How many feral cats are in Australia?

Legge, S., Murphy, B. P., McGregor, H., Woinarski, J. C. Z., Augusteyn, J., Ballard, G., ... & Edwards, G. (2016). Enumerating a continental-scale threat: How many feral cats are in Australia?. Biological Conservation.

Feral cats (Felis catus) have devastated wildlife globally. In Australia, feral cats are implicated in most recent mammal extinctions and continue to threaten native species. Cat control is a high-profile priority for Australian policy, research and management. To develop the evidence-base to support this priority, we first review information on cat presence/absence on Australian islands and mainland cat-proof exclosures, finding that cats occur across >99.8% of Australia's land area. Next, we collate 91 site-based feral cat density estimates in Australia and examine the influence of environmental and geographic influences on density. We extrapolate from this analysis to estimate that the feral cat population in natural environments fluctuates between 1.4 million (95% confidence interval: 1.0–2.3 million) after continent-wide droughts, to 5.6 million (95% CI: 2.5–11 million) after extensive wet periods. We estimate another 0.7 million feral cats occur in Australia's highly modified environments (urban areas, rubbish dumps, intensive farms). Feral cat densities are higher on small islands than the mainland, but similar inside and outside conservation land. Mainland cats reach highest densities in arid/semi-arid areas after wet periods. Regional variation in cat densities corresponds closely with attrition rates for native mammal fauna. The overall population estimate for Australia's feral cats (in natural and highly modified environments), fluctuating between 2.1 and 6.3 million, is lower than previous estimates, and Australian feral cat densities are lower than reported for North America and Europe. Nevertheless, cats inflict severe impacts on Australian fauna, reflecting the sensitivity of Australia's native species to cats and reinforcing that policy, research and management to reduce their impacts is critical.

The population size of feral cats in natural environments in Australia fluctuates between 1.4 and 5.6 million, depending on rainfall. An additional 0.7 million feral cats live in heavily modified environments like towns and intensive farms. The maps show the model predictions for cat density in natural environments across Australia during dry-average rainfall conditions (on the left) and after extensive rainfall events (on the right). They show that cat density is fairly uniform across the continent during average-dry conditions, but extensive rainfall events cause an increase in feral cat density in the inland of Australia. As predictors, the regression model includes mean annual rainfall, mean annual temperature, tree cover, ruggedness and fox presence/absence. For islands smaller than Tasmania, island area was also included as a predictor of density (small islands have higher cat densities). The dashed lines indicate the Tropic of Capricorn.

Preliminary data on the distribution of free-ranging dogs in a Bulgarian National Park

Doykin, N., Popova, E., Zlatanov, V., Petrov, P., & Zlatanova, D. 2016. Preliminary data on the distribution of free-ranging dogs (Canis familiaris L.) in NP Vitosha, Bulgaria. Annuaire de l’Université de Sofia “St. Kliment Ohridski” Faculte de Biologie 2016, volume 101, livre 4, pp. 11-22. Youth Scientific Conference “Kliment’s Days”, Sofia 2015

Free-ranging dogs often leave the urbanized areas and stray into nearby mountainous habitats, even entering protected areas. This causes problems for the wildlife due to either direct predation or disturbance. Our camera trap survey (July 2013 - November 2014) in NP Vitosha, Bulgaria resulted in a total of 199 independent registrations of free-ranging dogs in 81 locations. In this preliminary study, we present the distribution, habitat selection, and distance from settlements and activity of free ranging dogs in Vitosha NP. The free-ranging dogs in Vitosha are predominantly diurnal, and show preference towards coniferous and mixed forests, mostly closed. Their distribution and activity patterns are influenced by human presence, which is due to the fact that they at least partially rely on human-sourced food. Some data for observations of wild animals influenced by dogs is also discussed. 

Lack of hybridization between wild and domestic cats explained by spatial segregation

Gil-Sánchez, J. M., Jaramillo, J., & Barea-Azcón, J. M. (2015). Strong spatial segregation between wildcats and domestic cats may explain low hybridization rates on the Iberian Peninsula. Zoology.

