Exposure of free-ranging maned wolves to infectious and parasitic disease agents

Deem, S. L., & Emmons, L. H. (2005). Exposure of free-ranging maned wolves (Chrysocyon brachyurus) to infectious and parasitic disease agents in the Noel Kempff Mercado National Park, Bolivia. Journal of Zoo and Wildlife Medicine, 36(2), 192-197.

Maned wolves (Chrysocyon brachyurus) are neotropic mammals, listed as a CITES Appendix II species, with a distribution south of the Amazon forest from Bolivia, through northern Argentina and Paraguay and into eastern Brazil and northern Uruguay. Primary threats to the survival of free-ranging maned wolves include habitat loss, road kills, and shooting by farmers. An additional threat to the conservation of maned wolves is the risk of morbidity and mortality due to infectious and parasitic diseases. Captive maned wolves are susceptible to, and die from, common infectious diseases of domestic dogs (Canis familiaris) including canine distemper virus (CDV), canine parvovirus (CPV), rabies virus, and canine adenovirus (CAV). Results from this study show that free-ranging maned wolves in a remote area of Bolivia have been exposed to multiple infectious and parasitic agents of domestic carnivores, including CAV, CDV, CPV, canine coronavirus, rabies virus, Leptospira interrogans spp., Toxoplasma gondii, and Dirofilaria immitis, and may be at increased risk for disease due to these agents.

Cats linked to small gardens

Gaston, K.J., Warren, P.H., Thompson, K. & Smith, R.M. 2005. Urban domestic gardens (IV): the extent of the resource and its associated features. Biodiv. Conserv. 14: 3327–3349.

Domestic (‘private’) gardens constitute a substantial proportion of ‘green space’ in urban areas and hence are of potential significance for the maintenance of biodiversity in such areas. However, the size and nature of this resource and its associated features are poorly known. In this study, we provide the first detailed audit, using domestic gardens in the city of Sheffield as a model study system. Domestic gardens, the mean area of which was 151 m², cover approximately 33 km² or 23% of the predominantly urban area of the city. The smaller gardens contribute disproportionately to this total because, although individually they add little, they are large in number. Conversely, the regions of the city with proportionately more garden area contribute most to the total garden area of the city, although such regions are limited in number. Based on the findings of a telephone based survey, 14.4% of dwellings with gardens were estimated to have ponds, 26% to have nest-boxes, 29% to have compost heaps, 48% to hold trees more than 3 m tall, and 14% of dwellings were estimated to be home to one or more cats. Whilst the absolute frequency of these features is low to moderate, by extrapolation they nonetheless yield estimates for domestic gardens in Sheffield of a total of 25,200 ponds, 45,500 nest boxes, 50,750 compost heaps, 360,000 trees, and a population of 52,000 domestic cats. These results are considered in the context of the role of gardens in urban areas as habitats for wildlife and the implications for housing policy.

A new technique for monitoring the detailed behaviour of domestic cat

Watanabe, S., Izawa, M., Kato, A., Ropert-Coudert, Y., & Naito, Y. (2005). A new technique for monitoring the detailed behaviour of terrestrial animals: a case study with the domestic cat. Applied Animal Behaviour Science, 94(1), 117-131.

For many animal species that are difficult to access, the behaviour of free-ranging individuals cannot be assessed by direct observation. In order to remedy this, we developed a new technique using a motion detector (acceleration data-logger) for monitoring the activity and behaviour of free-ranging vertebrates and tested its efficiency on a domestic cat, Felis catus. A total of 3615 min of surging acceleration was measured along the longitudinal body axis of an adult male cat. The cat's behaviour was also filmed for 113 min, these video data being used to correlate the logger's signals with the cat's behaviour. Acceleration data-loggers attached on the cat's collar recorded acceleration signals which were influenced by both the gravitational acceleration resulting from the body posture and the dynamic acceleration resulting from the dynamic behaviour of the cat. By applying spectral analysis based on a fast Fourier Transform to acceleration signals, body postures and some of the dynamic behaviours of the cat such as drinking, eating, and several paces of travelling were efficiently determined. The present study shows that acceleration data-loggers represent a useful and reliable system for accurately recording the activities and detail behaviours of the terrestrial animals.

