鴿子的飛行方式與直升機(jī)類似（圖片來源：Ivo Ros）
生活在城市中的鴿子或許被嘲笑為就像只會飛的老鼠，然而在空中,，它們更像是直升飛機(jī),。這項(xiàng)關(guān)于鴿子在空中如何轉(zhuǎn)向的新研究的重要結(jié)果發(fā)表在11月28日出版的美國《國家科學(xué)院院刊》上。
美國哈佛大學(xué)康克德野外臺站的鳥類學(xué)家Ivo G. Ros和同事在一座室內(nèi)停車場用網(wǎng)圍住了一些常見的鴿子（Columba livia）,，并在它們于一個角落緩慢轉(zhuǎn)向時用高速攝像機(jī)對其進(jìn)行了拍攝,。
根據(jù)這些錄像，研究人員隨后計(jì)算了由鳥類所產(chǎn)生的保持它們在空中停留并運(yùn)動的氣動力,。
與一枚火箭簡單地旋轉(zhuǎn)其噴氣機(jī)不同,，一只鴿子并不會通過改變其所產(chǎn)生的力量相對于身體的方向來轉(zhuǎn)向。
而事實(shí)上,，這種飛鳥會通過旋轉(zhuǎn)整個身體,，主要是傾斜翅膀轉(zhuǎn)向來調(diào)整它們的力量。
而一架直升飛機(jī)也會采用相同的傾斜策略,，以降低它的噪音并加速前進(jìn),。
這項(xiàng)研究同時發(fā)現(xiàn)，轉(zhuǎn)向的鴿子向上所產(chǎn)生的升力居然可以媲美超級高空雜技演員蜂鳥所產(chǎn)生的升力——這對于鳥類世界的笑柄來說還不賴,。
doi:10.1073/pnas.1107519108
PMC:
PMID:
Pigeons steer like helicopters and generate down- and upstroke lift during low speed turns
Ivo G. Rosa,1, Lori C. Bassmanb, Marc A. Badgerb, Alyssa N. Piersonb, and Andrew A. Biewenera
Turning is crucial for animals, particularly during predator–prey interactions and to avoid obstacles. For flying animals, turning consists of changes in (i) flight trajectory, or path of travel, and (ii) body orientation, or 3D angular position. Changes in flight trajectory can only be achieved by modulating aerodynamic forces relative to gravity. How birds coordinate aerodynamic force production relative to changes in body orientation during turns is key to understanding the control strategies used in avian maneuvering flight. We hypothesized that pigeons produce aerodynamic forces in a uniform direction relative to their bodies, requiring changes in body orientation to redirect those forces to turn. Using detailed 3D kinematics and body mass distributions, we examined net aerodynamic forces and body orientations in slowly flying pigeons (Columba livia) executing level 90° turns. The net aerodynamic force averaged over the downstroke was maintained in a fixed direction relative to the body throughout the turn, even though the body orientation of the birds varied substantially. Early in the turn, changes in body orientation primarily redirected the downstroke aerodynamic force, affecting the bird’s flight trajectory. Subsequently, the pigeon mainly reacquired the body orientation used in forward flight without affecting its flight trajectory. Surprisingly, the pigeon’s upstroke generated aerodynamic forces that were approximately 50% of those generated during the downstroke, nearly matching the relative upstroke forces produced by hummingbirds. Thus, pigeons achieve low speed turns much like helicopters, by using whole-body rotations to alter the direction of aerodynamic force production to change their flight trajectory.
