Christin Sylvain, St-Laurent Martin-Hugues, Berteaux Dominique
Chaire de recherche du Canada en biodiversité nordique and Center for Northern Studies, Université du Québec à Rimouski, Rimouski, Québec, Canada.
Département de Biologie, Chimie et Géographie, Center for Northern Studies and Centre for Forest Research, Université du Québec à Rimouski, Rimouski, Canada.
PLoS One. 2015 Nov 6;10(11):e0141999. doi: 10.1371/journal.pone.0141999. eCollection 2015.
Animal tracking through Argos satellite telemetry has enormous potential to test hypotheses in animal behavior, evolutionary ecology, or conservation biology. Yet the applicability of this technique cannot be fully assessed because no clear picture exists as to the conditions influencing the accuracy of Argos locations. Latitude, type of environment, and transmitter movement are among the main candidate factors affecting accuracy. A posteriori data filtering can remove "bad" locations, but again testing is still needed to refine filters. First, we evaluate experimentally the accuracy of Argos locations in a polar terrestrial environment (Nunavut, Canada), with both static and mobile transmitters transported by humans and coupled to GPS transmitters. We report static errors among the lowest published. However, the 68th error percentiles of mobile transmitters were 1.7 to 3.8 times greater than those of static transmitters. Second, we test how different filtering methods influence the quality of Argos location datasets. Accuracy of location datasets was best improved when filtering in locations of the best classes (LC3 and 2), while the Douglas Argos filter and a homemade speed filter yielded similar performance while retaining more locations. All filters effectively reduced the 68th error percentiles. Finally, we assess how location error impacted, at six spatial scales, two common estimators of home-range size (a proxy of animal space use behavior synthetizing movements), the minimum convex polygon and the fixed kernel estimator. Location error led to a sometimes dramatic overestimation of home-range size, especially at very local scales. We conclude that Argos telemetry is appropriate to study medium-size terrestrial animals in polar environments, but recommend that location errors are always measured and evaluated against research hypotheses, and that data are always filtered before analysis. How movement speed of transmitters affects location error needs additional research.
通过Argos卫星遥测技术追踪动物，在检验动物行为、进化生态学或保护生物学方面的假设具有巨大潜力。然而，由于对于影响Argos定位准确性的条件尚无清晰认识，该技术的适用性无法得到全面评估。纬度、环境类型和发射器移动是影响准确性的主要候选因素。事后数据过滤可以去除“不良”定位，但仍需进行测试以优化过滤器。首先，我们通过实验评估了在极地陆地环境（加拿大努纳武特地区）中，由人类携带并与GPS发射器耦合的静态和移动发射器的Argos定位准确性。我们报告的静态误差处于已发表的最低水平。然而，移动发射器的第68百分位误差比静态发射器大1.7至3.8倍。其次，我们测试了不同的过滤方法如何影响Argos定位数据集的质量。当对最佳类别（LC3和2）的定位进行过滤时，定位数据集的准确性得到了最佳改善，而道格拉斯Argos过滤器和自制速度过滤器在保留更多定位的同时表现出相似的性能。所有过滤器都有效降低了第68百分位误差。最后，我们评估了定位误差在六个空间尺度上如何影响两种常见的家域大小估计器（动物空间利用行为综合运动的代理指标），即最小凸多边形和固定核估计器。定位误差有时会导致家域大小的大幅高估，尤其是在非常局部的尺度上。我们得出结论，Argos遥测技术适用于研究极地环境中的中型陆地动物，但建议始终根据研究假设测量和评估定位误差，并在分析前对数据进行过滤。发射器的移动速度如何影响定位误差需要进一步研究。
