video transcript

It's been 20 years since migrant starlings have been spotted soaring through Israel's skies. And onlookers who watched the mysterious creatures form dark-clouded shapes enjoyed the rare sighting. The behavior is called murmuration and Tel Aviv University professor Yossi Leshem says there's two reasons why the species stick together. SOUNDBITE: Yossi Leshem, Director of the International Center for the Study of Bird Migration, Tel Aviv University, saying (English): "Because one is to get the information where they have food and they will follow the ones who found the food. The second one is if a hawk is coming to catch one of the starlings, if it is by itself it has a problem, but if they are a big flock they can open and close and move dramatically and then the hawk cannot catch them." The common starling would fly in flocks of millions from Israel to Russia and other parts of Eastern Europe. But in the early 1990's they disappeared from the skies, baffling scientists. Mysteriously the birds began appearing again in 2012, seen for the first time above the Sea of Galilee. Experts say they're best to watch at dusk, when the birds flock together for some 20 minutes before retiring for the night.