Diet of feral cats at a rubbish dump

Hutchings, S. 2003. The diet of feral house cats (Felis catus) at a regional rubbish tip, Victoria. Wildlife Research, 30:103-110.

The diet of feral cats (Felis catus) inhabiting a regional rubbish tip (dump) in Victoria was studied to determine whether cats utilised garbage or live prey from the surrounding heathlands for food. Between 30 and 50 cat scats were collected from the tip over two years in each of four sampling periods: spring 1997, autumn 1998, spring 1998 and autumn 1999. The scats were analysed to determine major dietary components, dietary breadth and seasonal overlap of diet. Bone fragments from meat scraps were the most frequent dietary item detected in the scats. Vertebrate prey species occurred less often in the cats' diet but a variety of both introduced and native species were represented. Analysis of dietary breadth confirmed that cats selected mainly meat and chicken scraps from the garbage but indicated that vertebrates were hunted opportunistically. Control measures are suggested to reduce cat numbers at regional rubbish tips to relieve potential impact on native wildlife.

Demography of free roaming cats

Nutter, F. B., Levine, J. F., & Stoskopf, M. K. (2004). Reproductive capacity of free-roaming domestic cats and kitten survival rate. Journal of the American Veterinary Medical Association, 225(9), 1399-1402.

Objective—To determine reproductive capacity of naturally breeding free-roaming domestic cats and kitten survival rate.

Design—Prospective cohort and retrospective crosssectional study.

Animals—2,332 female cats brought to a trap-neuterreturn clinic for neutering and 71 female cats and 171 kittens comprising 50 litters from a cohort study of feral cats in managed colonies.

Procedure—Data collected for all cats included pregnancy, lactation, and estrus status and number of fetuses for pregnant cats. Additional data collected for feral cats in managed colonies included numbers of litters per year and kittens per litter, date of birth, kitten survival rate, and causes of death.

Results—Pregnant cats were observed in all months of the year, but the percentage of cats found to be pregnant was highest in March, April, and May. Cats produced a mean of 1.4 litters/y, with a median of 3 kittens/litter (range, 1 to 6). Overall, 127 of 169 (75%) kittens died or disappeared before 6 months of age. Trauma was the most common cause of death.

Conclusions and Clinical Relevance—Results illustrate the high reproductive capacity of free-roaming domestic cats. Realistic estimates of the reproductive capacity of female cats may be useful in assessing the effectiveness of population control strategies. 

Wild or feral cats in NE France

O’Brien, J., Devillard, S., Say, L., Vanthomme, H., Léger, F., Ruette, S., Pontier, D., 2009. Preserving genetic integrity in a hybridising world: are European Wildcats (Felis silvestris silvestris) in eastern France distinct from sympatric feral domestic cats? Biodiversity Conservation, 18, 2351–2360.

We investigate the genetic profile of putative European Wildcats in north-eastern France, possessing the wildcat phenotype, but sampled in an area where they are sympatric with free-roaming domestic cats and, thus, are exposed to potential hybridisation. From a sample of 209 cats, the programme STRUCTURE clearly identified two distinct genetic clusters that corresponded to European Wildcats and domestic cats. The cats from these two clusters were clearly differentiated from each other (F ST = 0.16). However, the genotypes of some individual cats were split between the two clusters, indicative of genetic admixture. Our analysis demonstrates that a genetically distinct population of cats that possess the European Wildcat phenotype persists in north-eastern France, but that there is a low, yet real, risk of hybridisation with sympatric domestic cats. These European Wildcats warrant conservation efforts to protect their genetic integrity.

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Cat hybridization in Germany

Krüger, M., Hertwig, S. T., Jetschke, G., & Fischer, M. S. (2009). Evaluation of anatomical characters and the question of hybridization with domestic cats in the wildcat population of Thuringia, Germany. Journal of Zoological Systematics and Evolutionary Research, 47(3), 268-282.

