de Silva Shermin, Webber C Elizabeth, Weerathunga U S, Pushpakumara T V, Weerakoon Devaka K, Wittemyer George
Colorado State University, Department of Fish, Wildlife and Conservation Biology, Fort Collins, Colorado, United States of America ; Elephant, Forest and Environment Conservation Trust, Colombo, Sri Lanka ; Trunks & Leaves Inc., Somerville, Massachusetts, United States of America.
Stirling University, Stirling, Scotland, United Kingdom.
PLoS One. 2013 Dec 20;8(12):e82788. doi: 10.1371/journal.pone.0082788. eCollection 2013.
Detailed demographic data on wild Asian elephants have been difficult to collect due to habitat characteristics of much of the species' remaining range. Such data, however, are critical for understanding and modeling population processes in this endangered species. We present data from six years of an ongoing study of Asian elephants (Elephas maximus) in Uda Walawe National Park, Sri Lanka. This relatively undisturbed population numbering over one thousand elephants is individually monitored, providing cohort-based information on mortality and reproduction. Reproduction was seasonal, such that most births occurred during the long inter-monsoon dry season and peaked in May. During the study, the average age at first reproduction was 13.4 years and the 50(th) percentile inter-birth interval was approximately 6 years. Birth sex ratios did not deviate significantly from parity. Fecundity was relatively stable throughout the observed reproductive life of an individual (ages 11-60), averaging between 0.13-0.17 female offspring per individual per year. Mortalities and injuries based on carcasses and disappearances showed that males were significantly more likely than females to be killed or injured through anthropogenic activity. Overall, however, most observed injuries did not appear to be fatal. This population exhibits higher fecundity and density relative to published estimates on other Asian elephant populations, possibly enhanced by present range constriction. Understanding the factors responsible for these demographic dynamics can shed insight on the future needs of this elephant population, with probable parallels to other populations in similar settings.
由于亚洲象现存大部分分布区域的栖息地特征，很难收集到关于野生亚洲象的详细人口统计学数据。然而，这些数据对于了解和模拟这个濒危物种的种群动态过程至关重要。我们展示了来自对斯里兰卡乌达瓦拉韦国家公园亚洲象（Elephas maximus）进行的一项为期六年的持续研究的数据。这个相对未受干扰的象群数量超过一千头，对其进行个体监测，提供了基于队列的死亡率和繁殖信息。繁殖具有季节性，大多数出生发生在漫长的季风间歇旱季，且在五月达到峰值。在研究期间，首次繁殖的平均年龄为13.4岁，出生间隔的第50百分位数约为6年。出生性别比与均等比例没有显著偏差。在个体观察到的整个生殖寿命（11 - 60岁）期间，繁殖力相对稳定，平均每年每个个体有0.13 - 0.17个雌性后代。基于尸体和失踪情况的死亡率和受伤情况表明，雄性比雌性更有可能因人为活动而被杀死或受伤。然而，总体而言，大多数观察到的伤害似乎并非致命。相对于已发表的其他亚洲象种群估计数据，这个象群表现出更高的繁殖力和密度，可能是由于目前的分布范围受限所致。了解导致这些种群动态变化的因素，有助于洞察这个象群未来的需求，这可能与类似环境中的其他象群情况相似。
