A couple things about your post.
So are you really looking for a solution or is this just tit for tat?
Seems strange to be so mad about him killing stuff that you'd turn around and kill the chickens.
He's not protecting his birds in the way I want him to so I'll show him he is doing it wrong by killing them.
Honestly I can't wrap my head around this.
Build a fence is the solution. It may not be your obligation to do so but you were already gonna give him fencing. Put it up on you all's property line and be done with it but doesn't seem like you're really looking for a solution but just want to be mad and spiteful.
So are you really looking for a solution or is this just tit for tat?
If you really don't mind the chickens why make it a big deal just because you don't like his wildlife control method?I wouldn't care about his chickens coming over EXCEPT he has traps set 24/7 by a wildlife control person to catch raccoons, foxes, possums, skunks, etc which are then killed.
I also don't get this part. You are so upset and furious about him killing predatory wildlife that you're willing to kill his chickens? That seems harsh and worse then what he is doing. Seems you dislike him so you're gonna take it out on these chickens.I am seriously to the point of contemplating shooting his chickens when they come on property.
Seems strange to be so mad about him killing stuff that you'd turn around and kill the chickens.
He's not protecting his birds in the way I want him to so I'll show him he is doing it wrong by killing them.
Honestly I can't wrap my head around this.
Build a fence is the solution. It may not be your obligation to do so but you were already gonna give him fencing. Put it up on you all's property line and be done with it but doesn't seem like you're really looking for a solution but just want to be mad and spiteful.