Cat detection depending on dominant native predator presence

Lazenby BT, & Dickman CR (2013) Patterns of Detection and Capture Are Associated with Cohabiting Predators and Prey. PLoS ONE 8(4): e59846. 

Avoidance behaviour can play an important role in structuring ecosystems but can be difficult to uncover and quantify. Remote cameras have great but as yet unrealized potential to uncover patterns arising from predatory, competitive or other interactions that structure animal communities by detecting species that are active at the same sites and recording their behaviours and times of activity. Here, we use multi-season, two-species occupancy models to test for evidence of interactions between introduced (feral cat Felis catus) and native predator (Tasmanian devil Sarcophilus harrisii) and predator and small mammal (swamp rat Rattus lutreolus velutinus) combinations at baited camera sites in the cool temperate forests of southern Tasmania. In addition, we investigate the capture rates of swamp rats in traps scented with feral cat and devil faecal odours. We observed that one species could reduce the probability of detecting another at a camera site. In particular, feral cats were detected less frequently at camera sites occupied by devils, whereas patterns of swamp rat detection associated with devils or feral cats varied with study site. Captures of swamp rats were not associated with odours on traps, although fewer captures tended to occur in traps scented with the faecal odour of feral cats. The observation that a native carnivorous marsupial, the Tasmanian devil, can suppress the detectability of an introduced eutherian predator, the feral cat, is consistent with a dominant predator – mesopredator relationship. Such a relationship has important implications for the interaction between feral cats and the lower trophic guilds that form their prey, especially if cat activity increases in places where devil populations are declining. More generally, population estimates derived from devices such as remote cameras need to acknowledge the potential for one species to change the detectability of another, and incorporate this in assessments of numbers and survival.

DNA to identify canid predation on livestock

Sundqvist, A. K., Ellegren, H., & Vilà, C. (2008). Wolf or dog? Genetic identification of predators from saliva collected around bite wounds on prey.Conservation Genetics, 9(5), 1275-1279.
Wolf predation on livestock is a management problem in many areas and is often used to justify control measures against the wolves. However, wolves coexist with dogs across their range, and dogs could be responsible for attacks blamed on wolves. In this study we evaluate the possibility of obtaining sufficient DNA for species identification of the predator from saliva remaining close to bite wounds following a canid attack. Predator DNA of reasonably high quality was successfully extracted from bite wounds on two sheep that had been attacked on a farm and were genotyped using six informative microsatellite markers. A single consensus genotype could be constructed from the bite wounds of both sheep which we compared to genotypes obtained from Scandinavian wolves and dogs. The results clearly showed that the saliva sampled originated from a single dog. This report thus demonstrates the feasibility of predator species identification from bite wounds and also illustrates that it can not be taken for granted that wolves are responsible for canid livestock kills.

DNA to prove dog attacks

Clarke, M., & Vandenberg, N. (2010). Dog attack: the application of canine DNA profiling in forensic casework. Forensic science, medicine, and pathology,6(3), 151-157.

More than 100,000 dog attacks occur each year in Australia and many go unsolved. Dog attacks are not only a cause of human injury but may also involve injury and death to family pets, prized livestock and wildlife. Canine biological evidence can often be left behind on a victim or at the scene of an attack. Our laboratory provides canine DNA profiling for forensic investigations, utilising an in-house panel of 11 canine-specific autosomal short tandem repeat markers previously validated for use in casework. Case studies will be presented that outline methods for sampling of suspected canine biological evidence, profiling of canine DNA, statistical analysis, case outcomes and challenges for investigators.

Population dynamics of a population of free roaming cats

Taylor, B. (2013). Population Dynamics of Free-Roaming Cats in Florida's Lee County. Undergraduate Journal of Mathematical Modeling: One+ Two, 3(1), 16.

We investigate whether the Trap-Neuter-Return (TNR) program can be effectively used to control the population of free-roaming cats in Florida's Lee County. We do this by estimating the number of cats that must be spayed/neutered in order to keep the population from increasing.

Our analysis shows that keeping the population of free-roaming cats in Lee County (98,000 individuals) from growing requires spaying/neutering of at least 370 cats per week. We suspect that this estimate is high because the model we considered is density independent. Nevertheless our results underline the rate at which the cat population can explode if not properly controlled.

Eradication of feral cats at Wake Atoll

Rauzon, M. J., Everett, W. T., Boyle, D., Bell, L., & Gilardi, J. (2008).Eradication of feral cats at Wake Atoll. National Museum of Natural History, Smithsonian Institution.

