Modifications of natural habitat in peridomestic rural areas could affect original rodent community composition, diversity, and evenness. In zoonoses such as hantavirus pulmonary syndrome, the presence of a diverse community can dilute the impact of the principal reservoir, reducing risk to humans. The goal of this study was to examine rodent community composition, abundance of Andes virus (ANDV) host (Oligoryzomys longicaudatus), ANDV prevalence, and temporal variability associated with rural peridomestic settings in Patagonia, Argentina. We trapped rodents in peridomestic settings and nearby sylvan areas for 2 years. The numerically dominant species differed between peridomestic and sylvan settings. O. longicaudatus was the most abundant species in peridomestic settings (>50% of individuals). Diversity and evenness in peridomestic settings fluctuated temporally, with an abrupt decline in evenness coinciding with peaks in ANDV prevalence. The probability of finding an ANDV-positive mouse in peridomestic settings was 2.44 times greater than in sylvan habitats. Changes in rodent communities in peridomestic settings may increase the probability for human exposure to ANDV because those settings promote the presence of O. longicaudatus with high ANDV antibody prevalence. High O. longicaudatus relative abundance in an unstable community associated with peridomestic settings may favor intraspecific contact, leading to a higher probability of virus transmission.

Predatory interactions involving large carnivores and their ungulate prey are increasingly recognized as important in structuring terrestrial communities, but such interactions have seldom been studied in the temperate Neotropics. Here, the large carnivore guild is limited to a single species, the puma Puma concolor, native prey populations have been drastically reduced and lagomorphs and ungulates have been introduced. We examined puma dietary patterns under varying abundances of native camelid prey -guanacos and vicu˜nas -in protected areas of northwestern Argentina. We collected puma feces from seven protected areas, and sampled each area for the relative abundance of camelids using on-foot strip and vehicle transects. In one area, where longitudinal studies have been conducted, we examined the remains of vicu˜nas and guanacos for evidence of puma predation in [2004][2005][2006]. We compared our results with a study conducted in 1978-1983, and contrasted the frequency of carcasses showing signs of puma predation with estimates of camelid abundance. Across sites, we observed a positive and significant relationship between camelid consumption by pumas and camelid abundance, with pumas about nine times more likely to consume camelids where the latter were most abundant. The temporal variation in predation rates on camelids differed by species. Guanacos, which did not change in abundance between periods, showed a slight decrease (1.5 times) in the relative frequencies of individuals killed by pumas. Conversely, vicu˜nas increased in abundance by a factor of $7 between periods, coinciding with an c. 3.4 times increase in individuals showing evidence of puma predation. Some protected areas of northwestern Argentina are conserving the trophic interaction between pumas and native camelid prey. This interaction may be the basis of the far-reaching community effects described for analogous systems on other continents. It also has implications for the possible recovery of or reintroduction of camelids to areas with high puma densities, where predation losses can be expected to be high, and possibly prohibitive.

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RESUMEN.Se estudiaron algunos aspectos de la ecología espacial de tres especies de roedores sigmodontinos (Oligoryzomys longicaudatus, Abrothrix olivacea y Abrothrix hirta) en el Paraje El Contra del Parque Nacional Lanín (Provincia de Neuquén, Argentina). Los resultados se analizaron en el marco del riesgo de exposición humana al Hantavirus "Andes", agente causal del Síndrome Pulmonar por Hantavirus. El trabajo se realizó en dos tipos de ambiente: silvestre y doméstico. Los roedores fueron capturados mensualmente con la metodología de captura-marcado-recaptura. De esta manera se estimaron y compararon los movimientos dentro y entre ambos ambientes y los tamaños de áreas de acción. Oligoryzomys longicaudatus, principal reservorio del Hantavirus "Andes" en Patagonia, presentó el mayor número de capturas en ambos ambientes y más de lo esperado por azar dentro de los ambientes domésticos. Además, mostró las áreas de acción con menor tamaño promedio y movimientos intra-ambiente estadísticamente significativos. Los ambientes domésticos rurales resultaron ser potencialmente los más riesgosos en términos de exposición y transmisión de Hantavirus a humanos. Como resultado de las capturas y movimientos dispersivos de O. longicaudatus, se discuten otras contribuciones de este trabajo a la salud humana.[Palabras clave: dispersión, ambientes domésticos y silvestres, Oligoryzomys longicaudatus, Parque Nacional Lanín, sigmodontinae, uso de hábitat, zoonosis]ABSTRACT. Intra-and inter-environment movements of rodents and risk of exposure to "Andes" Hantavirus in northern Patagonia, Argentina. Some aspects of the spatial ecology of three species of sigmodontine rodents (Oligoryzomys longicaudatus, Abrothrix olivacea and Abrothrix hirta) were studied in the Paraje El Contra, Lanín National Park (Province of Neuquén, Argentina), and the results were then analyzed in relation to the risk of human exposure to "Andes" Hantavirus, causative agent of Hantavirus Pulmonary Syndrome. The work was conducted in two environment types (sylvan and domestic), where mice were monthly captured using capture-mark-recapture methodology. Thus, movements within and between environments and home ranges sizes were estimated and compared. Oligoryzomys longicaudatus, principal reservoir of "Andes" Hantavirus in Patagonia, showed the largest number of captures in both environments and more captures than those expected by random within domestic environments. Moreover, it showed the lowest average home range sizes, and statistically significant intra environment movements. Rural domestic environments resulted to be the riskiest in terms of exposure and transmission of Hantavirus to humans. Other contributions of this work to human health are discussed as a result of captures and dispersal movements of O. longicaudatus.

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