B.U. Bridge is published by the Boston University Office of University Relations.

Contact Us

Staff

Ask the Bridge

Now that spring is here, I've noticed large flocks of birds darting to and fro in the sky. But I've never witnessed a midair avian collision. Why do all the birds in the flock know when and in which direction to turn?

First, the adage birds of a feather flock together has less to do with the desire for avian socialization and more about increasing chances of survival. "The reason for such flocking behavior," explains Fred Wasserman, CAS associate professor of biology, "is to avoid predation. The more numbers in the group, the less chance there is of getting picked off."
As to the exquisite choreography in the sky, Wasserman says, "Birds have tremendously good visual capabilities. Too, they can sense even the smallest changes in air pressure, which enables them to avoid midair collisions in flying-flock formations. In the same way, he adds, "fish that travel in schools are able to acutely sense changes in water pressure," which enables them to avoid undersea collisions.

6 April 2001
Boston University
Office of University Relations