Why do *thousands* of birds flock together and fly in loops and swirls?

This was a traffic stopper on the freeway. The flocks looked like someone waving a smokey veil through the sky, parts tearing off and then joinging back together. It went on for a long time and was quite dramatic. What are the birds and why do they do it? Location was Sunol Grade in SF Bay Area.

Why do *thousands* of birds flock together and fly in loops and swirls?
Birds (mostly starlings around here) eat the fermented pyracantha berries that grow along the freeways this time of year in california and become intoxicated. Birds do the same thing in Grape growing regions at this particular time of the year as the berries that are not picked become fermented on the vine. Their patterns are very hypnotic and interesting to watch. As funny as this my sound the birds get %26quot;hung over%26quot; after the big fly-by dance-party and find a place to sleep it off the next day. I have walked up to these hung over starlings and picked them up while they are inebriated. Some people (me) have mistaken their patterns for UFO%26#039;s. Don;t get into an accident watching them......
Reply:Because it%26#039;s beautiful and God wants us to see beauty.
Reply:They were probably swallows either migrating, searching for a new nesting spot, or had their habitat disturbed! Birds tend to stay in flocks to give them safety in numbers, more food producing, and tend to need a leader. Have you ever seen a flock of geese in the shape of a V? They take that form because of %26quot;rank%26quot;, there%26#039;s a head bird that leads the flock to safety, protection, and nourishment!
Reply:s
Reply:1.) Because it%26#039;s fun.


2.) Because they can.



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