The European wildcat (Felis silvestris silvestris) is an endangered felid impacted by genetic introgression with the domestic cat (Felis silvestris catus). The problem of hybridization has had different effects in different areas. In non-Mediterranean regions pure forms of wildcats became almost extinct, while in Mediterranean regions genetic introgression is a rare phenomenon. The study of the potential factors that prevent the gene flow in areas of lower hybridization may be key to wildcat conservation. We studied the population size and spatial segregation of wildcats and domestic cats in a typical Mediterranean area of ancient sympatry, where no evidence of hybridization had been detected by genetic studies. Camera trapping of wild-living cats and walking surveys of stray cats in villages were used for capture–recapture estimations of abundance and spatial segregation. Results showed (i) a low density of wildcats and no apparent presence of putative hybrids; (ii) a very low abundance of feral cats in spite of the widespread and large population sources of domestic cats inhabiting villages; (iii) strong spatial segregation between wildcats and domestic/feral cats; and (iv) no relationship between the size of the potential population sources and the abundance of feral cats. Hence, domestic cats were limited in their ability to become integrated into the local habitat of wildcats. Ecological barriers (habitat preferences, food limitations, intra-specific and intra-guild competition, predation) may explain the severe divergences of hybridization impact observed at a biogeographic level. This has a direct effect on key conservation strategies for wildcats (i.e., control of domestic cats).

 Read more on domestic wild feline hybridisation with domestic cat

Dogs in Lombok Island, Indonesia

Mustiana A, Toribio J-A, Abdurrahman M, Suadnya IW, Hernandez-Jover M, Putra AAG, et al. (2015) Owned and Unowned Dog Population Estimation, Dog Management and Dog Bites to Inform Rabies Prevention and Response on Lombok Island, Indonesia. PLoS ONE 10(5): e0124092. doi:10.1371/journal.pone.0124092

Although Indonesia has been rabies-infected since at least the 1880s, some islands remain rabies-free, such as Lombok. However, due to its adjacency to rabies-infected islands such as Bali and Flores, there is considerable risk of a rabies incursion. As part of a rabies risk assessment project, surveys were conducted to estimate the size of the dog population and to describe dog management practices of households belonging to different ethnic groups. A photographic-recapture method was employed and the number of unowned dogs was estimated. A total of 400 dog owning households were interviewed, 300 at an urban site and 100 at a rural site. The majority of the interviewed households belonged to the Balinese ethnic group. Owned dogs were more likely male, and non-pedigree or local breed. These households kept their dogs either fully restricted, semi-free roaming or free-roaming but full restriction was reported only at the urban site. Dog bite cases were reported to be higher at the urban site, and commonly affected children/young adults to 20 years old and males. A higher number of unowned dogs was observed at the urban site than at the rural site. Data generated within these surveys can inform rabies risk assessment models to quantify the probability of rabies being released into Lombok and resulting in the infection of the local dog population. The information gained is critical for efforts to educate dog owners about rabies, as a component of preparedness to prevent the establishment of rabies should an incursion occur.

Methods to estimate abundance and rabies vaccination coverage in Bhutan

Tenzin, T., McKenzie, J. S., Vanderstichel, R., Rai, B. D., Rinzin, K., Tshering, Y., Pemd, R., Tsheringf, C., Dahala, N., Dukpaa, K., Dorjeed, S., Wangchukh, S., Jollyb, P.D., Morrisi, R. & Ward, M. P. (2015). Comparison of mark-resight methods to estimate abundance and rabies vaccination coverage of free-roaming dogs in two urban areas of south Bhutan. Preventive Veterinary Medicine. Preventive Veterinary Medicine

In Bhutan, Capture-Neuter-Vaccinate-Release (CNVR) programs have been implemented to manage the dog population and control rabies, but no detailed evaluation has been done to assess their coverage and impact. We compared estimates of the dog population using three analytical methods: Lincoln-Petersen index, the Chapman estimate, and the logit-normal mixed effects model, and a varying number of count periods at different times of the day to recommend a protocol for applying the mark-resight framework to estimate free-roaming dog population abundance. We assessed the coverage of the CNVR program by estimating the proportion of dogs that were ear-notched and visually scored the health and skin condition of free-roaming dogs in Gelephu and Phuentsholing towns in south Bhutan, bordering India, in September–October 2012.

