In 1969, a professor of biology at Cornell University noticed a strange feature: generally well-versed in the area of domestic pigeons suddenly lost their ability. At the same time they began to wander in one particular place called Jersey Hill in Boston.

This question concerned local geologist John Hagstruma. Only many years later, he managed to solve the puzzle. As it turned out, the thing is, not far from Jersey Hill flew French supersonic aircraft "Concord" that his pigeons crash knocked out of the way.

Further studies have shown that birds navigate by the sounds of very low frequency (about 1 Hz). And if certain factors, such as aircraft, navigation pigeons straying. "If the low-frequency sounds are somehow connected with the topography of the Earth, the blue is obviously fancy card on which they have to navigate" — said Hagstrum.

Scientists conducted an experiment — on his computer, he created a model of the propagation of sound waves low around Cornell University. The result was a kind of network in which the pigeons could navigate, next to the institution for 14 years, is home to about 45 thousand pigeons. Jon Hagstrum noticed that pigeons changed their route depending on wind direction, carries with it a flow of low-frequency waves. Thus, to find a secret Hagstrum pigeon navigation.