Toxoplasma gondii in domestic and wild animals from forest fragments in Brazil

Fournier, G. F. D. S. R., Lopes, M. G., Marcili, A., Ramirez, D. G., Acosta, I. C. L., da Silva Ferreira, J. I. G., Aline Diniz Cabral, Ribeiro de Lima, J.T., de Jesus Pena,H.F., Dias, R.A. & Gennari, S. M. Toxoplasma gondii in domestic and wild animals from forest fragments of the municipality of Natal, northeastern Brazil. Braz. J. Vet. Parasitol., Jaboticabal, 23 (4): 501-508

Toxoplasmosis stands out as a global disease that has felines as definitive hosts. In the municipality of Natal, Rio Grande do Norte State, Brazil, two parks are notable for their ecological and social importance. This study aimed to investigate the presence of Toxoplasma gondii in short hair cats, bats and small non-volant mammals in these two ecological reserves. Altogether, biological samples were obtained from 154 mammals, 92 wild animals from both areas and 62 domestic cats of the Parque da Cidade. In total, 22 (53.7%) non-volant wild mammals, 11 (21.5%) bats and 28 (52.8%) cats were positive for IgG anti-T. gondii antibodies using the Modified Agglutination Test (≥ 25). It was
possible to detect the presence of T. gondii DNA, by means of a molecular amplification of a B1 gene fragment (155bp), in 92 tissue samples from wild animals, including Didelphis albiventris, Monodelphis domestica, Artibeus lituratus, Carollia perspicillata and Glossophaga soricina. Of the 62 cats examined by the same molecular method, T. gondii DNA could be detected in 4 cats. In this study, it was observed the circulation of T. gondii in wild species and domestic cats, demonstrating the involvement of wild and domestic animals in the cycle of T. gondii.

Domestic dogs and disease transmission in Atlantic forest, Brazil

Curi, N. H. D. A. (2014). Cães domésticos como espécie invasora na Mata Atlântica: sentinelas de saúde ecológica. Universidade Federal de Lavras.
The importance of health and diseases for biodiversity conservation is worldwide recognized since decades ago.  However, in Brazil, only recently this concern has entered the scientific and conservationist community. Despite the lack of data on the real impact of diseases over the Brazolian wildlife, some species shows ecological and epidemiological traits that may make them good health sentinels in certain scenarios, being also targets for prevention of outbreaks or disease-induced mortality in threatened populations. Domestic dogs (Canis lupus familiaris) are considered an invasive species with high negative impact over wildlife. The yact as efficient mesopredators, competitively interfere and are the main reservoirs of pathogens to wild carnivores. They are also an important source of zoonosis, and recent studies demonstrate that they are strongly present inside Brazilian protected areas. However, little is known about their potential as disease reservoirs for humans and animals in wildlife/domestic animal/human interface zones in the country. Even less is known about the factors associated with this potential. With this background in mind, the aims of this study were to assess the occurrence and prevalence of infectious agents and parasites important for conservation (especially of mammal carnivores) and for human health in rural dog populations living around and near Atlantic Forest fragments, and also to raise disease-related rixk factors. Such factors can be ultimately manageable to protect human and animal health in these areas. We used a cross-sectional epidemilogical approach to perform a serologic inquiry of dogs for several diseases, such as leishmaniasis, canine distemper, parvovirosis, adenovirosis, coronavirosis and gastrointestinal parasites, and tested associations betweeen seropositivity versus individual and envireomental features involved with disease transmission between domestic animals, humans and wildlife. For this end, we usesd statistical tools such as logistic regressions and generalized linear mixed models, depending on pathogen type. We then listed the factors associated with disease presence, and suggested preventive measures in a case basis. Free-roaming behavior and poor management practices were among them. These results are important for human health protection in these scenarios. And, principally, provide guidelines for conservation action targeting a reduction of an important but neglected cause of extinction and threatening of wild carnivores in Brazil:diseases introduced and maintained by ubiquitous domestic dog populations. We hope the results stimulate practices, public policies and legislation to reduce the ecological and epidemiological impact of domestic dogs in biodiversity-rich areas.