Genetic structure of the feral cat on a sub-Antarctic island

Pontier, D., Say, L., Devillard, S., & Bonhomme, F. (2005). Genetic structure of the feral cat (Felis catus L.) introduced 50 years ago to a sub-Antarctic island. Polar Biology, 28(4), 268-275.

Information about the invasion dynamics and demographic status of invasive species is essential to choose the optimal control options of population numbers. While long-term direct demographic and historical records are generally lacking, the analysis of the genetic variability of a current population might supply information about past and current demographic processes. In this study, we analysed the genetic variability of the cat population living on the main island of the Kerguelen archipelago. Genetic diversity was consistent with the introduction of a very small number of individuals followed by a demographic explosion of the cat population. Significant genetic structure among sites (Fst=0.06 ±0.005) and absence of isolation by distance could indicate that the initial phase of fast colonisation is now over. Estimates of individual relatedness indicated a significant kin structure. Overall data suggested that the cat population of the main island has probably reached carrying capacity.

Cats among the main causes of bird mortality

Erickson, W. P., Johnson, G. D., & Young Jr, D. P. (2005). A summary and comparison of bird mortality from anthropogenic causes with an emphasis on collisions. USDA Forest Service General Technical Report PSWGTR-191, 1029-1042.

We estimate that from 500 million to possibly over one billion birds are killed annually in the United States due to anthropogenic sources including collisions with human-made structures such as vehicles, buildings and windows, power lines, communication towers and wind turbines; electrocutions; oil spills and other contaminants; pesticides; cat predation; and commercial fishing by-catch. Many of the deaths from these sour- ces would be considered unlawful take under federal laws such as the Endangered Species Act, Migratory Bird Treaty Act, and the Bald and Golden Eagle Pro- tection Act. In this paper, we summarize this literature and provide the basis for the mortality projections for many of the apparent significant sources. Most of the mortality projections are based on small sample sizes, and on studies typically lacking adjustments for scav- enging and searcher efficiency biases. Although the estimates for each source often range by an order of magnitude, the cumulative mortality from all these sources continues to be a concern.

(There are more recent estimations in which cat's predation is 10 times more)

Control of feral cats for nature conservation (parts I to IV)

Risbey, D. A., Calver, M., & Short, J. (1997). Control of feral cats for nature conservation. I. Field tests of four baiting methods. Wildlife Research, 24(3), 319-326.

Four methods of baiting were evaluated on a radio-collared population of feral cats on Heirisson Prong, Shark Bay, Western Australia. Dried-meat baits, baiting rabbits to kill cats through secondary poisoning, a fishmeal-based bait and a bait coated in the flavour enhancer Digest were tested. All proved to be ineffective for controlling feral cats. Future research should explore baits more ‘natural’ in appearance and the effect of visual lures, and possibly bait over a larger area to increase the number of cats exposed to baits.

Short, J., Turner, B., Risbey, D. A., & Carnamah, R. (1997). Control of feral cats for nature conservation. II. Population reduction by poisoning. Wildlife Research, 24(6), 703-714.

A feral cat population was substantially reduced by poisoning at a semi-arid site in Western Australia. The control programme was designed to protect two species of endangered native mammals that had recently been reintroduced to the site. Feral cats were poisoned with carcasses of laboratory mice, each impregnated with 4.5 mg of sodium monofluoroacetate (1080). Baits were placed at 100-m intervals along the track system each night for four consecutive nights. Kill rates were assessed by monitoring survival of radio- collared cats and by spotlight counts of cats before and after baiting. All radio-collared cats were killed and there was a 74% reduction in spotlight counts of cats after baiting. Bait removal varied with the abundance of rabbits, the primary prey item for cats in this area. Effectiveness of control operations against feral cats is maximised by baiting at times of low prey abundance. Monitoring the changing abundance of the primary prey species provides important information for timing control operations against feral cats.

