HI Vee - I know the sound you are referring to very well. I spent a week one spring, assuming someone was playing tricks on me. Someone would bang on the back of the house, and be gone by the time I got to the back door. Finally, one day, I put on my shoes and ran around to the back of the house... there are fields behind my house, they couldn't get out of sight before I caught them. Nobody there. As I walked back I looked up. There were 6 flickers in a row, going after something in the wood of the house! Flickers are pretty big.. and stubborn. I tried yelling at them, throwing stones... nothing stopped them, until they got whatever they were after. They've never been back, except at the bird feeder, thank goodness! Kathy