Listen to part of a lecture in a biology class.

(professor) All right, any questions before we move on? Harry?

(male student) I saw this down at the beach and you know, sometimes hundreds of birds fly together in a large flock, and as they fly, all of these birds twist and turn and seem to move at the exact same time. It looks like the flock is one giant organism.

(professor) Spectacular, isn\'t it? We call that behavior coordinated group flight, and it takes many forms.

Sometimes it has a basis in aerodynamics. Um, for example, some bird species fly single file, one following the other; other species fly in V-formations. We think this has to do with aerodynamics.

Birds that fly single file create slip streams, you know, areas of decreased air resistance for the individuals behind them. While birds flying in a V-formation, take advantage of the rising currents of air from the wing tips of their neighbors.

(male student) But not all birds fly in a V-formation or in single file?

(professor) Right! Like the birds you saw at the beach. That\'s why researchers have traditionally accepted what\'s called the safety hypothesis.

You see with all the twist and turns you observed in their flight pattern. Birds can confuse predators quite a bit. So, predators won\'t attack.

One researcher observed that birds were most likely to be attacked when flying alone or in very small flocks.

Actually, surprisingly, she also found that they were likely to be attacked when in very large flocks.

(female student) When you say large flocks, do you mean like 100?

(professor) I\'m talking flocks with more than 500 birds. When in very large flocks, the birds might actually confuse each other instead of confusing the predator.

Anyway, this still supports the safety theory, because if the flocks contain an optimum number of birds, let\'s say, below 500, but more than just a few, predators are less successful in their attacks.

(female student) So, the safety hypothesis seems to make sense?

(professor) Well, yes. But the safety hypothesis can\'t explain everything.

Take starlings for example, it\'s common to see large flocks of these birds flying around above their roosting sites at night. Often for more than half an hour before landing.

(female student) Wow, that\'s like telling their predators here we are when they could have just landed and been safe.

(professor) Exactly. One proposed explanation for this is that maybe there are what we call bird leaders.

And maybe these other birds are just mindlessly following or imitating the leaders. Not for any particular reason as in the aerodynamic hypothesis, but maybe for no reason at all.

But remember, the birds at the front of the flock at one point, those that might be considered leaders can easily be at the back of the flock at another point.

(male student) So, you\'re saying that there really aren\'t any leaders of any kind?

(professor) Not during coordinated group flight.

(male student) Well, what if maybe birds are just programmed for coordinated group flight? You know, maybe it\'s all instinctual.

(professor) That\'s actually been suggested as a hypothesis. It\'s an interesting one.

Several computer programs have been designed to mimic flocks of flying birds with each individual computerized bird program to follow a few simple behavioral rules.

For example, maintaining enough distance to avoid colliding with other birds and attempting to fly the same speed in the direction of other birds.

And the results, well, one of these computer programs produce something so close to actual coordinated group flight. It was used in a Hollywood movie to create digital flocks.

But keep in mind that just because these computer simulations look like coordinated group flight, we can\'t say that real birds follow the rules that computerized birds do. We can\'t even say whether they follow any rules for sure.

Anyway, research continues. And what\'s so exciting is that we\'ve now got people from different fields, not just biology, studying coordinated group flight.

This is important because it\'s such a complex phenomenon that we need researchers with different kinds of expertise to approach things from different angles.

Um. For example, a group of physicists have been looking at bird flight as a statistical problem. Using special equipment, they filmed starlings in Rome and then statistically analyzed each bird\'s movements.

They found that when a bird changes direction, that affects the 6 or 7 birds closest to it, these 6 or 7 birds change direction, which affects more birds and so on.