Compensation for wind drift in relation to the side-wind velocity and altitude was investigated in Song Thrushes during autumn migration. The birds were recorded at night flying above the prominent leading line of a marine spit which coincided with the general direction of their migration. Among the large size passerine species, Song Thrushes were identified by a combination of five flight characteristics typical only of this species during particular periods of autumn. The thrushes showed different reactions to the crosswinds: complete and partial compensation for the displacement and drift. Under normal visibility, the completeness of compensation depended both on the velocity of the side-wind and altitude. The degree of compensation achieved was reduced with an increase of altitude, regardless of the wind. Under the same wind conditions, the angle of drift (the angle between the track direction and the leading line) increased with altitude, but the number of birds that compensated for drift decreased. On average, at heights below 300 m agl, the thrushes were capable of compensating completely for moderate winds; between 300 and 600 m agl compensation was partial; but above 600 m the birds drifted completely. Birds of the same species flying above the same terrain may demonstrate different reactions to the same crosswind depending on altitude. Meanwhile, flight tracks gradually deviated from the leading line with an increase in altitude, the headings of the birds got closer to the general migratory direction. It is more likely that the birds control displacement using the visual flow regulation principle by the angular velocity of the landmarks below them running aside in relation to their flight direction, which is inversely proportional to the altitude. Low flying thrushes promptly reacted to the shifting of the leading line of the spit with an average angular velocity of more than 0.8°/s perpendicular to the direction of flight and compensated completely for drift. Shifting of the leading line with an angular velocity of less than 0.4°/s, the high flying birds did not seem to notice or did not try to compensate for displacement deliberately.

中文翻译：

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夜间迁徙的松鸫的风漂移补偿与海拔和风的关系

在秋季迁徙期间研究了与侧风速度和高度相关的风漂移补偿在松画眉中。记录了这些鸟类在夜间飞行在海洋唾液的突出引导线上方的记录，该引导线与它们的总体迁徙方向一致。在大型雀形目物种中，松鸫是根据秋季特定时期特有的五种飞行特征的组合来识别的。画眉对侧风表现出不同的反应：完全和部分补偿位移和漂移。在正常能见度下，补偿的完整性取决于侧风的速度和高度。无论风如何，所达到的补偿程度随着高度的增加而降低。在相同的风力条件下，漂移角（轨道方向与引导线之间的夹角）随高度增加而增加，但补偿漂移的鸟类数量减少。平均而言，在海拔 300 米以下的高度，画眉能够完全补偿中等风；300 至 600 m agl 补偿是部分的；但在 600 米以上，鸟儿完全漂流了。在同一地形上空飞行的同一物种的鸟类可能会根据海拔高度对同一侧风表现出不同的反应。同时，随着高度的增加，飞行轨迹逐渐偏离引导线，鸟类的航向越来越接近总的迁徙方向。鸟类更有可能使用视觉流量调节原理通过其下方地标相对于其飞行方向跑到一边的角速度来控制位移，该角速度与高度成反比。低飞鸬鹚在垂直于飞行方向的平均角速度超过 0.8°/s 的情况下，迅速对吐出前线的移动做出反应，并完全补偿了漂移。以小于0.4°/s的角速度移动前导线，高飞的鸟类似乎没有注意到或没有刻意补偿位移。8°/s 垂直于飞行方向并完全补偿漂移。以小于0.4°/s的角速度移动前导线，高飞的鸟类似乎没有注意到或没有刻意补偿位移。8°/s 垂直于飞行方向并完全补偿漂移。以小于0.4°/s的角速度移动前导线，高飞的鸟类似乎没有注意到或没有刻意补偿位移。