Short, J., Turner, B., & Risbey, D. (2003). Control of feral cats for nature conservation. III. Trapping. Wildlife Research, 29(5), 475-487.

We present comparative success of various trapping methods trialed during control of feral cats at a site for the reintroduction of threatened mammals at Shark Bay, Western Australia. Our results come from 31 703 trap-nights that caught 263 cats (an average of 0.83 per 100 trap-nights). Cats differed markedly in their vulnerability to trapping depending on whether they primarily scavenged at rubbish tips or around human settlement or whether they hunted for their food in the bush. Cage traps were an effective means of controlling the former, with 9.4 cats captured per 100 trap-nights. Scavenging cats included a higher proportion of sub-adults and kittens and lower proportion of adult males than hunting cats. Variation between years in capture success for hunting cats was largely explained by the abundance of rabbits relative to that of cats and whether the rabbit population was increasing or decreasing. These factors accounted for a nine-fold difference in trap success. The number of cats caught in any particular trapping session could be explained by location (rubbish tip or town versus bush), trapping effort (typically greater effort yielded higher captures), abundance of cats at the site (captures were highest when cats were abundant), and season (captures were highest in the first half of the year when the young of the year were becoming independent). Concealed foot-hold traps, in a range of possible sets, provided effective methods for capturing cats that hunt, except where capture of non-target species was a critical limiting factor. Cage traps caught cats at a comparable rate to foot-hold traps for standard sets, but caught a significantly different cohort. Concealed foot-hold traps caught a higher percentage of adult cats, particularly males, than did cage traps. Mouse carcases and rabbit pieces were significantly more effective as lures when rabbits (the major food of cats at the site) were at low densities, whereas the success of commercial scent lures was unrelated to food availability. Significantly more cats than expected were caught using food as an attractant at times of food shortage (late summer, autumn and early winter) for both scavenging and hunting cats. In contrast, scent lures caught significantly more cats than expected in spring and summer when cats were defending access to mates and/or territory. Hence, no single trap type, trap set, or lure provided unequivocally superior performance over others. Control is likely to be best achieved by a variety of trapping methods and lure types used in combination, supplementing well timed poisoning efforts. Trap success is likely to be maximised by trapping at times when the dominant prey of cats are scarce relative to the number of cats and are decreasing in abundance.

Short, J., & Turner, B. (2005). Control of feral cats for nature conservation. IV. Population dynamics and morphological attributes of feral cats at Shark Bay, Western Australia. Wildlife Research, 32(6), 489-501.

The dynamics of feral cats (Felis catus) were assessed at Shark Bay at two adjoining sites subject to differing intensities of predator control. The Heirisson Prong conservation reserve (12 km²) was fenced to exclude predators and was subject to intensive control actions, while a portion of the adjoining Carrarang pastoral lease (60 km²) was subject to a lesser level of control. Foxes (Vulpes vulpes) were largely absent at both sites owing to effective control. Densities of cats were highly variable over time, showing strong annual fluctuations over 14 years of records Three independent estimates of peak density were made, varying between 1.5 and 2.8 km^-2. Rate of increase was assessed as 0.98 on the pastoral lease and 0.99 on the conservation reserve (to give an approximate doubling of the population every 8.5 months). A logistic model, with K = 1.5 km^-2 and r of 0.98, gave a maximum sustained yield of 0.37 cats km^-2 year^-1 and a harvest rate of >0.6 cats km^-2 year^-1 for their elimination in 5 years or less (for K = 2.8 km^-2  these values increase to 0.69 and >1.05 km^-2 year^-1 respectively). Harvest outcomes at both sites were consistent with these models. However, the effort required to maintain a given offtake rate increased 6-fold at low cat densities and offtake by trapping as a function of cat density took the form of a Type 3 functional response. The functional response for cat trapping (the offtake with constant effort per unit time) overlaid against the curve of cat productivity suggested a stable equilibrium point at low cat densities (0.07–0.13 cats km^-2). Hence, trapping effort needed to be greatly intensified at low cat densities and/or augmented by other methods of control to eradicate cats from the closed system of the reserve. The strongly male-biased sex ratio of captures at the barrier fence suggested high levels of reinvasion from beyond the harvested area of the pastoral lease and this made effective control in this open system difficult.

