Chan A N, Wittemyer G, McEvoy J, Williams A C, Cox N, Soe P, Grindley M, Shwe N M, Chit A M, Oo Z M, Leimgruber P
Conservation Ecology Center, Smithsonian National Zoo and Conservation Biology Institute, Front Royal, VA, 22630, USA.
Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, 80523, USA.
Mov Ecol. 2022 Feb 5;10(1):6. doi: 10.1186/s40462-022-00304-x.
Asian elephant numbers are declining across much of their range driven largely by serious threats from land use change resulting in habitat loss and fragmentation. Myanmar, holding critical range for the species, is undergoing major developments due to recent sociopolitical changes. To effectively manage and conserve the remaining populations of endangered elephants in the country, it is crucial to understand their ranging behavior.
Our objectives were to (1) estimate the sizes of dry, wet, and annual ranges of wild elephants in Myanmar; and quantify the relationship between dry season (the period when human-elephant interactions are the most likely to occur) range size and configurations of agriculture and natural vegetation within the range, and (2) evaluate how percentage of agriculture within dry core range (50% AKDE range) of elephants relates to their daily distance traveled.
We used autocorrelated kernel density estimator (AKDE) based on a continuous-time movement modeling (ctmm) framework to estimate dry season (26 ranges from 22 different individuals), wet season (12 ranges from 10 different individuals), and annual range sizes (8 individuals), and reported the 95%, 50% AKDE, and 95% Minimum Convex Polygon (MCP) range sizes. We assessed how landscape characteristics influenced range size based on a broad array of 48 landscape metrics characterizing aspects of vegetation, water, and human features and their juxtaposition in the study areas. To identify the most relevant landscape metrics and simplify our candidate set of informative metrics, we relied on exploratory factor analysis and Spearman's rank correlation coefficient. Based on this analysis we adopted a final set of metrics into our regression analysis. In a multiple regression framework, we developed candidate models to explain the variation in AKDE dry season range sizes based on the previously identified, salient metrics of landscape composition.
Elephant dry season ranges were highly variable averaging 792.0 km and 184.2 km for the 95% and 50% AKDE home ranges, respectively. We found both the shape and spatial configuration of agriculture and natural vegetation patches within an individual elephant's range play a significant role in determining the size of its range. We also found that elephants are moving more (larger energy expenditure) in ranges with higher percentages of agricultural area.
Our results provide baseline information on elephant spatial requirements and the factors affecting them in Myanmar. This information is important for advancing future land use planning that takes into account space-use requirements for elephants. Failing to do so may further endanger already declining elephant populations in Myanmar and across the species' range.
亚洲象数量在其大部分分布范围内都在下降，主要原因是土地利用变化带来的严重威胁，导致栖息地丧失和破碎化。缅甸拥有该物种的关键分布区域，由于近期的社会政治变革，该国正在经历重大发展。为了有效管理和保护该国濒危大象的剩余种群，了解它们的活动范围行为至关重要。
我们的目标是：（1）估计缅甸野生大象的旱季、雨季和年活动范围大小；量化旱季（人与象互动最可能发生的时期）活动范围大小与该范围内农业和自然植被配置之间的关系；（2）评估大象旱季核心范围（50% AKDE范围）内农业所占百分比与它们每日移动距离之间的关系。
我们使用基于连续时间运动建模（ctmm）框架的自相关核密度估计器（AKDE）来估计旱季（来自22个不同个体的26个活动范围）、雨季（来自10个不同个体的12个活动范围）和年活动范围大小（8个个体），并报告95%、50% AKDE以及95%最小凸多边形（MCP）活动范围大小。我们基于一系列48个景观指标评估了景观特征如何影响活动范围大小，这些指标表征了植被、水和人类特征以及它们在研究区域中的并置情况。为了确定最相关的景观指标并简化我们的信息指标候选集，我们依赖探索性因子分析和斯皮尔曼等级相关系数。基于此分析，我们在回归分析中采用了一组最终指标。在多元回归框架下，我们开发了候选模型，以根据先前确定的、突出的景观组成指标来解释AKDE旱季活动范围大小的变化。
大象旱季活动范围变化很大，95%和50% AKDE家域范围平均分别为792.0千米和184.2千米。我们发现，在个体大象活动范围内，农业和自然植被斑块的形状和空间配置在决定其活动范围大小方面都起着重要作用。我们还发现，在农业面积百分比更高的活动范围内，大象移动得更多（能量消耗更大）。
我们的结果提供了缅甸大象空间需求及其影响因素的基线信息。这些信息对于推进未来考虑大象空间利用需求的土地利用规划很重要。不这样做可能会进一步危及缅甸及该物种分布范围内已经在减少的大象种群。