Cat impact in Madagascar forests

Farris, Z. J., Karpanty, S. M., Ratelolahy, F., & Kelly, M. J. (2014). Predator–Primate Distribution, Activity, and Co-occurrence in Relation to Habitat and Human Activity Across Fragmented and Contiguous Forests in Northeastern Madagascar. International Journal of Primatology, 1-22.

Predator–primate interactions are understudied, yet predators have been shown to influence primate behavior, population dynamics, and spatial distribution. An understanding of these interactions is important for the successful management and conservation of these species. Novel approaches are needed to understand better the spatial relationships between predators and primates across changing landscapes. We combined photographic surveys of predators and humans with line-transect sampling of lemurs across contiguous and fragmented forests in Madagascar to 1) compare relative activity; 2) estimate probability of occupancy and detection; 3) estimate predator–primate and local people–primate co-occurrence; and 4) assess variables influencing these parameters across contiguous and fragmented forests. In fragmented (compared to contiguous) forest sites endemic predator and lemur activity were lower whereas introduced predator and local people activity were higher. Our two-species interaction occupancy models revealed a higher number of interactions among species across contiguous forest where predator and lemur occupancy were highest. Mouse lemurs show evidence of “avoidance” (SIF < 1.0) with all predator species (endemic and introduced) in contiguous forest whereas white-fronted brown lemurs show “attraction” (SIF > 1.0) with feral cats and local people in contiguous forest. Feral cats demonstrated the highest number of interactions with lemurs, despite their distribution being limited to only contiguous forest. Distance to forest edge and distance to nearby villages were important in predicting predator occupancy and detection. These results highlight the growing threat to endemic predators and lemurs as habitat loss and fragmentation increase throughout Madagascar. We demonstrate the effectiveness of a novel combination of techniques to investigate how predator species impact primate species across a gradient of forest fragmentation.

Cats and habitat fragmentation affecting distribution of small mammals

Baker, P. J., Ansell, R. J., Dodds, P. A., Webber, C. E., & Harris, S. (2003). Factors affecting the distribution of small mammals in an urban area. Mammal review, 33(1), 95-100.


We investigated the distribution of a range of small mammal species in five urban habitats in north-west Bristol: residential gardens, woodlands, allotment gardens, scrub and a cemetery. Wood mouse Apodemus sylvaticus abundance in residential gardens was negatively related to the abundance of cats and the distance to the nearest patch of natural or seminatural vegetation. These results suggest that urban small mammal populations may be limited by predation and habitat fragmentation, although the effects of the latter may be offset by the availability of good quality gardens

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

Fragmentation and disturbance effect on the impact of feral predators in Australia

May, S. A., & Norton, T. W. (1996). Influence of fragmentation and disturbance on the potential impact of feral predators on native fauna in Australian forest ecosystems. Wildlife Research, 23(4), 387-400.

The current knowledge is reviewed of the diet and predator–prey relationships of the feral cat (Felis catus), fox (Vulpes vulpes) and dingo (Canis familiaris dingo) (including wild dogs). The effect of forest fragmentation by roads on the use of native forest ecosystems by these species and the significance of this for native fauna is considered. The cat, fox and dingo are significant predators in Australia that interact with native fauna in various ways, including predation, competition for resources, and transmission of disease. On the basis of current knowledge, it is clear that the nature and impact of predation by the cat, fox and dingo on native fauna are primarily determined by prey availability, although there are exceptions to this rule. Generally, dingoes prey upon large to medium-sized prey species (e.g. wallabies, common wombats, and possums), foxes prey upon medium-sized to small prey (e.g. possums and rats) and consume a significant component of scavenged material and vegetation, while cats also prey upon medium-sized to small prey, but may have a greater proportion of reptiles and birds in their diet. The cat is generally considered to be an opportunistic predator and to have contributed to the demise of a number of mammals. The fox is considered more of a threat to small native mammals and it has been asserted that all species of mammals that fall within the critical weight range (CWR) of 120–5000 g are at risk of local extinction when the fox is present. The severity of the impact of the dingo upon the native fauna is considered to be minimal, at least in comparison with the impact that the cat and fox can have on populations. The dingo is not considered a threat to CWR mammals in undisturbed environments. The fox, feral cat and dingo are all considered to have the ability to selectivity prey upon species and, to some extent, individual sexes and age-classes of a number of larger prey species.

