Yes, owls are federally protected. And going on a public forum and advising someone else to break the law is well.........not responsible in my opinion. That being said I would recommend trying some deterrents. Of course you could use a sturdier roofing for your pen. You might also try flagging that waves around in the wind (probably white) and anything else that twirls and/or makes noise that would be disturbing to the owl. You might also spray paint white the wiring atop the pen so it is visible to nocturnal aerial predators. The owl obviously did not see it or it wouldn't have tried this stunt. A plastic owl or hawk mounted on or near your pen may deter the real thing since they are territorial. However, the owl is likely to have been seriously traumatized by this experience and will most likely not come back. Also, owls and other raptors are moving around this time of year and migrating to other areas for winter. Even owls will shift their ranges south from the northern latitudes. This was quite possibly not a resident owl and may simply be moving through your area. He may already be hundreds of miles away.