Feral cats (Felis catus) were introduced at Wake Atoll, (19°18' N, 166° 38' E) in the 1960s as pets and probably to control rats on this U.S. military base in the North Pacific Ocean. After base-downsizing in the 1970s, feral cats became a noticeable problem. Hunting and trapping to control their numbers has been sporadic over time but began seriously in 1996 and continued through 2002, during which time about 200 cats were removed. The eradication effort began in July 2003 and by January 2004 another 170 cats had been removed. During visits from late 2004 to 2007, two feral cats were seen but no cat reproduction was detected.
Bird populations responded quickly to the release of predation: Masked Boobies (Sula dactylatra) increased from three breeding pairs in 1996 to 25 by 2007; the Brown Booby (S. leucogaster) population rose from 73 nests in 1996 to 162 in 2003. Wedgetailed Shearwaters (Puffinus pacificus) recolonized around 1998 and populations expanded to form at least three colonies with individuals in numerous locations around the atoll. Gray-backed Terns (Onychoprion lunata), not recorded breeding on the atoll since the 1980s, began nesting in two new sites, and Great Frigatebirds (Fregata minor), which had not been recorded nesting since the 1960s, renewed reproductive efforts in 2005. Due to feral cat removal and wet weather, Pacific Rats (R. exulans) greatly increased. Current rodent control effort was less effective than it should be because hermit crabs (Coenobita perlata) ate the bait before the rats did. A bait station model design to exclude crabs was designed and tested. The island managers continued to control rats at Wake around housing areas, and rodent populations have declined since their peak following cat eradication.
On Aug. 31, 2006, Wake Island was struck by Super Typhoon Ioke. Winds over 130 mph knots broke many trees and damaged the island infrastructure but the island was soon functioning again. In June 2007, we returned and found a few cats survived. They appear to be the same cats known to remain at the end of our eradication, are likely the same sex since no kittens have been detected since then.

Cat and catkeepers in Rome

Natoli, E., Ferrari, M., Bolletti, E., & Pontier, D. (1999). Relationships between cat lovers and feral cats in Rome. Anthrozoos: A Multidisciplinary Journal of The Interactions of People & Animals, 12(1), 16-23.


The aim of this study was to assess the relationships between cat lovers and feral cats in Rome. One hundred and fifty-eight cats from 3 populations were observed for 1108 hours of data collection: some demographic characteristics of the colonies were investigated, together with the behavior of cat lovers (those who fed and cared for the cats). The quantity of food eaten and uneaten by the cats was recorded, and the cost to support each colony calculated. The quantity of food provided ranged from 20.47 to 264 kg/month. The mean quantity of food eaten/day by each cat in the study areas never surpassed 130.4 g. In total, the quantity of food wasted ranged from 522 g to 34.05 kg/month. The results of this study can help public administrations decide on how to allocate funds for the management of feral cats. Indeed, they provide statistics on the individual food intake/cat/day, as well as information on the type of collaboration one should expect from cat lovers. In addition, this study outlines advantages and limits of the "Roman model" where the Public Veterinary Services (PVS) and associations of cat lovers cooperate to manage feral cats.

Cat activity patterns in NY

Haspel, C., & Calhoon, R. E. (1993). Activity patterns of free-ranging cats in Brooklyn, New York. Journal of mammalogy 74(1), 1-8.

Activity patterns of free-ranging cats in Brooklyn, New York, varied with neighborhood, season, and hour of the night. Standardized partial-regression analysis identified temperature, humidity, precipitation, and hour as accounting for 32.6% of feral-cat activity. Cats in the area of private homes included free-ranging pets while those in the area of multiple dwellings were commonly feral. Regardless of neighborhood, nighttime activity was bimodal with peaks occurring at 0100 h and at sunrise. Activity levels declined throughout the autumn and increased in the spring.

Cat range on a small island

YAMANE, A., ONO, Y., & DOI, T. (1994). Home range size and spacing pattern of a feral cat population on a small island. Journal of the Mammalogical Society of Japan, 19(1), 9-20.

Home range size and spacing patterns of feral cats (Felis catus) were investigated and data analyzed quantitatively, to clarify the factors affecting their social organization. "Feeding groups" were identified. These consisted of male and female members which used the same garbage site mainly for feeding (Izawa et al. 1982). The spacing patterns of females showed that they defended their feeding sites from use by females of other groups. During each season mean home range size was significantly greater for males than for females. Males expanded their ranges during the females' estrous season when their mean size exceeded the predicted size based purely on metabolic requirements. Furthermore, male home range size (during the estrous season) was correlated directly with the number of females they courted. These results suggest that the mating resource, the number of receptive females, is more important in determining male home range size during the estrous season than is the food resource.

TNR needs reaching 90% of the population to be effective

Jones, A. L., & Downs, C. T. (2011). Managing feral cats on a university's campuses: how many are there and is sterilization having an effect?. Journal of Applied Animal Welfare Science, 14(4), 304-320.

Worldwide domestic and feral cat (Felis catus) numbers have increased. Concerns regarding high populations of feral cats in urban areas include wildlife predation, public nuisance, and disease. This study aimed to estimate the size of the feral cat population on 5 campuses of the University of KwaZulu-Natal, South Africa, to determine whether sterilization has an effect and to make management recommendations. The study used both the total count and mark-recapture methods to estimate the feral cat population on each campus. The study chose a noninvasive method of taking photographs to “mark” individuals and record those who were sterilized. The study estimated a total of 186 cats on all campuses and density at 161 cats/ km²  There was a negative relationship between sterilization and numbers. Sites with higher sterilization showed a lower proportion of younger cats. At the average sterilization of 55%, the population, according to predictions, would remain stable at fecundity, survival, and immigration rates reported by cat caretakers. However, caretakers underestimated cat abundance by 7 ± 37 SD%. Caretakers' feral cat sterilization and feeding programs appear to provide a service to the university community. Key management recommendations were to increase sterilization to 90% to reduce the population over the long term and to raise funds to support the costs incurred by voluntary cat caretakers.

Up to 31% of recoveries of banded birds killed by cats

Mead, C. J. (1982). Ringed birds killed by cats. Mammal Review, 12(4), 183-186.