Although many of Australia's forested areas are relatively heavily fragmented by roads, there are no published studies specifically investigating the use of roads by feral predators. Information on the distribution and abundance of foxes, cats and dingoes in these ecosystems, their ecology and their impact on native fauna is particularly limited. Further, the extent to which roads influence the distribution and abundance of these species and the consequences of these for native fauna are poorly known. One of the most important research needs is to establish the relative impact that exotic predators may have on native fauna under varying degrees of road construction within native forests. For example, are areas with and without roads in forests used differently by exotic predators and what is the significance of this in terms of the potential impact on fauna? The extent to which feral predators forage away from roads needs further investigation, as does the rates of predation within edges, because this may have several consequences for the design, location and size of retained strips and wildlife corridors as well as restoration programmes. Further observations on regional differences influencing predator–prey interactions are required, as is research on the potential impacts on native fauna resulting from prey selection in forests subjected to various degrees of fragmentation and modification.

Potential threats of domestic dogs to wild animals in fragmented Atlantic forest

Martinez, E.; C. Cesário; I. de Oliveira e Silva; V. Boere. 2013. Domestic dogs in rural area of fragmented Atlantic Forest: potential threats to wild animals. Ciencia Rural, 43 (11)

Domestic dogs' skills such as hunting and herding shifted as man migrated from rural areas to developing urban centers and led to a change in human-dog relationship and in the purpose of these animals in the properties. The countryside of Viçosa is characterized by small coffee farms surrounded by borders with fragments from the Brazilian Atlantic Forest. The close proximity of these environments favors the encounter between domestic and wild animals which may lead to dog attacks to wild animals and, consequently, disease transmission. The aim of this study was to understand the role of dogs in the rural environment and assess the possible risks they offer to native fauna. The data were obtained from structured questionnaires answered by dogs' owners from rural Viçosa. Results regarding the socioeconomic status of the owners revealed that the majority belonged to either the middle class or low educational level categories. In addition, it was observed that there is a preference for male dogs due to its guard activity and that most dogs live unconstrained. Even though most dogs are provided with good food management, 58% of them prey on wildlife. However, more than half of the dogs do not consume their prey which can be explained by the inherited ability of artificial selection but 36.5% of them have scavenger diet. Most of the dogs were immunized against rabies, whereas, only 28.8% were immunized against infectious diseases such as leptospirosis, distemper and parvovirus. In conclusion, the management of dogs by rural owners, mainly unrestrained living, and allied to inadequate vaccination coverage suggest that dogs are predators of Viçosa's rural wildlife and potential disseminators of disease.

Dogs in Atlantic forest fragments in Brazil

Galetti, M., & Sazima, I. (2006). Impact of feral dogs in an urban Atlantic forest fragment in southeastern Brazil. Natur. Conservation, 4, 146-151.

Feral domestic dogs are one of the main predators of native wildlife in protected areas all over the world. However, the number of prey killed by feral dogs is poorly recorded. A total of 46 carcasses of at least 12 vertebrate species killed by dogs were found along 44 months in an urban, 250 ha Atlantic forest fragment in southeastern Brazil. Feral dogs showed no apparent selection towards different species of prey, killing from small frogs to deer. Mammals were the most frequent prey found (75%). Our data indicate that feral dogs have a great impact on wildlife in the Atlantic forest, especially in areas where wildlife needs to move between forest fragments. Eradication programs, although controversial, are the only way to reduce wildlife predation by feral dogs.

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Gradient of habitat use of mammals

Goad, E. H. (2013). Mammalian habitat use along a residential development gradient in Northern Colorado (Doctoral dissertation, Colorado State University).

