Watch Clip
![](http://image.pbs.org/video-assets/pbs/supernature-wild-flyers/227311/images/mezzanine_225.jpg?resize=410x)
Inside a Giant Flock
2m 53s
/ TV-PG
A flock is one of the most spectacular sights in nature – but how does it work? The explanation comes down to some surprisingly simple rules that each bird applies to its seven closest neighbors.