Cats among the most usual targets of eradication programs on islands

Jones, H. P., Holmes, N. D., Butchart, S. H., Tershy, B. R., Kappes, P. J., Corkery, I., ... & Campbell, K. (2016). Invasive mammal eradication on islands results in substantial conservation gains. Proceedings of the National Academy of Sciences, 201521179.

More than US$21 billion is spent annually on biodiversity conservation. Despite their importance for preventing or slowing extinctions and preserving biodiversity, conservation interventions are rarely assessed systematically for their global impact. Islands house a disproportionately higher amount of biodiversity compared with mainlands, much of which is highly threatened with extinction. Indeed, island species make up nearly two-thirds of recent extinctions. Islands therefore are critical targets of conservation. We used an extensive literature and database review paired with expert interviews to estimate the global benefits of an increasingly used conservation action to stem biodiversity loss: eradication of invasive mammals on islands. We found 236 native terrestrial insular faunal species (596 populations) that benefitted through positive demographic and/or distributional responses from 251 eradications of invasive mammals on 181 islands. Seven native species (eight populations) were negatively impacted by invasive mammal eradication. Four threatened species had their International Union for the Conservation of Nature (IUCN) Red List extinction-risk categories reduced as a direct result of invasive mammal eradication, and no species moved to a higher extinction-risk category. We predict that 107 highly threatened birds, mammals, and reptiles on the IUCN Red List—6% of all these highly threatened species—likely have benefitted from invasive mammal eradications on islands. Because monitoring of eradication outcomes is sporadic and limited, the impacts of global eradications are likely greater than we report here. Our results highlight the importance of invasive mammal eradication on islands for protecting the world's most imperiled fauna.

Belling the cat

After reviewing the available articles considering the effect of bells on feline hunting behaviour, we found a big difference between results of surveys considering cats wearing bells previously to the study and studies where cats were experimentally provided with bells.

Surveys show that bells have little effect on predatory behaviour. After one study, 33% of pet cats wore a bell in UK. Cats wearing a bell hunted fewer mammals than un-belled ones, but there was no difference for birds and herps; probably birds rely more on visual cues than mammals, but maybe skilled cats wear bells more frequently than the rest (Woods et al. 2003). Paton (1991) relying on respondents' memory, found that belling cats has no incidence in the number of preys brought home. In Australia, Reark (1994) found that belled cats hunted more than un-belled ones, but there were not data on how much did they use to hunt before wearing a bell. Barrat (1998) did not find any difference between cats wearing bells or not. In New Zealand, Morgan et al. (2009) got similar results. Hansen (2010) also found no evidence of effect of bells on predation. Comparing sites where belling is compulsory and sites without obligation, no positive correlation was found between small mammal abundance and regulations (Lilith et al., 2010).

Experimental studies where cats were equipped with bells show a decrease between 30 and 50% in the number of preys (Ruxton et al., 2002; Nelson et al., 2005; Gordon et al., 2010). Nevertheless, those studies were, probably, too short (4-8 weeks) to allow cats to learn how to silently stalk their prey. Electronic devices tend to be more effective than bells anone, but are no exempt of problems (Clark & Burton, 1998; Clark, 1999; Nelson et al., 2005). Other devices were more effective, reducing up to 80% the number of preys, but the period was also short (3 weeks) (Calver et al., 2007).

Bright coloured collars seem to be very effective to warn birds on the approaching cat: collared cats kill as much as 19 times less than uncollared animals (Willson et al., 2015), and this could be independent of the cat's skills.

There is a need of longer term studies to better understand the whether

- the effect observed in experimental studies is due to the lack of training, and cats wearing a bell for a longer time will improve their chances

- the lack of effect in surveys is due to a potential bias towards skilled cats wearing bells more frequently that less capable ones.

Are dogs less likely to become truly feral?

Dogs were domesticated in Middle East (vonHoldt et al., 2010) and relationship with South-East Europe wolves has also been proven (Verginelli et al., 2005). In the early times, dogs were likely employed as food (Vigne & Guilaine, 2004), in addition to work and other uses. Interbreeding with local wolves occured in specific dog lineages (vonHoldt et al., 2010) but also modified local wolf genetic pools (Anderson et al., 2009).

Dogs, like cats, probably initiated a process of self-domestication selecting fearless traits in order to favour scavenging (Driscoll et al. 2009). Among the selected traits is, for instance, starch-tolerance (Axelsson et al. 2013).