Mead examined the fate of banded birds in Britain and discovered that for six species more than 25 percent of the recoveries were of birds caught by cats. He ascribed 31% of recoveries of ringed robins and dunnocks to cat predation, but believed that there was no evidence that cats affected the overall populations of these species. Catchability is very different in different species, depending on gregarious habits, terrestrial feeding, avoidance of potential hiding places, etc. but some cats are even able to catch aerial species.
He emphasised that birds in rural and suburban parts of Britain have co-existed with cats for hundreds of generations and may now be under less pressure from cats than they were in the past from assorted 'natural' predators.

Predation by house cat in Canberra

Barratt, D. G. (1997). Predation by house cats, Felis catus (L.), in Canberra, Australia. I. Prey composition and preference. Wildlife Research, 24(3), 263-277.

This paper attempts to apply theory from more than 100 years of scientific experience and experimentation in predator-prey ecology and introduced species ecology to predict the likely effects of predation by domestic cats (Felis catus) on prey populations and community structure. Those aspects of the predatory behaviour of domestic cats which are of most importance in predicting their impact on prey populations: I) the degree of prey selectivity or 'dietary preference'; 2) the exhibition of switching behaviour; 3) changes in predatory activity in response to changes in prey density; and 4) the extent to which high and constant densities of the predator are ameliorated by reduced prey consumption rates as a result of dietary supplement.

In suburban environments, the influence of predation by domestic cats on prey abundance and community structure probably increases, relative to the influence of habitat change, with increasing suburb age, particularly in the absence of physical disturbances such as fire. However, it may never be as important as habitat availability and indeed may never be significant at all. Removal of the predator may allow some animal species to increase in abundance but others may decline. The details of these changes are very difficult to predict. Similarly, following predator removal, total species diversity is as likely to decline due to increased inter-specific competition, as it is to increase due to the invasion of species previously excluded by predation.

In remnant habitat, the impact of predation by domestic cats is probably less likely to be important in determining the relative abundance of the more common species than in suburban environments, but more likely to contribute to local extinctions of rare species. As in suburban environments, predation on introduced species in remnant habitat may reduce predation on native species. However, the ability of domestic cats to control introduced species which prey on, or compete with, native species will be difficult to demonstrate. In light of this uncertainty, any attempt to prevent domestic cats hunting in remnant habitat patches should be integrated with a program to eliminate or control populations of other introduced species, such as black rats and rabbits, which are preyed upon by domestic cats and are known to prey on or compete with native species

Barratt, D. G. (1998). Predation by house cats, Felis catus (L.), in Canberra, Australia. II. Factors affecting the amount of prey caught and estimates of the impact on wildlife. Wildlife Research, 25(5), 475-487.

Information on the amount of vertebrate prey caught by house cats in Canberra was collected by recording prey deposited at cat owners’ residences over 12 months. The amount of prey taken was not significantly influenced by cat gender, age when neutered, or cat breed. Nor did belling or the number of meals provided per day have a significant influence on the amount of prey caught. The age of the cat and the proportion of nights spent outside explained approximately 11% of the variation in the amount of prey caught by individual cats. In all, 43% of variation in predation on introduced species (predominantly rodents) was explained by distance from potential prey source areas (i.e. rural/grassland habitat) and cat density. The mean number of prey reported per cat over 12 months (10.2) was significantly lower than mean predation per cat per year based on estimates made by cat owners before the prey survey began (23.3). Counts of the amount of prey caught by house cats were highly positively skewed. In all, 70% of cats were observed to catch less than 10 prey over 12 months, but for 6% of cats, more than 50 prey were recorded. Estimates of predation by house cats, particularly extrapolated estimates, should be treated with caution. The total number of prey caught by house cats in Canberra estimated using the sample median was approximately half the estimate based on the sample mean. Predation estimates alone do not prove that prey populations are detrimentally affected, especially in highly disturbed and modified environments such as suburbs. Impacts on native fauna are likely to be most significant in undisturbed habitat adjacent to new residential developments.



Read a short review about belling effectiveness

Bells reduce by half predation by cats

Ruxton, G. D., Thomas, S., & Wright, J. W. (2002). Bells reduce predation of wildlife by domestic cats (Felis catus). Journal of Zoology, 256(1), 81-83.

Twenty-one cat owners from a 100 km²  area, centred on Carnforth, Lancashire, England, recorded each dead prey item delivered by their cat or cats during an 8-week period, following one of three experimental schedules, each of which required each cat to have a bell on a collar for only half of the time. The mean number of items each cat delivered to the owner was 2.9 in the 4 weeks when the cats had a bell attached, compared to 5.5 for the equivalent time when the bell was absent. The bell had no effect on the relative numbers of different prey types delivered, and there was no evidence that the cats adapted their hunting behaviour to reduce the effect of the bell over time.


Read a short review about belling effectiveness

Cats as first cause of death of British ringed birds

The BTO (British Trust for Ornithology) started bird ringing 100 years ago, in 1909. To date some 36 million birds have been ringed, providing a unique insight into the birds of Britain and Ireland...

...The BTO receives reports of around 14,000 birds with rings every year, providing an invaluable source of information on the latest trends in bird conservation. I think that one of the telling statistics is the causes of death. For all those people who get very upset when birds are caught in oil spills, (5,600 records), collisions with windows (13,800) or collisions with overhead wires (9,400), all these numbers are dwarfed by the 41,900 birds killed by domestic cats.

