Strandberg Roine, Klaassen Raymond H G, Hake Mikael, Olofsson Patrik, Alerstam Thomas
Department of Animal Ecology, Lund University, 223 62 Lund, Sweden.
Proc Biol Sci. 2009 Feb 22;276(1657):727-33. doi: 10.1098/rspb.2008.1202.
Autumn migration of adult Eurasian hobbies Falco subbuteo from Europe to southern Africa was recorded by satellite telemetry and observed routes were compared with randomly simulated routes. Two non-random features of observed routes were revealed: (i) shifts to more westerly longitudes than straight paths to destinations and (ii) strong route convergence towards a restricted area close to the equator (1 degree S, 15 degrees E). The birds migrated south or southwest to approximately 10 degrees N, where they changed to south-easterly courses. The maximal spread between routes at 10 degrees N (2134 km) rapidly decreased to a minimum (67 km) close to the equator. We found a striking relationship between the route convergence and the distribution of continuous rainforest, suggesting that hobbies minimize flight distance across the forest, concentrating in a corridor where habitat may be more suitable for travelling and foraging. With rainforest forming a possible ecological barrier, many migrants may cross the equator either at 15 degrees E, similar to the hobbies, or at 30-40 degrees E, east of the rainforest where large-scale migration is well documented. Much remains to be understood about the role of the rainforest for the evolution and future of the trans-equatorial Palaearctic-African bird migration systems.
通过卫星遥测记录了成年欧亚燕隼从欧洲到南部非洲的秋季迁徙，并将观察到的路线与随机模拟路线进行了比较。观察到的路线有两个非随机特征：（i）路线向更偏西的经度偏移，而非直接通往目的地；（ii）路线强烈汇聚于赤道附近的一个受限区域（南纬1度，东经15度）。这些鸟类向南或向西南迁徙至大约北纬10度，然后转向东南方向。在北纬10度时路线之间的最大跨度（2134公里）迅速减小至接近赤道处的最小值（67公里）。我们发现路线汇聚与连续雨林的分布之间存在显著关系，这表明燕隼尽量减少穿越森林的飞行距离，集中在一个栖息地可能更适合飞行和觅食的走廊区域。由于雨林可能构成生态屏障，许多候鸟可能会在东经15度（类似于燕隼）或东经30 - 40度（雨林以东，有大量大规模迁徙记录）穿越赤道。关于雨林在跨赤道古北界 - 非洲鸟类迁徙系统的演化和未来中所起的作用，仍有许多有待了解的地方。