Reponen et al. (2013) state that few dog populations are truly feral. Following these authors, the only "Western breed" feral dog population occurred in Galápagos. Dingos were introduced in Australia from a small number of individuals (Savolainen et al., 2004) more than 3,500 years B.P. (Oskarsson et al., 2012) and they would be a more primitive breed that had not suffered strong traits selection for specific tasks. Thus, some authors, like Boltani& Ciucci (1995) state that feral dog populations are not self sustainable, having strong juvenile mortality rates compared to wolves.

Although social behaviour of feral dogs could be similar to that of wolves (Cafazzo et al. 2010), there are substantial differences. Free ranging dogs could have several types of mating (monogamy, polygyny, promiscuity, polyandry, opportunity and rape) (Pal, 2011) while in wolf packs alpha male and female are the only breeding individuals (Mech, 1999). This is one of the reasons that probably lead to the smaller link between dogs and their offspring, as they don't usually bring food and act mostly as guard (Pal, 2005). Nevertheless, during their oestrous period bitches clearly searched for the proximity of high-ranking males who displayed affiliative behaviour towards them, while they were more likely to reject the males who intimidated them, and males also seem to prefere dominant females (Cafazzo et al., 2014).

Dogs are also worse imitators of conspecific than wolves (Range & Virányi, 2014). Those differences probably are substantial to domestication process and also complicate the capacity of dogs to become truly independent of humans.

Vulture decline costs in India

Markandya, A., T. Taylor, A. Longo, M.N. Murty, S. Murty & K. Dhavala. 2008. Counting the cost of vulture decline—An appraisal of the human health and other benefits of vultures in India. Ecological Economics, 67 (2): 194–204

Widespread use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac to treat livestock has resulted in dramatic declines in the populations of vultures across India. This has become an issue of considerable concern as vultures are a keystone species and their decline has a range of socio-economic, as well as cultural and biodiversity impacts. In this paper, we review these impacts and estimate in detail the economic cost of one of them: the human health impacts of the vulture decline. Livestock carcasses provide the main food supply for vultures, and are also eaten by dogs. Dogs are the main source of rabies in humans in India, and their populations have increased substantially in parallel with the vulture decline. The potential human health impact of rabies associated with the vulture decline is found to be significant. This, and a wide range of other impacts suggest that significant resources should be put into (1) testing of pharmaceutical products to ensure that similar situations are not repeated, (2) helping vulture populations to recover through the use of alternative drugs to diclofenac that are of low toxicity to vultures, and (3) through conservation breeding programmes.

Review of cat ecology and management strategies in Australia

Denny, E. A., & Dickman, C. R. (2010). Review of cat ecology and management strategies in Australia. Invasive Animals Cooperative Research Centre, Canberra.

Felis catus, the domestic cat, occurs throughout the Australian mainland as well as on more than 40 islands off the Australian coast. Cats exploit diverse habitats, including deserts, forests, woodlands, grasslands, towns and cities, and occur from sea level to altitudes above 2000 m. The classification of cats as domestic, stray or feral (Moodie 1995) reflects the varied ecology of cats and their dichotomous status in Australia — as both a valued pet species and an introduced feral predator.

Impacts

Feral cats are carnivorous hunters that depredate animals up to 2 kg, but more often take prey under 200 g. The feral cat is linked to the early continental extinctions of up to seven species of mammals. They are also linked to island and regional extinctions of native mammals and birds and have caused the failure of reintroduction attempts aimed at re-establishing threatened species. Today, 35 vulnerable and endangered bird species, 36 mammal species, seven reptile species and three amphibian species are thought to be adversely affected by feral cats. Other species are potentially affected by infectious diseases transmitted by cats. The true environmental and economic impact of feral cats has not been calculated.

Legislation

In most Australian states and territories, legislation has been introduced to restrict the reproductive and predation potential of owned domestic cats. Many local government areas have introduced cat-specific legislation, with restrictions including the banning of cats as pets in some communities, compulsory neutering, individual identification, and containment of pet cats.

Predation by feral cats was listed as a Key Threatening Process under the Federal Endangered Species Protection Act 1992 (now incorporated in the Environment Protection and Biodiversity Conservation Act 1999). A Threat Abatement Plan for Predation by Feral Cats was produced in 1999 and amended in 2008 to promote the recovery of vulnerable and endangered native species and threatened ecological communities (Environment Australia 1999 and DEWHA 2008).

