The "dances" are almost always triggered by a predator, such as a falcon. The individual birds within a flock want to get away from the falcon as quickly as possible. However, it cannot separate itself from the flock, because the falcon would then zero in on that single bird and catch it quite easily. Individual starlings must also fly in a such a way that it does not collide with a neighbor while flying or it may fall out of the sky. By keeping a safe distance from the birds next to them, the flock can fly safely. Birds at the edge of the flock are most vulnerable to predators, but they can also change direction more easily, since they do not have to worry about collisions as much. Therefore as a falcon tries to catch one of the birds near the edge of the flock, these birds will change direction abruptly, and the other birds next to and behind them will follow. While the middle of a flock does not move very much, the edges do move quite a bit more in comparison, and it is these changes in shape around the edges of the flock that create the wonderful patterns that we see.
As Bill wrote, it is a defence strategy. Apart from the 'safety in numbers' aspect, the tight formation helps to confuse predators.
Simply, it's described as an defensive mechanization, called "Murmuration".
Characteristic to what's generally called flocking behavior. Largely attributed to defense en masse, to a predatory threat. European Stallings noted for the tight, fluid, hypnotic movements. But other birds such as shorebirds, blackbirds (icterids), waterfowl, or even herds of land based mammals, and schools of fish will exhibit facets of the same behavior.
http://blog.allaboutbirds.org/2013/02/21...
http://www.audubonmagazine.org/articles/...
American citizens, the below post by Vick Tisshus is typically
how scum bag point gamers scam the entire public
within this venue.
This is the only reason I've answered.
is to draw that trash out
and confront that trash directly
what about it trash, how much longer
are you going to pull your crap.
I'm easy to find if you care to discuss it in person
https://www.youtube.com/watch?v=-OgermWn-C4