The estimated free-roaming dog population in Gelephu using the Lincoln-Petersen index and Chapman estimates ranged from 612 to 672 and 614 to 671, respectively, while the logit-normal mixed effects model estimate based on the combined two count events was 641 (95% CI: 603-682). In Phuentsholing the Lincoln-Petersen index and Chapman estimates ranged from 525 to 583 and 524 to 582, respectively, while the logit-normal mixed effects model estimate based on the combined four count events was 555 (95% CI: 526-587). The total number of dogs counted was significantly associated with the time of day (AM versus PM; P = 0.007), with a 17% improvement in dog sightings during the morning counting events. We recommend to conduct a morning marking followed by one count event the next morning and estimate population size by applying the Lincoln-Peterson corrected Chapman method or conduct two morning count events and apply the logit-normal mixed model to estimate population size.

The estimated proportion of vaccinated free-roaming dogs was 56% (95% CI: 52–61%) and 58% (95% CI: 53–62%) in Gelephu and Phuentsholing, respectively. Given coverage in many neighbourhoods was below the recommended threshold of 70%, we recommend conducting an annual “mass dog vaccination only” campaign in southern Bhutan to create an immune buffer in this high rabies-risk area. The male-to-female dog ratio was 1.34:1 in Gelephu and 1.27:1 in Pheuntsholing.

Population size estimates using mark-resight surveys has provided useful baseline data for understanding the population dynamics of dogs at the study sites. Mark–resight surveys provide useful information for designing and managing the logistics of dog vaccination or CNVR programs, assessing vaccination coverage, and for evaluating the impact of neutering programs on the size and structure of dog populations over time.

Stray dog's census in Lima

Ochoa, A., Falcón, P., Zuazo, R., & Guevara, P. (2014). Estimated population of stray dogs in the district of Los Olivos, Lima, Peru. Revista de Investigaciones Veterinarias del Perú (RIVEP), 25(3), 366-373.
The aim of this study was to estimate and characterize the stray dog population in Los Olivos district, Lima, during the period November-December 2012. Eight of the 34 areas that comprise the district according the map of Los Olivos Municipality were selected. The selection of the areas was at random; dog population counting and calculations were based on the criteria outlined in the guide of the World Society for the Protection of Animals entitled "Recensusing roaming dog populations: guidelines on methodology". Three consecutive sampling were performed at daytime and evening hours in each area. The average of the three measurements was used for statistical calculations. There was an average of 332 stray dogs at daytime and 217 stray dogs at evening; males and bigger dogs were observed in higher number. Most of the dogs showed low body condition score. The estimated number of stray dogs in the district was 1411±643 at daytime and 922±497 at night. Results are expected to contribute with the dog control population programme that is being implemented by the Municipality of Los Olivos.

Size estimation and demography of owned pets in NE ITaly

Capello, K., Bortolotti, L., Lanari, M., Baioni, E., Mutinelli, F., & Vascellari, M. (2014). Estimate of the size and demographic structure of the owned dog and cat population living in Veneto region (north-eastern Italy). Preventive Veterinary Medicine.