Home ranges of feral cats in South Eastern Australia

Molsher, R., Dickman, C., Newsome, A., & Müller, W. (2005). Home ranges of feral cats (Felis catus) in central-western New South Wales, Australia. Wildlife Research, 32(7), 587-595.

Twenty-one feral cats were radio-tracked using direct sighting and triangulation techniques (amassing 730 location fixes) during winter in an agricultural landscape in central-western New South Wales. Factors affecting home-range size, home-range overlap and habitat use were assessed. Mean home-range size was 248 ha (s.e. = 34.9, n = 15 cats, 598 location fixes). Home-range size and habitat use were not influenced by sex or age of adult cats, prey abundance or time of day. However, cat weight significantly influenced range size, with heavier cats having larger ranges than smaller cats. Although the cats are apparently solitary, their home ranges overlapped considerably, particularly between young adults and old adult cats. Cats were active both by day and night and did not occupy permanent dens. Home ranges encompassed mixed habitat types that provided both shelter and prey. Open woodland and open forest were the main habitat types covered by home ranges, but within these areas cats showed a preference for grassland, where rabbits were more abundant. The results recorded in this study indicate that cat-control programs should concentrate in mixed habitat areas, where both shelter and food are available, and over widely dispersed areas. The absence of group living suggests that the effectiveness of virally vectored fertility or biological control agents would be limited.

Feral cat's demography in New South Wales

Molsher, R. L. (2001). Trapping and demographics of feral cats (Felis catus) in central New South Wales. Wildlife Research, 28(6), 631-636.

A total of 76 feral cats (Felis catus) (29 individuals; 47 recaptures) was trapped during 6027 trap-nights using both cage and leg-hold traps from November 1994 to August 1996 at Lake Burrendong in central New South Wales. No significant difference was found in the relative capture efficiency between cage and leg-hold traps (P > 0.05). Overall capture efficiency was 1.3 cats per 100 trap-nights, although this varied seasonally, being higher in late autumn and early winter. Most cats were caught with rabbit as bait, and visual and olfactory lures added to baits did not appear to increase capture efficiency, although the power of the test was limited. Most captured cats were adult males weighing 4.37 0.14 kg; these were larger than the females (3.34 0.06 kg). Litters, comprising 2–5 kittens, were born between September and March.

Cat and other predators' diet in desert Australia

Paltridge, R. (2002). The diets of cats, foxes and dingoes in relation to prey availability in the Tanami Desert, Northern Territory. Wildlife Research, 29(4), 389-403.


In most areas of Australia, mammals constitute the staple diets of cats, foxes and dingoes. In central Australia the abundance of mammals is often too low to meet the dietary requirements of these carnivores and yet populations of cats, foxes and dingoes persist. To investigate alternative feeding strategies of cats, foxes and dingoes in arid environments, their diets were monitored in relation to prey availability in two areas of the Tanami Desert where rabbits do not occur. Dietary information was obtained by analysing predator scats collected between 1995 and 1997. Prey availability was monitored by track counts, pitfall trapping, Elliott trapping, and bird counts along walked transects. In contrast to dietary studies elsewhere in Australia, it was found that reptiles were an important component of the diets of predators in the Tanami Desert, and should be classified as seasonal staples. Birds increased in importance in the diets of cats and foxes during the winter, when reptiles were less active. There was considerable overlap between the diets of all three predators, although dingoes ate more large prey items (e.g. macropods) than the other two predators. Results highlight the opportunistic feeding habits of cats, foxes and dingoes and show that, although mammalian prey are less important in central Australia than has been found elsewhere, species that are vulnerable to extinction, such as the bilby (Macrotis lagotis), mulgara (Dasycercus cristicauda) and marsupial mole (Notoryctes typhlops), are also consumed by these predators.

Feeding ecology and population dynamics of feral cats in New South Wales

Molsher, R., Newsome, A., & Dickman, C. (1999). Feeding ecology and population dynamics of the feral cat (Felis catus) in relation to the availability of prey in central-eastern New South Wales. Wildlife Research, 26(5), 593-607.

The diet of feral cats (Felis catus) was studied at Lake Burrendong, central-eastern New South Wales, from July 1994 to June 1997. Mammals were the major prey in 499 scats that were analysed. Rabbits (Oryctolagus cuniculus) were the staple prey, while carrion was an important secondary food. Invertebrates, other mammalian prey, vegetation, birds and reptiles were generally minor components of the diet. Few significant seasonal differences in diet were found; however, invertebrates contributed less and possums more to the diet in winter and summer respectively. A significant dietary response was found to changes in rabbit abundance, but not for the other prey types. Cats continued to prey heavily on rabbits even after a 90% decline in rabbit abundance occurred, which coincided with the advent of Rabbit Calicivirus Disease (RCD). House mice (Mus domesticus) increased in importance in the diet ten months post-RCD. Although the abundance of cats was correlated with the abundance of some prey species, other factors may have influenced the observed patterns; these are discussed.

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.

Estimation of urban free-roaming cats densities

Schmidt, P. M., Lopez, R. R., & Pierce, B. L. (2007). Estimating free-roaming cat densities in urban areas: comparison of mark-resight and distance sampling. Wildlife Biology in Practice, 3(1), 18-27.

