Bay Nature magazineApril-June 2010

Ask the Naturalist

Why Do Birds Flock?

April 1, 2010

Q: I recently saw a video of a cloud of birds moving in wild patterns. Then I saw shorebirds doing the same thing. Why do birds do this–other than because they can? [Michael, El Cerrito]

A: There are several kinds of bird flocks–huge numbers of geese taking off and landing, V-shaped formations of pelicans, mass surface movements of shearwaters. But you likely witnessed the dynamic and coordinated movement of a huge disk-shaped cluster of birds such as starlings, shorebirds, or pigeons.

Early researchers assumed each group had a leader. But video of flocks makes it clear there is no top bird. The flock is apparently acting as a superorganism.

So what is the advantage of flocking? The most obvious motivation is to avoid predators. A falcon may have problems concentrating on a single bird in a chaotic flock, or it may be reluctant to plunge into a huge group of birds. (Watch a video of starlings evading a falcon.)

In the 1980s researchers used computer modeling and chaos theory to derive some simple flocking rules: Birds are attracted to each other unless they are too close. Birds head in the direction of their neighbors and toward the group’s general position. A wind gust or a predator’s approach can alter the group’s course. And a single bird’s movement can quickly propagate through the group.

There are many ways to enjoy the world around us. We can use computers to tease out rules of behavior, but we can also simply enjoy the beauty in the patterns of life that whirl around us. I have watched many kinds of birds, even pigeons, wheeling in glorious formations and just felt plain lucky to be alive.

About the Author

Send your questions to Rosa-based naturalist Michael Ellis leads nature trips throughout the world with Footloose Forays (

Read This Next

The Hills Have Ears

The Comeback Quail

All Vaxxed Up and Ready to Roost, Six Captive-Born Condors Fly Free

Where to Watch Birds Migrate in the North Bay This Fall