RESUMEN

Large landscapes encompassing reserves and areas with other human uses are necessary for conservation of many species. Generating information for conservation planning over such landscapes may be expensive and time-consuming, though resources for conservation are generally limited and conservation is often urgent. We developed a sign-based occupancy survey to help prioritize conservation interventions by simultaneously assessing the distribution of 3 species, the lesser rhea, guanaco, and mara, and their association with human activities in a 20,000-km2 landscape in the northern Patagonian steppe. We used a single-season occupancy model with spatial rather than temporal replication of surveys in order to reduce costs of multiple visits to sites. We used covariates related to detectability, environmental factors, and different human activities to identify the most plausible models of occupancy, and calculated importance weights of covariates from these models to evaluate relative impacts of human activities on each species. Abundance of goats had the strongest negative association with lesser rheas and guanacos, and road density with maras. With six months of fieldwork, our results provided initial hypotheses for adaptive conservation interventions for each species. Addressing high livestock densities for rheas and guanacos, poaching by urban hunters for all three species, and hunting by rural people for rheas are priorities for conservation in this landscape. Our methodology provided new insights into the responses of these species, although low detection probabilities for maras indicate that the sampling scheme should be altered for future monitoring of this species. This method may be adapted for any large landscape where a rapid, objective means for prioritizing conservation actions on multiple species is needed and data are scarce.

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RESUMEN

Oligoryzomys longicaudatus is the main reservoir of Andes virus (AND), which causes hantavirus pulmonary syndrome in Patagonia. The factors associated with the presence of antibodies against AND in this species are unknown. This study used a logistic regression model to analyze which characteristics of O. longicaudatus, captured in northern Argentinean Patagonia, led to an increased probability of an animal having antibodies against AND and to relate these characteristics to possible mechanisms of transmission of the virus within the population. Sex, age, body mass, and wounds were important predictors regarding the presence of antibodies against AND within O. longicaudatus populations. The probability of a wounded male O. longicaudatus adult having AND antibodies increased in parallel with the body mass. The probability of having antibodies was more than 80% in individuals with body masses above 44 gram. However, the possible transmission mechanism of AND within O. longicaudatus population is still uncertain and further studies involving a larger number of individuals and prolonged monitoring including the process of seroconversion are needed.

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RESUMEN

Oligoryzomys longicaudatus is the main reservoir of Andes virus (AND), which causes hantavirus pulmonary syndrome in Patagonia. The factors associated with the presence of antibodies against AND in this species are unknown. This study used a logistic regression model to analyze which characteristics of O. longicaudatus, captured in northern Argentinean Patagonia, led to an increased probability of an animal having antibodies against AND and to relate these characteristics to possible mechanisms of transmission of the virus within the population. Sex, age, body mass, and wounds were important predictors regarding the presence of antibodies against AND within O. longicaudatus populations. The probability of a wounded male O. longicaudatus adult having AND antibodies increased in parallel with the body mass. The probability of having antibodies was more than 80% in individuals with body masses above 44 gram. However, the possible transmission mechanism of AND within O. longicaudatus population is still uncertain and further studies involving a larger number of individuals and prolonged monitoring including the process of seroconversion are needed.

Oligoryzomys longicaudatus es el principal reservorio del virus Andes Sur (AND) causante del síndrome pulmonar por hantavirus en la Patagonia. Aún se desconoce qué características individuales están asociadas a una mayor presencia de anticuerpos contra AND en esta especie. En este estudio, mediante un modelo de regresión logística evaluamos qué características de O. longicaudatus, capturados en la Patagonia norte de Argentina, incrementan la probabilidad de un individuo de presentar anticuerpos contra AND para relacionarlos con posibles mecanismos de transmisión del virus dentro de la población. El sexo, la edad, la masa corporal y las heridas resultaron factores importantes para la circulación y persistencia del virus dentro de la población de O. longicaudatus. La probabilidad de que un O. longicaudatus, macho, adulto con heridas presente anticuerpos contra AND aumentó con el incremento de la masa corporal, siendo esta probabilidad mayor al 80% en individuos con masas corporales mayores a 44 g. Sin embargo, el posible mecanismo de transmisión de AND dentro de la población de O. longicaudatus queda aún incierto, por lo que son necesarios estudios futuros que involucren un mayor número de individuos y un tiempo prolongado de seguimiento en su proceso de seroconversión.

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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.

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