The physics of how their wings are so quiet is really amazing.
I took an elective in during my bachelor’s degree where we studied how fish swim, birds fly, boundary layers of tree leaves, etc.
As part of it, we learned that owl feathers have microscopic hooks that are micro vortex generators. This causes a sound dampening during flight because there is next to no wingtip vortex (the main component of sound generation).
Thanks for sharing the video.