Potential nomadism in sub-adult Lesser Flamingos <i>Phoeniconaias minor</i>: insights from satellite telemetry on movement, home ranges and habitat use in India

Unlike in its African range, very little information is available on the movement patterns of Lesser Flamingos in India. In one of the first satellite telemetry studies of Lesser Flamingos in India, we provide novel insights into the species’ movement patterns, which may further supplement the existing management of their key feeding and breeding sites. We investigated the daily movement patterns corresponding to the Lesser Flamingo’s feeding strategies, long-distance movements corresponding to potential nomadism, home range patterns and habitat use across important feeding sites in India. We deployed GPS-GSM satellite transmitters on four sub-adults and tracked their movements between September 2022 and July 2023. Their home ranges were calculated using kernel density estimators, and movement patterns were calculated using the Tracking Analyst toolbox in ArcGIS software. Habitat use was investigated by employing a robust machine-learning algorithm, Random Forest. The four Lesser Flamingos covered a mean ± SD distance of 2541.55 ± 1946.04 km per month, and an average daily distance of 83.45 ± 64.63 km. Long-distance movements were observed in two individuals. Overall, the mean home ranges (95% KDE) were calculated as 223.82 ± 337.48 km² and core areas (50% KDE) as 39.14 ± 65.71 km². The birds’ movements were positively associated with saltpans, mudflats, waterbodies and intertidal swamps. The long-distance movement pattern observed hints at the Lesser Flamingos’ nomadism, switching between key feeding sites across Gujarat and Maharashtra. This requires the conservation of their key feeding sites, in particular, and their breeding sites in general.

与该物种在非洲分布范围内的研究现状不同，目前学界对印度境内小红鹳（Lesser Flamingo）的活动模式的了解十分有限。本研究作为印度境内首批针对小红鹳的卫星遥测研究之一，为该物种的活动模式提供了全新认知，可为其核心觅食与繁殖地的现有管理工作提供进一步补充。本研究针对印度境内重要觅食地，调查了与小红鹳觅食策略对应的日间活动模式、潜在漫游行为对应的长距离移动、家域模式以及生境利用情况。研究团队于2022年9月至2023年7月期间，为4只亚成体小红鹳佩戴了GPS-GSM卫星发射器，并对其移动轨迹进行追踪。研究采用核密度估计器（Kernel Density Estimator）计算个体家域，并借助ArcGIS软件中的Tracking Analyst工具箱分析活动模式。本研究采用性能优异的机器学习算法——随机森林（Random Forest）分析生境利用特征。4只受试小红鹳的月移动距离均值±标准差为2541.55±1946.04千米，日均移动距离为83.45±64.63千米。其中2只个体出现了长距离移动行为。整体而言，受试个体的平均家域（95%核密度估计，即95% KDE）为223.82±337.48平方千米，核心活动区（50%核密度估计，即50% KDE）为39.14±65.71平方千米。受试小红鹳的移动活动与盐田、潮间带泥滩、水体以及潮间带沼泽呈正相关。本次观测到的长距离移动模式，表明小红鹳存在漫游行为，会在古吉拉特邦与马哈拉施特拉邦的核心觅食地之间迁移。这一结果提示，需针对性保护其核心觅食地，同时整体加强其繁殖地的保护工作。