Wild pig (Sus scrofa L.) occupancy patterns in the Brazilian Atlantic forest

Abstract: Despite the great impacts of invasive wild pig (Sus scrofa) to natural ecosystems, habitat use by this species in the neotropics remains poorly studied. Here, we investigated the effects of local habitat and landscape covariates (vegetation types, running watercourses and roads) on occupancy patterns of wild pig in the Atlantic Forest of southern Brazil. We used single season occupancy modeling to estimate detection (p) and occupancy (ψ) probabilities, using 8-day camera-trap monitoring of 100 sampled sites. The cameras detected wild pig in 64 sites (naïve occupancy = 64 %). The four best models explained 72.7 % of the occupancy patterns, and the top model (with "water" variable) had a weight of 28.5 %. Even though none of the tested variables had high explanatory power of wild pig occupancy, the water variable had a negative effect trend (β = -1.124; SE = 0.734), with 59 % of occupancy when water was present and 82 % when it was absent around the sampling sites. Vestiges of the presence of wild pig in different vegetation types revealed that they used plantations of Pinus sp., native forests, and corn and oat crops. The occupation pattern shows that wild pig are generalist at our study site at the Atlantic Forest being found everywhere, raising ecological and economic concerns about the high potential negative effects of its invasion.

摘要：尽管入侵性野猪（Sus scrofa）对自然生态系统造成了显著影响，但该物种在新热带区的栖息地利用情况仍未得到充分研究。本研究以巴西南部大西洋森林为研究区域，探讨了局部生境与景观协变量（植被类型、径流河道与道路）对野猪占据格局的影响。我们采用单季占据模型（single season occupancy modeling）对检测概率（p）与占据概率（ψ）进行估算，共布设100个采样点，通过为期8天的红外相机监测获取数据。红外相机在64个采样点中记录到野猪出现，朴素占据率（naïve occupancy）为64%。排名前四的最优模型共解释了72.7%的野猪占据格局，其中包含“水体”变量的最优模型权重为28.5%。尽管所有测试变量对野猪占据率的解释能力均未达到较高水平，但水体变量呈现出负效应趋势（回归系数β=-1.124，标准误SE=0.734）：采样点周边存在水体时，野猪占据率为59%，无水体时则为82%。不同植被类型下的野猪活动痕迹显示，该物种可利用松属（Pinus sp.）人工林、原生林以及玉米和燕麦农田。本研究区域的大西洋森林中，野猪为泛化物种，几乎在所有生境中均有分布，其入侵所蕴含的潜在严重负面影响引发了生态与经济层面的高度担忧。