University of Georgia, Savannah River Ecology Laboratory, D.B. Warnell School of Forestry and Natural Resources, PO Drawer E, Aiken, SC, 29802, USA.
United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, 4101 Laporte Avenue, Fort Collins, CO, 80521, USA.
Sci Rep. 2017 Aug 25;7(1):9446. doi: 10.1038/s41598-017-09746-5.
Knowledge of population density is necessary for effective management and conservation of wildlife, yet rarely are estimators compared in their robustness to effects of ecological and observational processes, which can greatly influence accuracy and precision of density estimates. In this study, we simulate biological and observational processes using empirical data to assess effects of animal scale of movement, true population density, and probability of detection on common density estimators. We also apply common data collection and analytical techniques in the field and evaluate their ability to estimate density of a globally widespread species. We find that animal scale of movement had the greatest impact on accuracy of estimators, although all estimators suffered reduced performance when detection probability was low, and we provide recommendations as to when each field and analytical technique is most appropriately employed. The large influence of scale of movement on estimator accuracy emphasizes the importance of effective post-hoc calculation of area sampled or use of methods that implicitly account for spatial variation. In particular, scale of movement impacted estimators substantially, such that area covered and spacing of detectors (e.g. cameras, traps, etc.) must reflect movement characteristics of the focal species to reduce bias in estimates of movement and thus density.
了解种群密度对于野生动物的有效管理和保护是必要的，但很少有估计器在其对生态和观测过程的影响的稳健性方面进行比较，这些过程会极大地影响密度估计的准确性和精度。在这项研究中，我们使用经验数据模拟生物和观测过程，以评估动物运动范围、真实种群密度和检测概率对常见密度估计器的影响。我们还在现场应用常见的数据收集和分析技术，并评估它们估计全球广泛分布物种密度的能力。我们发现，动物运动范围对估计器的准确性影响最大，尽管当检测概率较低时，所有估计器的性能都会降低，我们还提供了建议，说明何时最适合使用每种现场和分析技术。运动范围对估计器准确性的巨大影响强调了有效计算采样面积或使用隐含考虑空间变化的方法的重要性。特别是，动物运动范围对估计器产生了重大影响，因此，探测器（例如相机、陷阱等）所覆盖的区域和间距必须反映焦点物种的运动特征，以减少对运动和因此对密度的估计偏差。
