Even the bird-brained can follow a leader. When pigeons fly in flocks, each bird falls behind another with better navigational skill, and the savviest among them leads the flock, scientists report in the April 8 Nature.

The research suggests hierarchies can serve peaceful purposes in the animal kingdom, where dominance by brute force is often the rule. "A pecking order tends to be just that — a pecking order," says Iain Couzin of Princeton University, a...