Naval Research Laboratory, Washington, D.C, 20375, USA.
Sci Rep. 2017 Oct 2;7(1):12551. doi: 10.1038/s41598-017-13035-6.
Two types of periodic and transient motions of large woodpeckers are considered. A drumming woodpecker may be modeled as a harmonic oscillator with a periodic forcing function. The transient behavior that occurs after the forcing is turned off suggests that the double knocks of Campephilus woodpeckers may be modeled in terms of a harmonic oscillator with an impulsive forcing, and this hypothesis is consistent with audio and video recordings. Wingbeats are another type of periodic and transient motion of large woodpeckers. A model for the flap rate in cruising flight is applied to the Pileated Woodpecker (Dryocopus pileatus) and the Ivory-billed Woodpecker (Campephilus principalis). During a brief transient just after taking off, the wing motion and flap rate of a large woodpecker may not be the same as in cruising flight. These concepts are relevant to videos that contain evidence for the persistence of the Ivory-billed Woodpecker.
考虑了两种大型啄木鸟的周期性和瞬态运动。啄木可能被建模为具有周期性外力的谐振子。外力关闭后发生的瞬态行为表明，双啄木可能可以用具有脉冲力的谐振子来建模，并且该假设与音频和视频记录一致。翅膀拍打是大型啄木鸟的另一种周期性和瞬态运动。在巡航飞行中，振翅频率模型适用于大斑啄木鸟（Dryocopus pileatus）和象牙喙啄木鸟（Campephilus principalis）。在起飞后的短暂瞬态期间，大型啄木鸟的翅膀运动和振翅频率可能与巡航飞行时不同。这些概念与包含象牙喙啄木鸟持续存在证据的视频相关。