Estimating abundance

The three most common techniques for estimating cat abundance in Australia are spotlighting, counting tracks, and bait uptake estimates. The accuracy of spotlighting is dependent upon the density of vegetative cover and cat behaviour; the accuracy of track counts depends upon where track pads are set and the competence of the operative in recognising tracks; and most bait uptake studies provide data on cat activity rather than relative abundance or densities.

All three techniques are best suited to open, dry habitats with low vegetative cover. In wetter, more closed and productive habitats with high vegetative cover, techniques such as remote photography and the analysis of DNA extracted from scats or hairs provide alternatives for estimating abundance or density. Such estimates are a necessary prerequisite for the implementation of control or eradication programs to avoid over- or under-commitment of labour, time and money, and are also necessary to measure the efficacy of management programs.

Techniques for control or eradication

A nationally co-ordinated program of feral cat control across Australia is not feasible, as it is with other introduced species, and control efforts are best targeted at protecting threatened species or habitats. All successful cat eradication programs in Australia have been conducted on islands or within areas bounded by predator-proof fencing, and most have required the use of more than one control method. Successful techniques for the control or eradication of cats on islands have proved largely impractical on the mainland. Hunting, trapping and shooting are time and labour intensive and not economically viable over large areas. Trap-neuter-return is unsuccessful in open populations and not practical over large areas. The introduction of disease (eg panleucopaenia) is restricted by the probable impact on owned domestic cats and the low transmission rate amongst widely dispersed feral cats. Toxins presently registered for cat baiting may have unacceptable environmental impacts on many habitats.

Research into more felid-specific toxins, cat attracting baits and lures and cat-specific toxin delivery systems may lead to the adoption of poisoning as the most widely used technique for the control or eradication of feral cats.

Management at the regional and local level

Management of feral cats requires reliable data on the density or relative abundance of cats in targeted areas, and analysis of the cost effectiveness and efficacy of the various control measures that may be implemented. At the regional and local level, eradication of cat colonies and the management of resource-rich artificial habitats to discourage colonisation by cats should be an adjunct to any feral cat control program. Implementation of companion animal legislation that requires firmer controls on the owned, domestic cat population is also an important consideration for the longer-term reduction of the feral cat population in Australia.

Factors limiting effective management

Although adequate legislation is in place in some jurisdictions, the problems associated with cat control programs in Australia include: the time, cost and social impacts associated with enforcing companion animal legislation; the acceptance in some states of cats as pest control agents; variable cat densities between habitats; relatively low bait acceptance by feral cats; a lack of programs aimed specifically at stray cat colonies exploiting highly modified habitats; little data on the impact of cat removal on populations of introduced rodents and rabbits; and few accurate estimates of the density or relative abundance of feral cats.

Research is needed to define the most successful methods for gaining public acceptance of the importance of maintaining effective companion animal legislation; estimating densities of cats in various habitats; the cost effectiveness of control techniques including broadscale baiting; assessing the impact of the removal of colony-forming cats in resource-rich artificial habitats on the broader feral cat population; and assessing the impact of cat removal on both native and introduced small mammal populations and the further indirect effects of removal on other components of the biota.

Assessment of the effort to eradicate feral cats

Parkes, J., Fisher, P., Robinson, S., & Aguirre-Muñoz, A. (2014). Eradication of feral cats from large islands: an assessment of the effort required for success.New Zealand Journal of Ecology, 38(2), 0-0.

Feral cats (Felis catus) are predators and competitors of native species on many islands and are therefore the target of control efforts. Cat eradication has been achieved on 83 islands worldwide. Six of these successes have been from large islands (over 2000 ha) and have reported sufficient data to examine how the eradication was achieved through combinations of aerial and ground-based poison baiting, fumigation in rabbit burrows used by cats, cage and leghold trapping, day and night shooting, and hunting with dogs. No common sequence of tactics was deployed although leghold traps were used in the latter phases of most projects. It took a mean reported effort of 543 ± 341 person-days per 1000 ha of island over 5.2 ± 1.6 years to completely remove cats and validate success from the six islands. These precedents may assist in planning future proposals to eradicate cats from other large islands.

Cats on islands: impacts other than predation

Medina, F. M., Bonnaud, E., Vidal, E., & Nogales, M. (2014). Underlying impacts of invasive cats on islands: not only a question of predation. Biodiversity and Conservation, 23 (2): 327-342.

