In this paper, the passive inertial emergency obstacle avoidance behavior of pigeons is studied and applied to the coordinated flight verification of an unmanned aerial vehicle (UAV) swarm. Pigeons in nature dynamically adjust their routes during flight. When they encounter obstacles, emergency behaviors are generated; i.e., they change the current direction passively, get cross obstacles toward the largest gap between obstacles, and thus complete obstacle avoidance. Prior to the flight verification, the design of the UAV swarm system architecture is explained. Further, two scenarios of static emergency obstacle avoidance on the ground and with moving obstacles in the air are set up. The corresponding timing sequence diagrams and flight path diagrams are also given.