I found a patch of guinea feathers yesterday while walking, this is right beside the house. I still have 5, so I’m no closer to solving the mystery. I also found two striped feathers that look older and at first I thought they were hanks, but now I think they might be barred owl. The call sounds like the one I hear at night. The two sites are probably unrelated, but I thought it was interesting.
https://www.fws.gov/lab/featheratlas/idresults.php
https://www.fws.gov/lab/featheratlas/idresults.php