“Exurban” development occupies nearly five times more land in the United States than urban and suburban development combined. Understanding the effects of exurban development on biodiversity thus has important and wide-ranging implications for the planning, construction and stewardship of sustainable communities and surrounding rural lands. To assess the impact of exurban development on mammalian habitat use, wildlife cameras were placed along a unique development gradient designed to capture landscape permeability in a rapidly growing rural region of Colorado. Multiple-season species occupancy and relative activity (frequency of detections) were measured in summer and winter seasons and these data were analyzed in conjunction with a novel, acoustic-based approach to assessing human activity. Impacts of exurban housing varied by mammal species, with some species, such as bobcats, elk, and coyotes, showing decreased activity and occupancy levels at higher housing densities, whereas others, including red foxes and Abert’s squirrels, occurred more frequently in these areas. Human-sourced activities associated with development and non-natural sound levels emerged as top models for most species. Relative activity rates corroborated occupancy results, indicating that some species not only use habitat in high density areas, they use it more frequently. In addition, some species, including black bears, preferentially used embedded reenbelts in highdensity exurban subdivisions, suggesting that greenbelts may be important for structural and functional connectivity. This study demonstrates that the impacts of exurban development are species–dependent. However, incorporating well-designed and naturally vegetated open spaces into development projects and minimizing human disturbance may be critical to mitigating development impacts to most wildlife in regions undergoing continued exurban expansion.

Effect of exurban growing on vertebrate abundance

Odell, E. A., & Knight, R. L. (2001). Songbird and Medium‐Sized Mammal Communities Associated with Exurban Development in Pitkin County, Colorado. Conservation Biology, 15(4), 1143-1150.

Residential development is occurring at unprecedented rates in the Rocky Mountain region of the United States, with unknown ecological consequences. We conducted our research in exurban development in Pitkin County, Colorado, between May and June in 1998 and 1999. Unlike suburban development, exurban development occurs beyond incorporated city limits, and the surrounding matrix remains the original ecosystem type. We surveyed songbirds and medium-sized mammals at 30, 180, and 330 m away from 40 homes into undeveloped land to examine the effect of houses along a distance gradient, and in developments of two different housing densities as well as undeveloped sites to examine the effect of housing density. We placed bird species into one of two groups for the house-distance effect: (1) human-adapted species, birds that occurred in higher densities close to developments and lower densities farther away and (2) human-sensitive species, birds that occurred in highest densities farthest from homes and in lowest densities close to development. For both groups, densities of individual species were statistically different between the 30- and 180-m sites. Six species were classified as human-adapted, and six were classified as human-sensitive for the house-distance effect. Dogs (Canis familiaris) and house cats ( Felis domesticus) were detected more frequently closer to homes than farther away, and red foxes ( Vulpes vulpes) and coyotes (Canis latrans) were detected more frequently farther away from houses. With respect to the effect of housing density, most avian densities did not differ significantly between high- and low-density development but were statistically different from undeveloped sites. Six species were present in higher densities in developed areas, and eight species were present in higher densities in undeveloped parcels. Similar results were found for mammalian species, with dogs and cats detected more frequently in high-density developments and red foxes and coyotes detected more frequently in undeveloped parcels of land. From an ecological standpoint, it is preferable to cluster houses and leave the undeveloped areas in open space, as opposed to dispersing houses across the entire landscape.

