Alerstam T, Gudmundsson G A, Green M, Hedenstrom A
Department of Animal Ecology, Lund University, Ecology Building, SE-22362 Lund, Sweden.
Science. 2001 Jan 12;291(5502):300-3. doi: 10.1126/science.291.5502.300.
Flight directions of birds migrating at high geographic and magnetic latitudes can be used to test bird orientation by celestial or geomagnetic compass systems under polar conditions. Migration patterns of arctic shorebirds, revealed by tracking radar studies during an icebreaker expedition along the Northwest Passage in 1999, support predicted sun compass trajectories but cannot be reconciled with orientation along either geographic or magnetic loxodromes (rhumb lines). Sun compass routes are similar to orthodromes (great circle routes) at high latitudes, showing changing geographic courses as the birds traverse longitudes and their internal clock gets out of phase with local time. These routes bring the shorebirds from high arctic Canada to the east coast of North America, from which they make transoceanic flights to South America. The observations are also consistent with a migration link between Siberia and the Beaufort Sea region by way of sun compass routes across the Arctic Ocean.
在高地理纬度和磁纬度迁徙的鸟类飞行方向，可用于测试极地条件下鸟类通过天体罗盘或地磁罗盘系统进行定向的情况。1999年沿着西北航道进行的破冰船考察期间，通过跟踪雷达研究揭示的北极滨鸟迁徙模式，支持了预测的太阳罗盘轨迹，但无法与沿着地理或磁等角航线（恒向线）的定向相协调。在高纬度地区，太阳罗盘路线类似于大圆航线，随着鸟类穿越经度且其内部时钟与当地时间不同步，显示出不断变化的地理航线。这些路线将北极加拿大的滨鸟带到北美东海岸，它们从那里进行跨洋飞行前往南美洲。这些观测结果也与通过横跨北冰洋的太阳罗盘路线在西伯利亚和波弗特海地区之间建立的迁徙联系相一致。
