No abstract

Intraguild competition may be reduced if ecologically similar species segregate temporally. Using data from 1,596 camera-trap photos, we present the 1st quantitative analyses of the activity patterns of Andean cats (Leopardus jacobita), Pampas cats (Leopardus colocolo), culpeos (Lycalopex culpaeus), and pumas (Puma concolor) in high-altitude deserts of the Andes. We compared daily activity patterns for these carnivores with those of mountain vizcachas (Lagidium viscacia), the main prey of Andean cats. Activity patterns of all species were positively skewed toward night. Pampas cats displayed the greatest proportion of nocturnal activity, whereas Andean cats were the most diurnal. Activity of Andean cats differed significantly only from that of Pampas cats; Pampas cats also differed from pumas. Activity of Andean cats was generally similar to that of mountain vizcachas. The dissimilar activity patterns of Andean and Pampas cats support the hypothesis of temporal niche segregation of these felids.

Summary 1.Under the source-sink model, persistence of populations in habitat sinks, where deaths outnumber births, depends on dispersal from high-quality habitat sources, where births outnumber deaths. The persistence of the regional population depends on the proportion of sink relative to source habitat. 2. Hunting that occurs in some parts of the landscape and not in others can create patches where deaths outnumber births. We tested whether hunting of culpeo foxes Pseudalopex culpaeus , which is patchily distributed in relatively homogeneous habitat in Argentine Patagonia, induces source-sink dynamics. 3. On Patagonian sheep ranches, culpeos are hunted for fur and to protect sheep, and on cattle ranches hunting is usually banned. We monitored culpeo densities using scent stations and estimated survival, fecundity and dispersal by radio-tracking 44 culpeos and analysing carcasses collected from hunters on two cattle and four sheep ranches between 1989 and 1997. 4. Survival of juvenile culpeos was lower on hunted than unhunted ranches, mainly as a result of hunting mortality. Reproduction could not compensate for high mortality on hunted ranches. Interruption of hunting led to an increase in juvenile survival, indicating that hunting and natural mortality were not compensatory. We concluded that sheep ranches were sinks because of the high mortality and that sink populations may be maintained by dispersal from cattle ranches. 5. We used a simulation model to assess implications of changes in the proportion of source and sink areas on population dynamics. The percentage of land on cattle ranches in the study area was 37%. Current hunting pressure on culpeos would not be sustainable if that percentage fell below 30%. 6. Synthesis and applications . Source-sink dynamics may occur in landscapes where hunting is intense and spatially heterogeneous. Wildlife management traditionally monitors demographic rates to evaluate the sustainability of hunting, but our results suggest that the size and spatial arrangement of areas with and without hunting should be considered as well. In regions where enforcement and monitoring are limited, securing large and regularly distributed source areas for hunted species may be more effective than trying to regulate harvest size.

No abstract

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.