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El desarrollo residencial esta ocurriendo en el oeste de las Montañas Rocallosas a ritmos sin precedente, con consecuencias ecológicas desconocidas. Desarrollamos nuestra investigación en un desarrollo exurbano en el Condado Pitkin, Colorado entre mayo y junio de 1998 y 1999. A diferencia del desarrollo suburbano, el desarrollo exurbano ocurre más allá de los límites de la ciudad y en la matriz que lo rodea permanece el ecosistema original. Registramos aves canoras y mamíferos pequeños a 30, 180 y 330 m de 40 casas en terrenos sin desarrollar para examinar el efecto de las casas a los largo de un gradiente de distancia, y en desarrollos con dos diferentes densidades de casas para examinar el efecto de la densidad. Colocamos a las especies de aves en uno de dos grupos para el efecto casa –distancia 1) especies adaptadas al humano, aves con la mayor densidad cerca de los desarrollos urbanos y menor densidad lejos de ellos y 2) especies sensibles al humano, aves que ocurrían con la mayor densidad lejos de los hogares y menor densidad cerca del desarrollo urbano. Para ambos grupos, las densidades de especies individuales fueron estadísticamente distintas en los sitios entre 30 y 180 m. Seis especies fueron clasificadas como adaptadas al humano y seis fueron clasificadas como especies sensibles al humano para el efecto casa – distancia. Se detectaron perros ( Canis familiaris) y gatos ( Felis domesticus) con mayor frecuencia cerca de las casas que lejos de ellas, y se detectaron zorros rojos ( Vulpes vulpes) y coyotes (Canis latrans) con mayor frecuencia lejos de las casas. Respecto al efecto de la densidad de casas, la mayoría de las densidades de aves no fueron significativamente diferentes entre el desarrollo de alta y baja densidad, pero fueron estadísticamente distintas de los sitios sin desarrollo. Seis especies tuvieron mayor densidad en los sitios desarrollados y ocho especies presentaron mayor densidad en las parcelas no desarrolladas. Se encontraron resultados similares para las especies de mamíferos, detectándose perros y gatos más frecuentemente en desarrollos con alta densidad; mientras que zorros rojos y coyotes fueron detectados más frecuentemente en las parcelas sin desarrollo. Desde una perspectiva ecológica, es preferible agrupar las casas y dejar las áreas sin desarrollo en espacios abiertos, y no dispersar las casas por todo el paisaje.

Dogs and cats in the mammal assemblage in a urban forest patch in Brazil

Bernardo, P. V. D. S., & Melo, F. R. D. (2013). Assemblage of medium and large size mammals in an urban Semideciduous Seasonal Forest fragment in Cerrado biome. Biota Neotropica, 13(2), 76-80.

Nowadays, the processes of deforestation and loss of habitats represent a major threat to many species of mammals. These processes cause changes in natural landscapes by decreasing area, connectivity, and fragment size, and increasing edge effects and number of fragments. Understanding which and how many species persist in disturbed fragments may indicate the species' minimum requirements and might contribute to their conservation. Here we show how the mammalian fauna of medium and large size (higher than 1 kg) are structured in a semideciduous seasonal forest fragment of 36.5 ha in the urban area of Jataí, Goiás. We performed the sampling with 30 sand track plots (1 x 1 m). We analyzed the relative record frequency and built a collector's curve to demonstrate the sampling effort. With a total effort of 600 track plots × days, we recorded twelve species of mammals with our tracks sampling method, from which only the wild mammals were included in the analyzes (11 species). The estimated species richness reached 13 species (SD (Standard Deviation) = ±1, CI (Confidence Interval) = ±2 (11 – 15 species). The species with the highest relative record frequency was Didelphis albiventris and the species with the lowest was Tamandua tetradactyla. The fragment size must be a limiting factor to the richness and to the occurrence of species, as it may not be sufficient to allow the persistence of a population or an individual. Disturbances that originated from houses, like domestic animals and movement of people, also contributed to the removal and extinction of species. To conserve the species in the fragment, we suggest the prevention of entrance of people and of domestic animals. We also recommend increased connectivity of the fragment with the landscape external to the urban area in order to allow the movement of the currently present species.

Cats favoured by habitat fragmentation and isolation

Crooks, K.R. 2002. Relative sensitivities of mammalian carnivores to habitat fragmentation. Conservation Biology 16(2): 488-502.

