Browsing by Author "Farias, Ariel A."

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Free-roaming domestic cats near conservation areas in Chile: Spatial movements, human care and risks for wildlife
    (2021) Jose Lopez-Jara, Maria; Sacristan, Irene; Farias, Ariel A.; Maron-Perez, Francisca; Acuna, Francisca; Aguilar, Emilio; Garcia, Sebastian; Contreras, Patricio; Silva-Rodriguez, Eduardo A.; Napolitano, Constanza
    Free-roaming domestic cats can negatively affect wildlife, and understanding how they use space is fundamental to predict their potential impacts. In this study we describe the use of space of 48 owned free-roaming cats and assess the level of care provided by owners in rural areas near priority conservation areas in southern Chile. Additionally, we use camera trap data from two protected areas to assess spatial overlap with wild vertebrates, particularly the guigna (Leopardus guigna), a vulnerable forest-dwelling felid. Cat home ranges were variable (1-47.2 hectares) and their activity was mostly concentrated within 100 meters of the household, with maximum foray distances up to 2.5 km. Cats used wooded areas (12% of fixes on average), mostly native forest, where spatial overlap with endemic and/or threatened species was documented. Nonetheless cats were infrequently detected in nearby protected areas (1.7% of GPS locations and 1% of the cameras). The use of wooded areas was strongly associated with the distance from the household to the forest edge and home range areas were negatively associated with house density. Our findings suggest that in areas isolated from households (>200 m), the problem of cats is marginal and restricted to the edges. Management was in general deficient, observing birth control in only 13% of cats and lack of preventive health care in 86% of cats. Cat impacts could be exacerbated under increasing land subdivision in southern Chile where, without population control strategies, cats may become an emergent threat for native wildlife.
  • No Thumbnail Available
    Item
    On the causes and consequences of the free-roaming dog problem in southern Chile
    (2023) Silva-Rodriguez, Eduardo A.; Cortes, Esteban I.; Zambrano, Brayan; Naughton-Treves, Lisa; Farias, Ariel A.
    Free-roaming dogs are an important concern for public health, livestock production and the environment. Human be-haviors-such as allowing pets to roam, abandoning dogs, or feeding stray animals-could influence free-roaming dog abundance and the frequency of occurrence of dog-caused problems. Here we aim to determine patterns of free-roaming dog abundance in urban and rural areas, to reveal spatial variation in human behaviors underlying the free-roaming dog problem, and to test for associations between free-roaming dog abundance and related problems. We conducted our study in Chile, where dogs are a major environmental issue. In Chile, as in many other Global South countries, many people leave their dogs to roam, partly due to norms and to lax enforcement of dog control laws. To address our objectives, we counted dogs in 213 transects in urban and rural areas to model dog abundance using N-mixture models. Then we conducted interviews in 553 properties around the transects to determine people's dog management, their behavior towards free-roaming dogs and the prevalence of dog-caused problems. Dog abun-dance was higher in transects where a higher number of owned dogs was allowed to roam, as well as in lower-income neighborhoods (based on property tax valuation). Meanwhile, rural citizens were more likely to let their dogs' roam. Dog abandonment was reported more frequently in lower-income urban neighborhoods and rural areas. Not surprisingly, we found that several problems-such as dog bites-were more frequent where we detected more free-roaming dogs. Our results highlight that the owned dog population is a central component of the free-roaming dog problem, and that human behavior is the key driver underlying the problem. Dog management programs should promote responsible dog-ownership, with a strong message focused on keeping dogs inside properties and preventing abandonment.
  • No Thumbnail Available
    Item
    Small-scale spatial variability in the diet of pampas foxes (Pseudalopex gymnocercus) and human-induced changes in prey base
    (2008) Farias, Ariel A.; Kittlein, Marcelo J.
