Other people have said it, but rat snakes are not venomous, and they are safe to handle. even if they bite, just keep it clean to prevent infection, thats all. It might hurt, but it wont kill you. Snakes are like ALL muscle and can be hard to pull out of a hiding place once they get themselves in. And you're a giant scary creature that, for all it knows, might be trying to kill and eat it, so of course it's going to make a show of trying to make itself seem dangerous. But it isnt, not to you at least. Best thing to do if you want it gone is get it over with and pull it out and release or cull it, but it will hunt and eat any rodents that make their way into the area which imo can do a lot more damage to eggs/very young chicks than a rat snake will do to grown chickens. HOWEVER, there is a chance that the snake might have a taste for chicken eggs, depending on species