Le Corre Mael, Dussault Christian, Côté Steeve D
Caribou Ungava, Département de Biologie and Centre d'Études Nordiques, Université Laval, Québec, Québec G1V 0A6 Canada.
Caribou Ungava, Département de Biologie and Centre d'Études Nordiques, Université Laval, Québec, Québec G1V 0A6 Canada ; Direction de la faune terrestre et de l'avifaune, Ministère des Forêts, de la Faune et des Parcs du Québec, 880, chemin Sainte-Foy, Québec, Québec G1S 4X4 Canada.
Mov Ecol. 2014 Aug 1;2:19. doi: 10.1186/s40462-014-0019-0. eCollection 2014.
Migratory species face numerous threats related to human encroachment and climate change. Several migratory populations are declining and individuals are losing their migratory behaviour. To understand how habitat loss or changes in the phenology of natural processes affect migrations, it is crucial to clearly identify the timing and the patterns of migration. We propose an objective method, based on the detection of changes in movement patterns, to identify departure and arrival dates of the migration. We tested the efficiency of our approach using simulated paths before applying it to spring migration of migratory caribou from the Rivière-George and Rivière-aux-Feuilles herds in northern Québec and Labrador. We applied the First-Passage Time analysis (FPT) to locations of 402 females collected between 1986 and 2012 to characterize their movements throughout the year. We then applied a signal segmentation process in order to segment the path of FPT values into homogeneous bouts to discriminate migration from seasonal range use. This segmentation process was used to detect the winter break and the calving ground use because spring migration is defined by the departure from the winter range and the arrival on the calving ground.
Segmentation of the simulated paths was successful in 96% of the cases, and had a high precision (96.4% of the locations assigned to the appropriate segment). Among the 813 winter breaks and 669 calving ground use expected to be detected on the FPT profiles, and assuming that individuals always reduced movements for each of the two periods, we detected 100% of the expected winter breaks and 89% of the expected calving ground use, and identified 648 complete spring migrations. Failures to segment winter breaks or calving ground use were related to individuals only slowing down or performing less pronounced pauses resulting in low mean FPT.
We show that our approach, which relies only on the analysis of movement patterns, provides a suitable and easy-to-use tool to study species exhibiting variations in their migration patterns and seasonal range use.
迁徙物种面临着与人类入侵和气候变化相关的众多威胁。一些迁徙种群数量正在减少，个体也在丧失其迁徙行为。为了了解栖息地丧失或自然过程物候变化如何影响迁徙，明确识别迁徙的时间和模式至关重要。我们提出了一种基于检测运动模式变化的客观方法，以确定迁徙的出发和到达日期。在将其应用于魁北克北部和拉布拉多地区里维耶尔 - 乔治河和里维耶尔 - 奥弗耶尔河鹿群的春季迁徙之前，我们使用模拟路径测试了该方法的效率。我们将首次通过时间分析（FPT）应用于1986年至2012年间收集的402只雌性鹿的位置，以描述它们全年的运动情况。然后，我们应用信号分割过程，将FPT值路径分割为均匀的片段，以区分迁徙和季节性活动范围的利用。由于春季迁徙由离开冬季活动范围并到达产仔地来定义，因此该分割过程用于检测冬季停歇期和产仔地利用情况。
模拟路径分割在96%的情况下成功，且精度很高（96.4%的位置被分配到适当的片段）。在FPT剖面图上预计检测到813个冬季停歇期和669次产仔地利用情况，假设个体在这两个时期中的每个时期运动总是减少，我们检测到了100%的预期冬季停歇期和89%的预期产仔地利用情况，并识别出648次完整的春季迁徙。未能分割冬季停歇期或产仔地利用情况与个体只是减速或停顿不明显导致平均FPT较低有关。
我们表明，我们的方法仅依赖于对运动模式的分析，为研究迁徙模式和季节性活动范围利用存在变化的物种提供了一种合适且易于使用的工具。
