the resource selection and spatial ecology of the Indian fox Vulpes bengalensis, a small canid endemic to the Indian subcontinent. Despite being widespread throughout India, and commonly occurring in many dry grassland habitats, little is known about the ecology of this species. I investigated habitat selection by the Indian fox in a grassland region in central India that represents a mix of natural and human-dominated habitats to discern if and how foxes respond to human encroachment on native habitats. I collected home range and habitat selection data on 32 radio-collared Indian foxes in the Great Indian Bustard Wildlife Sanctuary, Nannaj, Maharashtra over a one year period. Adult Indian fox 95% kernel density home-range sizes varied between sexes and among seasons. Males had consistently larger home-ranges than females across all seasons but there was no interseasonal variation. Females had smaller home-range sizes during the cool-dry season which is also the denning period, than during any other season. Compositional analysis of Indian fox selection of home-ranges at the landscape level showed heavy influence of the presence of grasslands, plantations and fallow land. Indian foxes avoided humanmodified habitat such as agricultural land and human settlements. The presence of grasslands was also the dominant predictor of Indian fox habitat selection across seasons within the home-range as determined by AIC ranked discrete-choice models. The results indicate that Indian foxes select for natural grasslands and avoid human-modified habitat.
The distribution, abundance and resource selection patterns of meso-carnivores such as the Indian fox are also heavily influenced by the effects of top-down intraguild competition with sympatric larger carnivores. Competitive dynamics among carnivores are asymmetric and interference competition and the associated occurrence of intraguild predation are unidirectional, with larger carnivores negatively influencing smaller carnivores. Competition can affect the subordinate competitor in several ways: by limiting spatial distributions resulting in scattered interspecies territories, constraining habitat selection, reducing prey encounter rates and food intake, or requiring increased hunting effort.
In my study area, the domestic dog Canis familiaris, is the most common midsized carnivore. As the world’s most common carnivore, dogs are known to interact with wildlife as predators, prey, competitors, and disease reservoirs or vectors. Despite these varied roles in the community, the interaction of dogs with sympatric carnivores is not well understood. Dogs have the potential to be exploitative, interference and apparent competitors with sympatric carnivores.
I examined competition for food between dogs and the Indian fox through dietary analysis. Dogs subsisted largely on human derived material from direct feeding, and scavenging on garbage, crop residue and livestock carcasses (83% relative occurrence).

Wild caught foods constituted only 11% relative occurrence of dog diet. Indian foxes are omnivorous and included a wide variety of food types in their diet. The majority of  Indian fox diet consisted of invertebrates (33% relative occurrence), rodents (20% relative occurrence) and fruits of Zizyphus mauritiana (18.5% relative occurrence). Indian foxes did not include any human derived material, nor did they scavenge from large mammal carcasses, and included only a small portion of agricultural produce in their diet. The diet of free-ranging dogs is typical of dogs from other parts of the world. However, the low contribution of human-derived food sources to the diet of Indian foxes was surprising since the species is a generalist carnivore. Although there was limited dietary overlap between dogs and foxes in this study, dogs may actually be preventing foxes from accessing agricultural lands and human associated foods by interference competition.

Dogs have the potential to be effective interference competitors, especially with medium and small-sized carnivores, and may fulfill the role of a mid-sized canid, especially in areas where the native large carnivore community is depauperate. I experimentally examined the behavioral responses of the Indian fox to the presence of dogs and dog odors. Since resource competition between dogs and foxes is low, it is unclear whether foxes perceive dogs as interference competitors. To test this I exposed foxes to neutral, live dog, and animal odor cues at food trays and recorded the amount of food eaten, time spent at food trays, and vigilance and non-vigilance behaviors. When dogs were visible, foxes continued to visit the food trays, but reduced the amount of time spent (by 83%) and food eaten (by 70%) at those trays. Foxes were 10 times more vigilant during dog trials than during neutral and odor trials and also exhibited lower levels of non-vigilance behavior (resting, playing) when dogs were visible. In contrast, dog odors did not affect fox foraging and activity. These results show that vigilance/foraging tradeoffs due to interference competition can occur between native and domestic carnivores, despite low dietary overlap.