I examined the effects of habitat fragmentation on the distribution and abundance of mammalian carnivores in coastal southern California and tested the prediction that responses to fragmentation varied with the body size of carnivore species. I conducted track surveys for nine native and two exotic carnivore species in 29 urban habitat fragments and 10 control sites. Fragment area and isolation were the two strongest landscape descriptors of predator distribution and abundance. Six species were sensitive to fragmentation, generally disappearing as habitat patches became smaller and more isolated; three species were enhanced by fragmentation, with increased abundance in highly fragmented sites; and two species were tolerant of fragmentation, with little to no effect of landscape variables on their distribution and abundance. Within urban habitat fragments, the carnivore visitation rate increased at sites with more exotic cover and closer to the urban edge, a pattern driven largely by the increased abundance of fragmentation-enhanced carnivores at edge sites. Finally, body size, in conjunction with other ecological characteristics, partially accounted for the heterogeneity in responses to fragmentation among carnivore species. These differential sensitivities are useful criteria for choosing appropriate focal species for ecological research and conservation planning, a choice that depends on the scale of fragmentation in a region and the commensurate responses of carnivore populations at that scale.

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Examiné los efectos de la fragmentación del hábitat sobre la distribución y abundancia de mamíferos carnívoros en la costa del sur de California y evalué la predicción de que las respuestas a la fragmentación variaban con el tamaño corporal de carnívoros. Se realizaron muestreos de huellas para nueve especies nativas y dos exóticas en 29 fragmentos de hábitat urbano y 10 sitios control. El área fragmentada y su aislamiento fueron los dos principales descriptores de la distribución y abundancia de depredadores. Seis especies fueron sensibles a la fragmentación, generalmente las especies desaparecían conforme los fragmentos eran más pequeños y aislados, tres especies fueron favorecidas por la fragmentación, con incremento en su abundancia en sitios altamente fragmentados, y dos especies fueron tolerantes a la fragmentación con poco o ningún efecto de las variables del paisaje sobre su distribución y abundancia. Dentro de los fragmentos de hábitat urbano, las tasas de presencia de carnívoros incrementaron en sitios con mayor cobertura exótica y cercanos al borde urbano, un patrón dirigido principalmente por el incremento en la abundancia de carnívoros favorecidos por la fragmentación en el borde de los sitios. Finalmente, el tamaño corporal, conjuntamente con otras características ecológicas, fueron parcialmente responsables de la heterogeneidad en respuestas a la fragmentación entre especies de carnívoros. Estas sensibilidades diferenciales son un criterio útil para seleccionar especies focales apropiadas para investigaciones ecológicas y la planeación de la conservación, una selección que depende de la escala de fragmentación en una región y de las respuestas apropiadas de las poblaciones de carnívoros a esa escala.

Dog, the most recorded carnivore in Brazilian Atlantic forest

Paschoal, A. M. O., Massara, R. L., Santos, J. L., & Chiarello, A. G. (2012). Is the domestic dog becoming an abundant species in the Atlantic forest? A study case in southeastern Brazil. Mammalia, 76(1), 67-76.

The Brazilian Atlantic forest has been reduced to a small fraction of its original area, with most remaining fragments being small and surrounded by anthropogenic matrices. This degree of disturbance, together with the increasing sprawl of cities towards the rural zone, greatly facilitates the entrance of domestic animals into these remnants. We used camera traps to compare the abundances of the domestic dog with a similarly sized native carnivore, the ocelot, in a 957-ha reserve of the Brazilian Atlantic forest in a landscape largely composed by pastures and agriculture. The dog was the most recorded species among all 17 mammal species “captured” by the cameras. Dog abundance (32–38 dogs) and density (0.812–1.813 dogs/km²) were significantly higher than that of the ocelot (n=2 ocelots; density=0.158–0.347 ocelots/km²). Although our result is restricted to a single study site, it is supported by an increasing number of recent studies, which have detected dogs inside other Atlantic forest reserves. Our study suggests, therefore, that this invasion might be more widespread than generally thought. The presence of the domestic dog is a threat to native fauna and constitutes an important edge effect of human presence at the rural zone.

Domestic dogs and edge effect

Lacerda, A. C. R., Tomas, W. M., & Marinho‐Filho, J. (2009). Domestic dogs as an edge effect in the Brasília National Park, Brazil: interactions with native mammals. Animal Conservation, 12(5), 477-487.