The knowledge of the size and demographic structure of animal populations is a necessary prerequisite for any population-based epidemiological study, especially to ascertain and interpret prevalence data, to implement surveillance plans in controlling zoonotic diseases and, moreover, to provide accurate estimates of tumours incidence data obtained by population-based registries. The main purpose of this study was to provide an accurate estimate of the size and structure of the canine population in Veneto region (north-eastern Italy), using the Lincoln-Petersen version of the capture-recapture methodology. The Regional Canine Demographic Registry (BAC) and a sample survey of households of Veneto Region were the capture and recapture sources, respectively. The secondary purpose was to estimate the size and structure of the feline population in the same region, using the same survey applied for dog population. A sample of 2,465 randomly selected households was drawn and submitted to a questionnaire using the CATI technique, in order to obtain information about the ownership of dogs and cats. If the dog was declared to be identified, owner's information was used to recapture the dog in the BAC. The study was conducted in Veneto Region during 2011, when the dog population recorded in the BAC was 605,537. Overall, 616 households declared to possess at least one dog (25%), with a total of 805 dogs and an average per household of 1.3. The capture-recapture analysis showed that 574 dogs (71.3%, 95% CI: 68.04% - 74.40%) had been recaptured in both sources, providing a dog population estimate of 849,229 (95% CI: 814,747 - 889,394), 40% higher than that registered in the BAC. Concerning cats, 455 of 2,465 (18%, 95%CI: 17% - 20%) households declared to possess at least one cat at the time of the telephone interview, with a total of 816 cats. The mean number of cats per household was equal to 1.8, providing an estimate of the cat population in Veneto region equal to 663,433 (95%CI: 626,585 - 737,159). The estimate of the size and structure of owned canine and feline populations in Veneto region provide useful data to perform epidemiological studies and monitoring plans in this area.

Estimating stray dogs in Lima, Perú

Ochoa, Y., Falcón, N., Zuazo, J., & Guevara, B. (2014). Estimación de la población de perros callejeros en el distrito de Los Olivos, Lima, Perú. Revista de Investigaciones Veterinarias del Perú, 25(3), 366-373.

El objetivo del estudio fue estimar y caracterizar la población de perros callejeros en el distrito de Los Olivos durante el periodo noviembre y diciembre 2012. Para ello se seleccionaron 8 de las 34 zonas que divide al distrito en el plano municipal. La selección de las zonas fue de forma aleatoria y para el conteo y cálculos de la población de perros se utilizaron los criterios expuestos en la guía «Censando poblaciones de perros callejeros: guía metodológica» de la World Society for the Protection of Animals. Se realizaron tres muestreos consecutivos en horarios diurno y nocturno en cada zona. Se utilizó la media de las tres mediciones para realizar los cálculos estadísticos. El estudio reportó un promedio de 332 perros callejeros en horario diurno y de 217 en horario nocturno. Los animales machos y los de tamaño grande se observaron en mayor número. La mayoría de perros poseía un índice de condición corporal bajo. La estimación del número de perros callejeros en el distrito fue de 1 411 ± 643 en horario diurno y de 922 ± 497 en horario nocturno. Se espera que los resultados aporten información de línea base al programa de control poblacional canino que viene trabajando la Municipalidad Distrital de Los Olivos.

The aim of this study was to estimate and characterize the stray dog population in Los Olivos district, Lima, during the period November - December 2012. Eight of the 34 areas that comprise the district according the map of Los Olivos Municipality were selected. The selection of the areas was at random; dog population counting and calculations were based on the criteria outlined in the guide of the World Society for the Protection of Animals entitled «Recensusing roaming dog populations: guidelines on methodology». Three consecutive sampling were performed at daytime and evening hours in each area. The average of the three measurements was used for statistical calculations. There was an average of 332 stray dogs at daytime and 217 stray dogs at evening; males and bigger dogs were observed in higher number. Most of the dogs showed low body condition score. The estimated number of stray dogs in the district was 1411 ± 643 at daytime and 922 ± 497 at night. Results are expected tocontribute with the dog control population programme that is being implemented by the Municipality of Los Olivos.

Cat population density in a sub-Antarctic island

Say, L., Gaillard, J. M., & Pontier, D. (2002). Spatio-temporal variation in cat population density in a sub-Antarctic environment. Polar Biology, 25(2), 90-95.

