I've been sleeping out for the past couple weeks and have my hammock set in the back of the backyard where there's a line of white pines. I was able to hang it in between two of the trees and that's where I swing in the evening time, listening to the tree frogs as the twilight slips into darkness.
Some of the nighttime sounds are what you'd expect: cats or raccoons. But I was thrilled to wake up in the darkest hours when there weren't any cars or the occasional motorcycle zooming by on the other side of the park and what did I hear but a Great Horned Owl! It was asking if I was there (I'm here, are you?) and got a response from another, farther off individual. Whoo knew?