Exurban development and biodiversity

Hansen, A. J., Knight, R. L., Marzluff, J. M., Powell, S., Brown, K., Gude, P. H., & Jones, K. (2005). Effects of exurban development on biodiversity: patterns, mechanisms, and research needs. Ecological Applications, 15(6), 1893-1905.

Low-density rural home development is the fastest-growing form of land use in the United States since 1950. This “exurban” development (6–25 homes/km²) includes urban fringe development (UFD) on the periphery of cities and rural residential development (RRD) in rural areas attractive in natural amenities. This paper synthesizes current knowledge on the effects of UFD and RRD. We present two case studies and examine the patterns of biodiversity response and the ecological mechanisms that may underlie these responses. We found that many native species have reduced survival and reproduction near homes, and native species richness often drops with increased exurban densities. Exotic species, some human-adapted native species, and species from early successional stages often increase with exurban development. These relationships are sometimes nonlinear, with sharp thresholds in biodiversity response. These effects may be manifest for several decades following exurban development, so that biodiversity is likely still responding to the wave of exurban expansion that has occurred since 1950. The location of exurban development is often nonrandom relative to biodiversity because both are influenced by biophysical factors. Consequently, the effects on biodiversity may be disproportionately large relative to the area of exurban development. RRD is more likely than UFD to occur near public lands; hence it may have a larger influence on nature reserves and wilderness species. The ecological mechanisms that may underlie these responses involve alteration of habitat, ecological processes, biotic interactions, and increased human disturbance. Research on the patterns and mechanisms of biodiversity remains underdeveloped, and comparative and experimental studies are needed. Knowledge resulting from such studies will increase our ability to understand, manage, and mitigate negative impacts on biodiversity.

Population dynamics of feral cats in relation to prey abundance

Harper, G. A. (2005). Numerical and functional response of feral cats (Felis catus) to variations in abundance of primary prey on Stewart Island (Rakiura), New Zealand. Wildlife Research, 32(7), 597-604.

Few studies of populations of feral cats have simultaneously monitored the seasonal abundance of primary prey and the possible ‘prey-switch’ to alternative prey when primary prey abundance declines. On Stewart Island, when the abundance of feral cats’ primary prey, rats (Rattus spp.), was very low, significantly more cats died or left the study area than when rats were abundant. Cats preferentially preyed on rats regardless of rat abundance. Birds were the main alternative prey but cats did not prey-switch to birds when rat abundance was low, possibly owing to the difficulty of capture, and small mass, of birds compared with rats. On Stewart Island numbers of feral cats are restricted by seasonal depressions in abundance of their primary prey, coupled with limited alternative prey biomass.

Mating and parental behaviour in free-ranging dogs

Pal, S. K. (2005). Parental care in free-ranging dogs,Canis familiaris. Applied Animal Behaviour Science, 90(1), 31-47.

Parental care in free-ranging dogs was investigated in Katwa town, India. Six lactating bitches, 4 were monogamous. The gestation period varied from 62 to 65 days. Mean (±S.D.) litter size of 5.83 (±1.57) with a sex ratio of 1.69:1 in favour of male was recorded in this study. High mortality (63%) of pups occurred by the age of 3 months. Mothers were in contact with the litters for 13 weeks of the litters’ life. There was a negative correlation between the duration of mother–litter contact in any observation session and the age of the pups. Milk feeding by the mothers was continued for 10–11 weeks of the litters’ life. The duration of milk feeding in any 30-min observation session reached a maximum of 27.54 min during the 1st week and a minimum of 2.22 min during the 11th week of the litters’ life. All the mothers in this study were observed to feed the pups by regurgitation. For the first 2 weeks immediately after parturition, the lactating females were observed to be more aggressive to protect the pups. The four males (male parents) were in contact with the litters as ‘guard’ dogs for the first 6–8 weeks of litters’ life. In absence of the mothers, they were observed to prevent the approach of strangers by vocalizations or even by physical attacks. Moreover, one male fed the litter by regurgitation showing the existence of paternal care in free-roaming domestic dogs.


