Wednesday, April 14, 2021
Migratory birds make good use of the vortex of air currents (wing tip vortex) when traveling long distances, and fly in a V-shape to save energy.
Migratory birds are nimbly flying away across the blue sky with white clouds in the sky!
![渡り鳥たちのv字飛行](https://portal.hokuryu.info/wp/wp-content/themes/the-thor/img/dummy.gif)
◇ noboru & ikuko