Obtaining reliable population estimates is imperative in managing wildlife populations, particularly when attempting to implement nuisance control measures. Free-roaming cats (Felis catus) impact wildlife worldwide through predation, competition and disease transmission. Ideally, measures of controlling free-roaming cat populations should be evaluated a priori, which requires obtaining population estimates for use in population control programs (e.g., euthanasia, trap/treat/neuter/release). We compared mark-resight and distance sampling abundance estimates of free-roaming cats in an urban landscape, where limited public access to habitat frequently hinders the use of probabilistic sampling designs and associated sampling methodologies. We marked a subset of free-roaming cats (n = 52) with radio-collars in Caldwell, Texas to aid in obtaining our estimates. From road surveys (n = 20) conducted in August 2005, we found mark-resight estimates (N = 744, 95% CI 518-1,135) were significantly different (p = 0.008) to distance sampling estimates (N = 296, 95% CI 262-333). Study results suggest that distance sampling provides wildlife managers a viable alternative for estimating free-roaming cat populations in urban areas where minimal cost and training influence policy decisions regarding the implementation of monitoring and population control measures.

Feral cat diet in Majorca

Millan, J. (2010). Feeding habits of feral cats Felis silvestris catus in the countryside of Majorca Island, Spain. Wildlife Biology in Practice, 6(1), 32-38.

The diet of feral cats (Felis silvestris catus) in the Mediterranean island of Majorca (Spain) was studied from July 2008 to June 2009 by the analysis of the scats of 75 feral cats captured in baited traps in 14 different areas. A total of 138 preys were identified in the analyzed scats. Mammals were the main group preyed on and constituted 93% both in frequency and biomass. Among them, mice were the most frequent prey consumed (55% Mus sp., 18% Apodemus sylvaticus) but represented only 20% of biomass. Rat was present in 29% of scats and was the main component in terms of biomass (57%). Rabbit was found at a frequency of 6.6%, and constituted 18% of biomass. Other prey (birds, geckos and insects) were found in lower frequency, and all pooled constituted only 7% of biomass. Reproductive females preyed less upon mice (20%) than the other cats (77%). This may indicate that these females tended to predate upon higher preys, which may be secondary to increased energetic requirements due to pregnancy or lactation. No seasonal variations were found in any of the different parameters studied. Results indicate that rodents constitute all year round the main prey item in feral cat diet in the countryside of Majorca.

Domestic cat gene introgression into wild cat in Europe

Randi, E., Pierpaoli, M., Beaumont, M., Ragni, B., & Sforzi, A. (2001). Genetic identification of wild and domestic cats (Felis silvestris) and their hybrids using Bayesian clustering methods. Molecular Biology and Evolution, 18(9), 1679-1693.

Crossbreeding with free-ranging domestic cats is supposed to threaten the genetic integrity of wildcat populations in Europe, although the diagnostic markers to identify "pure" or "admixed" wildcats have never been clearly defined. Here we use mitochondrial (mt) DNA sequences and allelic variation at 12 microsatellite loci to genotype 128 wild and domestic cats sampled in Italy which were preclassified into three separate groups: European wildcats (Felis silvestris silvestris), Sardinian wildcats (Felis silvestris libyca), and domestic cats (Felis silvestris catus), according to their coat color patterns, collection localities, and other phenotypical traits, independently of any genetic information. For comparison, we included some captive-reared hybrids of European wild and domestic cats. Genetic variability was significantly partitioned among the three groups (mtDNA estimate of F(ST) = 0.36; microsatellite estimate of R(ST) = 0.30; P < 0.001), suggesting that morphological diversity reflects the existence of distinct gene pools. Multivariate ordination of individual genotypes and clustering of interindividual genetic distances also showed evidence of distinct cat groups, partially congruent with the morphological classification. Cluster analysis, however, did not enable hybrid cats to be identified from genetic information alone, nor were all individuals assigned to their populations. In contrast, a Bayesian admixture analysis simultaneously assigned the European wildcats, the Sardinian wildcats, and the domestic cats to different clusters, independent of any prior information, and pointed out the admixed gene composition of the hybrids, which were assigned to more than one cluster. Only one putative Sardinian wildcat was assigned to the domestic cat cluster, and one presumed European wildcat showed mixed (hybrid) ancestry in the domestic cat gene pool. Mitochondrial DNA sequences indicated that three additional presumed European wildcats might have hybrid ancestry. These four cats were sampled from the same area in the northernmost edge of the European wildcat distribution in the Italian Apennines. Admixture analyses suggest that wild and domestic cats in Italy are distinct, reproductively isolated gene pools and that introgression of domestic alleles into the wild-living population is very limited and geographically localized.

Pierpaoli, M., Birò, Z.S., Herrmann, M., Hupe, K., Fernandes, M., Ragni, B., Szemethy, L. & Randi, E. (2003). Genetic distinction of wildcat (Felis silvestris) populations in Europe, and hybridization with domestic cats in Hungary. Molecular Ecology 12: 2585-2598.