Edge effects are a well-known result of habitat fragmentation. However, little has been published on fragmentation, isolation and the intrusive influence from the surrounding matrix at the landscape level. The objectives of the present study are to evaluate the presence of dogs in the Brasília National Park (BNP) in relation to habitat type and the influence from the surrounding matrix. In addition, this study examines the response of the native mammal fauna to the presence of dogs. Track stations were built along dirt roads in the BNP and subsequently examined for the presence or absence of tracks. We used a stepwise logistic regression to model the occurrence of five mammal species relative to habitat variables, with an α=0.05 to determine whether to enter and retain a variable in the model. A simulation of each species occurrence probability was conducted using a combination of selected habitat variables in a resource selection probability function. Results indicate a negative relationship between distance from the BNP edge and the probability of dog occurrences. From an ecological perspective, the presence of dogs inside the BNP indicates an edge effect. The occurrence of the maned wolf was positively associated with distance from a garbage dump site and negatively associated with the presence of dog tracks. The maned wolf and giant anteater seem to avoid areas near the garbage dump as well as areas with dog tracks. There is no support for the possible existence of a feral dog population inside the BNP, but the effects of free-ranging dogs on the wildlife population in such an isolated protected area must not be neglected. Domestic dog Canis familiaris populations and disease control programs should be established in the urban, sub-urban and rural areas surrounding the BNP, along with the complete removal of the garbage dump from the BNP surroundings.

Two classics in ecology: Mesopredator release

Soulé, M. E., Bolger, D. T., Alberts, A. C., Wrights, J., Sorice, M., & Hill, S. (1988). Reconstructed dynamics of rapid extinctions of chaparral‐requiring birds in urban habitat islands. Conservation Biology, 2(1), 75-92.

The distribution of native, chaparral-requiring bird species was determined for 37 isolated fragments of canyon habitat ranging in size from 0.4 to 104 hectares in coastal, urban San Diego County, California. The area of chaparral habitat and canyon age (time since isolation of the habitat fragment) explains most of the variation in the number of chaparral-requiring bird species. In addition, the distribution of native predators may influence species number. There is statistical evidence that coyotes control the populations of smaller predators such as foxes and domestic cats. The absence of coyotes may lead to higher levels of predation by a process of mesopredator release. The distance of canyons from other patches of chaparral habitat does not add significantly to the explained variance in chaparral-requiring species number–probably because of the virtual inability of most chaparral-requiring species to disperse through developed areas and nonscrub habitats. These results and other lines of evidence suggest that chaparral-requiring birds in isolated canyons have very high rates of extinction, in part because of their low vagility. The best predictors of vulnerability of the individual species are their abundances (densities) in undisturbed habitat and their body sizes; together these two variables account for 95 percent of the variation in canyon occupancy. A hypothesis is proposed to account for the similarity between the steep slopes of species-area curves for chaparral-requiring birds and the slopes for some forest birds on small islands or in habitat fragments. The provision of corridors appears to be the most effective design and planning feature for preventing the elimination of chaparral-requiring species in a fragmented landscape.