To avoid the effects of interference competition and intraguild predation, subordinate competitors such as the Indian fox can alter space use patterns which may result in a reduction of foraging opportunities. To determine if interference competition between dogs and foxes influences the space use patterns of foxes at a landscape level, I conducted a radio-telemetry study of 32 Indian foxes and 25 free-ranging dogs in and around the Great Indian Bustard Wildlife Sanctuary in central India. Using a logistic regression analysis in an information theoretic framework, I determined the effects of landcover type, primary prey abundance (rodents) and dog presence on the landscape on the space use of foxes. As expected, Indian foxes showed low overlap with dogs based on the volume of intersection index. Top AIC ranked models showed a positive influence of grasslands and a negative influence of agricultural land and dog presence. Rodent abundance only had a weak positive effect. This suggests that fox space use is determined not only by habitat type, but also influenced by the presence of a mid-sized carnivore, the dog.

These results suggest that the competitive intraguild dynamics that are seen among wild carnivores can also occur between wild and domestic carnivores, despite a seeming lack of competition for food and other resources. The role of dogs as intraguild competitors of wild carnivores has thus far been under-recognized. Dogs are among the world’s most common carnivores and are heavily subsidized by humans. As a result, they can occur at high densities even in rural areas, where they tend to range freely into wild habitats. Therefore, dogs can pose threats to native carnivore communities, and extend the edge of anthropogenic disturbance well beyond the borders of human settlements.

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Disease impact of dogs

Vanak, A. T., Belsare, A. V. & Gompper, M. E. 2007. Survey of Disease Prevalence in Free-Ranging Domestic Dogs and Possible Spill-Over Risk for Wildlife – A Case Study from the Great Indian Bustard Sanctuary, Maharashtra - India. Final report submitted to the Rufford Small Grants Foundation, UK. Pp 1-13

Domestic dogs are the world’s most common carnivore, and yet the ecology of free-ranging  dogs has rarely been investigated. Many dog populations are subsidized by humans resulting in  high population density, which presumably also have contact rates above the critical threshold  that allows diseases to persist enzootically within the population. Domestic dogs are the  reservoir of infectious diseases that have led to epidemics of rabies, canine distemper and  canine parvovirus in several wild carnivore species, yet little is known about the disease ecology  of domestic dogs in India, and the potential for spill-over risk to wildlife. This project was carried out to assess the disease exposure and health status of free-ranging domestic dogs in the vicinity of a wildlife reserve in central India. We carried out a sero-prevalence survey of canine distemper virus (CDV), canine parvovirus (CPV) and rabies in the dog population surrounding the Great Indian Bustard Sanctuary in Nannaj, Maharashtra. We sampled 74 dogs from four villages surrounding the wildlife reserve and obtained blood samples for testing for IgM and IgG antibodies to CDV and CPV. We also collected salivary swabs from 31 dogs to test for rabies antigen. Antibodies to CPV were detected in 93.3% of the sampled dogs, while 90.7% of dogs had evidence for recent or past exposure to CDV. This suggests that these diseases are enzootic in the dog population, and may pose a significant threat to wild carnivores if disease control measures are not implemented. Rabies was also detected in 2 (6%) of the dogs tested, raising human health concerns as well. We recommend a comprehensive vaccination and dog population control policy as well as an education campaign on responsible dog ownership among villagers.

Impacts of dogs on wildlife in India

Vanak, A.T. & M.T. Gompper. 2009. Dogs Canis familiaris as carnivores: their role and function in intraguild competition. Mammal Review, 39 (4): 265–283

1. Dogs Canis familiaris are the world’s most common carnivore and are known to interact with wildlife as predators, prey, competitors, and disease reservoirs or vectors.
2. Despite these varied roles in the community, the interaction of dogs with sympatric wild carnivore species is poorly understood. We review how dogs have been classified in the literature, and illustrate how the location and ranging behaviour of dogs are important factors in predicting their interactions with wild prey and carnivores.
3. We detail evidence of dogs as intraguild competitors with sympatric carnivores in the context of exploitative, interference and apparent competition.
4. Dogs can have localized impacts on prey populations, but in general they are not exploitative competitors with carnivores. Rather, most dog populations are highly dependent on human-derived food and gain a relatively small proportion of their diet from wild prey. However, because of human-derived food subsidies, dogs can occur at high population densities and thus could potentially outcompete native carnivores, especially when prey is limited.
5. Dogs can be effective interference competitors, especially with medium-sized and small carnivores. Dogs may fill the role of an interactive medium-sized canid within the carnivore community, especially in areas where the native large carnivore community is depauperate.
6. Dogs can also be reservoirs of pathogens, because most populations around the world are free-ranging and unvaccinated. Diseases such as rabies and canine distemper have resulted in severe population declines in several endangered carnivores coexisting with high-density dog populations. Dogs can therefore be viewed as pathogen-mediated apparent competitors, capable of facilitating large-scale population declines in carnivores.
7. Based on this information, we propose conceptual models that use dog population size and ranging patterns to predict the potential for dogs to be intraguild competitors. We discuss how interactions between dogs and carnivores might influence native carnivore communities.

