I think these might be poisonous to chickens...? I surely don't want your cure to cause another problem! Although chickens have a pretty good innate knowledge of what they should/shouldn't eat.
My chicks moved outside at 6 weeks. There was an iris leaf near enough to peck. One bird pecked it...
Gee willy wonkers, what an a-hole. Can you get together with any of your other neighbors to combat this? If he moved in, geez-o-friday, didn't he know what he was getting into?!?
So sorry to hear about your situation. I am definitely NOT taking your neighbor's side, but is his complaint stemming from a certain aspect of your having chickens, or just complaining? If it's the former (noise? smell?), is there anything you can do about it? Not to appease him, but to show...