Pal, S. K. (2011). Mating System of Free-Ranging Dogs (Canis familiaris).International Journal of Zoology, 2011.
Fourteen females belonging to five groups were selected for the study of mating system in free-ranging domestic dogs (Canis familiaris) All the matings occurred between August and December with a peak in late monsoon months (September to November). Both males and females differed in their degree of attractiveness to the opposite sex. The duration of courting association increased with the number of courting males in an association. The females exhibited selectivity by readily permitting some males to mate and avoiding, or even attacking others, if they attempted to mount. Frequency of mounting in courting association increased with the number of males present. There was a positive correlation between the duration of courting association and the frequency of mounting. The young adult males were more likely to copulate successfully than the old adult males. There was a negative correlation between the number of males present in an association and the number of successful copulations. In this study, six types of mating (monogamy, polygyny, promiscuity, polyandry, opportunity and rape) were recorded. Mean (±S.E.) duration of copulatory ties was 25.65 (±1.43) min. Several natural factors influencing the duration of copulatory ties were identified.

Introduced mammals as the first threat to Xantus' Murrelet

KEITT, B.S. 2005. Status of Xantus’s Murrelet and its nesting habitat in Baja California, Mexico. Marine Ornithology 33: 105–114.

A preliminary survey was conducted in 1999 to establish the status of the Xantus’s Murrelet Synthliboramphus hypoleucus in Baja California, Mexico. Seven island groups with prior evidence of breeding (Coronado, Todos Santos, San Martín, San Jerónimo, San Benito, Asunción and San Roque) and two potential breeding islands without prior evidence of nesting (Natividad and Adelaida) were examined. In 2004, additional work was conducted at Afuera Islet off Guadalupe Island. Presence of murrelets was detected through nest searches and by rough estimation of birds in nocturnal at-sea congregations using boat-based and land-based vocalization counts. Vocalizations were heard at six island groups (Coronado, Todos Santos, San Martín, San Jerónimo, San Benito and Guadalupe) and nests were found at four island groups (Coronado, San Jerónimo, San Benito and Guadalupe). Land-based and boat-based vocalization surveys both detected presence or apparent absence of murrelets at potential nesting islands, although boat-based vocalization rates were higher on average. Vocalization surveys cannot readily be converted to breeding population estimates, but overall population size of murrelets in Baja California appears to about 2300 pairs (range: 1000–4000 pairs), similar to previous estimates. Historically, nonindigenous mammals were introduced to most islands in Baja California; recent progress in removing introduced mammals should benefit Xantus’s Murrelets.

Methods and strategies to control feral cats to protect Galapagos land iguanas

Phillips, R. B., Cooke, B. D., Campbell, K., Carrion, V., Marquez, C., & Snell, H. L. (2005). Eradicating feral cats to protect Galapagos land iguanas: methods and strategies. Pacific Conservation Biology, 11(4), 257.

A three-year programme to eradicate Feral Cats Felis catus from the island of Baltra in the Galapagos archipelago achieved good results by Initially poisoning with sodium monofluoroacetate (compound 1080) then trapping or shooting the remaining cats. The poisoning campaign removed 90% of the cats, its success being attributable to pre-baiting with unpolsoned baits to accustom cats to eating baits and placing enough baits to ensure that all cats encountered several baits within their home range. This, together with the use of metaclopromide (Pileran) as an anti-emetic, overcame a problem associated with poor retention of 1080 in thawed fish baits that limited the dose available to 1 mg 1080 bait, a quality insufficient to kill large cats. Removal of the remaining cats was delayed by a weather-induced irruption of Black Rats Rattus rattus and House Mice Mus musculus that enabled recruitment of kittens in 2002, but made cats more susceptible to trapping and shooting in 2003 when rodent populations collapsed. Since July 2003 no sign of a cat has been detected on Baltra despite extensive searching and monitoring throughout 2004. As cat abundance has decreased there have been more locally-bred juvenile iguanas (Conolophus subcristatus) seen during annual censuses. However, such recruitment may reflect the increasing maturity and higher fecundity of iguanas repatriated from 1991 onwards rather than being a direct result of reduced cat predation alone. More time is necessary to determine the benefits of reduced cat predation on the Iguana population.