En el condado urbano de San Diego, California 37 fragmentos de hábitat de cañón que varían de tamaño de 0.4 a 104 hectáreas fueron examinados para determinar la distribución de especies de aves nativas que requieren de chaparral. El tamaño del área de hábitat de chaparral y la edad del cañón (tiempo transcurrido desde que ocurrió el aislamiento del fragmento de hábitat explican la mayor parte de la variación en el número de especies de aves que requieren de este hábitat Así mismo, la distribución de depredadores nativos puede influenciar el número de especies. Existen evidencias estadísticas de que los coyotes controlan las poblaciones de depredadores menores tales como los zorros y los gatos domésticos. La ausencia de coyotes puede conducir a niveles de depredación mas altos mediante un proceso de liberación de mesodepredadores. El aislamiento de cañones con respecto a otros pedazos de hábitat de chaparral no incrementa significativamente la varianza en el número de especies que requieren chaparral – probablemente debido a la virtual inhabilitad de la mayoría de las especies que requieren chaparral para dispersarse en áreas desarrolladas y en hábitats no—arbustivos. Estos resultados y otras evidencias sugieren que las aves que requieren chaparral en los cañones aislados tienen muy altas tasas de extinción, en parte debido a su baja dispersabilidad. Los mejores pronosticadores de la vulnerabilidad de una especie en particular son su abundancia (densidad) en habitats no perturbados y el tamaño de sus cuerpos; juntas, estas dos variables explican el 95% de la variación de su residencia en el cañón. Una hipótesis es propuesta para explicar la similaridad entre las fuertes pendientes de la curves de especies-área para las aves que requieren chaparral y las pendientes para algunas aves de bosque en pequeñas islas o en hábitats fragmentados. La provisión de corredores parece ser el diseño y el rasgo de la planificación más efectivo para prevenir la eliminación de especies que requieren chaparral en un paisaje fragmentado.

Crooks, K. R., & Soulé, M. E. (1999). Mesopredator release and avifaunal extinctions in a fragmented system. Nature, 400(6744), 563-566.

Mammalian carnivores are particularly vulnerable to extinction in fragmented landscapes, and their disappearance may lead to increased numbers of smaller carnivores that are principle predators of birds and other small vertebrates. Such 'mesopredator release' has been implicated in the decline and extinction of prey species. Because experimental manipulation of carnivores is logistically, financially and ethically problematic, however, few studies have evaluated how trophic cascades generated by the decline of dominant predators combine with other fragmentation effects to influence species diversity in terrestrial systems. Although the mesopredator release hypothesis has received only limited critical evaluation and remains controversial, it has become the basis for conservation programmes justifying the protection of carnivores. Here we describe a study that exploits spatial and temporal variation in the distribution and abundance of an apex predator, the coyote, in a landscape fragmented by development. It appears that the decline and disappearance of the coyote, in conjunction with the effects of habitat fragmentation, affect the distribution and abundance of smaller carnivores and the persistence of their avian prey.

Inside/outside cats' impact on a suburban nature reserve

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

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

Apparent lack of influence of cat regulations on small size mammals abundance in urban bushland

Lilith, M., Calver, M., & Garkaklis, M. (2010). Do cat restrictions lead to increased species diversity or abundance of small and medium-sized mammals in remnant urban bushland?. Pacific Conservation Biology, 16(3), 162.

We took advantage of cat regulations enacted within differing subdivisions in the City of Armadale, Western Australia, to test the hypotheses that the species diversity (measured by the Shannon-Weiner index) and abundance of small and medium-sized mammals should be higher in native bushland within or adjacent to subdivisions where cats are restricted compared to similar areas where cats are not restricted. There were three different regimes of cat regulation: no-cat zone (strict prohibition of cat ownership applying in one site), compulsory belling of cats and night curfew at one site, and unregulated zones (free-roaming cats applying at two sites). Both sets of cat regulations were in place for approximately 10 years prior to our survey. We also measured structural and floristic features of the vegetation at each site that might influence the species diversity and abundance of small and medium-sized mammals independently or interactively with cat activity.

No significant differences in species diversity were found across the sites and KTBA (known-to-be-alive) statistics for Brushtail Possums Trichosurus vulpecula and Southern Brown Bandicoots Isoodon obesulus, the two most abundant medium-sized mammals present, were similar across all sites. The smaller Mardo Antechinus flavipes, which could be regarded as the most susceptible to cat predation of all the native species trapped because of its size, was trapped mostly at an unregulated cat site. Total mammals trapped at the unregulated cat sites exceeded those caught at the two sites with restrictions, but these unregulated sites also had significantly denser vegetation and there was a borderline (p = 0.05) rank correlation between vegetation density and mammal captures across all sites. It appears that pet cats are not the major influence on the species diversity or abundance of small and medium-sized mammals at these sites and that vegetation characteristics may be more important.

Read a short review about belling effectiveness