Germany’s large population of wildcats (Felis silvestris silvestris) can be clearly distinguished from domestic cats on the basis of morphological characters. However, an examination of 71 specimens from Thuringia also illustrates the risks involved in using only a few such characters. The most reliable tool for identification in the field are three pelage characters (distinctness of tail bands, stripes on the nape and stripes on the shoulder). Only two morphological characters (intestine length and cranial volume) are unambiguous and demonstrate no overlap in distribution between domestic cats and wildcats. A linear discriminant analysis with forward selection of variables showed that only five skull variables are necessary to distinguish all four groups (subspecies × sex). Additionally, the high degree of correlation between most of the 49 variables examined (as indicated by Pearson’s r correlation matrix) speaks against the utility of measuring such high numbers of characters in the future. Principal component analysis (PCA) enabled the subspecies to be separated clearly. The first PCA axis was highly correlated with variables characterizing overall body size, thus separating male and female into wildcats and domestic cats. Even when the chief differentiating characters are missing, the PCA still resulted in a good separation of subspecies. None of the genetically determined hybrids could have been deciphered unambiguously using the morphological characters still intact after a road death. Hybridization seems to occur whenever wildcats change their ecological function and become field cats. The impulse to hybridize seems to come much more from the wildcat side than the side of feral cats, and deforestation represents the major threat to the wildcat.



Hertwig, S. T., Schweizer, M., Stepanow, S., Jungnickel, A., Böhle, U. R., & Fischer, M. S. (2009). Regionally high rates of hybridization and introgression in German wildcat populations (Felis silvestris, Carnivora, Felidae). Journal of Zoological Systematics and Evolutionary Research, 47(3), 283-297.

While the western populations of the wildcat (Felis silvestris silvestris) in Germany come into contact with wildcats in France and Switzerland, the eastern distribution area is geographically completely isolated and consists of scattered subpopulations. To investigate population structure, evolutionary relationships and degree of hybridization with domestic cats we analysed the mitochondrial control region of 86 cats in combination with 11 microsatellite loci of 149 cats. According to our microsatellite data, German wildcats are divided into two separate populations corresponding to the western and eastern distribution areas. We found no indication of a further subdivision of the eastern population. German wildcat populations are genetically distinct from domestic cats in the main, but we identified 18.4% of the whole wildcat sample as being of hybrid origin, corresponding to 4.2% of the eastern and 42.9% of the western wildcat population, and 2.7% of the domestic cat sample. The mitochondrial haplotypes form a network of three connected clusters and reveal a high level of genetic diversity, especially within the eastern population. Our findings are explained at best in terms of continuous introgression between domestic cats and wildcat populations and differing degrees of recent hybridization in the various populations. Future conservation efforts should focus on preserving the existing gene flow between the isolated distribution areas, but also on preventing the spread of hybrids and limiting the habitat alterations that lead to increased contact with domestic cats. In conclusion we discuss possible evolutionary reasons for the still traceable genetic integrity of the wildcat despite its long history of interbreeding.


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Demographic Cat–Rat interactions in an urban environment.

Glass GE, Gardner-Santana LC, Holt RD, Chen J, Shields TM, Roy M, Schachterle S & Klein SL (2009) Trophic Garnishes: Cat–Rat Interactions in an Urban Environment. PLoS ONE 4(6): e5794. doi:10.1371/journal.pone.0005794

Background

Community interactions can produce complex dynamics with counterintuitive responses. Synanthropic community members are of increasing practical interest for their effects on biodiversity and public health. Most studies incorporating introduced species have been performed on islands where they may pose a risk to the native fauna. Few have examined their interactions in urban environments where they represent the majority of species. We characterized house cat (Felis catus) predation on wild Norway rats (Rattus norvegicus), and its population effects in an urban area as a model system. Three aspects of predation likely to influence population dynamics were examined; the stratum of the prey population killed by predators, the intensity of the predation, and the size of the predator population.