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FIV and FeLV dynamics

Courchamp, F., C. Suppo, E. Fromont, & C. Bouloux. 1997. Dynamics of two feline retroviruses (FIV and FeLV) within one population of cats. Proceedings of the Royal Society, Biological Sciences, 264(1383): 785–794.
We present a deterministic model of the dynamics of two microparasites simultaneously infecting a single host population. Both microparasites are feline retroviruses, namely Feline Immunodeficiency Virus (FIV) and Feline Leukaemia Virus (FeLV). The host is the domestic cat Felis catus. The model has been tested with data generated by a long-term study of several natural cat populations. Stability analysis and simulations show that, once introduced in a population, FIV spreads and is maintained, while FeLV can either disappear or persist. Moreover, introduction of both viruses into the population induces an equilibrium state for individuals of each different pathological class. The viruses never induce the extinction of the population. Furthermore, whatever the outcome for the host population (persistence of FIV only, or of both viruses), the global population size at the equilibrium state is only slightly lower than it would have been in the absence of the infections (i.e. at the carrying capacity), indicating a low impact of the viruses on the population. Finally, the impact of the diseases examined simultaneously is higher than the sum of the impact of the two diseases examined separately. This seems to be due to a higher mortality rate when both viruses infect a single individual.

FeLV dynamics

Fromont, E., D. Pontier, M. Langlais, F. Courchamp, & M. Artois. 1997. Modelling the feline leukemia virus (FeLV) in natural populations of cats (Felis catus). Theoretical Population Biology 52: 60–70.

A compartmental model was built in order to study the circulation and impact of Feline Leukemia Virus (FeLV) in populations of domestic cats. The model was tested with data from a long-term study of several feline populations. The study of stability shows that FeLV is maintained in the population with a stable equilibrium and a slight reduction of population size. Estimation of the transmission rate allows us to make a comparison with the values previously estimated in the literature. We compare the impact of mass vaccination or removal programmes in controlling FeLV infection, and conclude that vaccination is more efficient

FIV dynamics

Courchamp F, D. Pontier, M. Langlais & M. Artois. 1995. Population dynamics of feline immunodeficiency virus within cat populations. Journal Theoretical Biolology, 175(4): 553–560.

A deterministic model was constructed for studying the circulation of Feline Immunodeficiency Virus (FIV), a feline retrovirus homologous to Human Immunodeficiency Virus (HIV) within populations of domestic cats. The model has been tested with data generated by a long!term study of several natural cat populations. Simulations and a study of stability show that once introduced\ the retrovirus is maintained within the population, with a stable equilibrium stage reached by both numbers of susceptible and infected individuals. An estimation of parameters indicates that the transmission rate is low and depends of the structure of the population. In addition, FIV has a low impact on the population in that the total number of cats at equilibrium when this virus is present is almost always equal to the habitat carrying capacity in the absence of the virus. Those results, in agreement with other observations, suggest that FIV originally arose in the distant past.

Transmision modes for FPLV

Berthier, K., M. Langlais, P. Auger, & D. Pontier. 2000. Dynamics of a feline virus with two transmission modes within exponentially growing host populations. Proceedings of the Royal Society, Biological Sciences, 267(1457): 2049–2056.

Feline panleucopenia virus (FPLV) was introduced in 1977 on Marion Island (in the southern Indian Ocean) with the aim of eradicating the cat population and provoked a huge decrease in the host population within six years. The virus can be transmitted either directly through contacts between infected and healthy cats or indirectly between a healthy cat and the contaminated environment: a specific feature of the virus is its high rate of survival outside the host. In this paper, a model was designed in order to take these two modes of transmission into account. The results showed that a mass-action incidence assumption was more appropriate than a proportionate mixing one in describing the dynamics of direct transmission. Under certain conditions the virus was able to control the host population at a low density. The indirect transmission acted as a reservoir supplying the host population with a low but sufficient density of infected individuals which allowed the virus to persist. The dynamics of the infection were more affected by the demographic parameters of the healthy hosts than by the epidemiological ones. Thus, demographic parameters should be precisely measured in field studies in order to obtain accurate predictions. The predicted results of our model were in good agreement with observations.

