Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, Virginia, United States of America.
PLoS One. 2017 Oct 18;12(10):e0186679. doi: 10.1371/journal.pone.0186679. eCollection 2017.
Camera trapping has become an increasingly widespread tool for wildlife ecologists, with large numbers of studies relying on photo capture rates or presence/absence information. It is increasingly clear that camera placement can directly impact this kind of data, yet these biases are poorly understood. We used a paired camera design to investigate the effect of small-scale habitat features on species richness estimates, and capture rate and detection probability of several mammal species in the Shenandoah Valley of Virginia, USA. Cameras were deployed at either log features or on game trails with a paired camera at a nearby random location. Overall capture rates were significantly higher at trail and log cameras compared to their paired random cameras, and some species showed capture rates as much as 9.7 times greater at feature-based cameras. We recorded more species at both log (17) and trail features (15) than at their paired control cameras (13 and 12 species, respectively), yet richness estimates were indistinguishable after 659 and 385 camera nights of survey effort, respectively. We detected significant increases (ranging from 11-33%) in detection probability for five species resulting from the presence of game trails. For six species detection probability was also influenced by the presence of a log feature. This bias was most pronounced for the three rodents investigated, where in all cases detection probability was substantially higher (24.9-38.2%) at log cameras. Our results indicate that small-scale factors, including the presence of game trails and other features, can have significant impacts on species detection when camera traps are employed. Significant biases may result if the presence and quality of these features are not documented and either incorporated into analytical procedures, or controlled for in study design.
相机陷阱已成为野生动物生态学家越来越广泛使用的工具，大量研究依赖于照片捕获率或存在/不存在信息。越来越明显的是，相机的放置位置可能会直接影响这种数据，但这些偏差还没有得到很好的理解。我们使用配对相机设计来调查小尺度生境特征对物种丰富度估计以及美国弗吉尼亚州谢南多厄谷几种哺乳动物的捕获率和检测概率的影响。相机要么安装在原木特征上，要么安装在附近随机位置的配对游戏小径上。与配对的随机相机相比，小径和原木相机的整体捕获率明显更高，一些物种在基于特征的相机上的捕获率高达 9.7 倍。我们在原木（17）和小径特征（15）上记录的物种数量都多于其配对对照相机（分别为 13 和 12 种），但在分别进行了 659 和 385 个相机夜的调查后，丰富度估计值没有区别。我们发现，由于存在游戏小径，五种物种的检测概率显著增加（范围从 11%到 33%）。对于六种物种，检测概率也受到原木特征存在的影响。对于我们调查的三种啮齿动物，这种偏差最为明显，在所有情况下，原木相机的检测概率都要高得多（24.9%至 38.2%）。我们的研究结果表明，当使用相机陷阱时，包括游戏小径和其他特征在内的小尺度因素会对物种检测产生重大影响。如果这些特征的存在和质量没有记录下来，并且没有将其纳入分析程序，或者在研究设计中进行控制，那么可能会导致显著的偏差。
