Temporal and spatial segregation of top predators (Felidae) in a Mexican tropical Biosphere Reserve

ABSTRACT Jaguars, Panthera onca (Linnaeus, 1758), and pumas, Puma concolor (Linnaeus, 1771) are the largest felids in the neotropics. Both can overlap in niche axes (time, space and prey), and are therefore potentially competing species. Segregation mechanisms presented by a low overlap in one of these axes of niche can facilitate the coexistence. Our aim was to analyze jaguar and puma temporal and spatial overlap for understanding their segregation mechanisms. Between 2015 and 2017, twenty-six camera trap stations were located in five habitat types of El Cielo Biosphere Reserve (ECBR) in northeastern Mexico. Temporal activity was analyzed using circular statistics and time overlap analysis. Spatial overlap was calculated with the Pianka index and a selectivity habitat analysis. Our results showed that jaguars and pumas were nocturnal and that the temporal overlap was high (∆4 = 0.77). We found an intermediate spatial overlap (Pianka index = 0.61). Jaguars were more selective and preferred the deciduous forest. In comparison, pumas preferred oak-pine forest, but also used oak and deciduous forest. Our results indicate that spatial segregation best explains the coexistence of jaguars and pumas in our study area, probably due to both habitat diversity in the reserve and the generalist habits of the puma.摘要：美洲豹（Panthera onca，Linnaeus, 1758）与美洲狮（Puma concolor，Linnaeus, 1771）是新热带界体型最大的猫科动物。二者在时间、空间与猎物等生态位维度上均存在重叠，因此属于潜在竞争物种。若某一生态位维度的重叠度较低，则对应的生态位分隔机制可促进二者共存。本研究旨在通过分析美洲豹与美洲狮的时间、空间生态位重叠情况，解析二者的生态位分隔机制。2015年至2017年间，研究团队在墨西哥东北部的埃尔西耶生物圈保护区（El Cielo Biosphere Reserve, ECBR）的5种生境类型中布设了26台红外相机监测站位。本研究采用圆形统计法与时间重叠分析法分析二者的活动时间模式，利用皮安卡指数（Pianka index）与生境选择性分析计算空间重叠度。研究结果显示，美洲豹与美洲狮均为夜行性动物，二者的时间生态位重叠度较高（∆4=0.77）；空间生态位重叠度则处于中等水平（皮安卡指数=0.61）。美洲豹的生境选择性更强，偏好落叶林生境；相较而言，美洲狮更偏爱橡松林，但同时也会利用栎林与落叶林。本研究结果表明，空间生态位分隔最能解释研究区域内美洲豹与美洲狮的共存现象，这可能得益于保护区内丰富的生境多样性，以及美洲狮的泛化生境利用习惯。