We used the walked-line transect method for estimating the density of cats and coefficients of variation of density estimates in 4 contrasted sites on the main island of Îles Kerguelen between 1998 and 2000. Density estimates varied from 0.44±0.15 cats per km² to 2.42±0.23 cats per km²  according to site and period. Coefficient of variation of density estimates ranged from 11.92% to 34.76%. The line transect method was, therefore, an efficient method for monitoring the density of the cat population in a sub-Antarctic environment characterised by short vegetation. Our results suggest that cat population size at the main island of Îles Kerguelen (the total number of cats expected is around 7,000) is much lower than previously thought.

Individual cat's scat detection probability

Forin-Wiart, M. A., Gotteland, C., Gilot-Fromont, E., & Poulle, M. L. (2014). Assessing the homogeneity of individual scat detection probability using the bait-marking method on a monitored free-ranging carnivore population. European Journal of Wildlife Research, 1-8.

Estimates of terrestrial carnivore populations are often based on information derived from scat collected during trail-based sampling. However, few attempts have been made to verify the homogeneity of individual scat detection probability because wild carnivore species seldom afford this opportunity. The present study aims to test this assumption on a free-ranging population of domestic cats (Felis silvestris catus), as this carnivore has ranging behaviours close enough to its wild ancestor to provide useful information for wild carnivore surveys. The homogeneity of scat detection probability was investigated using the bait-marking method on a previously monitored population of 142 individuals, composed of free-roaming house cats (43 %) and farm cats (57 %). An 11-km trail was walked twice a week over a 58-day period to individually feed cats with marked baits and to collect their faeces. From the 8,236 faeces expected to be dropped by cats over that period, less than 2 % were collected, and from the 215 baits distributed to 44 cats (31 % of the population), only 13.5 % of the expected marked faeces were found. Detectability of faeces producers did not differ between free-roaming house cats and farm cats, but faeces detection probability was linked with sex and reproductive status. This study, conducted on a monitored population of free-roaming carnivores, stresses that it is possible to make only cautious conclusions about population estimates supported by trail-based scat samplings, since only a few individuals may be responsible for many scat detections.

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 brings cats and dogs and changes bird communities

Maestas, J. D., Knight, R. L., & Gilgert, W. C. (2003). Biodiversity across a Rural Land‐Use Gradient. Conservation Biology, 17(5), 1425-1434.

Private lands in the American West are undergoing a land-use conversion from agriculture to exurban development, although little is known about the ecological consequences of this change. Some nongovernmental organizations are working with ranchers to keep their lands out of development and in ranching, ostensibly because they believe biodiversity is better protected on ranches than on exurban developments. However, there are several assumptions underlying this approach that have not been tested. To better inform conservation efforts, we compared avian, mesopredator, and plant communities across the gradient of intensifying human uses from nature reserves to cattle ranches to exurban developments. We conducted surveys at randomly selected points on each type of land use in one Colorado watershed between May and August of 2000 and 2001. Seven bird species, characterized as human commensals or tree nesters, reached higher densities (all p < 0.02) on exurban developments than on either ranches or reserves. Six bird species, characterized as ground and shrub nesters, reached greater densities (all p < 0.015) on ranches, reserves, or both of these types of land use than on exurban developments. Domestic dogs (Canis familiaris) and house cats (Felis catus) were encountered almost exclusively on exurban developments, whereas coyotes (Canis latrans) were detected more frequently (p = 0.047) on ranchlands than exurban developments. Ranches had plant communities with higher native species richness and lower non-native species richness and cover than did the other types of land use (all p < 0.10). Our results support the notion that ranches are important for protecting biodiversity and suggest that future conservation efforts may require less reliance on reserves and a greater focus on private lands.