TNR for feral cat: demography, ecology and potential pathogens

Nutter, F. B. (2006). Evaluation of a Trap-Neuter-Return Management Program for Feral Cat Colonies: Population Dynamics, Home Ranges, and Potentially Zoonotic Diseases. PhD
Management of feral cats is controversial, and alternatives to lethal control methods are gaining popularity. To evaluate the effectiveness of sterilization programs, nine feral cat colonies were divided into groups of three, managed either by spaying females and castrating males, spaying females and vasectomizing males, or leaving all cats intact. Colonies were followed intensively for four years, and intermittently for three additional years. Most cats were trapped in fewer than ten trap nights each. Breeding females produced a mean of 1.4 litters/year and 3 kittens/litter. Kitten mortality was 75% by 6 months of age. Feral and pet domestic cats had similar baseline health status and prevalences of FIV, FeLV, Cryptosporidium, Giardia, and Toxocara cati, but feral cats had higher prevalences of Bartonalla henselae and Toxoplasma gondii. Castrated male and spayed female cats survived longer than intact male and female cats. Survival times of vasectomized males were equivalent to those of intact males. Control colonies decreased in size and remained stable in composition, while intact colonies increased in size and had high turnover. One neutered colony went extinct and several others had fewer than five cats at the end of the project. Home ranges of both intact and neutered cats were small, usually less than 1 ha. Vasectomized males had larger home ranges than either intact or castrated males, probably because they were searching for intact females. Community-level stakeholder meetings were successful in building consensus among groups, and a basic decision tree for feral cat management was developed. Computer simulation modeling using VORTEX software suggested that harvesting breeding colonies every one or two years at 50% to 100% can keep colonies small, but will not lead to long-term reductions in cat numbers. Models of neutered colonies suggested that 75% to 80% sterilization is necessary to cause population decrease and eventual extinction. The mean estimated time to extinction of 12.8 years fits well with ongoing observations of steady decline in sterilized colonies.

Gonadotropin releasing hormone vaccine to control of female feral cats

Friary, J. (2006). Evaluation of a Gonadotropin releasing hormone vaccine for the humane control of female feral cats. (Doctoral dissertation, University of Florida).

The unwanted cat population in the United States numbers in the tens of millions and current control measures have only had limited success in reducing it. Immunocontraception has the potential to humanely reduce this population. The purpose of this study was to investigate the effectiveness of a GnRH-based vaccine for immunocontraception of female cats. It was expected that the treated cats would produce antibodies against GnRH and there would be a positive correlation between high titer and contraception. Adult female cats were divided into a sham group (n = 5) and a treatment group (n = 15) that was immunized once with 200 µg of synthetic GnRH coupled to keyhole limpet hemocyanin and combined with a mycobacterial adjuvant. GnRH antibody titer and serum concentrations of progesterone and estradiol-17β were determined monthly. For the duration of the study the daily photoperiod was manipulated in an attempt to induce estrus. A male breeding cat was housed with the females during the long-day periods, and continuous videography was used to monitor for signs of estrus and breeding. GnRH antibodies were detected in all treated cats by 150 days after immunization, but when the titer in four cats fell below 16,000, they became pregnant and were classified as nonresponders. The titers of the remaining 11 cats (responders) never decreased below 16,000. These cats displayed no signs of behavioral estrus and did not become pregnant by the end of the study 24 months after immunization. All five sham cats became pregnant within one month of the introduction of the male cat. From 60 days after immunization until the end of the study, progesterone concentrations in all responders remained at basal levels, and increased two months before parturition in all cats that became pregnant. The responder cats gained more weight than the nonresponders during the 14 months after immunization (P = 0.004), which is the same response observed in surgically sterilized cats. A single dose of GnRH vaccine resulted in contraception in 73% of the cats for at least 24 months.

Cats around a wetland

Morgan, S. A., Hansen, C. M., Ross, J. G., Hickling, G. J., Ogilvie, S. C., & Paterson, A. M. (2009). Urban cat (Felis catus) movement and predation activity associated with a wetland reserve in New Zealand. Wildlife Research,36(7), 574-580.

Context. 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.

Aims. This study examines the movement and foraging behaviour of house cats living on the periphery of a wetland reserve in Christchurch city, New Zealand.

Methods. 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.

Key results. 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.

Conclusions.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.

