Unexplained altitude changes in a migrating thrush: Long-flight altitude data from radio-telemetry
Unexplained altitude changes in a migrating thrush: Long-flight altitude data from radio-telemetry
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DOI：
10.1642/auk-15-33.1
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发表时间：
2015-10-01
期刊：
影响因子：
2.8
通讯作者：
Cochran, James
中科院分区：
文献类型：
--
作者：
Bowlin, Melissa S.;Enstrom, David A.;Cochran, James
描述并解释迁徙过程中的个体行为可以帮助我们理解为什么（在近端和最终层面上）鸟类会迁徙;例如，候鸟飞行的高度可能会产生深远的影响。然而，迄今为止，还没有小型（100克）候鸟的详细的全飞行高度数据。我们跟踪7斯文森的画眉（Catharus ustulatus）携带高度计从起飞，直到着陆或接近着陆在9个迁徙航班。9次飞行的平均记录飞行高度为673.0 +/- 523.2 m（平均值+/- SD）; 9次飞行的平均最大飞行高度为1，199.5 +/- 862.7 m（范围：319.2- 2，744.5 m）。初始上升速率（0.42 x 0.15 m s（-1），n = 8）与预测值相匹配;最终下降速率为0.55 x 0.30 m s（-1）（n = 5）。与预期相反，画眉在飞行期间（1.44小时-1）进行了多次（9.33 x 4.42），显著（>100米）的高度调整，不包括初始上升和最终下降。我们观察到的飞行高度的反复变化应该会导致这些鸟类使用更多的能量，而不是在一个高度或接近一个高度飞行几个小时。我们推测，这些高度的变化可能是由于大气条件的变化，或从鸟类下降到人为光源在飞行过程中。
Describing and then explaining individual behavior during migration can help us to understand why (on both proximate and ultimate levels) birds migrate; the altitude(s) at which migratory birds fly, for example, can have farreaching consequences. However, to date, no fine-scale, full-flight altitude data have been available for small (, 100 g) migratory birds. We tracked 7 Swainson's Thrushes (Catharus ustulatus) carrying altimeters from takeoff until landing or near-landing during 9 migratory flights. The average recorded flight altitude for the 9 flights was 673.0 +/- 523.2 m (mean +/- SD); average maximum flight altitude for the 9 flights was 1,199.5 +/- 862.7 m (range: 319.2-2,744.5 m). Initial ascent rates (0.42 x 0.15 m s(-1), n = 8) matched predictions; final descent rates were 0.55 x 0.30 m s(-1) (n = 5). Contrary to expectations, the thrushes made numerous (9.33 x 4.42), significant (>100 m) altitude adjustments during their flights (1.44 hr(-1)), not including initial ascent and final descent. The repeated changes in flight altitude that we observed should cause these birds to use more energy than they would if they flew at or near a single altitude for several hours at a time. We speculate that these altitude modifications may result from variation in atmospheric conditions or from the birds descending toward anthropogenic light sources during the flights.