Roads have no effect on guanaco habitat selection at a Patagonian site with limited poaching

How Roads Affect the Spatial Use of the Guanaco in a South American Protected Area: Human Connectivity vs Animal Welfare

Roads can affect animals as well as their habits at different levels. Avoidance behavior is a common response of animals to this type of perturbation, preventing access to areas rich in resources. The effects of roads on ungulates have not been studied in South America extensively, especially in arid environments. We have studied the space use by ungulates in relation to roads, using a dung heap count and camera traps. The aim was to evaluate whether paved road and unpaved road may have an effect on the spatial use of a low density population of guanacos (Lama guanicoe) in Ischigualasto Provincial Park, Argentina. We observed an increase in dung heap abundance in unpaved road as respect to paved road, this difference was larger for both. Besides, we recorded less individuals in paved road zones than in unpaved road zones. This showed that roads, especially paved roads, negatively affect the space used by guanacos. Our results are relevant to the management and conservation of animal populations in protected areas since spatial segregation due to the presence of roads may lead to the isolation of individuals. It is important to pay attention and further assess the effects that roads can have in the native fauna.

Environmental factors influencing guanaco distribution and abundance in central Patagonia, Argentina

Context The guanaco is the largest wild herbivore inhabiting the Patagonian steppes. Since the end of the 19th Century, it has suffered a progressive decline in numbers owing to poaching and unregulated hunting because of on an assumed competition with sheep. Unfortunately, there has never been a management program for guanaco populations in Argentine Patagonia. Consequently, the guanaco is still considered a pest species by ranchers and has never been considered profitable in the range management model implemented in Patagonia. Aims The present article updates the distribution limits of guanaco and estimate its abundance across Chubut, a large province of Patagonia, Argentina. The relative effects of several environmental and anthropogenic factors on guanaco distribution are also assessed. Methods Road surveys (7010km) and species distribution modelling were used to build a habitat suitability model and a distribution map. A distance sampling method was used to estimate guanaco population densities and size. The survey effort required to monitor population trends in this region was also calculated. Key results According to the best habitat suitability model, guanaco distribution decreased with altitude and primary productivity, as measured by Normalised Difference Vegetation Index (NDVI), and increased with the distance to the nearest urban centre and oil field. Guanaco distribution showed a clear geographical pattern in Chubut, with low to medium occurrence probability towards the west and higher values towards the east. Guanaco population size was estimated as 657304 individuals (95% CI 457437 to 944059), with a mean density of 2.97 guanacos km–2. Finally, through simulations of guanaco monitoring, it was estimated that an annual survey effort of 10 to thirty 30-km road transects is needed to detect with confidence a significant population decrease or increase over the next 6 or 10 years. Conclusions The habitat suitability map presented herein highlights areas with high guanaco densities in Chubut, where it would be possible to identify ranches suitable for performing profitable herding and shearing experiences. Implications The maps of guanaco distribution and density, as well as the survey effort required to monitor population trends, may be used to inform decisions concerning the sustainable use of this species.