From Russel Wiitala:
"18 August 2014, at approximately 2:25 a.m. in western Washington. I've been hearing this clan and maybe another for several weeks in this area. I finally purchased a Sony ICD-PX 312. This was the first time I used it. I believe this is a juvenile male having fun. He woke me up so that I wouldn't miss his impressive call. A few seconds after the call you can hear, who I think is his younger brother stationed to the northeast, knock in reply to the call.
Very intriguing. I have NEVER hear ANY animals like that in the North American woods. Whatever that animal was, it was LARGE. To read more and view the video, click here.