Anthropogenic and environmental effects on invasive mammal distribution in northern Patagonia, Argentina
Anthropogenic disturbance is an important factor influencing biological invasions. The European hare (Lepus europaeus) and wild boar (Sus scrofa) are invasive species known to cause substantial environmental damage, and were introduced to Argentina during the early 1900s. We compared the relative importance of anthropogenic and environmental factors in hare and boar occurrence in Nahuel Huapi National Park, Argentina, and assessed the hypothesis that invasion can occur regardless of anthropogenic disturbance. Also, we assessed whether hare and boar occupancy offered support for the disturbance hypothesis, which states that invasive species are facilitated by anthropogenic disturbance. We deployed 80 cameras from February to May 2012 and January to April 2013 and at each site measured three environmental (land cover, horizontal cover, and percentage herbaceous vegetation) and three anthropogenic (distance to nearest human settlement, distance to nearest road, and average daily number of people) variables. We used likelihood-based occupancy modeling to estimate site occurrence and detectability. We obtained 480 independent detections of hares and 134 of boars in 1680 camera days. Environmental factors had a greater effect on hare occupancy than anthropogenic disturbances, and hare occupancy was greater in more open areas and closer to human settlements, supporting both hypotheses. Boar occurrence was equally influenced by anthropogenic and environmental factors, and offered mixed support for both hypotheses; boars were present only in humid land covers, and occupancy was lesser closer to settlements but greater closer to roads. Species responses to anthropogenic and environmental factors can vary based on life history traits and role in human society. Identifying the effect of environmental factors and human disturbances on species is fundamental for allocating limited resources in management and conservation.
KeywordsEuropean hare Wild boar Invasive mammal Patagonia Disturbance
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