High pitched squeak at night?

by mjs
(seminole, FL)

The bird comes to the yard every night and sits in the trees up high it emitts a high pitch squeak (chirp) almost like and baby rodent, with no pattern. Chirp.....chirp....chirp.... with 2-4 second pauses between each single chirp. When we try to illuminate the bird with a light it ducks it's head and runs up the branches of the tree VERY quickly. If it moves to another tree it flys very quickley. Best we can tell it is ligth brown in color. We are in west central Florida.