This audio story is brought to you by BirdNote, a partner of The 约炮视频. BirdNote episodes air daily on public radio stations nationwide. 5765 Transcript: This is BirdNote. During a rainstorm, you’re more likely to see birds perched and hunkered down than flying around. Most birds are mostly waterproof. Their feathers, combined with oil from preen glands, keep them pretty watertight. So why do birds avoid flying during rainstorms? It’s not just about getting wet. It may have more to do with the air than with the water. Storms alter the medium in which flight takes place: the air itself. Rainstorms tend to occur when atmospheric pressure is low. Air in a low-pressure system is less dense. But it’s dense air that gives birds the aerodynamic lift they need to take wing. Falling rain and high humidity also add lots of water molecules to the air. That water takes up space in the air, making it even less dense. So rather than fly, many birds...