Methodology/Principal Findings
Predation pressure was estimated from the sizes of the rat and cat populations, and the characteristics of rats killed in 20 alleys. Short and long term responses of rat population to perturbations were examined by removal trapping. Perturbations removed an average of 56% of the rats/alley but had no negative long-term impact on the size of the rat population (49.6±12.5 rats/alley and 123.8±42.2 rats/alley over two years). The sizes of the cat population during two years (3.5 animals/alley and 2.7 animals/alley) also were unaffected by rat population perturbations. Predation by cats occurred in 9/20 alleys. Predated rats were predominantly juveniles and significantly smaller (144.6 g±17.8 g) than the trapped rats (385.0 g±135.6 g). Cats rarely preyed on the larger, older portion of the rat population.

Conclusions/Significance
The rat population appears resilient to perturbation from even substantial population reduction using targeted removal. In this area there is a relatively low population density of cats and they only occasionally prey on the rat population. This occasional predation primarily removes the juvenile proportion of the rat population. The top predator in this urban ecosystem appears to have little impact on the size of the prey population, and similarly, reduction in rat populations doesn't impact the size of the cat population. However, the selected targeting of small rats may locally influence the size structure of the population which may have consequences for patterns of pathogen transmission.

Incursion of domestic carnivores around urban areas: Three camera-trapping studies

Marks, B. K., & Duncan, R. S. (2009). Use of forest edges by free-ranging cats and dogs in an urban forest fragment. Southeastern Naturalist, 8(3), 427-436.

Free-ranging Felis catus (Domestic Cat) and Canis familiaris (Domestic Dog) can greatly impact native prey populations, but little is known about their occurrence in urban forest fragments. In this study, we used camera traps to photograph (capture) cats, dogs, and native wildlife in a 409-ha urban forest in Birmingham, AL from Jan–Apr 2007. Habitat treatments included forest interior and forest edges by industrial lands, neighborhoods with higher house values, and neighborhoods with lower house values. We employed both conservative (n = 31) and liberal (n = 64) methods of tallying the number of individual dogs, cats, and native mammals captured. Dogs and cats combined comprised 19% (conservative) and 26% (liberal) of all photographic captures. Procyon lotor (Raccoon) were the most abundant of the 7 native species at 32% (conservative) and 53% (liberal) of all captures. Dogs were more abundant in neighborhood edges, and cats were more abundant in the forest interior. Cats and dogs combined were 75% (conservative) and 86% (liberal) of captures from the forest interior. Captures of native species were far more frequent in neighborhood edges (conservative = 86.9%, and liberal = 92.3%) than in other treatments. These findings demonstrate that exotic predators can be an important ecological presence in certain portions of urban forest fragments, and more extensive studies of their impact are needed.

Ordeñana, M.A, K. R. Crooks, E.E. Boydston, R.N. Fisher, L.M. Lyren, S. Siudyla, C.D. Haas, S. Harris, S.A. Hathaway, G.M. Turschak, A. K. Miles, & D.H. Van Vuren (2010) Effects of urbanization on carnivore species distribution and richness. Journal of Mammalogy, 91 (6): 1322-1331.

Urban development can have multiple effects on mammalian carnivore communities. We conducted a meta-analysis of 7,929 photographs from 217 localities in 11 camera-trap studies across coastal southern California to describe habitat use and determine the effects of urban proximity (distance to urban edge) and intensity (percentage of area urbanized) on carnivore occurrence and species richness in natural habitats close to the urban boundary. Coyotes (Canis latrans) and bobcats (Lynx rufus) were distributed widely across the region. Domestic dogs (Canis lupus familiaris), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), gray foxes (Urocyon cinereoargenteus), mountain lions (Puma concolor), and Virginia opossums (Didelphis virginiana) were detected less frequently, and long-tailed weasels (Mustela frenata), American badgers (Taxidea taxus), western spotted skunks (Spilogale gracilis), and domestic cats (Felis catus) were detected rarely. Habitat use generally reflected availability for most species. Coyote and raccoon occurrence increased with both proximity to and intensity of urbanization, whereas bobcat, gray fox, and mountain lion occurrence decreased with urban proximity and intensity. Domestic dogs and Virginia opossums exhibited positive and weak negative relationships, respectively, with urban intensity but were unaffected by urban proximity. Striped skunk occurrence increased with urban proximity but decreased with urban intensity. Native species richness was negatively associated with urban intensity but not urban proximity, probably because of the stronger negative response of individual species to urban intensity.