The domestic cat has been introduced on most islands worldwide, where it has established feral populations and is currently known to be one of the worst invasive mammalian predators. Predation is the strongest deleterious effect of cats on wildlife, inducing a direct negative impact on population size and dynamics, breeding success and changes in species assemblages. Direct predation is not the only damaging impact on native wildlife, since cats can be responsible for other poorly-documented underlying ecological impacts, like competition, hybridization, disease transmission, ecological process alteration, and behavioral change. Here, we pinpoint relevant examples of these ecological impacts, by searching for accurate data from published literature. We used electronic databases covering most of the world islands where the effects of cats were documented. Knowledge of these impacts can be of great importance to preserve insular ecosystem functions and persistence of endangered native species. We emphasize that direct predation processes should not be the only factor considered in the management of invasive cats on islands.

Impact of introduced cats on island biodiversity

Hervías, S., Oppel, S., Medina, F. M., Pipa, T., Díez, A., Ramos, J. A., Ruiz de Ybáñez, R. & Nogales, M. (2014). Assessing the impact of introduced cats on island biodiversity by combining dietary and movement analysis. Journal of Zoology, 292: 39-47

Populations of feral (not owned by humans) and domestic cats Felis catus coexist in most inhabited islands, and they have similar impacts on native species. Feral cats are generally believed to vary their diet according to prey availability; however, no previous studies of diet have tested this hypothesis on insular ecosystems with a limited range of available prey. Because domestic cats kill prey independently of hunger, the spatial extent of their impact on wildlife will be influenced by home-range size. In this study, we combined dietary information with cat movements to assess the impacts of feral and domestic cats on island biodiversity. We quantified the diet of cats from scat samples collected across one year and tested whether diet varies by season. The abundance of main prey categories was also estimated to document seasonal variation in prey availability for cats. Finally, we tracked domestic cats by global positioning system units in all four seasons to examine whether home-range patterns varied seasonally. The diet of cats constituted three prey groups (rodents, birds and invertebrates), and the seasonal variation in consumption of each taxon matched the seasonal variation in prey availability, thus supporting the generalist behaviour of cats on oceanic islands. Roaming behaviour varied among individuals and across seasons, but could not be explained by availability of prey. Unconfined cats had larger home-ranges than confined cats, but most domestic cats strayed <1 km from home. Thus, confinement of domestic cats might reduce the spatial extent of cat impact on native prey populations on oceanic islands.

Biology and impact of domestic cat in the Pacific

Duffy, D. C., & Capece, P. (2012). Biology and Impacts of Pacific Island Invasive Species. 7. The Domestic Cat (Felis catus) 1. Pacific Science, 66(2), 173-212.

This article reviews the biology, ecological effects, and management of the domestic cat (Felis catus) in the Pacific basin. The cat is one of the most controversial invasive species in the Pacific region because of its complex relations with humans. At one extreme, well-fed domestic house pets are allowed outdoors where they may hunt native animals; at the other, unsocialized feral cats have replaced native predators as apex predators or occupy a new niche on oceanic islands, where they have devastated native faunas. In the middle are stray cats that are still socialized around humans. Feral and stray cats can be reservoirs of diseases that infect free-roaming domestic cats, humans, and wildlife. Given these problems, the best response would be to keep domestic cats indoors, restrict cat breeding, and remove feral populations. However, most Pacific basin societies have failed to reach a consensus on the cat problem, so solutions are ad hoc, often lacking in any scientific basis, and reflect our conflicting views. Compromise management might best fall into three broad classes: (1) eradication of cats should be confined to islands and other areas of high native biodiversity where reintroduction can be prevented; (2) in a landscape of low or moderate biological value, efforts should be made to educate the public to reduce the impact of their cats on remaining wildlife, while excluding cats from “islands” of elevated biodiversity values or human sensitivity; (3) in drastically simplified urban ecosystems, management perhaps should occur only in response to local complaints.

The catastrophic impact of invasive mammalian predators on birds of the UK Overseas Territories

Hilton, G. M., & Cuthbert, R. J. (2010). Review article: The catastrophic impact of invasive mammalian predators on birds of the UK Overseas Territories: a review and synthesis. Ibis, 152(3), 443-458.

