Many persons concluded that the unknowns must be interplanetary in origin because, as _Life_ magazine commented, no natural object hurtling at such a speed could execute a right-angled turn, and no known machine could fly so fast without making a sound or leaving a trail. No one could quarrel with this statement, but it has no obvious relation to the incident in question. Technical writers are not necessarily trained observers, and these witnesses had no way to make a reliable estimate of the height of the objects. Without an accurate estimate of at least one quantity--true altitude, true size, or true speed--the others are meaningless. The unknowns were probably birds, but they could equally well have been butterflies, bits of paper, or merely ashes blowing over the two-story building. Winged creatures sometimes avoid the interplanetary label only by staying in sight long enough to be examined. About sundown on May 19, 1955, switchboards at police stations in the Los Angeles area were swamped by telephone calls reporting a fleet of silvery flying saucers, changing formation with incredible speeds “as if playing tag in the sky.” One witness, however, had the presence of mind to get out his binoculars and look at the objects; they were birds with dark wing tips. Thinking they might be geese, he called the State Division of Fish and Game, which identified the “saucers” as a flock of _Pelicanus erythrorhynchos_, an inland species of pelican that float on the prevailing wind currents[VI-12]. Sometimes an observer identifies such objects correctly, but later begins to doubt his own judgment. About 7:30 in the evening of August 26, 1956, a man driving along a highway in California noticed a flock of about nine small birds flying northward, dark against the blue sky. In a random group, they moved freely among themselves as birds do but continued in a northern direction. The witness watched the birds as carefully as possible, but the intermittent glimpses possible when a man is driving a car did not allow him to make good estimates of their size or height. Nevertheless, he guessed at their distance and calculated that they covered an arc of 60 degrees in five seconds, which would mean a speed of about 1000 miles an hour. Instead of questioning the accuracy of his estimate, for some reason he doubted his first identification. If the objects could fly 1000 miles an hour, he reasoned, then they were not birds after all, and must be flying saucers![VI-13] _The Tremonton Movies_ One of the most famous controversies resulting from a flight of birds centered on the Tremonton, Utah, films of UFOs.