The genetic integrity and evolutionary persistence of declining wildcat populations are threatened by crossbreeding with widespread free-living domestic cats. Here we use allelic variation at 12 microsatellite loci to describe genetic variation in 336 cats sampled from nine European countries. Cats were identified as European wildcats (Felis silvestris silvestris), Sardinian wildcats (F. s. libyca) and domestic cats (F. s. catus), according to phenotypic traits, geographical locations and independently of any genetic information. Genetic variability was significantly partitioned among taxonomic groups (FST = 0.11; RST = 0.41; P < 0.001) and sampling locations (FST = 0.07; RST = 0.06; P < 0.001), suggesting that wild and domestic cats are subdivided into distinct gene pools in Europe. Multivariate and Bayesian clustering of individual genotypes also showed evidence of distinct cat groups, congruent with current taxonomy, and suggesting geographical population structuring. Admixture analyses identified cryptic hybrids among wildcats in Portugal, Italy and Bulgaria, and evidenced instances of extensive hybridization between wild and domestic cats sampled in Hungary. Cats in Hungary include a composite assemblage of variable phenotypes and genotypes, which, as previously documented in Scotland, might originate from long lasting hybridization and introgression. A number of historical, demographic and ecological conditions can lead to extensive crossbreeding between wild and domestic cats, thus threatening the genetic integrity of wildcat populations in Europe.

Lecis, R., Pierpaoli, M., Biro, Z. S., Szemethy, L., Ragni, B., Vercillo, F., & Randi, E. (2006). Bayesian analyses of admixture in wild and domestic cats (Felis silvestris) using linked microsatellite loci. Molecular Ecology, 15(1), 119-131.

Methods recently developed to infer population structure and admixture mostly use individual genotypes described by unlinked neutral markers. However, Hardy–Weinberg and linkage disequilibria among independent markers decline rapidly with admixture time, and the admixture signals could be lost in a few generations. In this study, we aimed to describe genetic admixture in 182 European wild and domestic cats (Felis silvestris), which hybridize sporadically in Italy and extensively in Hungary. Cats were genotyped at 27 microsatellites, including 21 linked loci mapping on five distinct feline linkage groups. Genotypes were analysed with structure 2.1, a Bayesian procedure designed to model admixture linkage disequilibrium, which promises to assess efficiently older admixture events using tightly linked markers. Results showed that domestic and wild cats sampled in Italy were split into two distinct clusters with average proportions of membership Q > 0.90, congruent with prior morphological identifications. In contrast, free-living cats sampled in Hungary were assigned partly to the domestic and the wild cat clusters, with Q < 0.50. Admixture analyses of individual genotypes identified, respectively, 5/61 (8%), and 16–20/65 (25–31%) hybrids among the Italian wildcats and Hungarian free-living cats. Similar results were obtained in the past using unlinked loci, although the new linked markers identified additional admixed wildcats in Italy. Linkage analyses confirm that hybridization is limited in Italian, but widespread in Hungarian wildcats, a population that is threatened by cross-breeding with free-ranging domestic cats. The total panel of 27 loci performed better than the linked loci alone in the identification of domestic and known hybrid cats, suggesting that a large number of linked plus unlinked markers can improve the results of admixture analyses. Inferred recombination events led to identify the population of origin of chromosomal segments, suggesting that admixture mapping experiments can be designed also in wild populations.


See more on domestic cat gene introgression in wildcat

Feral cat predation on ocellated lizard

Díaz-Ruiz, F., & Ferreras, P. (2011). Depredación de Timon lepidus por gato asilvestrado. Revista Española de Herpetología, 3, 237-257.

The authors observed abundant feral cats in a natural area (Lagunas de Ruidera, Central Spain). They preyed on the ocellated lizard Timon lepidus and the authors think that feral cats could have an important role on reptiles decline.

Ayudanos a mapear a los gatos asilvestrados / Help us to map feral cats!!

Nuestro colega Javier Vázquez ha iniciado este mapa donde podemos añadir las citas de gatos domésticos en lugares donde no deberían.
Para editarlo, es fácil. Pulsa EDITAR y añade un nuevo punto, indicando la localidad o cualquier información complementaria. En azul (por defecto) allí donde hay gatos, en verde (seleccionar durante la edición), donde se han erradicado. Después, pulsa LISTO.
Iremos actualizando la imagen.

Our colleague Javier Vázquez has started this map where we can add sites where domestic cats shouldn't be in the wild (wetlands, islands, protected areas, etc.).
Just click EDIT and add a new point, indicating site and any complementary information. Show blue (default) wherever there are feral cats, and green (select when editing) where they have been eradicated. Then, click DONE.
We should update the image.

Feral cat in UK

From GWCT

Legislation

Protection of Wild Mammals (Scotland) Act 2002
Animal Welfare Act 2006
Welfare of Animals Act Northern Ireland 2011
Wild Mammals (Protection) Act 1996 
Hunting Act 2004
Animal Health and Welfare (Scotland) Act 2006
Wildlife and Natural Environment (Scotland) Act 2011

Distribution and abundance

Feral cats are most conspicuous in areas of urban development, but also occur widely in the countryside. They have been introduced to many offshore islands to control rats and rabbits. The scarcity of mapped records outside urban areas probably reflects the difficulty in separating feral from dependent domestic cats.

Estimates of feral cat abundance (numbers of individuals in the spring) across the UK, from Harriset al. (1995):

United Kingdom	813,000
England	625,000
Scotland	130,000
Wales	58,000
N Ireland	no estimate

Recent trends from the National Gamebag Census

Huge feral cats in Northern Australia

The feral cat population across Arnhem Land in the Northern Territory has exploded, with traditional owners saying they've noticed a steep decline in local birds and other wildlife.

The Warddeken ranger group has taken some amazing pictures of how big the feral cats are getting in the region, and has used them to leverage funding from the Federal Government to monitor and kill the pests.

Chairman of the ranger group, Dean Yirbarbuk, says the cats are getting bigger and there are "several thousand" of them in the Warddeken area of central Arnhem Land.