Fandos, G., Fernández-López, J., & Tellería, J. L. (2012). Incursion of domestic carnivores around urban areas: a test in central Spain. Mammalia, 76(2), 223-225.

Although domestic carnivores are frequently considered a threat to wildlife inside and around urban areas, little is known about the incursions of these animals from urban areas to the surrounding habitats. To explore this, we sampled carnivores in wooded areas surrounding four villages located in the mountains north of Madrid by using 40 camera-trapping stations. They were distributed at regular distances within a perpendicular transect distributed from 10 to 2000 m from the urban border. The results suggest that the incidence of domestic carnivores (cats and dogs) was constrained to <400 m from the urban border, and that the presence of domestic carnivores did not interfere with the distribution of wild carnivores (foxes, beech martens, badgers, genets, etc.), which show random distribution patterns around villages. This means that overpredation at the village edges could mainly be due to the effect of domestic animals and not to that of wild carnivores attracted to urban areas

Costs of rabies control at Flores Island.

Wera, E., Velthuis, A. G., Geong, M., & Hogeveen, H. (2013). Costs of Rabies Control: An Economic Calculation Method Applied to Flores Island. PLOS ONE,8(12), e83654.

Background

Rabies is a zoonotic disease that, in most human cases, is fatal once clinical signs appear. The disease transmits to humans through an animal bite. Dogs are the main vector of rabies in humans on Flores Island, Indonesia, resulting in about 19 human deaths each year. Currently, rabies control measures on Flores Island include mass vaccination and culling of dogs, laboratory diagnostics of suspected rabid dogs, putting imported dogs in quarantine, and pre- and post-exposure treatment (PET) of humans. The objective of this study was to estimate the costs of the applied rabies control measures on Flores Island.

Methodology/principal findings

A deterministic economic model was developed to calculate the costs of the rabies control measures and their individual cost components from 2000 to 2011. The inputs for the economic model were obtained from (i) relevant literature, (ii) available data on Flores Island, and (iii) experts such as responsible policy makers and veterinarians involved in rabies control measures in the past. As a result, the total costs of rabies control measures were estimated to be US$1.12 million (range: US$0.60–1.47 million) per year. The costs of culling roaming dogs were the highest portion, about 39 percent of the total costs, followed by PET (35 percent), mass vaccination (24 percent), pre-exposure treatment (1.4 percent), and others (1.3 percent) (dog-bite investigation, diagnostic of suspected rabid dogs, trace-back investigation of human contact with rabid dogs, and quarantine of imported dogs).

Conclusions/significance

This study demonstrates that rabies has a large economic impact on the government and dog owners. Control of rabies by culling dogs is relatively costly for the dog owners in comparison with other measures. Providing PET for humans is an effective way to prevent rabies, but is costly for government and does not provide a permanent solution to rabies in the future.