    Predators display functional responses to variation in prey availability that result in dietary distinction at different spatial scales. Such differentiation can be enhanced when human-induced changes in land use increase spatial heterogeneity in prey availability. This has been recorded for canids, but available information is skewed to regional scales. Further, though human activities have strongly altered neotropical biomes, knowledge about small-scale dietary differentiation of canids come mainly from holartic species. Thus, we quantified variability in the diet of a ubiquitous South American canid species (i.e., the pampas fox, Pseudalopex gymnocercus) over a relatively small area of grasslands in Argentina, comparing its diet at three close sampling sites varying in human disturbance. We found that small-scale dietary differentiation was influenced by human-induced habitat modifications, both directly by local subsidizing of introduced prey (e.g., livestock carrion and hares) and indirectly by altering the availability of native prey. Overall, pampas foxes seemed to be highly flexible in their trophic ecology, being able to cope with marked habitat alterations and likely benefiting from food cross-subsidizing from agricultural landscape to protected grassland relicts. This has implications for management and conservation purposes, and highlights the importance of quantifying variability in foraging behavior of carnivores over small spatial scales.
  • No Thumbnail Available
    Item
    Species interactions across trophic levels mediate rainfall effects on dryland vegetation dynamics
    (2021) Farias, Ariel A.; Armas, Cristina; Gaxiola, Aurora; Cea, Alex P.; Luis Cortes, Jose; Lopez, Ramiro P.; Casanoves, Fernando; Holmgren, Milena; Meserve, Peter L.; Gutierrez, Julio R.; Kelt, Douglas A.
    Arid ecosystems are strongly limited by water availability, and precipitation plays a major role in the dynamics of all species in arid regions, as well as the ecosystem processes that occur there. However, understanding how biotic interactions mediate long-term responses of dryland ecosystems to rainfall remains very fragmented. We report on a unique large-scale field experiment spanning 25 yr and three trophic levels (plants, small mammal herbivores, predators) in a dryland ecosystem in the northern Chilean Mediterranean Region where we assessed how biotic interactions influence the long-term plant community responses to precipitation. As the most persistent ecological changes in dryland systems may result from changes in the structure, cover, and composition of the perennial vegetation, we emphasized the interplay between bottom-up and top-down controls of perennial plants in our analyses. Rainfall was the primary factor affecting the dynamics of, and interactions among, plants and small mammals. Ephemeral plant cover dynamics closely tracked short-term annual rainfall, but seemed unaffected by top-down controls (herbivory). In contrast, the response of the perennial plant cover to precipitation was mediated by (1) a complex interplay between subtle top-down (herbivory) controls that become more apparent in the long-term, (2) competition with ephemeral plants during wet years, and (3) an indirect effect of predators on subdominant shrubs and perennial herbs. This long-term field experiment highlights how climate-induced responses of arid perennial vegetation are influenced by interactions across trophic levels and temporal scales. In the face of global change, understanding how multi-trophic controls mediate dryland vegetation responses to climate is essential to properly managing the conservation of biodiversity in arid systems.
  • No Thumbnail Available
    Item
    Sub-regional to local topographic features shape resources, land use and disturbances determining forest distribution in old-growth grasslands of subtropical South America
    (2023) Berazategui, Mauro; Raftopulos, Pablo; Farias, Ariel A.; Bernardi, Rafael E.
    What determines the presence (or lack) of trees in grasslands is a long-standing question in ecology. Views of trees in grasslands have shifted from generally considering grasslands as degraded forests that need to be restored, to a more recent perspective on many regions as ancient grassy biomes that have long been neglected and are, according to their climate conditions, maintained as stable biomes by internal feedbacks involving fire and/or herbivory. In addition, there are currently concerns about trends of woody expansion or "encroachment" in grasslands, i.e. potential transitions between grassy and wooded ecosystems driven by local and global changes. In this study, we use high-resolution local databases and generalized additive models (GAMLSS) to analyze the factors that determine forest cover in the Campos grasslands of Uruguay in southeastern South America. We consider climate, local conditions, land use and disturbances to understand what explains the distribution of forests. Forests were associated with areas of steeper slopes, watercourses and higher surface runoff, in deeper soils with higher water availability, along a longitudinal climatic gradient, with less livestock and land-use intensity and higher human presence. We discuss how, in ancient grasslands such as this one, sub-regional geology and local topography can be permanent features that generate spatial heterogeneity in forest cover probability by mediating resource availability and influencing land use and disturbance regimes.