Age-specific differences in Asian Elephant defecation, dung decay, detection and their implication for dung count

In vertebrate population estimation, converting faecal density into animal density requires information on faecal production rate, decay rate, and faecal density. Differences in the above factors for long-lived species across age classes were not evaluated. We have evaluated these factors associated with the dung count of Asian elephants (Elephas maximus) in the tropical forest of Southern India.   The defecation rate of elephants was determined in semi-wild elephants at the Mudumalai elephant camp. The relationship between dung bolus diameter and age was determined to estimate the age of the elephant. Total and age-specific elephant density based on dung bolus diameter were estimated. A total of 24 transect lines of 2-4 km (125 km) were sampled in the study area. An experiment was conducted to assess detection probability across the age classes of dung piles. The dung decay rates across age classes and seasons were determined by marking fresh dung piles (n=1551). The dung-based age...在脊椎动物种群估算工作中，将粪便密度转换为动物种群密度，需获取粪便产出率、粪便衰减率以及粪便密度相关数据。此前尚未针对长寿命物种的上述因素在不同年龄阶层间的差异开展评估。本研究针对印度南部热带森林中的亚洲象（Elephas maximus）的粪便计数相关影响因素展开了评估。 研究团队在穆杜马莱大象营地的半野生亚洲象群中测定了亚洲象的排便速率；通过建立粪便团直径与亚洲象年龄的关联关系，实现了亚洲象的年龄估算，并基于粪便团直径估算了亚洲象总种群密度及按年龄分层的种群密度。本研究在调查区域内共布设24条样线，单条样线长度为2至4千米，总样线长度达125千米。此外开展了一项实验，以评估不同年龄阶层的粪便堆的检出概率。通过标记1551堆新鲜粪便，研究人员测定了不同年龄阶层以及不同季节下的粪便衰减率。基于粪便的年龄……