Implications. 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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Do wild dogs exclude foxes?

Mitchell, B. D., & Banks, P. B. (2005). Do wild dogs exclude foxes? Evidence for competition from dietary and spatial overlaps. Austral Ecology, 30(5), 581-591.

The management of wild canids (wild dogs/dingoes and foxes) presents a conservation dilemma for land managers across Australia. These canids are predators of wildlife and domestic stock but dingoes are considered native and anecdotal reports suggest that they may suppress foxes such that dingo/dog conservation may have a net benefit to wildlife. This study examines dietary and spatial interactions between wild dogs and foxes in the Greater Blue Mountains region of NSW to address the possibility of suppression through competitive exclusion by dogs on foxes. Predator diets were compared using faecal analysis as well as an analysis of 19 dietary studies from similar forest habitats in eastern Australia. Spatial relationships were examined using data from an extensive canid control programme. Diets of wild dogs and foxes showed a high degree of overlap in species taken, indicating potential for competition. But there was also evidence of resource partitioning with the size and arboreality of mammalian prey differing between the two predators. Wild dogs and foxes responded to different landscape-scale variation in the physical environment, but there was no clear evidence of large-scale differences in their distribution. At the fine scale there was a negative association between these predators that indicated possible temporal avoidance or localized habitat shifts. Therefore, there is evidence for dietary competition and fine-scale exclusion, but no support for landscape-scale exclusion of foxes by wild dogs in the Blue Mountains.

Other perspective on the impact of urban cats

Although the summary don't come into detail, the author states that feral cats have positive effects: predation on rodents, anti-depressive effect for cat-carers, educative impact for children and adults and aesthetic effects. On the negative side, just hygiene and public health.

Natoli, E. 1994. Urban feral cats (Felis catus L.): perspectives for a demographic control respecting the psycho-biologicalwelfare of the species. Ann. Ist. Super. Sanità, 30 (2): 223-227

The presence of feral cats in the urban environment is creating problems of acceptance by human beings, especially in relation to health aspects. In accordance with the protectionist spirit of the law 281 of 14/8/91, the new sensitivity of the Public Veterinary Services for feral cat control in the cities are proposed. These consist mainly in demographic control by means of neutering the cats, with particular attention to the psycho-biological welfare of the species. 

Do domestic cats impose an unsustainable harvest on urban bird populations?

van Heezik Y., A. Smyth, A. Adams & J. Gordon. 2010. Do domestic cats impose an unsustainable harvest on urban bird populations? Biological Conservation. 143(1): 121-130

We assessed the impact of domestic cats on population persistence of native and exotic urban bird populations using a model adjusted for habitat-specific catch rates, cat ownership and hunting activity data. GPS-derived home ranges of 32 cats and resource selection indices demonstrated the degree of penetration and preference for native vegetation fragments. Owners reported on prey brought back by 144 domestic cats in Dunedin, New Zealand, during 12 months. One third of cats never brought back prey, and 21% returned more than one item/month. Cats brought back a mean of 13.4 prey items/year (median = 4), with cats aged <1 year returning more prey than older cats. Birds were the most common prey, followed by rodents. Although cats penetrated adjacent vegetation fragments they did not catch more birds and preferred garden habitat, suggesting that predation pressure may be reduced in fragments. Cat home range size appears to be constrained by cat density while the number of birds caught depends on the density of available prey. Estimates of city-wide catch for six bird species were either more than total urban population size estimates or close to lower confidence intervals. Modelling of three species indicated low likelihood of population persistence with cat predation. The observed persistence of these prey species suggests a meta-population structure with urban populations acting as sinks with source populations located on the city fringe.

Diet of domestic cats in Auckland, NZ

Gillies, C. & M. Clout. 2003. The prey of domestic cats (Felis catus) in two suburbs of Auckland City, New Zealand. Journal of Zoology. 259(3): 309-315

The prey brought in by 80 cats Felis catus over 1 year was monitored in two suburbs of Auckland, New Zealand: one suburb was completely urban, the other on the urban/forest fringe. Cat owners were asked to record and, if possible, keep the prey that their cats brought in. Rodents were the main prey brought in by domestic cats in the urban/forest fringe habitat, whereas invertebrates were the main prey in the fully urban habitat. Birds were caught in similar numbers by cats in both areas and were the second most important prey group at both study sites. However, more native birds were caught by cats in the urban/forest fringe area than in the fully urban habitat. Lizards were caught in similar numbers and were the third most important prey group in both study areas.

