Midnight Flying Birds or UFO?

April 18, 2012 around Midnight. I saw something flying in the midnight sky. Could be an UFO, whose knows. May be a flock of birds; it almost looked like a flying wing at one moment. Absolutely no wind blowing: dead calm. And I didn’t hear any sounds of birds or jet noise. Whatever it was made a wide, sweeping turn coming from the south then going east or northeast at a quick pace. This is second night I seen this occur.