Salt pork, bacon, beef or pork suet, or peanut butter, but the meat is the best. You want them to go for that meat rather than your chickens. Fatty, greasy meat is nice and smelly.
You want it to be irresistible to them.
That way even if they are a little bit leery, they won't be able to resist. Weasels and rats are very hard to trap, dead or alive, so make the bait something unbelievable, something much better than chicken. I just thought also, if it's a skunk, you might want to put a piece of raw liver or some gizzards in there. I'd just make sure it was loaded for bear
(no pun intended) not that you're trying for a bear. Sorry about the sick humor. I sure hope you get it, whatever it is. You are living my nightmare, and I am so afraid that something is going to happen to mine one night. I think I've done everything I can do to make them safe, but I particularly don't trust raccoons. I think they are capable of anything once they decide they want something.