Home range and movements of feral cats on Mauna Kea

Goltz, D. M., Hess, S. C., Brinck, K. W., Banko, P. C., & Danner, R. M. (2008). Home range and movements of feral cats on Mauna Kea, Hawai ‘i. USGS Staff -- Published Research.Paper 644
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Feral cats Felis catus in dry subalpine woodland of Mauna Kea, Hawai‘i, live in low density and exhibit some of the largest reported home ranges in the literature. While 95% fixed kernel home range estimates for three females averaged 772 ha, four males averaged 1 418 ha, and one male maintained a home range of 2 050 ha. Mean daily movement rates between sexes overlapped widely and did not differ significantly (P = 0.083). Log-transformed 95% kernel home ranges for males were significantly larger than those of females (P = 0.024), but 25% kernel home ranges for females were larger than those of males (P = 0.017). Moreover, log-transformed home ranges of males were also significantly larger than those of females in this and seven other studies from the Pacific region (P = 0.044). Feral cats present a major threat to endangered Hawaiian birds, but knowledge of their ecology can be used for management by optimizing trap spacing and creating buffer zones around conservation areas.

Using genetics to plannify feral cat control

Hansen, H., Hess, S. C., Cole, D., & Banko, P. C. (2008). Using population genetic tools to develop a control strategy for feral cats (Felis catus) in Hawai'i.Wildlife Research, 34(8), 587-596.


Population genetics can provide information about the demographics and dynamics of invasive species that is beneficial for developing effective control strategies. We studied the population genetics of feral cats on Hawai‘i Island by microsatellite analysis to evaluate genetic diversity and population structure, assess gene flow and connectivity among three populations, identify potential source populations, characterise population dynamics, and evaluate sex-biased dispersal. High genetic diversity, low structure, and high number of migrants per generation supported high gene flow that was not limited spatially. Migration rates revealed that most migration occurred out of West Mauna Kea. Effective population size estimates indicated increasing cat populations despite control efforts. Despite high gene flow, relatedness estimates declined significantly with increased geographic distance and Bayesian assignment tests revealed the presence of three population clusters. Genetic structure and relatedness estimates indicated male-biased dispersal, primarily from Mauna Kea, suggesting that this population should be targeted for control. However, recolonisation seems likely, given the great dispersal ability that may not be inhibited by barriers such as lava flows. Genetic monitoring will be necessary to assess the effectiveness of future control efforts. Management of other invasive species may benefit by employing these population genetic tools.

Impact of feral cat and fox on Socrota cormorant on Siniya Island

Muzaffar, S. B., Benjamin, S., & Gubiani, R. E. (2013). The impact of fox and feral cat predation on the population viability of the threatened, endemic Socotra cormorant on Siniya Island, United Arab Emirates. Marine Ornithology, 41, 171-177.

Seabirds are vulnerable to a variety of threats occurring at breeding colonies, including disturbance, habitat degradation and predation from terrestrial predators. Socotra Cormorants Phalacrocorax nigrogularis are threatened, regionally endemic seabirds restricted to the Arabian Gulf and Gulf of Oman regions. Populations have been collapsing throughout their range, mostly in response to habitat loss from oil exploitation and disturbance at breeding sites. Almost half of the historically abundant colonies have disappeared, and the global breeding population has suffered catastrophic declines over the last 30 years. Siniya Island, Umm Al Quwain, hosts the largest colony in the United Arab Emirates with an estimated 15 500 breeding pairs. Predation by feral cats Felis catus and native red foxes Vulpes vulpes constitutes a major threat to this colony. We simulated population trends under different mortality levels using the software Vortex. The baseline model was parameterized using data on Socotra Cormorants or other cormorant species. Simulation of the baseline model showed a gradual increase in population, assuming carrying capacity of Siniya Island was 50 000 individuals. Compared with the baseline, within 50 years, a mortality of 900 individuals per year would reduce the population to fewer than 5 000 breeding pairs; mortality of 1 800 or 2 000 individuals per year would reduce the population to a few hundred pairs. Populations were more susceptible to adult mortality in all mortality scenarios (900, 1 800, and 2 000 individuals/year), leading to reductions to near-extinction levels. Our estimates of predation-related mortality were conservative, and the trends implied by the population model could potentially be catastrophic to the species. Eradication of feral cats and red foxes is recommended as a management tool to ensure long-term survival of this colony

Cat responsible of extinctions on Mangere Is.