"All we know is our birds and animals are declining," he says.

"We hope this project will help us to try and find a way to get rid of the cats."

 

(continue reading ...)

From http://www.abc.net.au

Role of ferals in the population dynamics of cats

Bradshaw JWS, Horsfield GF, Allen JA, Robinson IH (1999) Feral cats: their role in the population dynamics of the Felis catus. Applied Animal Behaviour Science 65: 273–283.

The so-called domestic cat occupies a unique position within the truly domestic animals since it freely interbreeds with feral populations, and there is considerable gene flow in both directions. This is possible because the likelihood of an individual cat forming a relationship with people is strongly affected by its experiences during the socialisation period (3–8 weeks of age), although this does not preclude differences between owned and feral populations in the relative frequencies of alleles which affect social behaviour towards humans. We suggest a hitherto unconsidered reason why a separate domesticated population of cats (apart from pedigree breeds) has not yet emerged: the unusual and stringent nutrient requirements of the cat may historically have militated against successful breeding on a completely human-provided diet, and led to the retention of the ability to achieve a nutritionally complete diet by scavenging and/or hunting. More recently, the widespread availability of nutritionally complete manufactured foods and veterinary care in western countries appears to be leading towards a rapid change in the population dynamics and population genetics of both owned and feral cats.

Inside/outside cats' impact on a suburban nature reserve

Roland K, DeWan A (2004) Ecological impacts of inside/outside cats around a suburban nature preserve. Animal Conservation 7: 1–11.

While subsidised populations of feral cats are known to impact their prey populations, little is known about the ecological impact of inside/outside hunting cats (IOHC). We studied IOHC around a suburban nature preserve. Mail surveys indicated an average of 0.275 IOHC/house, leading to a regional density estimate of 0.32 IOHC/ha. A geographical model of cat density was created based on local house density and distance from forest/neighbourhood edge. IOHC hunted mostly small mammals, averaging 1.67 prey brought home/cat/month and a kill rate of 13%. Predation rates based on kills brought home was lower than the estimate from observing hunting cats (5.54 kills/cat/month). IOHC spent most outside time in their or their immediate neighbours’ garden/yard, or in the nearby forest edge; 80% of observed hunts occurred in a garden/yard or in the first 10 m of forest. Radio-tracked IOHC averaged 0.24 ha in home range size (95% minimum convex polygon (MCP)) and rarely entered forest. Confirming this, scent stations detected cats more often near the edge and more cats were detected in smaller forest fragments. There was no relationship between the number of cats detected in an area and the local small mammal abundance or rodent seed predation rates. Cold weather and healthy cat predator populations are speculated to minimise the ecological impact of IOHC on this area.

Feral cats in Mallorca: a major reservoir of toxoplasmosis

Millán, J., Cabezón, O., Pabón, M., Dubey, J. P., & Almería, S. (2009). Seroprevalence of Toxoplasma gondii and Neospora caninum in feral cats (Felis silvestris catus) in Majorca, Balearic Islands, Spain.Veterinary parasitology, 165(3), 323-326.

Felids are important in the epidemiology of Toxoplasma gondii infection because they are the only hosts that can excrete environmentally-resistant oocysts, and there is little information of infections in truly free-living cats (Felis silvestris catus) because these cats are difficult to catch. These cats have no specific owner, are not subject of vaccination programs and do not receive prophylactic or curative treatments against parasites.

Antibodies to T. gondii assayed by the modified agglutination test (MAT) were found in 50 (84.7%) of 59 cats with a majority of cats having high MAT titers (>1:500 in 45 cats). Seroprevalence (MAT, 1:25 or more) was significantly higher in adults (94.6%) than in juveniles (<6 month old; 40.0%). Seroprevalence to N. caninum, assayed by cELISA (VMRD) and confirmed by an indirect fluorescent antibody test, was low (6.8%, 4 of 59). The prevalence of T. gondii observed in wild cats in Majorca is one of the highest reported worldwide in this species and the highest observed in Europe to date. The results suggest that feral cats in Majorca have a high rate of T. gondii infection with important implications for public health on the island since the seropositive cats are likely to have already shed T. gondii oocysts in the environment.

TNR ineffective without awareness

Natoli, E., Maragliano, L., Cariola, G., Faini, A., Bonanni, R., Cafazzo, S., & Fantini, C. (2006). Management of feral domestic cats in the urban environment of Rome (Italy). Preventive veterinary medicine, 77(3), 180-185.

In Italy, which is rabies-free, the national Law No. 281 [Legge Nazionale 14 agosto 1991. No. 281: Legge Quadro in materia di animali di affezione e prevenzione del randagismo. Gazz. Uff. Rep. Ital. no 203 del 30 agosto 1991: p. 3] on the management of pets and on the control of feral cats has introduced the no-kill policy for this species. Thus, “trap-neuter-release” (TNR) programs have been carried out for >10 years. In this paper we present data on registered colonies and censused cats in Rome from 1991 to 2000; the results of the neutering campaign from 1991 to 2000; and a survey, on 103 cat colonies, on the effects of demographic control of urban feral-cat colonies in the city of Rome, carried out by the local Veterinary Public Services (VPS) in collaboration with the associations of cat care-takers. In 10 years almost 8000 were neutered and reintroduced in their original colony. The spay/neuter campaigns brought about a general decrease in cat number but the percentage of cat immigration (due to abandonment and spontaneous arrival) is around 21%. This suggests that all these efforts without an effective education of people to control the reproduction of house cats (as a prevention for abandonment) are a waste of money, time and energy.