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Los terrenos privados del oeste de América están experimentando una conversión del suelo de un uso agrícola a un uso urbano, aunque se conoce poco acerca de las consecuencias ecológicas de este cambio. Algunas organizaciones no gubernamentales están trabajando con granjeros para que sus tierras permanezcan sin urbanizar, ostensiblemente porque piensan que la biodiversidad se protege mejor en tierras rurales que en urbanizaciones. Sin embargo, hay varios supuestos subyacentes a este modelo que no han sido comprobadas. Para informarnos mejor sobre los esfuerzos de conservación, comparamos comunidades de aves, mesodepredadores y plantas a lo largo del gradiente de intensidad de uso humano de reservas naturales, granjas y zonas de urbanización. Realizamos muestreos en sitios seleccionados aleatoriamente en cada uso de suelo en una cuenca del Colorado entre mayo y agosto de 2000 y 2001. Siete especies de aves, caracterizadas como comensales humanos o nidificantes arbóreos, alcanzaron densidades más altas (todas p < 0.02) en urbanizaciones nuevas que en granjas o reservas. Seis especies de aves, caracterizadas como nidificantes de suelo y arbustos, alcanzaron densidades mayores (todas p < 0.015) en granjas, reservas o usos mixtos del suelo que en las nuevas urbanizaciones. Se encontraron perros (Canis familiaris) y gatos (Felis catus) domésticos casi exclusivamente en nuevas urbanizaciones, mientras que se detectaron coyotes (Canis latrans) más frecuentemente (p = 0.047) en granjas que en nuevas urbanizaciones. Las granjas tenían comunidades de plantas con mayor riqueza de especies nativas y menor riqueza y cobertura de especies no nativas que en todos los demás usos de suelo (todas p < 0.10). Nuestros resultados apoyan la noción de que las granjas son importantes para la protección de la biodiversidad y sugieren que los futuros esfuerzos de conservación pueden requerir de menos confianza en las reservas y un mayor enfoque en terrenos privados.

Evaluating two census methods

Edwards, G. P., De Preu, N. D., & Crealy, B. S. I. (2000). An evaluation of two methods of assessing feral cat and dingo abundance in central Australia.Wildlife Research, 27(2), 143-149.

We evaluated the efficacy of spotlight surveys and passive track surveys conducted along roads for assessing the relative abundance of feral cats and dingoes in a semi-arid rangeland environment in central Australia. Track surveys were more time-efficient than spotlight surveys and offered higher precision. We cover a range of issues that need to be considered when using track-based surveys to assess population change. We also discuss the merits of other techniques used to monitor the abundance of mammalian carnivores.

Rapid assessment of feral cats and other invasive mammals in Santa María key, Cuba

BORROTO, R., PLASENCIA, I. R., & ALBERNAS, J. H. 2013. Valoración rápida de gatos ferales y otros mamíferos invasores en cayo Santa María, norte de Villa Clara, Cuba. Solenodon, 11: 120-130. (In Spanish, with English abstract)

The presence of cats in touristic and natural areas was evaluated in Santa María key, North of Villa Clara, Cuba. Trapping methods in touristic areas produced a low index of 0.1 cats/trap-night, possibly due to the cat rejection of traps; however, visual counts resulted in a high index of 42.8 cats/ha, with a minimum of 1.7 cat/ha in two hotels. Trapping in natural areas was not successful due to the consumption of bait by ants, other reasons for trap failure are discussed, and the cat evaluation was indirectly evaluated. In touristic areas the dog/ha index varied from 11.3 to 0.1 and the dogs entered protected areas constantly. The presence of black rats was detected indirectly by skeletal and pellet remains in a cave and owl perchs (Tyto alba). The implication of the presence of cats and other invasive mammals in touristic areas and the importance of control and management to avoid faunal impacts in the protected area are discussed.

Estimation of stray dog population in Timor Leste

Amaral, A. C., Ward, M. P., & Freitas, J. D. C. (2013). Estimation of roaming dog populations in Timor Leste. Preventive Veterinary Medicine.

The continued spread of rabies through the eastern islands of Indonesia poses a risk of rabies introduction to Timor Leste. To prepare for such an incursion and to undertake surveillance activities, the size and distribution of the roaming dog population needs to be estimated. We present the results of the first such surveys ever undertaken in Timor Leste.

