Owls are known to have excellent night vision and they completely make use of it to seize their prey.
Nevertheless, what was unknown was the mechanism behind them being such great hunters. Now a new study has brought forth the refined ‘stealth techniques,’ which owls are fortified with. They silently pounce on preys without the latter’s knowledge.
It has long been a question mark for researchers about these creatures flapping their wings so rapidly to descend in the air, and yet not produce any audible sound for its preys, which are fast-moving rodents, generally, giving them no scope even for any alert during the night.
For the research, the scientists utilized the feathers of two kinds of birds – a pigeon and a golden eagle, along with an owl with long ears. Feigning wing-beats, they calculated the vibrations and discovered that the feathers of these birds consumed the energy of wing vibrations and transformed it to heat.
However, owls did it much more proficiently than other birds. In fact, the research team could duplicate the owl’s noise-decreasing capability to the thrum of onshore wind turbines that shows the same mechanism, informed Jinkui Chu who is the professor of Dalian University, China and the lead researcher of the study.
This capability of the owls triggered the scientists to term them as the “king of acoustic stealth”.
Producing the proper thrust that would suffice for a bird to rise high engages a good amount of force and disrupts a lot of air. Nonetheless, majority of the owl species accomplish to do it at below 2 kHz frequencies, which is nowhere near their prey’s audible range.
Being stunned to notice that an owl’s flying capability is a lot higher than their expectation, Chu further said that besides subduing aerodynamic noise when soaring high, owls subdue mechanical noise as well that are triggered by wing vibrations at the time of flying. “This is remarkable, considering the noise that creates for other birds,” he added.
This study has been published in the Institution of Civil Engineer’s journal “Bioinspired, Biomimetic and Nanobiomaterials”.
In November 2013 a similar study was conducted by scientists from Lehigh University in the United States. Justin Jaworski who is the assistant professor of the university as well as a member of the research team said that owls comprise of three distinguished physical characteristics, which could be the key of their noiseless flying mechanism – a comb of hard feathers by the primary edge of their wing; a supple fringe at the straggling edge of their wing; and a soft, silky material spread on the upper side of their wing.
Although, their report informed that their work foresaw the sound that was created as a result of air moving over the downy material and the mechanism behind the aerodynamic noise level varying with fiber composition, it didn’t establish anything.
Apart from this, earlier in June 2015, scientists from the University of Cambridge in collaboration with Lehigh, and two other US institutes – Virginia Tech and Florida Atlantic Universities, utilized the “silent flight mechanism” of owls to create a prototype coating for making wind turbine blades. Their goal was to reduce the level of noise made by the turbines while rotating.