Controversy around feral cats at Rome's archeological sites

Squires, N. 2012. Stray cat colony in ancient Roman temple is declared a health hazard. The Telegraph 3/11/12.

For as long as anyone can remember, cats have roamed the marble columns of the ancient site in Rome where Julius Caesar was murdered by Marcus Brutus and his band of senators.

Now, though, the felines of the Largo Argentina archaeological site have fallen victim to a conspiracy themselves. Rome's modern-day rulers have declared them a health hazard.

Both the cats and the staff at the informal sanctuary that looks after them have been given their marching orders, despite the animals becoming a popular tourist attraction in their own right.

City heritage officials say that the sanctuary, which lies just on a pedestal just a few yards from where Caesar was hacked down, must close because it is unhygienic, was built without proper planning permission and compromises one of Italy's most important archaeological sites.

"How was it possible that these cat lovers were able to construct their refuge on an ancient monument?" asked Andrea Carandini, a former president of the national cultural heritage council.

But the volunteers who run the refuge, a tiny, cave-like space packed with cats of every colour and pattern, have vowed to fight the eviction order. They said they provide a vital service for the city, taking in strays, sterilising them, and giving them food and medicine.

The cats – there are currently 250 of them – have free run of the adjoining remains and can be seen lounging in the sun on broken bits of marble, padding along fallen pillars and sleeping curled up on the corrugated iron roofs which protect the monuments from rain."Without us here the cats would be begging for food on the pavements and getting run over by trams and buses on the streets – it would be a disaster," said Lia Dequel, one of the founders of the refuge.The volunteers also denied that they had built the facility illegally, saying the space they took over 19 years ago had been dirty, damp and abandoned. The site itself was discovered in the 1920s after falling into decay at the end of the Roman Empire and lying buried for centuries."From what the authorities are saying, you would think we were occupying the Parthenon," said Silvia Viviani, co-founder of the refuge. "I'm a Roman and I'm very proud of our ancient heritage but we are not damaging anything here." The refuge attracts tens of thousands of tourists a year, who descend the metal steps leading down from street level to stroke the cats and buy cat-related t-shirts, fridge magnets and other souvenirs, the money from which helps keep the place going."It's a fantastic place," said Cristina Lazzaroni, who was visiting from Milan. "I cannot see that it is damaging the ruins. Romans have always lived with cats. These people are doing good work."However, the issue has now even been taken up by parliament, with a senator from the centre-left Democratic Party declaring last week that it was "unthinkable" that ancient Roman ruins should be treated in such a wayValerio Massimo Manfredi, an archaeologist, insisted the cats should be transferred elsewhere. "This is an extraordinarily important area that dates from the Roman Republican era and is where Julius Caesar was murdered," he said.

Two papers on cat colonies and TNR

Levy, J. K., Gale, D. W., & Gale, L. A. (2003). Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population. Journal of the American Veterinary Medical Association, 222(1), 42-46.

Objective—To evaluate the effect of a long-term trapneuter-return program, with adoption whenever possible, on the dynamics of a free-roaming cat population.

Design—Observational epidemiologic study.

Animals—155 unowned free-roaming cats.

Procedures—Free-roaming cats residing on a university campus were trapped, neutered, and returned to the environment or adopted over an 11-year period.

Results—During the observation period (January 1991 to April 2002), 75% of the cats were feral, and 25% were socialized. Kittens comprised 56% of the original population. Male cats were slightly more numerous (55%) than females. At the conclusion of the observation period, 47% of the cats had been removed for adoption, 15% remained on site, 15% had disappeared, 11% were euthanatized, 6% had died, and 6% had moved to the surrounding wooded environment. Trapping began in 1991; however, a complete census of cats was not completed until 1996, at which time 68 cats resided on site. At completion of the study in 2002, the population had decreased by 66%, from 68 to 23 cats (of which 22 were feral). No kittens were observed on site after 1995, but additional stray or abandoned cats continued to become resident. New arrivals were neutered or adopted before they could reproduce.

Conclusions and Clinical Relevance—A comprehensive long-term program of neutering followed by adoption or return to the resident colony can result in reduction of free-roaming cat populations in urban areas.

Foley, P., Foley, J. E., Levy, J. K., & Paik, T. (2005). Analysis of the impact of trap-neuter-return programs on populations of feral cats. Journal of the American Veterinary Medical Association, 227(11), 1775-1781.

Objective—To evaluate 2 county trap-neuter-return (TNR) programs for feral cat population management via mathematical modeling.

Design—Theoretical population model.

Animals—Feral cats assessed from 1992 to 2003 in San Diego County, California (n = 14,452), and from 1998 to 2004 in Alachua County, Florida (11,822).

Procedure—Data were analyzed with a mathematical Ricker model to describe population dynamics of the feral cats and modifications to the dynamics that occurred as a result of the TNR programs.

Results—In both counties, results of analyses did not indicate a consistent reduction in per capita growth, the population multiplier, or the proportion of female cats that were pregnant.

Conclusions and Clinical Relevance—Success of feral cat management programs that use TNR can be monitored with an easily collected set of data and statistical analyses facilitated by population modeling techniques. Results may be used to suggest possible future monitoring and modification of TNR programs, which could result in greater success controlling and reducing feral cat populations.