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 pathogens in threatened wild canids

Deem, Sharon L., & Louise H. Emmons. 2005. Exposure of free-ranging maned wolves (Chrysocyon brachyurus) to infectious and parasitic disease agents in the Noel Kempff Mercado National Park, Bolivia. Journal of zoo and wildlife medicine 36 (2): 192-197.

Maned wolves (Chrysocyon brachyurus) are neotropic mammals, listed as a CITES Appendix II species, with a distribution south of the Amazon forest from Bolivia, through northern Argentina and Paraguay and into eastern Brazil and northern Uruguay. Primary threats to the survival of free-ranging maned wolves include habitat loss, road kills, and shooting by farmers. An additional threat to the conservation of maned wolves is the risk of morbidity and mortality due to infectious and parasitic diseases. Captive maned wolves are susceptible to, and die from, common infectious diseases of domestic dogs (Canis familiaris) including canine distemper virus (CDV), canine parvovirus (CPV), rabies virus, and canine adenovirus (CAV). Results from this study show that free-ranging maned wolves in a remote area of Bolivia have been exposed to multiple infectious and parasitic agents of domestic carnivores, including CAV, CDV, CPV, canine coronavirus, rabies virus, Leptospira interrogans spp., Toxoplasma gondii, and Dirofilaria immitis, and may be at increased risk for disease due to these agents.

Domestic dogs and SE European wolves

Verginelli, F., Capelli, C., Coia, V., Musiani, M., Falchetti, M., Ottini, L., Palmirotta, R., Tagliacozzo, A., de Grossi Mazzorin, I. & Mariani-Costantini, R. (2005). Mitochondrial DNA from prehistoric canids highlights relationships between dogs and South-East European wolves.Molecular biology and evolution, 22(12), 2541-2551.

The question of the origins of the dog has been much debated. The dog is descended from the wolf that at the end of the last glaciation (the archaeologically hypothesized period of dog domestication) was one of the most widespread among Holarctic mammals. Scenarios provided by genetic studies range from multiple dog-founding events to a single origin in East Asia.
 The earliest fossil dogs, dated ≈17–12,000 radiocarbon (¹⁴C) years ago (YA), were found in Europe and in the Middle East. Ancient DNA (a-DNA) evidence could contribute to the identification of dog-founder wolf populations. To gain insight into the relationships between ancient European wolves and dogs we analyzed a 262-bp mitochondrial DNA control region fragment retrieved from five prehistoric Italian canids ranging in age from ≈15,000 to ≈3,000 ¹⁴C YA. These canids were compared to a worldwide sample of 547 purebred dogs and 341 wolves. The ancient sequences were highly diverse and joined the three major clades of extant dog sequences. Phylogenetic investigations highlighted relationships between the ancient sequences and geographically widespread extant dog matrilines and between the ancient sequences and extant wolf matrilines of mainly East European origin. The results provide a-DNA support for the involvement of European wolves in the origins of the three major dog clades. Genetic data also suggest multiple independent domestication events. East European wolves may still reflect the genetic variation of ancient dog-founder populations.

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Bells and electronic sonic device reducing predation by cats in UK

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

Volunteer cat owners from across the UK were recruited to take part in two trials designed to test the efficacy of collar-mounted warning devices in reducing cat predation rates of native wildlife. Cats equipped with a bell returned 34% fewer mammals and 41% fewer birds than those with a plain collar. Those equipped with an electronic sonic device returned 38% fewer mammals and 51% fewer birds compared with cats wearing a plain collar. There was no significant difference in prey return rates by cats wearing collars equipped with one bell, two bells or the sonic device. Warning devices mounted on quick-release collars are recommended as an effective way of reducing wildlife kill rates by domestic cats. Future research and development aimed at further improving the efficacy of sonic devices is recommended.