Roaming dog surveys were undertaken in each capital of the 13 districts of Timor Leste, including the national capital, Dili. Within these locations, local urban areas (aldeias) were targeted and sight-re-sight counts were undertaken on consecutive days. Estimated dog populations were adjusted for the sampling fraction.

Overall, counts were performed in a total of 53 of 131 (40.5%) sucos and in 192 of 797 (24.1%) aldeias in these selected sucos. Within the surveyed urban areas, there were an estimated 21.2 people per roaming dog, a ratio substantially higher than the World Health Organization's average global estimate of 10 people per dog. The highest populations of dogs were estimated in the cities of Dili (4,919), Baucau vila (3,449) and Lospalos (2,536). The latter two are important because of their location in the northeast of Timor Leste, where the risk of rabies incursion from recently infected islands in eastern Indonesia, is likely greatest. The sight-resight method of estimating roaming dog populations is practical in developing countries; more use of photography to aid resighting of dogs could increase the accuracy of this method.

Human attitude towards cat fecal deposition

Dabritz, H.A.,  E. R. Atwill, I.A. Gardner, M.A. Miller & P.A. Conrad. (2006) Outdoor fecal deposition by free-roaming cats and attitudes of cat owners and nonowners toward stray pets, wildlife, and water pollution. Journal of the American Veterinary Medical Association 229 (1): 74-81

Objective—To estimate cat population size, management, and outside fecal deposition and evaluate attitudes of cat owners and nonowners to stray animal control, water pollution, and wildlife protection.

Design—Cross-sectional survey.

Sample Population—294 adult residents of Cayucos, Los Osos, and Morro Bay, Calif.

Procedures—Telephone survey.

Results—The region's cat population was estimated at 7,284 owned and 2,046 feral cats, and 38% of surveyed households owned a mean of 1.9 cats/household. Forty-four percent of cats defecated outside >75% of the time. Annual fecal deposition (wet weight) by owned cats in the 3 communities was estimated to be 77.6 tonnes (76.4 tons). Cat owners were more likely to oppose cat licensing and impounding stray cats and support trap-neuter-return for stray cats and less likely to be concerned about water pollution, than were noncat owners.

Conclusions and Clinical Relevance—Feral cats represented a sizeable proportion (22%) of the free roaming cats in this area and could be contributing 30.0 tonnes (29.5 tons) of feces to the environment per year. However, feral cats are not the principal source of fecal loading because owned cats defecating outdoors contribute an estimated 77.6 tonnes (76.4 tons) or 72% of the annual outdoor fecal deposition.

Planning cat eradication on Guadalupe Island

Luna-Mendoza,L., J. M. Barredo-Barberena, J. C. Hernández-Montoya, A. Aguirre-Muñoz, F. A. Méndez-Sánchez, A. Ortiz-Alcaraz, & M. Félix-Lizárraga. 2011. Planning for the eradication of feral cats on Guadalupe Island, México: home range, diet, and bait acceptance. Pages 192-197 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN, Gland, Switzerland.

Feral cats (Felis catus) introduced to new environments have caused the extinction of many vertebrate species, including six species of birds on Guadalupe Island, México. To save species from extinction and restore natural processes, cats have been eradicated from islands using a variety of techniques. Eradication campaigns have to be planned carefully; ideally supported by information about the population to be eradicated. Our study focuses on home range estimation (fixed kernel); bait consumption by feral cats and non-target species; and diet of feral cats on Guadalupe Island. Home range was 76 to 1098 ha (KE 95) and core areas 21 to 196 ha (KE 50). Feral cats and non-target species including Guadalupe junco (Junco hyemalis insularis), Guadalupe rock wren (Salpinctes obsoletus guadalupensis), western gull (Larus occidentalis), and house mouse (Mus musculus) consumed baits. Items most commonly found in diet samples were mice (66.5%) and birds (16.8%). Male cats were 2.9 ± 0.6 kg, and females 2.4 ± 0.9 kg. The results of this study will inform eradication decisions for Guadalupe Island, especially regarding the use of poison baits.

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.

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.

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.