Data from: Migratory connectivity at high latitudes: Sabine’s gulls (Xema sabini) from a colony in the Canadian High Arctic migrate to different oceans

The world's Arctic latitudes are some of the most recently colonized by birds, and an understanding of the migratory connectivity of circumpolar species offers insights into the mechanisms of range expansion and speciation. Migratory divides exist for many birds, however for many taxa it is unclear where such boundaries lie, and to what extent these affect the connectivity of species breeding across their ranges. Sabine’s gulls (Xema sabini) have a patchy, circumpolar breeding distribution and overwinter in two ecologically similar areas in different ocean basins: the Humboldt Current off the coast of Peru in the Pacific, and the Benguela Current off the coasts of South Africa and Namibia in the Atlantic. We used geolocators to track Sabine’s gulls breeding at a colony in the Canadian High Arctic to determine their migratory pathways and wintering sites. Our study provides evidence that birds from this breeding site disperse to both the Pacific and Atlantic oceans during the non-breeding season, which suggests that a migratory divide for this species exists in the Nearctic. Remarkably, members of one mated pair wintered in opposite oceans. Our results ultimately suggest that colonization of favorable breeding habitat may be one of the strongest drivers of range expansion in the High Arctic.

世界北极纬度带是鸟类最晚开拓的栖息地之一，理解环极物种的迁徙连通性有助于揭示其分布范围扩张与物种形成的机制。许多鸟类存在迁徙分隔，但对多数类群而言，此类边界的位置尚不明确，且其对跨分布范围繁殖物种连通性的影响程度亦有待探究。萨宾鸥（Xema sabini）的繁殖分布呈斑块状且环极分布，越冬于不同大洋盆地中两个生态相似的区域：太平洋秘鲁沿岸的洪堡寒流区，以及大西洋南非与纳米比亚沿岸的本格拉寒流区。我们使用地理定位器（geolocators）追踪在加拿大高北极地区某繁殖群繁殖的萨宾鸥，以确定其迁徙路径与越冬地点。研究表明，该繁殖群的个体在非繁殖季节分散至太平洋与大西洋两地，这提示萨宾鸥在新北界（Nearctic）存在迁徙分隔。值得注意的是，一对配偶的个体越冬于相反的大洋。研究结果最终表明，适宜繁殖栖息地的开拓可能是高北极地区物种分布范围扩张的最强驱动因素之一。