Recently I had a United flight from Dulles, VA to San Francisco, CA and the boarding started on time and when half of the first part of boarding group 1 had walked into the airplane, the entire boarding stopped abruptly. All the crew ran away from their boarding control terminal and into the air gate. After about 15 minutes one United lady came out and said the flight will be delayed due to a bird flying around in the airplane. This is the only time I have ever heard United passenger laugh loud when the flight delay was announced. about 30 minutes delayed, the flight was off to San Francisco.