Barred owls are deadly enemies of purple martins and frequently raided martin colonies around the Tallahassee, Florida area where I previously lived. This photo shows the power of a barred owl which pulled off the flip up door panels on the Trio castle when he predated the martins. He even carried several of the doors off with him! This castle was once nearly fully occupied by martins until barred owls discovered the easy food source. The owls completely destroyed the colony. These type of houses with shallow compartments and no outside guards are extremely vulnerable to large owl attacks.
Steve