The UK has sovereignty over 16 Overseas Territories, which hold some of the world’s great seabird colonies and collectively support more endemic and globally threatened bird species than the whole of mainland Europe. Invasive alien mammalian predators have spread throughout most of the Territories, primarily since European expansion in the 16th century. Here we review and synthesize the scale of their impacts, historical and current, actions to reduce and reverse these impacts, and priorities for conservation. Mammalian predators have caused a catastrophic wave of extinctions and reductions in seabird colony size that mark the UKOTs as a major centre of global extinction. Mammal-induced declines of threatened endemics and seabird colonies continue, with four Critically Endangered endemics on Gough Island (Tristan da Cunha), St Helena and Montserrat directly threatened by invasive alien House Mice Mus musculus, Feral Cats Felis catus and rats Rattus spp. Action to reduce these threats and restore islands has been modest in comparison with other developed countries, although some notable successes have occurred and a large number of ambitious eradication and conservation plans are in preparation. Priority islands for conservation action against mammalian predators include Gough (which according to one published prioritization scheme is the highest-ranked island in the world for mammal eradication), St Helena and Montserrat, but also on Tristan da Cunha, Pitcairn and the Falkland Islands. Technical, financial and political will is required to push forward and fund the eradication of invasive mammalian predators on these islands, which would significantly reduce extinction risk for a number of globally threatened species.

Review of feral cat control

Robertson, S. A. (2008). A review of feral cat control. Journal of Feline Medicine and Surgery, 10(4), 366-375.

Animal overpopulation including feral cats is an important global problem. There are many stakeholders involved in the feral cat debate over ‘what to do about the problem’, including those who consider them a nuisance, the public at risk from zoonotic disease, people who are concerned about the welfare of feral cats, those concerned with wildlife impacts, and the cats themselves. How best to control this population is controversial and has ranged from culling, relocation, and more recently ‘trap neuter return’ (TNR) methods. Data support the success of TNR in reducing cat populations, but to have a large impact it will have to be adopted on a far greater scale than it is currently practised. Non-surgical contraception is a realistic future goal. Because the feral cat problem was created by humans, concerted educational efforts on responsible pet ownership and the intrinsic value of animals is an integral part of a solution.

Feral cats and biodiversity conservation

Nogales, M., E. Vidal, F.M. Medina, E.Bonnaud, B.R. Tershy, K. J. Campbell, & E.S. Zavaleta. 2013. Feral Cats and Biodiversity Conservation: The Urgent Prioritization of Island Management. BioScience 63: 804–810

A great part of the Earth’s biodiversity occurs on islands, to which humans have brought a legion of invasive species that have caused population declines and even extinctions. The domestic cat is one of the most damaging species introduced to islands, being a primary extinction driver for at least 33 insular endemic vertebrates. Here, we examine the role of feral cats in the context of the island biodiversity crisis, by combining data from reviews of trophic studies, species conservation status reports, and eradication campaigns. The integration of these reviews permits us to identify priority islands where feral cat eradications are likely to be feasible and where cats are predicted to cause the next vertebrate extinctions.
Funding agencies and global conservation organizations can use these results to prioritize scarce conservation funds, and national and regional natural resource management agencies can rank their islands in need of feral cat eradication within a global context.

Domestic dogs in Wildlife habitats

Sime, C. A. 1999. Domestic Dogs in Wildlife Habitats. Pages 8.1-8.17 in G. Joslin and H. Youmans, coordinators. Effects of recreation on Rocky Mountain wildlife: A Review for Montana. Committee on Effects of Recreation on Wildlife, Montana Chapter of The Wildlife Society. 307pp.