Biased perception of predation rate by domestic cats in Switzerland

Tschanz B., D. Hegglin, S. Gloor & F. Bontadina. 2011. Hunters and non-hunters: skewed predation rate by domestic cats in a rural village. European Journal of Wildlife Research. 57(3): 597-602

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 48 days 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.

Domestic cat diet within an Australian National Park

Meek, P.D. 1998. Food items brought home by domestic cats Felis catus (L) living in Booderee National Park, Jervis Bay. Proceedings of The Linnean Society of New South Wales 120: 43-47

Cat owners kept records or the food items brought home by domestic cats living in two adjacent villages surrounded by Booderee National Park, NSW. Durint a 12 motn period food items brought home by seven cats comprise eleven native and three introduced species. One endangered bird was recorded although mammals were the largest prey group.

Home range of domestic cats within an Australian National Park

Meek, P.D. 2003. Home range of house cats Felis catus living within a National Park. Australian Mammalogy 25(1) 51 - 60

Fourteen house cats living in residential areas surrounded by National Park were studied using radio telemetry to determine whether they roamed beyond the urban boundary. Eight cats were recorded using natural habitat, predominantly heath the most abundant habitat type adjacent to residential areas. Ninety two percent of fixes were taken within the fringes of the urban boundary. Mean home range size of house cats was 2.9 ha and two categories of cats were identified based on their tendency to wander away from home. Wandering cats had a home range of 5.1 ha and sedentary cats had a range of 0.4 ha. The mean distance travelled by male cats was 70 m and 30 m for females (range 1.5 – 272 m). The longest straight line distance travelled by a house cat in a single foray from a residence was 1.17 km. The major proportion of forays away from the home environs were undertaken at night and in the afternoon.

Intraguild predation and mesopredator release effect

Russell, J.C., Lecomte, V., Dumont, Y. & Le Corre, M. 2009. Intraguild predation and mesopredator release effect on long-lived prey. Ecological Modelling 220: 1098–1104.

Complete extirpation of a species can generate cascading effects throughout an ecosystem, yet are precisely the goal of island eradications of pest species. “Mesopredator release effect”, an asymmetrical special case of intraguild predation, has been hypothesised as a possible indirect effect from eradications, where superpredator removal can generate a mesopredator increase which may increase the impact on their shared prey. Theoretically this suggests that for intraguild predators, the superpredator may protect the shared prey from mesopredation, and removal of superpredators alone is not recommended. We create a model of long-lived age-structured shared prey and explore the non-equilibrium dynamics of this system. The superpredator can impact all prey life-stages (adult survival and reproductive success) whereas the smaller mesopredator can only impact early life-stages (reproductive success). This model is independently tested with data from a closed oceanic island system where eradication of introduced intraguild predators is possible for conservation of threatened birds. Mesopredator release only occurs in strongly top-down moderated (resource-abundant) systems. Even when mesopredator release can occur, the negative impact of more mesopredators is outweighed by the benefit of superpredator removal, allowing recovery of the prey population. Results are robust to 10% variation in model parameters. The consideration of age-structured prey contradicts previous theoretical results for mesopredator release effect and intraguild predation. Superpredator eradication is vital for population recovery of longlived insular species. Nonetheless island conservation must retain a whole-ecosystem perspective given the complex trophic relationships among multiple species on islands

Free ranging cats' diet in urban and rural Virginia

Mitchell, J.C. & R.A. Beck. 1992. Free-ranging domestic cat predation on native vertebrates in rural and urban Virginia. Virginia journal of Science, 43 (1B): 197-207

Introduced as early as 1614 and imported into the United States in the early 1800s to control rodents in eastern cities, domestic cats (Felis catus) have become major predators on native vertebrates. We studied the diversity and seasonality of free-ranging domestic cat predation on native Virginia vertebrates in a rural environment July 1989-November 1990 and in an urban environment January-November 1990. A total of 27 species (8 bird, 2 amphibian, 9 reptile, 8 mammal) was captured by a single rural cat. One was a mammal of special concern (star-nosed mole), Four urban cats captured 21 species (6 bird, 7 reptile, 8 mammal). The mean number of individuals caught per cat Jan-Nov 1990 was 26 in the urban area and 83 in the rural area. Extrapolation of the number of native vertebrates killed annually by the estimated 1,048,704 free-ranging cats reveals a large, but unrecognized and understudies, negative impact on the biota of Virginia.