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You can see early reports of CatAlert device here

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

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

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Read a short review about belling effectiveness

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.

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.

TNR evaluation: demography, home range and potential zoonosis

Nutter, F. B. 2005. Evaluation of a trap-neuter-return management program for feral cat colonies: population dynamics, home ranges, and potentially zoonotic diseases. PhD dissertation, North Carolina State University. Raleigh, NC. 

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

Cats and other predators disrupting mutualistic relationships between endemic threatened lizards and plants

Traveset, A. & N. Riera. 2005. Disruption of a plant-lizard seed dispersal system and its ecological effect on a threatened endemic plant in the Balearic Islands. Conservation Biology. 19 (2): 421-431

The introduction of exotic species to an island can have significant effects on the population density and distribution of native species and on the ecological and evolutionary interactions among them (e.g., plant-animal mutualisms). The disruption of these interactions can be dramatic, significantly reducing the reproductive success of the species and even leading to their extinction. On Menorca Island (Balearic Islands, western Mediterranean), we examined the consequences of the disruption of the mutualism between two endemic species: a perennial shrub, ( Daphne rodriguezii [Texidor]) and a frugivorous lizard (Podarcis lilfordi [Günther]). The lizard became extinct from this island (as well as from Mallorca) as a result of the introduction of carnivorous mammals, which has continued since Roman times. The relict mutualism between D. rodriguezii and the lizard currently persists only in an islet (60 ha) where P. lilfordi is still abundant. We hypothesized that the absence of this lizard from most Menorcan populations is the factor causing the regression of this plant, currently considered at risk of extinction. Through observation and experimentation in the field and laboratory, we found strong evidence that a lack of seed dispersal in Menorca is the main cause of the low seedling recruitment. First, the population with greatest seedling recruitment was that in the islet where lizards were abundant. Second, lizards appeared to be the only dispersers of D. rodriguezii. Lizards consumed large amounts of fruits, without affecting either germination or seedling growth, and moved seeds to sites suitable for plant establishment. Seedlings in Menorca, in contrast, recruited almost exclusively under the parent plants. Third, the effect of other factors that may influence plant population growth (a low fruit set and a high postdispersal seed predation) was similar between the islet and the Menorcan populations. To our knowledge, our results are the first that quantitatively show that a biological invasion can cause a disruption of a specialized plant-vertebrate mutualism that sets the plant partner on the road to extinction.

Impact of domestic cats in an urban area

Baker, P. J., A. J. Bentley, R. J. Ansell, & S. Harris. 2005. Impact of predation by domestic cats Felis catus in an urban area. Mammal Review 35:302–312.

As companion animals, domestic cats Felis catus can attain very high densities, and have the potential to exert detrimental effects on prey species. Yet, there is a paucity of information on the impact of cat predation in urban areas, where most cats are likely to be present.

We quantified the minimum number of animals killed annually by cats in a 4.2-km2 area of Bristol, UK, by asking owners to record prey animals returned home by their pets. The potential impact of cat predation on prey species was estimated by comparing the number of animals killed with published estimates of prey density and annual productivity.

Predator density was 229 cats/km2.

Five mammal, 10 bird and one amphibian prey species were recorded. Mean predation rate was 21 prey/cat/annum. The most commonly recorded prey species was the wood mouse Apodemus sylvaticus.

Predation on birds was greatest in spring and summer, and probably reflected the killing of juvenile individuals. For three prey species (house sparrow Passer domesticus, dunnock Prunella modularis, robin Erithacus rubecula), estimated predation rates were high relative to annual productivity, such that predation by cats may have created a dispersal sink for juveniles from more productive neighbouring areas. The impact of cats on these species therefore warrants further investigation.