Jia Ying-Hui, Qiu Jun, Ma Cang, Wang Jin-Zhao, Wang Guang-Qian, Li Fang-Fang
College of Water Resources & Civil Engineering China Agricultural University Beijing China.
State Key Laboratory of Plateau Ecology and Agriculture Qinghai University Xining China.
Ecol Evol. 2021 Jul 13;11(15):10566-10581. doi: 10.1002/ece3.7865. eCollection 2021 Aug.
As an important species in the Qinghai-Tibet Plateau, the roles played by plateau pikas in grassland degradation and protection are controversial. The behavior characteristics and population density of this species are important in answering this question, but these traits have not been fully elucidated to date. Camera-capture methods have been used widely in recent years to characterize or calculate population density with the advantage of simple operation and nonintrusive investigation. However, establishing the relationship between actual population density and monitoring data with the condition that individual identification is not possible is a major challenge for this method. In this study, a model composed of a behavioral module and a burrow system module is proposed and applied to simulate the moving path of each individual pika. Based on Monte Carlo method, the model is used to develop the relationship between population density and recorded capture number, which is compared with the results derived from the random encounter model (REM) based on field observations. The simulated results mixed with the calculated density based on observation data could reach = 0.98 using linear fitting, with proper parameter settings. A novel index named activity intensity of pikas per population density is also proposed, providing information on both the ecological physical characteristics and monitoring space. The influence of different parameters on this index, mainly the pika number per burrow system, pika activity time outside the burrow, and activity intensity, is discussed. The proposed methodology can be applied to different scenarios in further studies when behavioral characteristics of pikas change for such reasons as climate change and vegetation degradation.
作为青藏高原的重要物种，高原鼠兔在草地退化与保护中所起的作用存在争议。该物种的行为特征和种群密度对于回答这一问题至关重要，但迄今为止这些特征尚未得到充分阐明。近年来，相机捕捉方法已被广泛用于描述或计算种群密度，其优点是操作简单且调查非侵入性。然而，在无法进行个体识别的情况下，建立实际种群密度与监测数据之间的关系是该方法面临的一项重大挑战。在本研究中，提出了一个由行为模块和洞穴系统模块组成的模型，并将其应用于模拟每只高原鼠兔的移动路径。基于蒙特卡洛方法，该模型用于建立种群密度与记录的捕获数量之间的关系，并将其与基于实地观察的随机相遇模型（REM）得出的结果进行比较。在适当的参数设置下，将模拟结果与基于观测数据计算出的密度进行线性拟合，相关系数可达 = 0.98。还提出了一个名为单位种群密度高原鼠兔活动强度的新指标，该指标提供了有关生态物理特征和监测空间的信息。讨论了不同参数对该指标的影响，主要包括每个洞穴系统中的高原鼠兔数量、高原鼠兔在洞穴外的活动时间以及活动强度。当高原鼠兔的行为特征因气候变化和植被退化等原因发生变化时，所提出的方法可应用于进一步研究中的不同场景。
