Birds That Fly in a V Formation Use An Amazing Trick

Why do some birds fly in a V?

Most people would say that they do it to save energy, which would be right. But it turns out that birds in a V are actually pulling of a feat that’s more complicated and more impressive than anyone had imagined.

Here is the standard explanation for the V-formation:
As a bird flaps, a rotating vortex of air rolls off each of its wingtips. These vortices mean that the air immediately behind the bird gets constantly pushed downwards (downwash), and the air behind it and off to the sides gets pushed upwards (upwash). (See this image if that’s not clear.) If another bird flies in either of these upwash zones, it gets free lift. It can save energy by mooching off the air flow created by its flock-mate.

This all makes sense, but it represents decades of largely theoretical work. Scientists calculated how air should flow around a flying bird based on what we know about planes, but almost no one had taken any  actual measurements. Henri Weimerskirch changed that in 2001, when he fitted pelicans with heart-rate monitors. He found that birds at the back of the V had slower heart rates than those in the front, and flapped less often.

It was an interesting study, which confirmed that birds benefit from flying in a V. But it didn’t address why or how they do so. That’s what Steven Portugal wanted to know.

Lees meer:  Not exactly rocket science