Tennyson, A. J. D., & Millener, P. R. (1994). Bird extinctions and fossil bones from Mangere Island, Chatham Islands. Notornis, 41(supplement), 165-178.

Fossil bones and earlier observations indicate that up to 22 species of bird have become extinct on Mangere Island. The extinctions appear to have been primarily a result of predation by cats, but human hunting and bush clearance are likely to account for the disappearance of some species. A crested penguin Eudyptes ?n.sp., two species of Pterodroma petrel, a shelduck Tadorna ?n.sp., Dieffenbach's Rail Gallirallus dieffenbachii, and a kaka Nestor ?n.sp. are present in fossil deposits on Mangere Island, but have not been reported from the island before. The relative proportion of remains in the deposits suggest that Blue Penguins Eudyptula minur, Broad-billed Prions Pachyptila vinata and Sooty Shearwaters Puffinus griseus have become more common on the island. Any such increases on Mangere Island, could have been a response of a few species to the large decrease in numbers and diversity that has affected seabirds as a whole at the Chatharns. Some seabird species mav have been able to increase because of reduced competition for-food.

Demographics of rabies in Iran

Vahdati, S. S., Mesbahi, N., Anvarian, M., Habibollahi, P., & Babapour, S. 2013. Demographics of rabies exposure in north-west of Iran: 5 years experience. J Analyt Res Clin Med; 1(1): 18-21.

BACKGROUND: Rabies is a neuropathogenic disease, always fatal, which involves domestic and wild animals and attracted global concern for its distribution. This research aimed to demonstrate potential rabies infected animal bites and related risk factors in North-West of Iran in order to evaluate the area’s demographics and risk factors.

METHODS: A retrospective cross-sectional review was done for patients referred to Rabies Disease Control and Prevention Center placed in Sina Hospital, Tabriz, Iran.

RESULTS: A total of 1084 patients, 918 men and 166 women (777 city and 307 rural residential) were enrolled in this study. Median age ranged from 20 to 30 years. Accidents were the highest in January and May. Dogs accounted for 72.4%, cats 20.6%, rats 4.1% and others 3%. 45.8% of the attacks occurred at homes, 41.8% outdoors, and 12.4% at work. 80.4% of them were pet animals, 15.6% were outdoors and 4.1% were wild. 80.4% were under observation, 17.5% escaped, and 2.1% were killed. Superficial bites accounted for 78.7% of all bites, and 21.3% were deeply bitten. Bites conflicted to upper limbs (50.6%), lower limb (43.5%), head (2.4%), neck (0.6%), chest (1.8%), abdomen (0.7%), and genitalia (0.3%). 54.3% of all the bite exposures occurred in covered sites whereas 45.7% affected naked sites. Surprisingly, 98.6% of the animal, mostly pets, had no history of vaccination.

CONCLUSIONS: This research admitted lacked attention in vaccination when it would have been appropriate, led to rabies disease which is always fatal. Bite rates were higher among adult males, in cities by dogs. Upper limbs, mostly covered, were bitten commonly superficial.

Sanitary conditions of a colony of urban feral cats in a zoological garden of Rio de Janeiro

Mendes-de-Almeida, F., Faria, M. C. F., Branco, A. S., Serrão, M. L., Souza, A. M., Almosny, N., Charme, M. & Labarthe, N. (2004). Sanitary conditions of a colony of urban feral cats (Felis catus Linnaeus, 1758) in a zoological garden of Rio de Janeiro, Brazil. Revista do Instituto de Medicina Tropical de São Paulo, 46(5), 269-274.

