In ft. lauderdale, Fl I have been haunted by a strange, raspy "coo" noise at night, can anyone identify?

This only seems to happen during the warmer months, and follows me without being seen or heard other than the noise described above. For example, I'll hear it coming from a palm tree, then suddenly it will be inches above my head (the first time it did this I literally ducked, because it seemed to be INCHES from the top of my head.) I can't think of any better way to describe the noise, other than a raspy, dropping coo-type noise.