It is difficult to segregate human demographic trends from trends in rural development and outdoor recreational participation in settings like the West where they appear to be interrelated. One extension of human recreation in wildlife habitats is the effect of disturbance, harassment, displacement, or direct mortality of wildlife attributable to domestic dogs that accompany recreationists. At some level, domestic dogs still maintain instincts to hunt and/or chase. Given the appropriate stimulus, those instincts can be triggered in many different settings. Even if the chase instinct is not triggered, dog presence in and of itself has been shown to disrupt many wildlife species. Authors of many wildlife disturbance studies concluded that dogs with people, dogs on-leash, or loose dogs provoked the most pronounced disturbance reactions from their study animals. During winter, concerns are primarily related to human activity on ungulate winter ranges. Dogs extend the zone of human influence when off-leash. Many ungulate species demonstrated more pronounced reactions to unanticipated disturbances, as a dog off-leash would be until within very close range. In addition, dogs can force movement by ungulates (avoidance or evasion during pursuit), which is in direct conflict with overwinter survival strategies which promote energy conservation. During summer, concerns are primarily related to the birth and rearing of young for all wildlife species. Dogs are noted predators for various wildlife species in all seasons. Domestic dogs can potentially introduce diseases (distemper, parvovirus, and rabies) and transport parasites into wildlife habitats. While dog impacts to wildlife likely occur at the individual scale, the results may still have important implications for wildlife populations. For most wildlife species, if a “red flag” is raised by pedestrian-based recreational disturbance, there could also be problems associated with the presence of domestic dogs. Managers may consider the following when evaluating recreational impacts of dogs in wildlife habitats: species biology, reproductive potential, abundance, density, distribution, degree of habitat specificity or reliance on certain habitat components, and predisposition and sensitivity to disturbance by other agents. This information is intended to increase awareness among natural resource professionals and the public about the potential implications of uncontrolled domestic dogs in wildlife habitats and to encourage responsible outdoor recreation ethics.

Managing impacts of cats in peri-urban reserves

McCarthy, S. (2005). Managing impacts of domestic cats in peri-urban reserves. In Proceedings of the Fourteenth National Conference on Urban Animal Management in Australia.(Australian Veterinary Committee: Canberra.) Available at http://www. uam. net. au/Publications/

Impacts of domestic cats in peri-urban reserves may occur directly through predation, indirectly through disease transmission, by competition with native species and by supplementation of the feral cat population. Predation, in particular, has been the subject of increasing community concern and scientific research in the last decade which has resulted in increased pressure on local government to develop domestic cat control strategies. This literature review discusses domestic cat impacts in peri-urban reserves and management strategies for their control.

Dog as a disturbance agent

Holderness-Roddam, B (2011) The effects of domestic dogs (Canis familiaris) as a disturbance agent on the natural environment. Research Master thesis, University of Tasmania.

This study assesses the impact of domestic dogs on the natural environment. The principal issue investigated is that of disturbance and the consequences for native wildlife, particularly vertebrate species. In addition to the catastrophic effects of killing, maiming and orphaning of wildlife; disturbance can contribute to energetic loss through premature flight or reduced feed intake and reproductive disruption due to nest disturbance. Dogs have been implicated in disease transmission to native wildlife; with faecal contamination of waterways having potential negative affects for marine mammal health. Hybridisation with other canid species is also an issue of concern, as is expropriation of land for the production of food for pet dogs.

The study commences with an overview of ecological disturbance. The literature review then assesses the role of domestic dogs in ecological disturbance, public attitudes towards compliance with dog management legislation and the remediation and mitigation of disturbance by dogs. 

Data obtained from the Resource Management and Conservation section of the Tasmanian Department of Department of Primary Industries, Parks, Water and Environment regarding native wildlife presenting for care was analysed in order to determine the principal reported causes of death and injury to native wildlife in Tasmania. These results were then compared with data from the Australian Wildlife Health Centre - Wildlife Hospital at Healesville Sanctuary in Victoria and the data submitted by Tasmanian veterinarians through a three month diary of wildlife presentations recorded by ten practices.
The data is indicative of domestic dogs having a more deleterious effect than domestic cats on native wildlife in Tasmania; particularly in urban and suburban areas and on beaches.

Nutrient profile of feral cats

Plantinga, E. A., Bosch, G., & Hendriks, W. H. (2011). Estimation of the dietary nutrient profile of free-roaming feral cats: possible implications for nutrition of domestic cats. Br J Nutr, 106, S35-S48.

Cats are strict carnivores and in the wild rely on a diet solely based on animal tissues to meet their specific and unique nutritional requirements. Although the feeding ecology of cats in the wild has been well documented in the literature, there is no information on the precise nutrient profile to which the cat’s metabolism has adapted. The present study aimed to derive the dietary nutrient profile of free-living cats. Studies reporting the feeding habits of cats in the wild were reviewed and data on the nutrient composition of the consumed prey items obtained from the literature. Fifty-five studies reported feeding strategy data of cats in the wild. After specific exclusion criteria, twentyseven studies were used to derive thirty individual dietary nutrient profiles. The results show that feral cats are obligatory carnivores, with their daily energy intake from crude protein being 52 %, from crude fat 46 % and from N-free extract only 2 %. Minerals and trace elements are consumed in relatively high concentrations compared with recommended allowances determined using empirical methods. The calculated nutrient profile may be considered the nutrient intake to which the cat’s metabolic system has adapted. The present study provides insight into the nutritive, as well as possible non-nutritive aspects of a natural diet of whole prey for cats and provides novel ways to further improve feline diets to increase health and longevity.