The colony of urban stray cats living in the Rio de Janeiro zoological garden was studied in order to develop a population and health control program. As many cats as possible were captured during two months (47 animals) and were classified according to gender, age, weight and coat markings. They were submitted to a general health evaluation, examined for the presence of ectoparasites and sent to a surgical neutering program. All animals had a blood sample drawn for CBC, platelet count, heartworm and retroviruses detection. Capillary blood smears were made for hemoparasites detection. Coat marking and colors were tabby (59.7%), followed by solid black (17%); torbie (10.6%); bicolor (10.6%) and harlequin (2.1%). The only ectoparasites found were fleas, which infested 28% of the animals. The hemoparasites found were Haemobartonella felis (38%) and piroplasmas that could not be differentiated between Cytauxzoon spp. and Babesia spp. (47%). No cat was found infected by Dirofilaria immitis or FeLV (Feline Leukemia Virus), although FIV (Feline Immunodeficiency Virus) antibodies could be detected (21%). There was no correlation between hemoparasites and FIV infections. The estimated total cat population (mark-recapture method) was 59; 68% female and 32% male, suggesting that a neutering program is in fact needed.

Fencing to eradicate cats, and others, from large islands

Bode, M., Brennan, K. E., Helmstedt, K., Desmond, A., Smia, R., & Algar, D. (2013). Interior fences can reduce cost and uncertainty when eradicating invasive species from large islands. Methods in Ecology and Evolution, 4 ( 9): 819–827

1. The conservation of many threatened species can be advanced by the eradication of alien invasive animals from islands. However, island eradications are an expensive, difficult and uncertain undertaking. An increasingly common eradication strategy is the construction of ‘interior fences’ to partition islands into smaller, independent eradication regions that can be treated sequentially or concurrently. Proponents argue that, while interior fences incur substantial up front construction costs, they reduce overall eradication costs. However, this hypothesis lacks an explicit theoretical or empirical justification.
2. We formulate a general theory that relates the number of interior fences to the magnitude and variation of the economic cost of island eradication. We use this theory to explore the conditions under which interior fences represent a defensible management strategy, under cost and risk minimisation objectives. We then specifically consider the forthcoming eradication of cats Felis catus from Dirk Hartog Island, Western Australia, by parameterising our general theory using published data on the cost and success of previous projects.
3. Our results predict that under a wide range of reasonable conditions, interior fences can reduce the expected cost of a successful invasive alien animal eradication from large islands. On Dirk Hartog Island, interior fences will marginally reduce eradication costs, with two fences reducing expected costs by 3%. Interior fences have a much more substantial effect on the variability of eradication costs: two fences reduce the width of the 95% confidence bounds by more than one-third and halve the size of the average project cost overrun/underrun.
4. Our results reveal that the construction of interior fences is a defensible management strategy for eradicating alien invasive species from islands. However, the primary benefit of interior fences will be risk management, rather than a reduction in expected project costs.

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Social and genetic analysis of a population of free-living cats at a waste disposal site

Denny, E., Yakovlevich, P., Eldridge, M. D., & Dickman, C. (2002). Social and genetic analysis of a population of free-living cats (Felis catus L.) exploiting a resource-rich habitat. Wildlife Research, 29(4), 405-413.

Free-living cats (Felis catus L.) exploiting a waste-disposal site in rural Australia were studied for two years to investigate population structure and dynamics, and the relatedness of constituent individuals. The density of the population was equivalent to 700–750 cats  km^-2  the sex ratio was heavily skewed towards males, breeding occurred from July to April, and kitten survival rates were low. A combination of observational data, biometrics and microsatellite loci analyses was used to assess the relatedness of individuals in the population; these methods yielded highly congruent results. Thus, a female kin-group of three was identified, there was no female immigration, the average relatedness amongst the population was high and there was no indication of male dominance. The results indicate that cats at the site formed a tightly structured group, rather than an ad hoc collection of individuals. The stable, resource-rich habitat of waste-disposal sites may generally support high densities of group-forming cats in rural Australia, and pose broad-scale but previously unrecognised problems for effective management of free-living cats.