One day I stayed home to meet the HVAC guy at the house and after I had to get two ladders so I could get my youngest son to climb up and down over a 6' fence into the neighbors back yard to get our Barred Rock I knew I had to do something about this. To top it off my wife spent the afternoon putting the neighbors mulch back in their flower bed. So that night I clipped the offending chickens' feathers. I read all the stuff online and watched the Youtube videos of it. I cut one wing and not the other so they couldn't fly straight or with control.
I got home the next day and there was the neighbor talking to my wife. So I cut a little more of the feathers and the rest of the chickens as well and then fixed my neighbors mulch. The next day was a repeat of the previous day, our neighbor in the front yard talking to my wife. So I cut a little more and fixed my neighbors mulch. This was an off and on thing for a bit. It involved me pulling weeds, putting my neighbors mulch and rocks back in his flower bed multiple times, buying new mulch for my neighbor, and giving him about 3 dozen eggs. It was more of an ordeal than I would have liked.
We have since given the main offenders the Barred Rock, Rhode Island Red, and Australorp to my aunt-in-law. It seems to not be an issue now that we have the chickens back. Hopefully it won't be now that we have reduced our flock size.