Quackcrazy...... As much as I too would be tempted to drop these jerks with a hot-wire, you could find yourself being arrested for assault, or worse if one dropped dead.... especially if the LEO's were to determine that your wire was set for humans. I know, it's not fair, blah, blah, blah. You could also be subject to a lawsuit.... I know, that's also not fair either, but it is a risk you have in todays world, though not likely.
You know your world, but if it were me, there would be three choices. After posting "No Trespassing" signs in conspicuous places, I would either hide out and catch them in the act.... but you better now what you're doing and how to handle such a confrontation, especially if they are dopers or already wanted for previous crimes. Second, simply walk over to the barn and confront them. I can be extremely intimidating, so they would likely move on.
OR, arguably the best course of action, depending on the caliber of your local Law Enforcement agency... call the cops TODAY and report it, and demand that they take action to get them out of the neighborhood. If the jerks are trespassing at the time of your call, report this as a "trespass in progress" by multiple persons, and that you are frightened. This is truthful and should light a fire under their response. You see, it sounds as if the jerks are already trespassing, so if they are there when the LEO's show up, they can be arrested for criminal trespass and depending on your laws, possibly burglary.. a felony in most places.
When you talk to the cops, tell them that while you are concerned about the theft of your chickens, that you are concerned for the well being and safety of yourself and family members. Tell them that you want them to deal with it, so that in defense of your life, you won't be forced to take care of the problem yourself. If the deputy shines you on, be nice, but demand to speak with his supervisor, if he/she fails to resolve this, be nice, but keep going up the chain. If you get all the way to the top, and the Sheriff fails to deal with this, let him know that as much as you had not wanted to that you will talk to a lawyer about bringing a lawsuit against the county, the agency and him personally. If he still fails to resolve this, then and only then call the media and tell them what's been going on.....
Disclaimer: I am not a lawyer, none of this has been legal advice. I am a retired (thank all that is good and holy.. lol) Detective Sergeant for a Sheriff's department with 30 years of service. I retired 8 years ago, so the laws might have changed such that you are now authorized to shoot them and burying them out behind the barn... but I would check. LOL
Good luck.