蜂鳥可謂鳥類家族中的雜技演員——它們每秒鐘至少拍打翅膀45次,，并且能夠盤旋著前進、后退,，甚至倒置,。然而,，蜂鳥的空中行動非常消耗能量，因此它們每天至少要大吃大喝一次花蜜,，即便在惡劣的天氣中也是如此,，否則這種小鳥便會死去。
那么當一場暴風雨來臨之際,，在它們被重量達到自身體重35%的雨滴狠狠敲打時,，這些蜂鳥究竟是如何過活的呢？根據日前在線發(fā)表于英國《皇家學會學報B》（Proceedings of the Royal Society B: Biological Sciences）上的一項研究,，它們干得很出色,。
科學家之前在今年夏季的早些時候也曾對蚊子進行過類似的試驗。在這項研究中,，美國加利福尼亞大學伯克利分校的動物學家Victor Manuel Ortega-Jimenez和Robert Dudley將5只雄性安娜蜂鳥（Calypte anna）在實驗室中置于小雨,、中雨和大雨的環(huán)境中，并利用高速錄像機分析了它們的飛行響應,。
研究人員發(fā)現,，這些小鳥幾乎沒有受到小雨和中雨的影響，但它們在大雨中不得不采取一種完全不同的姿勢以確保對飛行的控制,，蜂鳥會水平地轉移自己的身體和尾巴,，并更迅速地拍打翅膀，同時減少翅膀運動的角度,。
研究人員發(fā)現,，蜂鳥位置的變化最初是似是而非的，這是因為每只蜂鳥都會更多地將它們的背部暴露在正在到來的雨水中,。
然而,，更進一步的研究顯示，這種姿勢或許減少了雨滴擊中蜂鳥翅膀的總量,，從而使其能夠更加穩(wěn)定地停留在空中,。
研究人員同時發(fā)現，蜂鳥抗水的羽毛吸收了傾盆大雨帶來的50%的沖擊,，從而幫助它們在飛行中保持輕盈,，并且無論在何種天氣情況下都能夠掌控身體。
蜂鳥是雨燕目蜂鳥科約600種動物的統(tǒng)稱,，是世界上已知最小的鳥類,。蜂鳥因拍打翅膀的嗡嗡聲而得名。蜂鳥是唯一可以向后飛行的鳥,。蜂鳥也可以在空中懸停以及向左和向右飛,。（生物谷Bioon.com）
doi:10.1098/rspb.2012.1285
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PMID:
Flying in the rain: hovering performance of Anna's hummingbirds under varied precipitation
Victor Manuel Ortega-Jimenez1,* and Robert Dudley1,2
Flight in rain represents a greater challenge for smaller animals because the relative effects of water loading and drop impact are greater at reduced scales given the increased ratios of surface area to mass. Nevertheless, it is well known that small volant taxa such as hummingbirds can continue foraging even in extreme precipitation. Here, we evaluated the effect of four rain intensities (i.e. zero, light, moderate and heavy) on the hovering performance of Anna's hummingbirds (Calypte anna) under laboratory conditions. Light-to-moderate rain had only a marginal effect on flight kinematics; wingbeat frequency of individuals in moderate rain was reduced by 7 per cent relative to control conditions. By contrast, birds hovering in heavy rain adopted more horizontal body and tail positions, and also increased wingbeat frequency substantially, while reducing stroke amplitude when compared with control conditions. The ratio between peak forces produced by single drops on a wing and on a solid surface suggests that feathers can absorb associated impact forces by up to approximately 50 per cent. Remarkably, hummingbirds hovered well even under heavy precipitation (i.e. 270 mm h?1) with no apparent loss of control, although mechanical power output assuming perfect and zero storage of elastic energy was estimated to be about 9 and 57 per cent higher, respectively, compared with normal hovering.