Hybridization between wolves and dogs

Vila, C., & Wayne, R. K. (1999). Hybridization between wolves and dogs.Conservation Biology, 13(1), 195-198.

Concern has been expressed that European populations of gray wolves (Canis lupus) have extensively hybridized with domestic dogs (C. familiaris). We reviewed and analyzed surveys of mitochondrial and biparentally inherited genetic markers in dogs and wild populations of wolf-like canids. Although dog-wolf hybrids have been observed in the wild, significant introgression of dog markers into wild wolf populations has not yet occurred. Our investigation suggests that hybridization may not be an important conservation concern even in small, endangered wolf populations near human settlements. The behavioral and physiological differences between domestic dogs and gray wolves may be sufficiently great such that mating is unlikely and hybrid offspring rarely survive to reproduce in the wild.


En algunas ocasiones se ha sugerido que las poblaciones europeas de lobos (Canis lupus) pueden estar profundamente hibridadas con perros domésticos (C. familiaris). Revisamos y analizamos estudios que utilizan marcadores genéticos mitocondriales y de herencia biparental en perros y poblaciones silvestres de cánidos del grupo del lobo. Aunque existen observaciones de híbridos entre perros y lobos en condiciones naturales, nunca se ha observado una significativa introducción de marcadores genéticos de perros en las poblaciones de lobos. Nuestra revisión sugiere que la hibridación puede no ser un problema importante ni tan sólo para la conservación de poblaciones de lobos pequeñas y amenazadas, cerca de asentamientos humanos. Las diferencias fisiológicas y de comportamiento entre perros y lobos pueden ser suficientemente grandes como para que su apareamiento sea improbable y los híbridos tengan escasas posibilidades de sobrevivir y reproducirse en libertad.

See more about wild canid hybridisation with dogs

Another review on dog's impacts on wildlife

Brickner, I. 2003. The impact of domestic dog (Canis familiaris) on  wildlife welfare and conservation: a literature review with a situation summary from Israel. Tel Aviv University report.

Reviews dozens of articles on dog's impact on wildlife. After discussing domestication and marooning of dogs, the author reviews behaviour, ecology and predation around the world. The document also discusses hybridization problems and diseases transmition, to wildlife and to humans. It also gives some data on domestic and feral dogs in Israel.

See more about wild canid hybridisation with dogs

Diet of cats on islands

Bonnaud, E., F. M. Medina, E. Vidal, M. Nogales, B. Tershy, E. Zavaleta, C. J. Donlan,  B. Keitt, M. Le Corre & S. V. Horwath. 2011. The diet of feral cats on islands: a review and a call for more studies. Biological Invasions, 13: 581–603.

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.

Impact of cats on islands endangered vertebrates

Medina, F.M., E. Bonnaud, E. Vidal, B. Tershy, E.S. Zavaleta, C. J. Donlan, B.S . Keitt, M. Le Corre, S.V. Horwath & M. Nogales. 2011. A global review of the impacts of invasive cats on island endangered vertebrates.Global Change Biology, 17, 3503–3510


Cats are generalist predators that have been widely introduced to the world’s ~179 000 islands. Once introduced to islands, cats prey on a variety of native species many of which lack evolved defenses against mammalian predators and can suffer severe population declines and even extinction. As islands house a disproportionate share of terrestrial biodiversity, the impacts of invasive cats on islands may have significant biodiversity impacts. Much of this threatened biodiversity can be protected by eradicating cats from islands. Information on the relative impacts of cats on different native species in different types of island ecosystems can increase the efficiency of this conservation tool. We reviewed feral cat impacts on native island vertebrates. Impacts of feral cats on vertebrates have been reported from at least 120 different islands on at least 175 vertebrates (25 reptiles, 123 birds, and 27 mammals), many of which are listed by the International Union for the Conservation of Nature. A meta-analysis suggests that cat impacts were greatest on endemic species, particularly mammals and greater when non-native prey species were also introduced. Feral cats on islands are responsible for at least 14% global bird, mammal, and reptile extinctions and are the principal threat to almost 8% of critically endangered birds, mammals, and reptiles.